A Hirschberg

J Gilbert

R Msallam

A P J Wijnands

Shock Waves in Trombones

Based on physical models of musical instruments and of the human voice, a new generation of sound syntesizers is born: virtual instruments. The models used for wind-instruments are simple feedback loops in uhich a non-linear sound source drives a linear,filter representing the pipe of the instrument. While very rewarding musical sounds have been obtained with these models, it has become obvious that some essential phenomena escape such a description. In particular the brightness of the sound generated by trombones is expected to be due to the essential non-linearity of the wave propagation in the pipe. At fortissimo levels this leads to shock wave formation observed in our experiments both from pressure measurements and flow visualization. A modest modification of the physical model could already take this phenomenon into account. The key idea is that the non-linear effect is essential for the transfer of sound from the source towards the listener, but can be ignored in a model of the generation of the pipe oscillations.

Wind instruments are currently described as feedback system in which a non-linear amplifier, the sound source, drives a linear filter, the pipe [START_REF] Fletcher | The Physics of Musical Intrument[END_REF] . Highly simplified physical models of the clarinet and of the violin based on the method propoed by Mc Intyre, Schumacher and Woodhouse [START_REF] Mcityre | On the oscillations of musical instruments[END_REF] have demonstrated that musically interesting signals could be obtained by caricatures which require only a modest computational power to produce sound in real time. The first commercial "virtual instruments" based on this principle were welcomed last year as musically very rewarding [START_REF] Rideout | Yamaha VL1 virtual acoustic synthesiser[END_REF] . These models are obviously also useful as design tools for the craftsmen of conventional musical instruments. Even more simplified "source/filter" models in which the feedback from the filter towards the source is ignored, allow a considerable data compression of the speech signal in telecommunication. Better physical models of both wind instruments and of the human voice production would certainly he welcome for a wide range of applications

The non-linearity of the oscillator is a key aspect which is essential to reach steady oscillations in a feedback system and to determine the perceptive quality of the sound [START_REF] Fletcher | The Physics of Musical Intrument[END_REF] . We focus in this paper on the hypothesis of a linear response of the pipe which has already been subject to controversy in the recent past. Backus and Hundley [START_REF] Backus | Harmonic generation in the trumpet[END_REF] report an essentially linear transfer function between the mouthpiece pressure fluctuations of an artificially blown trumpet and the radiated sound field at the listener position. Only a few per cent second harmonic generation by non-linear distortion were observed at the highest levels. These results were contradicted by later measurements of the amplitude dependency of the transfer function of a trombone by Beauchamp ( [START_REF] Beauchamp | Analysis of simultaneous mouthpiece and output waveforms[END_REF] , [START_REF] Beauchamp | Wind instrument transfer rsponse[END_REF] ). Beauchamp [START_REF] Beauchamp | [END_REF] had some doubt about his data, in particular the analogous tape recorder which had been used. In our experiments we used piezo electrical gauges (Kistler 603-A) with corresponding charge amplifiers (Kistler type 5007, band width lHz < f < 180kHz) for the internal pressure measurements and a l/8 inch BK condensator microphone with corresponding electronics outside the pipe. This in combination with modern electronic registration garantees the linearity and the bandwidth necessary in order to observe shock waves. Our experimental results, shown in Figure 1, confirm a violent non-linear behaviour of a trombone and provide an indication for the cause of the brightness of related brass instruments played at fortissimo levels. We observe the formation of stepwise pressure jumps. For the fortissimo level (ff) of the higher note shown in Figure 1 b), the pressurerise time corresponds to the travel time of the wave on the surface of the microphone As we will explain further on, the non-linerity in the tranfer function depends crucially on a primary nonlinearity of the source. The flow control by the lip-mouthpiece combination results into a particularly sharp presure rise during the oscillation. It is this compression phase which by non-linear wave propagation generate a shock wave. We now therefore try to understand why this occurs in a trombone while it does not occur in most instruments. A simple explanation for the generation of this highly non-sinusoidal mouthpiece pressure p m has been proposed for the trumpet by Backus and Hundley [START_REF] Backus | Harmonic generation in the trumpet[END_REF] and for the trombone by Elliot and Bowsher [START_REF] Elliott | Regeneration in brass wind instruments[END_REF] . As shown in Figure 1 for a low pitch, the observed mouthpiece pressure signal p m , is rather constant during much of the cycle, remaining close to the players driving pressure. This is due to the fact that the aperture between the lip is large compared to the neck of thc mouthpiece shown in Figure2: the neck controls the flow. The pressure varies sudddenly during the short time intervals in which the lips take the flow control over because they close completely. This results into the characteristic strong negative pressure pulses observed in Figure 1. This effect becomes stronger with increasing playing level. The details of the collision of the lips at closure is certainly critical. In voiced speech production [START_REF] Pelorson | Theoretical and experimental study of quasisteady-flow separation within the glottis during phonation[END_REF] or in double red instruments [START_REF] Gokhshtein | Self-vibration of finite amplitude in a tube with a reed[END_REF] most of the radiated high frequency sound is generated in the closing phase of the "reed" movement. In contrast to this we will see that for the trombone the crucial phase of the cycle is the opening of the lips, corresponding to the compresion phase in p m It appears that, Backus and Hundley's mouthpiece pressure signals are dominated by much lower frequencies than our signals. Their signals do certainly not display such high pressure rise rates ( p m / t) max as the signals we have measured. The 160dB mouth pressure amplitude reported by Backus and Hundley in their experiments, correspond to oscillation amplitudes of about 3kPa. This is much lower than our pressure fluctuations as shown in Figure 1. Also Backus and Hundley report measurements on a trumpet which can have a much shorter pipe than our trombone.

