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Optical depth

In physics, optical depth or optical thickness is the natural logarithm of the ratio of incident to transmitted radiant power through a material. Thus, the larger the optical depth, the smaller the amount of transmitted radiant power through the material. Spectral optical depth or spectral optical thickness is the natural logarithm of the ratio of incident to transmitted spectral radiant power through a material. Optical depth is dimensionless, and in particular is not a length, though it is a monotonically increasing function of optical path length, and approaches zero as the path length approaches zero. The use of the term "optical density" for optical depth is discouraged.

In chemistry, a closely related quantity called "absorbance" or "decadic absorbance" is used instead of optical depth: the common logarithm of the ratio of incident to transmitted radiant power through a material. It is the optical depth divided by $log_{e}(10)$, because of the different logarithm bases used.

Optical depth
Optical depth of a material, denoted $\tau$, is given by: $$\tau = \ln\!\left(\frac{\Phi_\mathrm{e}^\mathrm{i}}{\Phi_\mathrm{e}^\mathrm{t}}\right) = -\ln T$$where
 * $\Phi_\mathrm{e}^\mathrm{i}$ is the radiant flux received by that material;
 * $\Phi_\mathrm{e}^\mathrm{t}$ is the radiant flux transmitted by that material;
 * $T$ is the transmittance of that material.

The absorbance $A$ is related to optical depth by:$$\tau = A \ln{10}$$

Spectral optical depth
Spectral optical depth in frequency and spectral optical depth in wavelength of a material, denoted $$\tau_\nu$$ and $$\tau_\lambda$$ respectively, are given by: $$\tau_\nu = \ln\!\left(\frac{\Phi_{\mathrm{e},\nu}^\mathrm{i}}{\Phi_{\mathrm{e},\nu}^\mathrm{t}}\right) = -\ln T_\nu$$$$\tau_\lambda = \ln\!\left(\frac{\Phi_{\mathrm{e},\lambda}^\mathrm{i}}{\Phi_{\mathrm{e},\lambda}^\mathrm{t}}\right) = -\ln T_\lambda,$$ where
 * $$\Phi_{\mathrm{e},\nu}^\mathrm{t}$$ is the spectral radiant flux in frequency transmitted by that material;
 * $$\Phi_{\mathrm{e},\nu}^\mathrm{i}$$ is the spectral radiant flux in frequency received by that material;
 * $$T_\nu$$ is the spectral transmittance in frequency of that material;
 * $$\Phi_{\mathrm{e},\lambda}^\mathrm{t}$$ is the spectral radiant flux in wavelength transmitted by that material;
 * $$\Phi_{\mathrm{e},\lambda}^\mathrm{i}$$ is the spectral radiant flux in wavelength received by that material;
 * $$T_\lambda$$ is the spectral transmittance in wavelength of that material.

Spectral absorbance is related to spectral optical depth by: $$\tau_\nu = A_\nu \ln 10,$$$$\tau_\lambda =A_\lambda \ln 10,$$ where
 * $$A_\nu$$ is the spectral absorbance in frequency;
 * $$A_\lambda$$ is the spectral absorbance in wavelength.

Attenuation
Optical depth measures the attenuation of the transmitted radiant power in a material. Attenuation can be caused by absorption, but also reflection, scattering, and other physical processes. Optical depth of a material is approximately equal to its attenuation when both the absorbance is much less than 1 and the emittance of that material (not to be confused with radiant exitance or emissivity) is much less than the optical depth: $$\Phi_\mathrm{e}^\mathrm{t} + \Phi_\mathrm{e}^\mathrm{att} = \Phi_\mathrm{e}^\mathrm{i} + \Phi_\mathrm{e}^\mathrm{e},$$$$T + ATT = 1 + E,$$ where and according to the Beer–Lambert law, $$T = e^{-\tau},$$so:$$ATT = 1 - e^{-\tau} + E \approx \tau + E \approx \tau,\quad \text{if}\ \tau \ll 1\ \text{and}\ E \ll \tau.$$
 * Φet is the radiant power transmitted by that material;
 * Φeatt is the radiant power attenuated by that material;
 * Φei is the radiant power received by that material;
 * Φee is the radiant power emitted by that material;
 * T = Φet/Φei is the transmittance of that material;
 * ATT = Φeatt/Φei is the attenuation of that material;
 * E = Φee/Φei is the emittance of that material,

Attenuation coefficient
Optical depth of a material is also related to its attenuation coefficient by:$$\tau = \int_0^l \alpha(z)\, \mathrm{d}z,$$where and if α(z) is uniform along the path, the attenuation is said to be a linear attenuation and the relation becomes: $$\tau = \alpha l$$
 * l is the thickness of that material through which the light travels;
 * α(z) is the attenuation coefficient or Napierian attenuation coefficient of that material at z,

Sometimes the relation is given using the attenuation cross section of the material, that is its attenuation coefficient divided by its number density:$$\tau = \int_0^l \sigma n(z)\, \mathrm{d}z,$$ where and if $$n$$ is uniform along the path, i.e., $$n(z)\equiv N$$, the relation becomes:$$\tau = \sigma Nl$$
 * σ is the attenuation cross section of that material;
 * n(z) is the number density of that material at z,

Atomic physics
In atomic physics, the spectral optical depth of a cloud of atoms can be calculated from the quantum-mechanical properties of the atoms. It is given by$$\tau_\nu = \frac{d^2 n\nu} {2\mathrm{c} \hbar \varepsilon_0 \sigma \gamma} $$where
 * d is the transition dipole moment;
 * n is the number of atoms;
 * ν is the frequency of the beam;
 * c is the speed of light;
 * ħ is the reduced Planck constant;
 * ε0 is the vacuum permittivity;
 * σ is the cross section of the beam;
 * γ is the natural linewidth of the transition.

Atmospheric sciences
In atmospheric sciences, one often refers to the optical depth of the atmosphere as corresponding to the vertical path from Earth's surface to outer space; at other times the optical path is from the observer's altitude to outer space. The optical depth for a slant path is, where τ′ refers to a vertical path, m is called the relative airmass, and for a plane-parallel atmosphere it is determined as where θ is the zenith angle corresponding to the given path. Therefore,$$T = e^{-\tau} = e^{-m\tau'}$$The optical depth of the atmosphere can be divided into several components, ascribed to Rayleigh scattering, aerosols, and gaseous absorption. The optical depth of the atmosphere can be measured with a Sun photometer.

The optical depth with respect to the height within the atmosphere is given by $$\tau(z) = k_\text{a}w_1\rho_0H e^{-z/H}$$ and it follows that the total atmospheric optical depth is given by $$\tau(0) = k_\text{a}w_1\rho_0H$$

In both equations:
 * ka is the absorption coefficient
 * w1 is the mixing ratio
 * ρ0 is the density of air at sea level
 * H is the scale height of the atmosphere
 * z is the height in question

The optical depth of a plane parallel cloud layer is given by $$\tau = Q_\text{e} \left[\frac{9\pi L^2 H N}{16\rho_l^2}\right]^{1/3}$$where:
 * Qe is the extinction efficiency
 * L is the liquid water path
 * H is the geometrical thickness
 * N is the concentration of droplets
 * ρl is the density of liquid water

So, with a fixed depth and total liquid water path, $\tau \propto N^{1/3}$.

Astronomy
In astronomy, the photosphere of a star is defined as the surface where its optical depth is 2/3. This means that each photon emitted at the photosphere suffers an average of less than one scattering before it reaches the observer. At the temperature at optical depth 2/3, the energy emitted by the star (the original derivation is for the Sun) matches the observed total energy emitted.

Note that the optical depth of a given medium will be different for different colors (wavelengths) of light.