We now also can rationalize the behaviour of the pipe of the clarinet which we described earlier [START_REF] Hirschberg | Musical aero-acoustics of the clarinet[END_REF] . The reed channel of a clarinet is always much smaller than the pipe cross sectional area. The flow therefore is always controlled by the reed movement. In addition to this, the lay of the mouthpiece of a clarinet is curved in such a way that the reed closes gradually, the flow is never interrupted abruptly. This results into a fairly sinuoidal oscillation of the presure in the mouthpiece, even at fortissimo levels. Even though the oscillation amplitudes where comparable to lose found in the trombone, we found a very reasonable prediction of a linear model for the transfer of sound from the pipe to the listener in the case of a clarinet [START_REF] Hirschberg | Musical aero-acoustics of the clarinet[END_REF] . We could not even observe the non-linearities which certainly occur, for low pitches at fortissimo levels a result of vortex shedding at the pipe end and tone holes [START_REF] Disselhorst | Flow in the exit of open pipes during acoustic resonance[END_REF] .

The very strong non-linearity of the acoustical drive of the trombone already explains much of the observed difference between the sounds of the clarinet and of the trombone. Simple models as proposed by Strong [START_REF] Strong | Simulation of a player-trumpet system[END_REF] already generate typical brass sounds but certainly not the specific brightness of the sound at fortissimo levels. This effect is controlled by the non-linear wave propagation in the pipe which we discuss now.

As the most relevant high frequencies are very efficiently radiated away at the horn, we neglect reflection at the pipe termination. We therefore can assume the propagation of a simple wave into a uniform region. Starting from the measured mouthpiece pressure p m (t) and assuming a frictionless simple wave propagation along a pipe of uniform cross section, we can obtain an analytical prediction of the wave distortion. Thc calculation is based on the classical method of characteristics [START_REF] Pierce | Acoustics[END_REF] . Due to the increase in speed of sound c with the temperature and the convective effects, the top of compression side of waves tend to catch up with the foot of thc wave. It appcars that the ratio of the pressure fluctuations p m to the mean atmospheric pressure P at is not the relevant parameter to judge the severity of the non-linear steepning. Theory predicts that for distance larger than the critical distance x, given by: where = 1.4 is the Poisson constant, a shock wave is formed. The pressure profile predicted by integration along characteristics becomes multiple valued. The position and strength of this shock can be estimated from this multiple valued solution within the framework of a frictionless theory as for example the weak shock theory ( [START_REF] Pierce | Acoustics[END_REF] , [START_REF] Crighton | Modern Mathematical Methods In Acustics[END_REF] ). The shock path in a (x, t) diagram is along the bisectrice of the angle formed by two characteristics of the same family which intersect in the region of multiple value solution. The weak shock speed is the mean value of the speed of the two intersecting characteristics. Equation (1) gives the first point of the shock path from which the shock path can be integrated numerically.

Even for the weak shock which we expect here, shock wave certainly correspond to a dramatic amount of high frequencies in the radiated sound: a bright "metallic" soud. As x S , is determined by ( p m / t) max we understand the importance of the initial non-linearity of the source which we discussed above.

Using data shown in Figure 1 we see by using the formula for x S that shock waves can be expected at fortissimo level because the cylindrical pipe segment in the trombone (2m to 3m) is longer than S . Indeed in Figure 1 we see pressure discontinuities in the pressure signal measured at the end of this cylindrical pipe segment. Schlieren flow visualisation obtained with a Nanolite spark discharge (80 ns) indicates again a very sharp wave front at exit of thc horn (see Figure 2). This wave of at most a millimeter thickness corresponds to the sharp pulse in the pressure signal p r detected by the microphone (see Figure 1). Shock waves are certainly formed in a trombone under typical playing conditions. We can also expect that non-linear wave propagation is musically relevant for thc trumpet.

It is interesting to note that "bright" instruments such as the trumpet and the trombone are different from brass instruments such as Saxhorns or Fluglehorns. The bright instruments have a cylindrical pipe segment just downstream of the mouthpiece. The conical bore of the Saxhorns implies a faster decay of the wave which reduces the non-linear wave steepening. This seems to confirm that the brightness is associated with shock wave formation.

The essential role of the cylindrical portion of the bore and the strong increase of radiation efficiency with the frequency are the important components in a simple explanation of this effect. As high frequencies are not reflected at the pipe termination they do not contribute to the regeneration of the lip oscillation. We expect that a simple linear model of the pipe taking into account at least the eight first resonances should be able to describe the lip oscillation. Once the lip movement is known, the calculated mouthpiece pressure could be used for a non-linear propagation model. In this model the mouthpiece pressure would drive a simple wave into a cylindrical bore. Weak shock theory can be used to predict the shock wave, if relevant. The calculated pressure signal at the end of the cylindrical bore would then be radiated away by a linear model of the horn, keeping by filtering the relevant audio-range of frequency, to avoid numerical problems with the shock waves. This type of carricature is simple enough so that it could be implemented in a virtual instrument. Pressure measured in the first position of a trombone for two pitches a)low and b)high at various playing levels : piano(p), mezzo-forte(mf), fortissimo(ff). We clearly observe the increased non-harmonicity of mouthpiece pressure p m and non-linear wave steepening in the pipe pressure p p with increasing playing level. Comparison of p m and p p with the pressure p measured at the horn exit clearly demonstrate that the radiated sound is dominated by the high frequencies. The pressures p m in the mouthpiece and p p at the end of the cylindrical pipe section, have been measured by means of acceleration compensated piezoelectrical gages (Kistler 60A) coated with a O.lmm silicone layer to avoid thermal effects. The band-width of the filters of the charge amplifiers was 1 Hz < f < 180 kHz. An additional condensator microphone with a comparable bandwith (BK 1/8 inch.) measures the acoustical pressure p at 4.5 cm from the horn exit on the axis.

Figure Captions:

Figure 1 :

 1 Figure 1:

Figure 2 :

 2 Figure 2: A schematic representation of the trombone used in our experiments (A.Courtois trombone type 155, A. Courtois mouthpiece type 10 PM) with an indication of the position of the microphones. A typical flow visualization of a shock wave at the exit of the horn is shown. The mouthpiece geometry is specified.

Acknowledgements:

This collaboration between various institutes has been made possible by the support of the French Research Council (CNRS), the Dutch Research Council (NWO) and the French Embassy in the Den Haag.


Bernard Kamsu-Foguem
email: bernard.kamsu-foguem@enit.fr

Clovis Foguem

Telemedicine and mobile health with integrative medicine in developing countries

Keywords: Telemedicine, Mobile health, Complementary healthcare, Integrated medicine, Collaborative knowledge building

African Home-based Care (AHC) and African Traditional Medicine (ATM) provide a number of self-sustainable primary health care workers in a rural region with the appreciation of ancestral knowledge and its contextual management. Even though most urban residents are able to afford and use conventional medicine to large extent, the implementations of modern medicine in rural areas and in poor peri-urban areas are limited. Our proposal is on how telemedicine solutions could enhance AHC and ATM practices and facilitate simultaneous delivery of both modern and traditional healthcare with evident added value to the recipients. This is indeed a fresh angle, as information and communication technologies (ICTs) could play an important role in developing countries in the management of patients and enhance quality care for patients in particular and healthcare (both traditional and modern heath systems) in general. This delivers comprehensive insights concerning the implementation on telemedicine where integrative medicine and African traditional medicine is in the back seat.

Objective

The term African Home-based Care (AHC) is used differently in different parts of Africa. In some cases it is managed by public health department and offers primary care, health promotion and prevention programs. In other cases, it is a traditional community health center that serves as the point of contact between the community members and the traditional health care provider for counseling and traditional medicine.

African Home-based Care (AHC) offers self-sustainable primary healthcare workers in a rural region with the appreciation of ancestral knowledge and its contextual management. Even though most urban residents are able to afford and use conventional medicine to a large extent, the implementation of modern medicine in remote rural or poor peri-urban African areas is limited. Especially in rural communities where there are few or no doctors, AHC or ATM are usually the primary source of medical care. Many local communities consider ATM as a complementary medical system. The activities of an AHC are supported by informal and formal primary caregivers that deliver extensive basic nursing services, such as physical, educational, psychological and spiritual care for both patients and their relatives [START_REF] Mashiri | PG report: rural accessibility & development, unpacking the relationship between rural healthcare, mobility & access[END_REF].