For planetary rings, the optical depth is the (negative logarithm of the) proportion of light blocked by the ring when it lies between the source and the observer. This is usually obtained by observation of stellar occultations.

title: Optical depth


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Pepper

Pepper(s) may refer to:

Film and television

 * Pepper (film), a 1936 American comedy film
 * "Pepper" (The Brak Show), a 2002 episode

Food and spice

 * Piperaceae or the pepper family, a large family of flowering plant
 * Black pepper
 * Long pepper
 * Capsicum or pepper, a genus of flowering plants in the nightshade family Solanaceae
 * Bell pepper
 * Chili pepper
 * Sichuan pepper, a strong spice
 * "Alder pepper", the flower of Alnus alnobetula
 * Peppermint, a hybrid species of mint

Music

 * Pepper (band), a rock-reggae band originally from Hawaii
 * The Peppers, a French male instrumental group
 * "Pepper" (song), a 1996 song by Butthole Surfers
 * "Pepper", an instrumental song by Linkin Park from LP Underground 12
 * "Pepper", a song by Death Cab for Cutie from the 2022 album Asphalt Meadows
 * "Pepper Time", a 2024 song by Afelna.

People and fictional characters

 * Pepper (name), a list of people and fictional characters with either the given name or surname
 * Peppers (surname), a list of people with the surname

Science and technology

 * Pepper (cryptography), a secret value added before hashing
 * Pepper (robot), a humanoid robot by Aldebaran Robotics and SoftBank Mobile
 * PPAPI or Pepper Plugin API, an interface for web browser plugins

Sports

 * Pepper (baseball), an exercise and a game
 * Pepper (volleyball), a drill
 * Newark Peppers, a defunct Major League Baseball team in the Federal League

Other uses

 * Pepper (card game), an alternate name for bid euchre
 * Pepper (dog), a Dalmatian whose death led to the U.S. Animal Welfare Act of 1966
 * Pepper, West Virginia
 * Perets' or Pepper, a Ukrainian satirical newspaper
 * Cynthia Peretti or Pepper, professional wrestler from the Gorgeous Ladies of Wrestling

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Pepper


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Vulcanization

Vulcanization (British English: Vulcanisation) is a range of processes for hardening rubbers. The term originally referred exclusively to the treatment of natural rubber with sulfur, which remains the most common practice. It has also grown to include the hardening of other (synthetic) rubbers via various means. Examples include silicone rubber via room temperature vulcanizing and chloroprene rubber (neoprene) using metal oxides.

Vulcanization can be defined as the curing of elastomers, with the terms 'vulcanization' and 'curing' sometimes used interchangeably in this context. It works by forming cross-links between sections of the polymer chain which results in increased rigidity and durability, as well as other changes in the mechanical and electrical properties of the material. Vulcanization, in common with the curing of other thermosetting polymers, is generally irreversible.

The word was suggested by William Brockedon (a friend of Thomas Hancock who attained the British patent for the process) coming from the god Vulcan who was associated with heat and sulfur in volcanoes.

History
Rubber – latex – had been known for thousands of years in Mesoamerican cultures, used to make balls, sandal soles, rubber bands, and waterproof containers. Rubber was processed for specific applications within the Aztec Empire – rubber and latex goods were processed and constructed, and then shipped to the capital for use or further distribution.

Early rubber tube tires in the 19th century would grow sticky on a hot road. Debris would get stuck in them and eventually the tires would burst.

Charles Goodyear, in the 1830s, was working to improve those tube tires. He tried heating up rubber in order to mix other chemicals with it. This seemed to harden and improve the rubber, though this was due to the heating itself and not the chemicals used. Not realizing this, he repeatedly ran into setbacks when his announced hardening formulas did not work consistently. One day in 1839, when trying to mix rubber with sulfur, Goodyear accidentally dropped the mixture in a hot frying pan. To his astonishment, instead of melting further or vaporizing, the rubber remained firm and, as he increased the heat, the rubber became harder. Goodyear worked out a consistent system for this hardening, and by 1844 was producing the rubber on an industrial scale.

Applications
There are many uses for vulcanized materials, some examples of which are rubber hoses, shoe soles, toys, erasers, hockey pucks, shock absorbers, conveyor belts, vibration mounts/dampers, insulation materials, tires, and bowling balls. Most rubber products are vulcanized as this greatly improves their lifespan, function, and strength.

Overview
In contrast with thermoplastic processes (the melt-freeze process that characterize the behaviour of most modern polymers), vulcanization, in common with the curing of other thermosetting polymers, is generally irreversible. Five types of curing systems are in common use:

 * 1) Sulfur systems
 * 2) Peroxides
 * 3) Metallic oxides
 * 4) Acetoxysilane
 * 5) Urethane crosslinkers

Vulcanization with sulfur
The most common vulcanizing methods depend on sulfur. Sulfur, by itself, is a slow vulcanizing agent and does not vulcanize synthetic polyolefins. Accelerated vulcanization is carried out using various compounds that modify the kinetics of crosslinking; this mixture is often referred to as a cure package. The main polymers subjected to sulfur vulcanization are polyisoprene (natural rubber) and styrene-butadiene rubber (SBR), which are used for most street-vehicle tires. The cure package is adjusted specifically for the substrate and the application. The reactive sites—cure sites—are allylic hydrogen atoms. These C-H bonds are adjacent to carbon-carbon double bonds (>C=C<). During vulcanization, some of these C-H bonds are replaced by chains of sulfur atoms that link with a cure site of another polymer chain. These bridges contain between one and several atoms. The number of sulfur atoms in the crosslink strongly influences the physical properties of the final rubber article. Short crosslinks give the rubber better heat resistance. Crosslinks with higher number of sulfur atoms give the rubber good dynamic properties but less heat resistance. Dynamic properties are important for flexing movements of the rubber article, e.g., the movement of a side-wall of a running tire. Without good flexing properties these movements rapidly form cracks, and ultimately will make the rubber article fail.

Vulcanization of polychloroprene
The vulcanization of neoprene or polychloroprene rubber (CR rubber) is carried out using metal oxides (specifically MgO and ZnO, sometimes Pb3O4) rather than sulfur compounds which are presently used with many natural and synthetic rubbers. In addition, because of various processing factors (principally scorch, this being the premature cross-linking of rubbers due to the influence of heat), the choice of accelerator is governed by different rules to other diene rubbers. Most conventionally used accelerators are problematic when CR rubbers are cured and the most important accelerant has been found to be ethylene thiourea (ETU), which, although being an excellent and proven accelerator for polychloroprene, has been classified as reprotoxic. From 2010 to 2013, the European rubber industry had a research project titled SafeRubber to develop a safer alternative to the use of ETU.

Vulcanization of silicones

Room-temperature vulcanizing (RTV) silicone is constructed of reactive oil-based polymers combined with strengthening mineral fillers. There are two types of room-temperature vulcanizing silicone:
 * 1) RTV-1 (One-component systems); hardens due to the action of atmospheric humidity, a catalyst, and acetoxysilane. Acetoxysilane, when exposed to humid conditions, will form acetic acid. The curing process begins on the outer surface and progresses through to its core. The product is packed in airtight cartridges and is either in a fluid or paste form. RTV-1 silicone has good adhesion, elasticity, and durability characteristics. The Shore hardness can be varied between 18 and 60. Elongation at break can range from 150% up to 700%. They have excellent aging resistance due to superior resistance to UV radiation and weathering.
 * 2) RTV-2 (Two-component systems); two-component products that, when mixed, cure at room-temperature to a solid elastomer, a gel, or a flexible foam. RTV-2 remains flexible from −80 to 250 C. Break-down occurs at temperatures above 350 C, leaving an inert silica deposit that is non-flammable and non-combustible. They can be used for electrical insulation due to their dielectric properties. Mechanical properties are satisfactory. RTV-2 is used to make flexible moulds, as well as many technical parts for industry and paramedical applications.

title: Vulcanization


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Bolesław I the Brave

Bolesław I the Brave (c. 967 – 17 June 1025), less often known as Bolesław the Great, was Duke of Poland from 992 to 1025, and the first King of Poland in 1025. He was also Duke of Bohemia between 1003 and 1004 as Boleslaus IV. A member of the Piast dynasty, Bolesław was a capable monarch and a strong mediator in Central European affairs. He continued to proselytise Western Christianity among his subjects and raised Poland to the rank of a kingdom, thus becoming the first Polish ruler to hold the title of rex, Latin for king.