In Africa, African Traditional Medicine (ATM) is believed to sometimes offer unsuspected efficacy where the practices of modern medicine fail or are powerless to supply treatment, particularly for routine ailments such as tropical diseases, allergies or psychiatric diseases. The spirit of ATM is human interaction using indigenous knowledge that is gained experientially, externalized and transmitted mostly through verbal expressions and gestures with some secret initiatic traditions [START_REF] David | South African indigenous healing: how it works[END_REF]. At present, the practice of ATM is evolving; for instance, some urban Traditional Practitioners (TP) use conventional medicine facilities including medical tests for diagnosis and/or post-treatment checking [START_REF] Hillenbrand | Improving traditional-conventional medicine collaboration: perspectives from Cameroonian traditional practitioners[END_REF]. However, this is not the generally reported experience, especially in rural communities throughout Africa.

Telemedicine is a sub-set of eHealth electronic process in health using information and communication technologies (ICT) for [START_REF] Simon | Le décret français de télémédecine: une garantie pour les médecins[END_REF]:

Teleconsultation, a procedure whereby medical profes- sionals can consult a patient remotely and interpret the necessary data remotely. This consists of explanations and their rationale for suggested diagnosis and management plans with counseling in risk factor control and indications of treatment designed to reduce problem. After it is possible to make actions for medical followup.

Medical Second Opinion Service or Teleexpertise, whereby a medical professional can seek remotely an opinion of other medical professionals who have the relevant training or skills. It allows people to obtain a valuable medical second opinion in the case of the diagnosis and treatment of non-critical and critical illnesses (e.g. skin and respiratory diseases, as well as nephrology disorders). This telemedicine service is intended to assist patients and their attending physician to improve healthcare outcome by a diagnostic revision and treatment enhancement.

Telemonitoring, the ability to monitor and supervise patients remotely. The medical data can be obtained automatically on a pre-defined periodic basis (remote follow-up) or on a daily basis (remote monitoring) by the device which dispatches them from the patient's home to the medical doctor.

Remote handling or Teleassistance, a procedure which enables a medical professional to assist remotely another healthcare professional during the realization of a medical act. This would correspond to two typical situations. First case: it may concern robotic telesurgery in which the expert surgeon performs the surgery form a distance through a robotic device. Second case: remote ultrasound examination in which the expert physician remotely directs the local ultrasonographer as to how to position the probe, and sometimes the expert may control the movements of a medical probe using ultrasonographic visualizations to perform useful assessments.

The objectives of telemedicine and its applications are to enhance the availability of various medical services and healthcare despite geographical and economic barriers, to reduce direct and indirect cost to patients and the healthcare industry, to save travel time and costs for both practitioners and patients from one geographical location to another, and to improve consultation and co-operation among various units of healthcare in both special cases and primary care by bridging the distance between practitioners and specialists [START_REF] Louis | Telemedicine in Europe[END_REF][START_REF] Lareng | Telemedicine: greatness and sadness[END_REF]. There is an expectation that mobile phones will facilitate a range of telemedicine activities (cardiology, radiology, dermatology, obstetrics, psychiatry and ophthalmology) in Africa with a deep cultural immersion experience that generates a better understanding of local cultures' values, activities and prerequisites [START_REF] Mars | Telemedicine and advances in urban and rural healthcare delivery in Africa[END_REF].

It is crucial to make this medical framework a systemic and very well locally integrated model by ensuring that practices are suited to the patient's belief and cultural environment. In primary care the concept "holistic", has been used to describe models that take into account social reflections and other contextual approaches [START_REF] Julian | The political economy of health care[END_REF]. Our research interest with telemedicine in Africa speaks most pointedly to this, as it indicates the possible way to embed the holistic concept into the management practices. As the informal and formal primary caregivers offer cultural and social insights to conventional medical staff (including information regarding local traditional medical activities), the cultural immersion they experience makes it easier for them to adapt allopathic medicine by integrating some cultural elements from ATM environment. Looking at it from the alternate aspect, these holistic medical practices play an important role for caregivers and patients in AHC, as they could use the facilities to stay in touch with their cultural background. Patient care tends to become more comprehensive when complementary medicine is integrated conventional healthcare organizations [START_REF] Keshet | Can holism be practiced in a biomedical setting? A qualitative study of the integration of complementary medicine to a surgical department[END_REF].

Traditional medicine is now offered alongside allopathic medicine at several locations in the African countries. Supply and distribution of medicinal products is mainly through the informal sector (e.g. traveling vendors of drugs (hucksters and peddlers), traditional health units or other informal drugstores). So, in these contextual situations, treatment is a broad concept and includes western, allopathic medicine as well as traditional medicine (complementary and alternative medicine). All these forms of conventional or traditional treatments, to some levels in their composition and properties, rely on natural substances, or elements synthesized from the natural environment.

The application of information and communication technologies can facilitate knowledge and information exchanges within the different actors with a view to improve patient health care services. It could stimulate information transfer in both directions, opens opportunities and improves experience feedbacks through possible useful collaborations and helps organize primary health care needs. Therefore this offers exceptional value to collaborative activities between informal and formal primary caregivers by creating networking opportunities, supporting and augmenting the visibility of initiatives that help sustain Western health and traditional practitioners' participation in efficient and safe practices.

Proposed approach to eHealth (telemedicine and mHealth) in Africa

According to World Health Organization (WHO) and International Telecommunication Union (ITU), eHealth (electronic process in health) is defined as "the use of information and communication technologies (ICT) for health" [START_REF]ITU: National eHealth Strategy Toolkit[END_REF]. In particular, the applications of mHealth (mobile Health) and telemedicine are two sub-sets of eHealth as both involve the use of information and communications technology. These two applications have their own distinct features, varying in dimensions, deployments and configurations.

Telemedicine in Africa

In African countries, predominantly a great percentage of the people still live in rural regions and peri-urban areas, where healthcare access and delivery are sometimes reduced, and would possibly profit from advanced service schemes with supporting technical architectures and tools.

Tools such as telemedicine, tele-education, and health informatics have of late been incorporated in the health sector to enable easy access to essential services [START_REF] Wamala | A meta-analysis of telemedicine success in Africa[END_REF]. Training programmes and collaborative ways of working also contribute to fresh online services where teamwork between the official heath care actors and its community volunteers (with modern or traditional medical knowledge) takes a very new scope. The ICT work environment and associated workflow open doors and create opportunities for these formal and informal healthcare actors through unique sustainable programs [START_REF] Joseph | A sustainable and affordable support system for rural healthcare delivery[END_REF]. Optimally used, the telemedicine would provide best practices and virtual learning facilities, especially with respect to AHC methods. For an optimum adaptation to the prevailing terrain conditions, telemedicine needs to incorporate flexibility with traditional symbols and teachings in the contextual health delivery schemes.

There is need to explain the constraints that generate some mismatches between Information System designs and local user actuality in developing countries [START_REF] Heeks | Information systems and developing countries: failure, success, and local improvisations[END_REF]. It therefore appears desirable to provide the full range of along with counseling, to help primary caregivers obtain a method that best suits their necessities in both preventive and therapeutic activities. The idea is to facilitate access to the basic primary care -first-aid instruction, emergency response and medical information for communities who are isolated from appropriate medical institutions. It requires strategies to be means of guidance, training, support and long-term monitoring; or in the other sides to ensure information sharing to better understand a specific endemic situation and health system context. Patient information is best understood through the use of simple terminology, visual language (e.g. signs of cleansing and healing), readable images and the use of both scientific and vernacular names [START_REF] Bernard | Conceptual graph-based knowledge representation for supporting reasoning in African traditional medicine[END_REF][START_REF] Bernard | Adverse drug reactions in some African Herbal medicine: literature review and stakeholders' interview[END_REF]. Due to remote solutions it is possible to reach optimally collective intelligence in collaborative actions between local health actors. The considered collaborative framework can include computerized guidelines for a group of local health actors. It may also be possible to combine this assistance with traditional medicinal knowledge that are evidence-based and integrate best practices in order to provide an understandable overview of the full nature and extent of the considered diseases and treatments for improvements in the contextual care system.

Mobile health technology

The mobile health (mHealth) technology is considered to refer to the incorporation of mobile computing, medical sensors, and portable devices to ensure health care [START_REF] Istepanian | Guest editorial introduction to the special section on m-health: beyond seamless mobility and global wireless health-care connectivity[END_REF]. Furthermore, mHealth affirms its interest further to investigate and to draw up an integration of the advances in wireless communication, ubiquitous computing and "wearable" devices technologies in the health area [START_REF] Abajo | m-Health y T-Health[END_REF][START_REF] Tachakra | Mobile e-Health: the unwired evolution of telemedicine[END_REF].

The services of eHealth care actors are helping to address the issues of access, improvement of primary care, particularly for the most vulnerable people (e.g. the seniors' population) and undeserved communities in both developed and developing regions of the world [START_REF] Iwaya | Mobile health in emerging countries: A survey of research initiatives in Brazil[END_REF]. More generally, the creative applications of remote health information and sensing technologies are potentially useful for checking health status, enhancing patient care and supporting service delivery. This includes different activities, namely measurement, diagnostic, treatment/prevention or the global healthcare [START_REF] Santosh | Mobile health technology evaluation: the mHealth evidence workshop[END_REF]:

Measurement: remote application enables statistical measurements, thresholds for alarms, environmental temporary assessment and global positioning system.