The son of Mieszko I of Poland by his first wife Dobrawa of Bohemia, Bolesław ruled Lesser Poland already during the final years of Mieszko's reign. When the country became divided in 992, he banished his father's widow, Oda of Haldensleben, purged his half-brothers along with their adherents and successfully reunified Poland by 995. As a devout Christian, Bolesław supported the missionary endeavours of Adalbert of Prague and Bruno of Querfurt. The martyrdom of Adalbert in 997 and Bolesław's successful attempt to ransom the bishop's remains, paying for their weight in gold, consolidated Poland's autonomy from the Holy Roman Empire.

At the Congress of Gniezno (11 March 1000), Emperor Otto III permitted the establishment of a Polish church structure with a metropolitan see at Gniezno, independent from the Archbishopric of Magdeburg. Bishoprics were also established in Kraków, Wrocław, and Kołobrzeg, and Bolesław formally repudiated paying tribute to the Empire. Following Otto's death in 1002, Bolesław fought a series of wars against Otto's cousin and heir, Henry II, ending in the Peace of Bautzen (1018). In the summer of 1018, in one of his expeditions, Bolesław I captured Kiev, where he installed his son-in-law Sviatopolk I as ruler. According to legend, Bolesław chipped his blade when striking Kiev's Golden Gate. In honour of this legend, the Szczerbiec ("Jagged Sword") would later become the coronation sword of Polish kings.

Bolesław is widely considered one of Poland's most accomplished Piast monarchs; he was an able strategist and statesman, who transformed Poland into an entity comparable to older Western monarchies and arguably raised it to the front rank of European states. Bolesław conducted successful military campaigns to the west, south and east of his realm, and conquered territories in modern-day Slovakia, Moravia, Red Ruthenia, Meissen, Lusatia, and Bohemia. He established the "Prince's Law" and sponsored the construction of churches, monasteries, military forts as well as waterway infrastructure. He also introduced the first Polish monetary unit, the grzywna, divided into 240 denarii, and minted his own coinage.

Early life
Bolesław was born in 966 or 967, the first child of Mieszko I of Poland and his wife, the Bohemian princess Dobrawa, known in Czech as Doubravka. His Epitaph, which was written in the middle of the 11th century, emphasised that Bolesław had been born to a "faithless" father and a "true-believing" mother, suggesting that he was born before his father's baptism. Bolesław was baptised shortly after his birth. He was named after his maternal grandfather, Boleslaus I, Duke of Bohemia. Not much is known about Bolesław's childhood. His Epitaph recorded that he underwent the traditional hair-cutting ceremony at the age of seven and a lock of his hair was sent to Rome. The latter act suggests that Mieszko wanted to place his son under the protection of the Holy See. Historian Tadeusz Manteuffel says that Bolesław needed that protection because his father had sent him to the court of Otto I, Holy Roman Emperor in token of his allegiance to the emperor. However, historian Marek Kazimierz Barański notes that the claim that Bolesław was sent as a hostage to the imperial court is disputed.

Bolesław's mother, Dobrawa, died in 977; his widowed father married Oda of Haldensleben who had already been a nun. Around that time, Bolesław became the ruler of Lesser Poland, through it is not exactly clear in what circumstances. Jerzy Strzelczyk says that Bolesław received Lesser Poland from his father; Tadeusz Manteuffel states that he seized the province from his father with the local lords' support; and Henryk Łowmiański writes that his uncle, Boleslav II of Bohemia, granted the region to him.

Accession and consolidation

Mieszko I died on 25 May 992. The contemporaneous Thietmar of Merseburg recorded that Mieszko left "his kingdom to be divided among many claimants", but Bolesław unified the country "with fox-like cunning" and expelled his stepmother and half-brothers from Poland. Two Polish lords Odilien and Przibiwoj, who had supported her and her sons, were blinded on Bolesław's order. Historian Przemysław Wiszewski says that Bolesław had already taken control of the whole of Poland by 992; Pleszczyński writes that this only happened in the last months of 995.

Bolesław's first coins were issued around 995. One of them bore the inscription Vencievlavus, showing that he regarded his mother's uncle Duke Wenceslaus I of Bohemia as the patron saint of Poland. Bolesław sent reinforcements to the Holy Roman Empire to fight against the Polabian Slavs in summer 992. Bolesław personally led a Polish army to assist the imperial troops in invading the land of the Abodrites or Veleti in 995. During the campaign, he met the young German monarch, Otto III.

Soběslav, the head of the Bohemian Slavník dynasty, also participated in the 995 campaign. Taking advantage of Soběslav's absence, Boleslav II of Bohemia invaded the Slavníks' domains and had most members of the family murdered. After learning of his kinsmen's fate, Soběslav settled in Poland. Bolesław gave shelter to him "for the sake of [Soběslav's] holy brother", Bishop Adalbert of Prague, according to the latter's hagiographies. Adalbert (known as Wojciech before his consecration) also came to Poland in 996, because Bolesław "was quite amicably disposed towards him". Adalbert's hagiographies suggest that the bishop and Bolesław closely cooperated. In early 997 Adalbert left Poland to proselytise among the Prussians, who had been invading the eastern borderlands of Bolesław's realm. However, the pagans murdered him on 23 April 997. Bolesław ransomed Adalbert's remains, paying its weight in gold, and buried it in Gniezno. He sent parts of the martyr bishop's corpse to Emperor Otto III who had been Adalbert's friend.

Congress of Gniezno and its aftermath (999–1002)
Emperor Otto III held a synod in Rome where Adalbert was canonised on the emperor's request on 29 June 999. Before 2 December 999, Adalbert's brother, Radim Gaudentius, was consecrated "Saint Adalbert's archbishop". Otto III made a pilgrimage to Saint Adalbert's tomb in Gniezno, accompanied by Pope Sylvester II's legate, Robert, in early 1000. Thietmar of Merseburg mentioned that it "would be impossible to believe or describe" how Bolesław received the emperor and conducted him to Gniezno. A century later, Gallus Anonymus added that "[m]arvelous and wonderful sights Bolesław set before the emperor when he arrived: the ranks first of the knights in all their variety, and then of the princes, lined up on a spacious plain like choirs, each separate unit set apart by the distinct and varied colors of its apparel, and no garment there was of inferior quality, but of the most precious stuff that might anywhere be found."

Bolesław took advantage of the emperor's pilgrimage. After the Emperor's visit in Gniezno, Poland started to develop into a sovereign state, in contrast with Bohemia, which remained a vassal state, incorporated in the Kingdom of Germany. Thietmar of Merseburg condemned Otto III for "making a lord out of a tributary" in reference to the relationship between the Emperor and Bolesław. Gallus Anonymus emphasised that Otto III declared Bolesław "his brother and partner" in the Holy Roman Empire, also calling Bolesław "a friend and ally of the Roman people". The same chronicler mentioned that Otto III "took the imperial diadem from his own head and laid it upon the head of Bolesław in pledge of friendship" in Gniezno. Bolesław also received "one of the nails from the cross of our Lord with the lance of St. Maurice" from the Emperor.

Gallus Anonymus claimed that Bolesław was "gloriously raised to kingship by the emperor" through these acts, but the Emperor's acts in Gniezno only symbolised that Bolesław received royal prerogatives, including the control of the Church in his realm. Radim Gaudentius was installed as the archbishop of the newly established Roman Catholic Archdiocese of Gniezno. At the same time, three suffragan bishoprics, subordinated to the see of Gniezno—the dioceses of Kołobrzeg, Kraków and Wrocław—were set up. Bolesław had promised that Poland would pay Peter's Pence to the Holy See to obtain the pope's sanction to the establishment of the new archdiocese. Unger, who had been the only prelate in Poland and was opposed to the creation of the archdiocese of Gniezno, was made bishop of Poznań, directly subordinated to the Holy See. However, Polish commoners only slowly adopted Christianity: Thietmar of Merseburg recorded that Bolesław forced his subjects with severe punishments to observe fasts and to refrain from adultery:

"If anyone in this land should presume to abuse a foreign matron and thereby commit fornication, the act is immediately avenged through the following punishment. The guilty party is led on to the market bridge, and his scrotum is affixed to it with a nail. Then, after a sharp knife has been placed next to him, he is given the harsh choice between death or castration. Furthermore, anyone found to have eaten meat after Septuagesima is severely punished, by having his teeth knocked out. The law of God, newly introduced in these regions gains more strength from such acts of force than from any fast imposed by the bishops"

- Thietmar of Merseburg: Chronicon

During the time the Emperor spent in Poland, Bolesław also showed off his affluence. At the end of the banquets, he "ordered the waiters and the cupbearers to gather the gold and silver vessels ... from all three days' coursis, that is, the cups and goblets, the bowls and plates and the drinking-horns, and he presented them to the emperor as a toke of honor ... [h]is servants were likewise told to collect the wall-hangings and the coverlets, the carpets and tablecloths and napkins and everything that had been provided for their needs and take them to the emperor's quarters", according to Gallus Anonymus. Thietmar of Merseburg recorded that Bolesław presented Otto III with a troop of "three hundred armoured warriors". Bolesław also gave Saint Adalbert's arm to the Emperor.