Diagnostic: point-of-care diagnostics, graphics applications, remote analysis, sending of information on the patients' symptoms and signs for remote analysis, interpretation and diagnostics.

Treatment/prevention: prevention and wellness interventions, remote behavioral treatment, medication adherence tracking, chronic disease management, dissemination of health information and disaster support/ care.

Global healthcare: access to healthcare services, remote behavioral treatment, dissemination of health information, disease surveillance, medication tracking and safety and wellness intervention.

During the course of the last few years, there are a growing number of mHeath initiatives, but some of which will involve different application procedures. On the basis of comprehensive characteristics of employed terminology and their meaning, the World Health Organization (WHO) has proposed a classification of key research areas in mHealth [START_REF] Who | New horizons for health through mobile technologies: second global survey on eHealth[END_REF] The WHO's analysis provides an overview of adoption of mHealth initiatives and their implementation stages in America [START_REF] Institute | Barriers and gaps affecting mhealth in low and middle income countries: a policy white paper[END_REF]. The survey indicates that the less wellestablished applications are the following classes: health surveys & surveillance (e.g. through the implementation of the District Health Information Software (DHIS2) [START_REF] Aksel Sanner Terje | From pilot to scale: towards an mHealth typology for low-resource contexts[END_REF]), patient records, patient monitoring, decision support systems, treatment compliance and awareness raising.

A recent report of the World Bank has classified mHealth initiatives in developing countries into the seven distinct categories described in Table 1. Some studies of selected mobile health deployments in Africa have been added, and summarized in Table 2 emphasizing their main specificities.

There are also different projects for screening and treatment aided by the use of telemedicine established in some developing countries (e.g. mobile diabetic retinopathy screening and treatment models in India [START_REF] Krishna | Mobile diabetes eye care: experience in developing countries[END_REF]), which can be readily replicated in African countries presented with similar difficulties. Given the shortage of corroborations about the scope and the impact of the mobile phone research programs concentrated on health purposes [START_REF] Gurman | Effectiveness of mHealth behavior change communication interventions in developing countries: a systematic review of the literature[END_REF], the data from some recent studies may aid health professionals and those responsible for implementing programs and technical conditions to measure the utility or value of reaching African people via mobile phone [START_REF] Vahdat Heather | There are some questions you may not ask in a clinic: providing contraception information to young people in Kenya using SMS[END_REF].

Discussion

In the foreseeable future, we hope that telehealth solutions could enhance AHC or ATM practices and facilitate the complementary delivery of both modern and traditional healthcares with evident added value to the recipients.

In principle, there are two ways in which the use of telemedicine can help promoting the understanding and establishment of communication between African traditional medicine practitioners and doctors providing Western medicine:

(i) either in a direct way through political integrative medicine actions for rural communities that create opportunities to integrate traditional and allopathic healthcare issues; (ii) or in an indirect way through a network of primary-care actors acting as bedside intermediaries between the allopathic health practitioners and the African traditional practitioners.

Therefore, the emergence of telemedicine can be seen as an opportunity for national health authorities to renew knowledge for medical policy-making and actions in response to the need to improve health care services (quality and safety) for rural communities. The major problem which is making a huge negative impact on Africa's telecommunications today is the high cost of bandwidth and this in turn affects connectivity for an effective electronic network in order to provide rural telemedicine solutions in Africa.

More effective and transparent price ICT (as mobile phone and Internet services) is needed in order to deliver the full advantages of advanced information technology infrastructures to African people. In this context, the technological progresses shall be accompanied by a better understanding of the wide-area of social science research on health in Africa. In a great many situations, compared to traditional communication means, telemedicine could potentially play an important role in developing countries, for improvements in traditional health systems and the use of news ICT to inform general populations on health and healthcare [START_REF] Henry | Information and communications technology for future health systems in developing countries[END_REF].