After the meeting, Bolesław escorted Otto III to Magdeburg in Germany where "they celebrated Palm Sunday with great festivity" on 25 March 1000. A continuator of the chronicle of Adémar de Chabannes recorded, decades after the events, that Bolesław also accompanied Emperor Otto from Magdeburg to Aachen where Otto III had Charlemagne's tomb reopened and gave Charlemagne's golden throne to Bolesław.

An illustrated Gospel, made for Otto III around 1000, depicted four women symbolising Roma, Gallia, Germania and Sclavinia as doing homage to the Emperor who sat on his throne. Historian Alexis P. Vlasto writes that "Sclavinia" referred to Poland, proving that it was regarded as one of the Christian realms subjected to the Holy Roman Empire in accordance with Otto III's idea of Renovatio imperii—the renewal of the Roman Empire based on a federal concept. Within that framework, Poland, along with Hungary, was upgraded to an eastern foederatus of the Holy Roman Empire, according to historian Jerzy Strzelczyk.

Coins struck for Bolesław shortly after his meeting with the emperor bore the inscription Gnezdun Civitas, showing that he regarded Gniezno as his capital. The name of Poland was also recorded on the same coins referring to the Princes Polonie [sic]. The title princeps was almost exclusively used in Italy around that time, suggesting that it also represented the Emperor's idea of the renewal of the Roman Empire. However, Otto's premature death on 23 January 1002 put an end to his ambitious plans. The contemporaneous Bruno of Querfurt stated that "nobody lamented" the 22-year-old emperor's "death with greater grief than Bolesław".

In 1000 Bolesław issued a law prohibiting hunting beavers and created a office called "Bobrowniczy" whose task was to enforce prince's ordinances.

Expansion (1002–1018)
Three candidates were competing with each other for the German crown after Otto III's death. One of them, Duke Henry IV of Bavaria, promised the Margraviate of Meissen to Bolesław in exchange for his assistance against Eckard I, Margrave of Meissen who was the most powerful contender. However, Eckard was murdered on 30 April 1002, which enabled Henry of Bavaria to defeat his last opponent, Herman II, Duke of Swabia. Fearing that Henry II would side with elements in the German Church hierarchy which were unfavorable towards Poland, and taking advantage of the chaos that followed Margrave Eckard's death and Henry of Bavaria's conflict with Henry of Schweinfurt, Bolesław invaded Lusatia and Meissen. He "seized Margrave Gero's march as far as the river Elbe", and also Bautzen, Strehla and Meissen. At the end of July, he participated at a meeting of the Saxon lords where Henry of Bavaria, who had meanwhile been crowned king of Germany, only confirmed Bolesław's possession of Lusatia, and granted Meissen to Margrave Eckard's brother, Gunzelin, and Strehla to Eckard's oldest son, Herman. The relationship between King Henry and Bolesław became tense after assassins tried to murder Bolesław in Merseburg, because he accused the king of conspiracy against him. In retaliation, he seized and burned Strehla and took the inhabitants of the town into captivity. Duke Boleslaus III of Bohemia was dethroned and the Bohemian lords made Vladivoj, who had earlier fled to Poland, duke in 1002. The Czech historian Dušan Třeštík writes that Vladivoj seized the Bohemian throne with Bolesław's assistance. After Vladivoj died in 1003, Bolesław invaded Bohemia and restored Boleslaus III who had many Bohemian noblemen murdered. The Bohemian lords who survived the massacre "secretly sent representatives" to Bolesław, asking "him to rescue them from fear of the future", according to Thietmar of Merseburg. Bolesław invaded Bohemia and had Boleslaus III blinded. He entered Prague in March 1003 where the Bohemian lords proclaimed him duke. King Henry sent his envoys to Prague, demanding that Bolesław take an oath of loyalty and pay tribute to him, but Bolesław refused to obey. He also allied himself with the king's opponents, including Henry of Schweinfurt to whom he sent reinforcements. King Henry defeated Henry of Schweinfurt, forcing him to flee to Bohemia in August 1003. Bolesław invaded the Margraviate of Meissen, but Margrave Gunzelin refused to surrender his capital. It is also likely that Polish forces took control of Moravia and the northern parts of the Kingdom of Hungary (present-day mostly Slovakia) in 1003 as well. The proper conquest date of the Hungarian territories is 1003 or 1015 and this area stayed a part of Poland until 1018.

King Henry allied himself with the pagan Lutici, and broke into Lusatia in February 1004, but heavy snows forced him to withdraw. He invaded Bohemia in August 1004, taking the oldest brother of the blinded Boleslaus III of Bohemia, Jaromír, with him. The Bohemians rose up in open rebellion and murdered the Polish garrisons in the major towns. Bolesław left Prague without resistance, and King Henry made Jaromír duke of Bohemia on 8 September. Bolesław's ally Soběslav died in this campaign.

During the next part of the offensive King Henry retook Meissen and in 1005, his army advanced as far into Poland as the city of Poznań where a peace treaty was signed. According to the peace treaty Bolesław lost Lusatia and Meissen and likely gave up his claim to the Bohemian throne. Also in 1005, a pagan rebellion in Pomerania overturned Bolesław's rule and resulted in the destruction of the newly established local bishopric.

In 1007, after learning about Bolesław's efforts to gain allies among Saxon nobles and giving refuge to the deposed duke of Bohemia, Oldřich, King Henry denounced the Peace of Poznań, which caused Bolesław's attack on the Archbishopric of Magdeburg as well as the re-occupation of the marches of Lusatia, though he stopped short of retaking Meissen. The German counter-offensive began three years later (previously, Henry was occupied with rebellion in Flanders), in 1010, but it was of no significant consequence. In 1012, another ineffective campaign by archbishop Walthard of Magdeburg was launched, as he died during that campaign and, consequently, his forces returned home. Later that year, Bolesław once again invaded Lusatia. Bolesław's forces pillaged and burned the city of Lubusz (Lebus). In 1013, a peace accord was signed at Merseburg. As part of the treaty, Bolesław paid homage to King Henry for the March of Lusatia (including the town of Bautzen) and Sorbian Meissen as fiefs. A marriage of Bolesław's son Mieszko with Richeza of Lotharingia, daughter of the Count Palatine Ezzo of Lotharingia and granddaughter of Emperor Otto II, was also performed. During the brief period of peace on the western frontier that followed, Bolesław took part in a short campaign in the east, towards the Kievan Rus' territories. In 1014, Bolesław sent his son Mieszko to Bohemia in order to form an alliance with Duke Oldrich against Henry, by then crowned emperor. Oldrich imprisoned Mieszko and turned him over to Henry, who, however, released him in a gesture of good will after being pressured by Saxon nobles. Bolesław nonetheless refused to aid the emperor militarily in his Italian expedition. This led to imperial intervention in Poland and so in 1015 a war erupted once again. The war started out well for the emperor, as he was able to defeat the Polish forces at the Battle of Ciani. Once the imperial forces crossed the river Oder, Bolesław sent a detachment of Moravian knights in a diversionary attack against the Eastern March of the empire. Soon after, the imperial army, having suffered a defeat near the Bóbr marshes, retreated from Poland without any permanent gains. After this event, Bolesław's forces took the initiative. Margrave Gero II of Meissen was defeated and killed during a clash with the Polish forces in late 1015. In 1015 and 1017, Bolesław I attacked the Eastern March and was defeated twice by Henry the Strong and his forces.

Later that year, Bolesław's son Mieszko was sent to plunder Meissen. His attempt at conquering the city, however, failed. In 1017, Bolesław defeated Duke Henry V of Bavaria. In that same year, supported by his Slavic allies, Emperor Henry once again invaded Poland, albeit once again to very little effect. He did besiege the cities of Głogów and Niemcza, but was unable to conquer them. The imperial forces once again were forced to retreat, suffering significant losses. Taking advantage of the involvement of Czech troops, Bolesław ordered his son to invade Bohemia, where Mieszko met very little resistance. On 30 January 1018, the Peace of Bautzen was signed. The Polish ruler was able to keep the contested marches of Lusatia and Sorbian Meissen not as fiefs, but as a part of Polish territory, and also received military aid in his expedition against Rus'. Also, Bolesław (then a widower) strengthened his dynastic bonds with the German nobility through his marriage with Oda, daughter of Margrave Eckard I of Meissen. The wedding took place four days later, on 3 February in the castle of Cziczani (also Sciciani, at the site of either modern Groß-Seitschen or Zützen).

War in Kiev (1018)
Bolesław organised his first expedition east, to support his son-in-law Sviatopolk I of Kiev, in 1013, but the decisive engagements were to take place in 1018 after the Peace of Bautzen was already signed. At the request of Sviatopolk I, in what became known as the Kiev Expedition of 1018, the Polish duke sent an expedition to Kievan Rus' with an army of 2,000–5,000 Polish warriors, in addition to Thietmar's reported 1,000 Pechenegs, 300 German knights, and 500 Hungarian mercenaries. After collecting his forces during June, Bolesław led his troops to the border in July and on 23 July at the banks of the Bug River, near Wołyń, he defeated the forces of Yaroslav the Wise, Prince of Kiev, in what became known as the Battle of the River Bug. All primary sources agree that the Polish prince was victorious in battle. Yaroslav retreated north to Novgorod, opening the road to Kiev. The city, which suffered from fires caused by the Pecheneg siege, surrendered upon seeing the main Polish force on 14 August. The entering army, led by Bolesław, was ceremonially welcomed by the local archbishop and the family of Vladimir I of Kiev. According to popular legend Bolesław notched his sword (Szczerbiec) hitting the Golden Gate of Kiev. Although Sviatopolk lost the throne soon afterwards and lost his life the following year, during this campaign Poland re-annexed the Red Strongholds, later called Red Ruthenia, lost by Bolesław's father in 981.

Last years (1019–1025)
Historians dispute the exact date of Bolesław's coronation. The year 1025 is most widely accepted by scholars, though the year 1000 is also likely. According to an epitaph, the crowning took place when Otto bestowed upon Bolesław royal regalia at the Congress of Gniezno. However, independent German sources confirmed that after Henry II's death in 1024, Bolesław took advantage of the interregnum in Germany and crowned himself king in 1025. It is generally assumed that the coronation took place on Easter Sunday although Tadeusz Wojciechowski believes that the coronation took place prior to that, on 24 December 1024. The basis for this assertion is that the coronations of kings were usually held during religious festivities. The exact place of the coronation is also highly debated, with the cathedrals of Gniezno or Poznań being the most probable locations. Poland was thereafter raised to the rank of a kingdom before its neighbour, Bohemia.

Wipo of Burgundy in his chronicle describes the event:

"[In 1025] Boleslaus [of the Slavic nation], duke of the Poles, took for himself in injury to King Conrad the regal insignia and the royal name. Death swiftly killed his temerity."

- Wipo: The Deeds of Conrad II

It is widely believed that Bolesław had to receive permission for his coronation from the newly-elected Pope John XIX. John was known to be corrupt, and it is likely that consent was or may have been obtained through bribes. However, Rome also hoped for a potential alliance to defend itself from Byzantine Emperor Basil II, who launched a military expedition to recover the island of Sicily and could subsequently threaten the Papal States from the south. Stanisław Zakrzewski put forward the theory that the coronation had the tacit consent of Conrad II and that the pope only confirmed that fact. That is corroborated by Conrad's confirmation of the royal title to Mieszko II, his agreement with the counts of Tusculum and the papal interactions with Conrad and Bolesław.

Death and burial
According to Cosmas of Prague, Bolesław I died shortly after his coronation on 17 June 1025. Already in advanced age for the time, the true cause of death is unknown and remains a matter of speculation. Chronicler Jan Długosz (and followed by modern historians and archaeologists) writes that Bolesław was laid to rest at the Archcathedral Basilica of St. Peter and St. Paul in Poznań. In the 14th century, Casimir III the Great reportedly ordered the construction of a new, presumably Gothic, sarcophagus to which he transferred Bolesław's remains.

The medieval sarcophagus was partially damaged on 30 September 1772 during a fire, and completely destroyed in 1790 due to the collapse of the southern tower. Bolesław's remains were subsequently excavated from the rubble and moved to the cathedral's chapter house. Three bone fragments were donated to Tadeusz Czacki in 1801, at his request. Czacki, a notable Polish historian, pedagogue, and numismatist, placed one of the bone fragments in his ancestral mausoleum in Poryck (now Pavlivka) in the Volhynia region; the other two were given to Princess Izabela Flemming Czartoryska, who placed them in her recently founded Czartoryski Museum in Puławy.

After many historical twists, the burial place of Bolesław I ultimately remained at Poznań Cathedral, in the Golden Chapel. The content of his epitaph is known to historians. It is Bolesław's epitaph, which, in part, came from the original tombstone, that is one of the first sources (dated to the period immediately after Bolesław's death, probably during the reign of Mieszko II) that gave the King his widely known nickname of "Brave" (Polish: Chrobry). Later, Gallus Anonymus, in Chapter 6 of his Gesta principum Polonorum, named the Polish ruler as Bolezlavus qui dicebatur Gloriosus seu Chrabri.

Family
The contemporaneous Thietmar of Merseburg recorded Bolesław's marriages, also mentioning his children. Bolesław's first wife was a daughter of Rikdag, Margrave of Meissen. Historian Manteuffel says that the marriage was arranged in the early 980s by Mieszko I who wanted to strengthen his links with the Saxon lords and to enable his son to succeed Rikdag in Meissen. Bolesław "later sent her away", according to Thietmar's Chronicon. Historian Marek Kazimierz Barański writes that Bolesław repudiated his first wife after her father's death in 985 which left the marriage without any political value.

Bolesław "took a Hungarian woman" as his second wife. Most historians identify her as a daughter of the Hungarian ruler Géza, but this theory has not been universally accepted. She gave birth to a son, Bezprym, but Bolesław repudiated her.

Bolesław's third wife, Emnilda, was "a daughter of the venerable lord, Dobromir". Her father was a West Slavic or Lechitic prince, either a local ruler from present-day Brandenburg who was closely related to the imperial Liudolfing dynasty, or the last independent prince of the Vistulans, before their incorporation into Poland. Wiszewski dates the marriage of Bolesław and Emnilda to 988. Emnilda exerted a beneficial influence on Bolesław, reforming "her husband's unstable character", according to Thietmar of Merseburg's report. Bolesław's and Emnilda's oldest (unnamed) daughter "was an abbess" of an unidentified abbey. Their second daughter Regelinda, who was born in 989, was given in marriage to Herman I, Margrave of Meissen in 1002 or 1003. Mieszko II Lambert who was born in 990 was Bolesław's favorite son and successor. The name of Bolesław's and Emnilda's third daughter, who was born in 995, is unknown; she married Sviatopolk I of Kiev between 1005 and 1012. Bolesław's youngest son, Otto, was born in 1000.

Bolesław's fourth marriage, from 1018 until his death, was to Oda (c. 995–1025), daughter of Margrave Eckard I of Meissen. They had a daughter, Matilda (c. 1018–1036), betrothed (or married) on 18 May 1035 to Otto of Schweinfurt.