Despite their apparent promise, advanced health information technologies have proved difficult to implement in rural African settings, since there are some local technical difficulties (e.g. Internet access limited to the minority of people) caused by the delay in delivery or unavailability of mobile communication network equipments and handsets, optical transmission equipments and communication cables and cultural constraints (e.g. challenges posed by a large number of indigenous African languages). The costs and infrastructural difficulties have limited the penetration of 3G services in rural areas of African countries. They are in fact two of the Asia's leading companies in telecommunications (India's Bharti Airtel and Japan's Softbank Corp), which are working together to engineer new cost-effective solutions using satellites to increase 3G coverage on African continent and to make satellite 3G transmission more viable [START_REF]Rural Africa, meet 3G: Asian telecoms using satellites to increase coverage[END_REF], resulting in fewer difficulties and more opportunities for the various remote services to rural areas of Africa. The evolution of the telecentre movement with sustainability considerations have generated various types of public ICT access centers in developing countries: initiatives such as the Internet café or cybercafé, Internet kiosks, Community Multimedia Centers, and 'private hucksters phone booth' have conveyed the reality of the Internet and ICT closer to more persons in developing countries [START_REF] Fillip | Making the connection: scaling telecentres for development[END_REF]. The mobile phone is the ICT of choice in the sub-Sahara [START_REF] Nicholas | Sizing up information and communication technologies as agents of political development in sub-Saharan Africa[END_REF]. Sharing mobile phones are more common in developing countries (partly for cultural and economic reasons) and this sharing has some implications for the digital divide that is greatly reduced in mobile phones [START_REF] Jeffrey | Sharing mobile phones in developing countries: implications for the digital divide[END_REF]. So, the mobile phone use in Africa offsets the inequality in mobile phone adoption and mobile penetration rate [START_REF] Jeffrey | Product use and welfare: the case of mobile phones in Africa[END_REF]. The use of shared tools for mHealth implementation require an effective strategy by the health regulators to ensure the protection of privacy and personal data, regardless of the technology used to deliver a particular medical service. This can be done through the introduction of coordinated instruments (economic and technical assistance, social dialogue and legislation) or the development of existing ones for deployment and controlling the application of operating procedures and practices. Pending resolution of the outstanding issues, the first applications of the telemedicine management services are expected to be education and counseling medical services for people in rural African regions.

There are two possible mechanisms of access to the Internet in rural areas of developing countries: one that involves intermediation at a distance (blending) and the other that takes place at close range (via say Internet kiosks) [START_REF] Jeffrey | Mechanisms of access to the Internet in rural areas of developing countries[END_REF]. Internet access in community multimedia centers, and other fixed or mobile telecentres in public or private places offer a low cost opportunity for the people who cannot afford their own phone or Internet connection [START_REF] Henten | Telecommunications development in Africa[END_REF]. Provincial urban hubs could at that moment be points of dissemination of health information to the rural areas [START_REF] Ajuwon | The level of Internet access and ICT training for health information professionals in sub-Saharan Africa[END_REF]. Levi Obijiofor describes a research-based framework for the analysis of the successful diffusion and use of ICTs at micro and macro levels in Africa; so he provides practical issues in the uptake of new technologies in different countries and communities [START_REF] Levi | Mapping theoretical and practical issues in the relationship between ICTs and Africa's socioeconomic development[END_REF]. Ousmane Birba and Abdoulaye Diagne have developed a survey (covering 17 African countries) about factors explaining the adoption of Internet with determinants that favor or hamper the use of Internet in Africa. Their study also suggests that a rural individual can probably use Internet if he has at least completed primary education [START_REF] Ousmane | Determinants of adoption of Internet in Africa: case of 17 sub-Saharan countries[END_REF]; but this is subject to Internet availability and verification of connectivity. The ICT divide is not defined as much by the economic status of a geographic location as it is by an individual user's educational background [START_REF] Dutta | Information needs and information-seeking behavior in developing countries: a review of the research[END_REF]. Furthermore, wireless technologies present great potential to reach unserved and underserved areas [START_REF] Ignatius | Exploring the potential of wireless technologies to accelerate universal Internet access in Ghana[END_REF].

There was a broad consensus that many of the legal and ethical issues (security, confidentiality and privacy) arising from the practice of eHealth have not been resolved in general [START_REF] Eike-Henner | Ethical and legal challenges for health telematics in a global world: telehealth and the technological imperative[END_REF]. Particularly, telemedicine creates new clinical risks and responsibilities that are associated to product liability and safety issues [START_REF] Benedict | Legal ethical and risk issues in telemedicine[END_REF]. Hence, there are some needs of a rigorous application of available guidelines and the legal resolution of the pending issues (lack of reimbursement, safety and quality of care, privacy, human dignity and rights) [START_REF] Gil | Telemedicine: licensing and other legal issues[END_REF].

Finally, the main challenge is moving mHealth approaches from pilot projects to national scalable programs while accurately engaging health workers and communities in the development [START_REF] Källander | Mobile Health (mHealth) approaches and lessons for increased performance and retention of community health workers in low-and middle-income countries: a review[END_REF].