Predslava, a daughter of Vladimir the Great and Rogneda, whom, along with her sister Mstislava, he had taken from Kiev in 1018, was his concubine.

Marriages and Issue:

Oda/Hunilda?, daughter of Rikdag

Unknown Hungarian woman (sometimes identified as Judith of Hungary):

 * 1) Bezprym (c. 986–1032) – became Duke of Poland

Emnilda, daughter of Dobromir:

 * 1) Unknown abbess of an unidentified abbey
 * 2) Regelinda (c. 989 – 21 March aft. 1014), married Herman I, Margrave of Meissen becoming Margravine of Meissen
 * 3) Mieszko II Lambert (c. 990 – 10/11 May 1034), became king and subsequent to his dethronement, regained power as duke of Poland
 * 4) Unknown daughter, married Grand Prince Sviatopolk I of Kiev and became Grand Princess of Kiev
 * 5) Otto Bolesławowic (c. 1000–1033)

Oda of Meissen

 * 1) Matilda (c. 1018–1036), betrothed to Otto of Schweinfurt but the marriage was rejected.

title: Bolesław I the Brave


text:
Robert Broom

Robert Broom FRS FRSE (30 November 1866 – 6 April 1951) was a British- South African medical doctor and palaeontologist. He qualified as a medical practitioner in 1895 and received his DSc in 1905 from the University of Glasgow.

From 1903 to 1910, he was professor of zoology and geology at Victoria College, Stellenbosch, South Africa, and subsequently he became keeper of vertebrate palaeontology at the South African Museum, Cape Town.

Life
Broom was born at 66 Back Sneddon Street in Paisley, Renfrewshire, Scotland, the son of John Broom, a designer of calico prints and Paisley shawls, and Agnes Hunter Shearer.

In 1893, he married Mary Baird Baillie, his childhood sweetheart.

In his medical studies at the University of Glasgow Broom specialised in obstetrics. After graduating in 1895 he travelled to Australia, supporting himself by practising medicine. He settled in South Africa in 1897, just prior to the South African War. From 1903 to 1910, he was professor of Zoology and Geology at Victoria College, Stellenbosch (later Stellenbosch University), but was forced out of this position for promoting belief in evolution. He established a medical practice in the Karoo region of South Africa, an area rich in therapsid fossils. Based on his continuing studies of these fossils and mammalian anatomy he was made a Fellow of the Royal Society in 1920. Following the discovery of the Taung child he became interested in the search for human ancestors and commenced work on much more recent fossils from the dolomite caves north-west of Johannesburg, particularly Sterkfontein Cave (now part of the Cradle of Humankind World Heritage Site). As well as describing many mammalian fossils from these caves he identified several hominin fossils, the most complete of which was an australopithecine skull, nicknamed Mrs Ples, and a partial skeleton that indicated that australopithecines walked upright.

Broom died in Pretoria, South Africa in 1951.

Contributions
Broom was first known for his study of therapsids. After Raymond Dart's discovery of the Taung Child, an infant australopithecine, Broom's interest in palaeoanthropology was heightened. Broom's career seemed over and he was sinking into poverty, when Dart wrote to Jan Smuts about the situation. Smuts, exerting pressure on the South African government, managed to obtain a position for Broom in 1934 with the staff of the Transvaal Museum in Pretoria as an Assistant in Palaeontology.

Broom has been described as "one of the great Karoo (and, in particular, therapsid) palaeontologists", having managed to describe 369 therapsid holotypes in his lifetime, which he ascribed to 168 new genera. Broom has a reputation as a "splitter" that has resulted in only around 57% of his holotypes still being considered valid as of 2003.

In the following years, he and John T. Robinson made a series of spectacular finds, including fragments from six hominins in Sterkfontein, which they named Plesianthropus transvaalensis, popularly called Mrs. Ples, but which was later classified as an adult Australopithecus africanus, as well as more discoveries at sites in Kromdraai and Swartkrans. In 1937, Broom made his most famous discovery, by defining the robust hominin genus Paranthropus with his discovery of Paranthropus robustus. These discoveries helped support Dart's claims for the Taung species.

For his volume, The South Africa Fossil Ape-Men, The Australopithecinae, in which he proposed the Australopithecinae subfamily, Broom was awarded the Daniel Giraud Elliot Medal from the National Academy of Sciences in 1946.

The remainder of Broom's career was devoted to the exploration of these sites and the interpretation of the many early hominin remains discovered there. He continued to write to the last. Shortly before his death he finished a monograph on the Australopithecines and remarked to his nephew:

 * "Now that's finished ... and so am I."

Spiritual evolution
Broom was a nonconformist and was deeply interested in the paranormal and spiritualism; he was a critic of Darwinism and materialism. Broom was a believer in spiritual evolution. In his book The Coming of Man: Was it Accident or Design? (1933) he claimed that "spiritual agencies" had guided evolution as animals and plants were too complex to have arisen by chance. According to Broom, there were at least two different kinds of spiritual forces, and psychics are capable of seeing them. Broom claimed there was a plan and purpose in evolution and that the origin of Homo sapiens is the ultimate purpose behind evolution. According to Broom "Much of evolution looks as if it had been planned to result in man, and in other animals and plants to make the world a suitable place for him to dwell in."

After discovering the skull of Mrs. Ples, Broom was asked if he excavated at random, Broom replied that spirits had told him where to find his discoveries.

Research on the Khoisan
Broom had a noted interest in the Khoisan peoples, which included collecting their remains, including those of the recently deceased, as well as by digging up old graves. Broom first began collecting modern human remains in 1897, shortly after he moved to South Africa. In that year he collected the remains of three elderly "Hottentot" people that had died around Port Nolloth following a drought in the region. Broom stated that he "cut their heads off and boiled them in paraffin tins on the kitchen stove". Their skulls were later sent to the medical school of the University of Edinburgh, alongside a 7 month old foetus, from which Broom had removed the brain which he preserved separately. Broom also obtained remains of deceased prisoners, stating: "If a prisoner dies and you want his skeleton, probably two or three regulations stand in the way, but the enthusiast does not worry about such regulations." Broom said that he had buried several corpses in his garden allowing them to decay before later retrieving their bones. These include the remains of two men who were imprisoned in Douglas jail: Andreas Links, an 18 year old !Ora man, (catalogued as MMK 264), as well an unnamed 18 year old "bushman" from Langeberg (catalogued as MMK 283), who was photographed while alive at the request of Broom, despite this being against policy. The skeletons of both men were added to the collections of the McGregor Museum in 1921.

Broom described the Khoisan peoples as a "degenerate" and "degraded race", speculating in 1907 that they descended from "the race which built the Pyramids" and "Mongoloids", but had "degenerated" due to South Africa's hot climate. In his later works he divided the Khoisan peoples into three races, the Bushmen, Hottentot and Korana, based on supposed typological differences, with the type specimen of the Korana race being the skeleton of Links. Other contemporary anthropologists questioned this classification scheme, especially the Korana race. Broom later said that he had "invented the Korana". All such typological racial classification schemes are discredited today, due to being based on vague criteria, resulting in the rigid categorization ultimately being arbitrary. Anatomist Goran Štrkalj wrote that: "It is obvious that Broom's anthropological work was ... influenced by the racist stereotypes and prejudices of the day".

Publications
Among hundreds of articles contributed by him to scientific journals, the most important include:
 * "Fossil Reptiles of South Africa" in Science in South Africa (1905)
 * "Reptiles of Karroo Formation" in Geology of Cape Colony (1909)
 * "Development and Morphology of the Marsupial Shoulder Girdle" in Transactions of the Royal Society of Edinburgh (1899)
 * "Comparison of Permian Reptiles of North America with Those of South Africa" in Bulletin of the American Museum of Natural History (1910)
 * "Structure of Skull in Cynodont Reptiles" in Proceedings of the Zoölogical Society (1911).
 * The South Africa Fossil Ape-Men, The Australopithecinae (1946).

Books

 * The origin of the human skeleton: an introduction to human osteology (1930)
 * The mammal-like reptiles of South Africa and the origin of mammals (1932)
 * The coming of man: was it accident or design? (1933)
 * The South African fossil ape-man: the Australopithecinae (1946)
 * Sterkfontein ape-man Plesianthropus (1949)
 * Finding the missing link (1950)

Legacy
Robert Broom is commemorated in the scientific name of a species of Australian blind snake, Anilios broomi, the Triassic archosauromorph reptile Prolacerta broomi, the rhinesuchid amphibian Broomistega and the Permian dicynodont Robertia broomiana.

title: Robert Broom


text:
Antenna

Antenna (: antennas or antennae) may refer to:

Biology

 * Antenna (biology), one of one or more pairs of appendages used for sensing in arthropods
 * Antenna (journal), the journal of the Royal Entomological Society

Other uses in science and engineering

 * Antenna (radio), also known as an aerial, a transducer designed to transmit or receive electromagnetic (e.g., TV or radio) waves
 * Antenna types, a list of the many different types of radio and microwave antennas
 * Antennae Galaxies, the name of two colliding galaxies NGC 4038 and NGC 4039
 * Microwave antenna, a physical transmission device used to broadcast microwave transmissions between two or more locations
 * Television antenna, a device used to pick up terrestrial television signals so that they may be viewed on a television set

Broadcast channels and stations

 * ANT1, a Greek-language terrestrial channel
 * Antena Internațional, a Romanian television channel
 * Antena 1 (Romania), a Romanian television channel
 * Antena 2 (Romania), a Romanian television channel
 * Antena 3 (Romania), a Romanian television channel
 * Antena 3 (Spain), a Spanish terrestrial television channel
 * Antenna TV, a U.S. television channel established in 2011 by Tribune Broadcasting
 * RDP Antena 1, Portuguese public radio station
 * RDP Antena 2, Portuguese public radio station
 * RDP Antena 3, Portuguese public radio station
 * Antena Radio Jelah, Bosnian commercial radio station from Tešanj
 * Antena Sarajevo, Bosnian commercial radio station from Sarajevo
 * Radio Antena M, Montenegrin commercial radio station from Podgorica

Film and television

 * "Antenna", an episode of the Adult Swim animated television series, Aqua Teen Hunger Force
 * Antenna (film), a satirical 1969 Dutch film directed by Adriaan Ditvoorst
 * Antenna Documentary Film Festival, an international film festival held in Sydney, Australia
 * Antenna Awards, an annual awards ceremony for television programs broadcast on Australia's Channel 31 stations

Albums

 * Antennae (album), a 1997 album by jazz guitarist Joe Morris
 * Antenna (Cave In album), 2003
 * Antenna (GO!GO!7188 album), 2009
 * Antenna (Mrs. Green Apple album), 2023
 * Antenna (ZZ Top album), 1994

Songs

 * "Antenna" (song), a 2013 song released by Fuse ODG
 * "Antenna", a single by The Church from Starfish
 * "Antenna", a song by Kraftwerk from Radio-Activity
 * "Antenna", a single by Sonic Youth band from The Eternal
 * "Antenna", a song released by Bonobo on the album The North Borders

Other uses in music

 * Antenna (band), an American indie rock band
 * Antena, a French-Belgian synth pop band, led by Isabelle Antena (a pseudonym for Isabelle Powaga)
 * Antenna (record label), a South Korean record label

Other media

 * Antenna (magazine), a web publication owned by Townsquare Media, formerly a print magazine

title: Antenna


text: Normoxic

title: Normoxic


text:
Wall

A wall is a structure and a surface that defines an area; carries a load; provides security, shelter, or soundproofing; or, is decorative. There are many kinds of walls, including:
 * Border barriers between countries
 * Brick walls
 * Defensive walls in fortifications
 * Permanent, solid fences
 * Retaining walls, which hold back dirt, stone, water, or noise sound
 * Stone walls
 * Walls in buildings that form a fundamental part of the superstructure or separate interior rooms, sometimes for fire safety
 * Glass walls in which the primary structure is made of glass; does not include openings within walls that have glass coverings as these are windows
 * Walls that protect from oceans (seawalls) or rivers (levees)

Etymology

The term wall comes from the Latin vallum meaning "an earthen wall or rampart set with palisades, a row or line of stakes, a wall, a rampart, fortification", while the Latin word murus means a defensive stone wall. English uses the same word to mean an external wall and the internal sides of a room, but this is not universal. Many languages distinguish between the two. In German, some of this distinction can be seen between Wand and Mauer, in Spanish between pared and muro.

Defensive wall
The word wall originally referred to defensive walls and ramparts.

Building wall
The purposes of walls in buildings are to support roofs, floors and ceilings; to enclose a space as part of the building envelope along with a roof to give buildings form; and to provide shelter and security. In addition, the wall may house various types of utilities such as electrical wiring or plumbing. Wall construction falls into two basic categories: framed walls or mass-walls. In framed walls the load is transferred to the foundation through posts, columns or studs. Framed walls most often have three or more separate components: the structural elements (such as 2×4 studs in a house wall), insulation, and finish elements or surfaces (such as drywall or panelling). Mass-walls are of a solid material including masonry, concrete including slipform stonemasonry, log building, cordwood construction, adobe, rammed earth, cob, earthbag construction, bottles, tin cans, straw-bale construction, and ice. Walls may or may not be leadbearing. Walls are required to conform to the local building and/or fire codes.

There are three basic methods walls control water intrusion: moisture storage, drained cladding, or face-sealed cladding. Moisture storage is typical of stone and brick mass-wall buildings where moisture is absorbed and released by the walls of the structure itself. Drained cladding also known as screened walls acknowledges moisture will penetrate the cladding so a moisture barrier such as housewrap or felt paper inside the cladding provides a second line of defense and sometimes a drainage plane or air gap allows a path for the moisture to drain down through and exit the wall. Sometimes ventilation is provided in addition to the drainage plane such as in rainscreen construction. Face-sealed also called barrier wall or perfect barrier cladding relies on maintaining a leak-free surface of the cladding. Examples of face sealed cladding are the early exterior insulation finishing systems, structural glazing, metal clad panels, and corrugated metal.

Building walls frequently become works of art, externally and internally, such as when featuring mosaic work or when murals are painted on them; or as design foci when they exhibit textures or painted finishes for effect.

Curtain wall

In architecture and civil engineering, curtain wall refers to a building facade that is not load-bearing but provides decoration, finish, front, face, or historical preservation.

Precast wall
Precast walls are walls which have been manufactured in a factory and then shipped to where it is needed, ready to install. It is faster to install compared to brick and other walls and may have a lower cost compared to other types of wall. Precast walls are cost effective compare to Brick Wall compound wall.

Mullion wall
Mullion walls are a structural system that carries the load of the floor slab on prefabricated panels around the perimeter.

Partition wall
A partition wall is a usually thin wall that is used to separate or divide a room, primarily a pre-existing one. Partition walls are usually not load-bearing, and can be constructed out of many materials, including steel panels, bricks, cloth, plastic, plasterboard, wood, blocks of clay, terracotta, concrete, and glass.

Some partition walls are made of sheet glass. Glass partition walls are a series of individual toughened glass panels mounted in wood or metal framing. They may be suspended from or slide along a robust aluminium ceiling track. The system does not require the use of a floor guide, which allows easy operation and an uninterrupted threshold.

A timber partition consists of a wooden framework, supported on the floor or by side walls. Metal lath and plaster, properly laid, forms a reinforced partition wall. Partition walls constructed from fibre cement backer board are popular as bases for tiling in kitchens or in wet areas like bathrooms. Galvanized sheet fixed to wooden or steel members are mostly adopted in works of temporary character. Plain or reinforced partition walls may also be constructed from concrete, including pre-cast concrete blocks. Metal framed partitioning is also available. This partition consists of track (used primarily at the base and head of the partition) and studs (vertical sections fixed into the track typically spaced at 24", 16", or at 12").

Internal wall partitions, also known as office partitioning, are usually made of plasterboard (drywall) or varieties of glass. Toughened glass is a common option, as low-iron glass (better known as opti-white glass) increases light and solar heat transmission.

Wall partitions are constructed using beads and tracking that is either hung from the ceiling or fixed into the ground. The panels are inserted into the tracking and fixed. Some wall partition variations specify their fire resistance and acoustic performance rating.

 * Movable partitions

Movable partitions are walls that open to join two or more rooms into one large floor area. These include:
 * Sliding—a series of panels that slide in tracks fixed to the floor and ceiling, similar sliding doors
 * Sliding and folding doors —similar to sliding folding doors, these are good for smaller spans
 * Folding partition walls - a series of interlocking panels suspended from an overhead track that when extended provide an acoustical separation, and when retracted stack against a wall, ceiling, closet, or ceiling pocket.
 * Screens—usually constructed of a metal or timber frame fixed with plywood and chipboard and supported with legs for free standing and easy movement
 * Pipe and drape—fixed or telescopic uprights and horizontals provide a ground supported drape system with removable panels.

Party wall
Party walls are walls that separate buildings or units within a building. They provide fire resistance and sound resistance between occupants in a building. The minimum fire resistance and sound resistance required for the party wall is determined by a building code and may be modified to suit a variety of situations. Ownership of such walls can become a legal issue. It is not a load-bearing wall and may be owned by different people.

Infill wall
An infill wall is the supported wall that closes the perimeter of a building constructed with a three-dimensional framework structure.

Fire wall
Fire walls resist spread of fire within or sometimes between structures to provide passive fire protection. A delay in the spread of fire gives occupants more time to escape and fire fighters more time to extinguish the fire. Some fire walls allow fire resistive window assemblies, and are made of non-combustible material such as concrete, cement block, brick, or fire rated drywall. Wall penetrations are sealed with fire resistive materials. A doorway in a firewall must have a rated fire door. Fire walls provide varying resistance to the spread of fire, (e.g., one, two, three or four hours). Firewalls can also act as smoke barriers when constructed vertically from slab to roof deck and horizontally from an exterior wall to exterior wall subdividing a building into sections.

Shear wall
Shear walls resist lateral forces such as in an earthquake or severe wind. There are different kinds of shear walls such as the steel plate shear wall.

Knee wall
Knee walls are short walls that either support rafters or add height in the top floor rooms of houses. In a $1 1/2$-story house, the knee wall supports the half story.

Cavity wall
Cavity walls are walls made with a space between two "skins" to inhibit heat transfer.

Pony wall
Pony wall (or dwarf wall) is a general term for short walls, such as:
 * A half wall that only extends partway from floor to ceiling, without supporting anything
 * A stem wall—a concrete wall that extends from the foundation slab to the cripple wall or floor joists
 * A cripple wall—a framed wall from the stem wall or foundation slab to the floor joists

Demountable wall
Demountable walls fall into 3 different main types:
 * Glass walls (unitesed panels or butt joint),
 * Laminated particle board walls (this may also include other finishes, such as whiteboards, cork board, magnetic, etc., typically all on purpose-made wall studs)
 * Drywall

Solar energy
A trombe wall in passive solar building design acts as a heat sink.

Shipbuilding
On a ship, a wall that separates major compartments is called a bulkhead. A thinner wall between cabins is called a partition.

Boundary wall
Boundary walls include privacy walls, boundary-marking walls on property, and town walls. These intergrade into fences. The conventional differentiation is that a fence is of minimal thickness and often open in nature, while a wall is usually more than a nominal thickness and is completely closed, or opaque. More to the point, an exterior structure of wood or wire is generally called a fence—but one of masonry is a wall. A common term for both is barrier, which is convenient for structures that are partly wall and partly fence—for example the Berlin Wall. Another kind of wall-fence ambiguity is the ha-ha—which is set below ground level to protect a view, yet acts as a barrier (to cattle, for example).

Before the invention of artillery, many of the world's cities and towns, particularly in Europe and Asia, had defensive or protective walls (also called town walls or city walls). In fact, the English word "wall" derives from Latin vallum—a type of fortification wall. These walls are no longer relevant for defense, so such cities have grown beyond their walls, and many fortification walls, or portions of them, have been torn down—for example in Rome, Italy and Beijing, China. Examples of protective walls on a much larger scale include the Great Wall of China and Hadrian's Wall.

Border wall
Some walls formally mark the border between one population and another. A border wall is constructed to limit the movement of people across a certain line or border. These structures vary in placement with regard to international borders and topography. The most famous example of border barrier in history is probably the Great Wall of China, a series of walls that separated the Empire of China from nomadic powers to the north. The most prominent recent example is the Berlin Wall, which surrounded the enclave of West Berlin and separated it from East Germany for most of the Cold War era. The US-Mexico border wall, separating the United States and Mexico, is another recent example.

Retaining wall
Dry Stone Wall - Blackmile Lane, Grendon, Northamptonshire.jpg wall - Inca wall at Machu Picchu, Peru]] Western side of the Great Mosque of Kairouan.jpg (also called the Mosque of Uqba) in the city of Kairouan in Tunisia.]] In areas of rocky soils around the world, farmers have often pulled large quantities of stone out of their fields to make farming easier and have stacked those stones to make walls that either mark the field boundary, or the property boundary, or both.
 * Dry-stone wall - Grendon]]

Retaining walls resist movement of earth, stone, or water. They may be part of a building or external. The ground surface or water on one side of a retaining wall is typically higher than on the other side. A dike is a retaining wall, as is a levee, a load-bearing foundation wall, and a sea wall.

Shared wall
Special laws often govern walls that neighbouring properties share. Typically, one neighbour cannot alter the common wall if it is likely to affect the building or property on the other side. A wall may also separate apartment or hotel rooms from each other. Each wall has two sides and breaking a wall on one side will break the wall on the other side.

Portable wall
Portable walls, such as room dividers or portable partitions divide a larger open space into smaller rooms. Portable walls can be static, such as cubicle walls, or can be wall panels mounted on casters to provide an easy way to reconfigure assembly space. They are often found inside schools, churches, convention centers, hotels, and corporate facilities.

Temporary wall
A temporary wall is constructed for easy removal or demolition. A typical temporary wall can be constructed with 1⁄2" (6 mm) to 5⁄8" (16 mm) sheet rock (plasterboard), metal 2 × 3s (approx. 5 × 7 cm), or 2 × 4s, or taped, plastered and compounded. Most installation companies use lattice (strips of wood) to cover the joints of the temporary wall with the ceiling. These are sometimes known as pressurized walls or temporary pressurized walls.

Walls in popular culture
Walls are often seen in popular culture, oftentimes representing barriers preventing progress or entry. For example:

 * Fictional and symbolic walls

The progressive/psychedelic rock band Pink Floyd used a metaphorical wall to represent the isolation felt by the protagonist of their 1979 concept album The Wall.

The American poet laureate Robert Frost describes a pointless rock wall as a metaphor for the myopia of the culture-bound in his poem "Mending Wall", published in 1914.

Walls are a recurring symbol in Ursula K. Le Guin's 1974 novel ''The Dispossessed'.

In some cases, a wall may refer to an individual's debilitating mental or physical condition, seen as an impassable barrier.

In George R. R. Martin's A Song of Ice and Fire series and its television adaptation, Game of Thrones, The Wall plays multiple important roles: as a colossal fortification, made of ice and fortified with magic spells; as a cultural barrier; and as a codification of assumptions. Breaches of the wall, who is allowed to cross it and who is not, and its destruction have important symbolic, logistical, and socio-political implications in the storyline. Reportedly over 700 feet high and 100 leagues (300 miles) wide, it divides the northern border of the Seven Kingdoms realm from the domain of the wildlings and several categories of undead who live beyond it.

In a real-life example, the Berlin Wall, constructed by the Soviet Union to divide Berlin into NATO and Warsaw Pact zones of occupation, became a worldwide symbol of oppression and isolation.
 * Historical walls

Another common usage is as a communal surface to write upon. For instance the social networking site Facebook previously used an electronic "wall" to log the scrawls of friends until it was replaced by the "timeline" feature.
 * Social media walls

title: Wall


text:
User:Sandos

Swede working with Java programming.

My /sandbox.

title: User:Sandos