Conclusion

ICT has a major role to play in generating the availability and accessibility of care facilities for rural communities. In fact, ICT applications have great potential to benefit lower isolated groups and other disadvantaged populations through the elaboration of specific small progress in the efficiency of the health care delivery system, including improvements in primary health care provisions. The influence stems in large part from the availability of prepaid Internet services, coupled with the development of mobile payphone services. The integration of remote expertise in healthcare has significant benefits for patient management in remote locations or precarious areas or situations. Periodic reviews of contextual requirements and advanced benchmarks will take place to provide the information to improve telemedicine or healthcare programs knowledge. The gained knowledge could guide the deployment of new network technologies with a long-term perspective of diagnostic/prescription system prototypes in order to improve disease surveillance and monitoring of ATM products or others drugs.

By improving their medical knowledge, primary caregivers we will be better able to target the disease and adapt treatment to achieve the best results and good safety. Telemedicine in AHC fosters a better understanding of the special needs of rural patients and primary caregivers, in addition to providing healthcare delivery organizations with reasonable access to traditional knowledge and vital information about sustainable use of natural resources. From a technology acceptance view, human factors and adoption by end users (determined by attitude, perceived usefulness, and perceived ease of use) is a key restrictive factor to successful ICT adoption in developing countries [START_REF] Russell | Implementation science approaches for integrating eHealth research into practice and policy[END_REF]. So more understanding of the current human environment in working out some knowledge-based applications that would meet the ICT prerequisites of the primary health sector in Africa is essential. The deployment of assessment studies that integrate the accessibility of technology and end-user preference is a significant human factor that should be measured in developing an appropriate ICT implementation strategy in low-resource settings [START_REF] Lanrewaju | A model for the adoption of ICT by health workers in Africa[END_REF].

The deployment of new technologies and sustainable medical practices continue to be hampered by logistical factors (e.g. the poor availability of communication equipments and terminal products or the delivery of electricity is unreliable owing to frequent power outages) as well as by organizational factors (e.g. weak human resource and management capacities) that may also be affected by general cultural, political and economic considerations (e.g. the debt burden on the national economy prevents sufficient spending on rural health program). Hence, the advances in technology need to be accompanied by the development of effective delivery mechanisms (e.g., using evidence-based intervention strategies) and novel organizational approaches (e.g., assistance in integrating the system into practice workflows and allowing for local customization) with sustainable implementations (e.g., targeting actionable priority issues for patients and healthcare teams) [START_REF] Russell | eHealth evaluation and dissemination research. (Supplement)[END_REF][START_REF] Peter | Technologies for global health[END_REF][START_REF] Patricia | Complexity and the science of implementation in Health ITknowledge gaps and future visions[END_REF]. Telemedicine could bring the best of sophisticated approaches and latest medical expertise in African Home-based Care (AHC) and permit to share and formalize African traditional medicine. The principles of providing health information feedback to frontline health staffs and community-based organizations are fundamental to support decentralized medical activities in remote areas [START_REF] Shirin | Can mobile phones help control neglected tropical diseases? Experiences from Tanzania[END_REF][START_REF] Doumbouya | Telemedicine using mobile telecommunication: towards syntactic interoperability in teleexpertise[END_REF][START_REF] Kamsu-Foguem | Systemic modeling in telemedicine[END_REF][START_REF] Kamsu-Foguem | Ontological view in telemedicine[END_REF][START_REF] Kamsu-Foguem | User-centered visual analysis using a hybrid reasoning architecture for intensive care units[END_REF][START_REF] Kamsu-Foguem | Conceptual graph operations for formal visual reasoning in the medical domain[END_REF][START_REF] Kamsu-Foguem | Using conceptual graphs for clinical guidelines representation and knowledge visualization[END_REF][START_REF] Kamsu-Foguem | Could telemedicine enhance traditional medicine practices?[END_REF][START_REF] Kamsu-Foguem | Verifying a medical protocol with temporal graphs: The case of a nosocomial disease[END_REF][START_REF] Tafin-Kampé | Acute osteomyelitis due to Staphylococcus aureus in children: What is the status of treatment today?[END_REF][START_REF] Tafin-Kampé | Vitamine D et personnes âgées : enquête auprès de 192 médecins généralistes dans les Hautes-Pyrénées[END_REF].

Ethical approval

Not required.

:

  Health call centers/Health care telephone help line, Toll-free emergency, Public health emergencies, Mobile telemedicine, Appointment reminders, Community mobilization & health promotion, Patient records, Information initiatives, Patient monitoring, Health surveys, Surveillance, Awareness raising and Decision support systems.

Table 1

 1 Seven kind of mHealth initiatives[START_REF]World Bank, maximizing mobile, information and communications for development[END_REF].

	mHealth category	Fields of application	Description/practical use
	Improving management and	Treatment of medical	Remote patient tracking
	decision-making by health	conditions	Updating and verification of digital medical records,
	care professionals	Prescriptions	accessible to health care providers and pharmacists
		Targeted provision of	Delivery of health insurance and savings products
		information and marketing
		about health care products
	Real-time and location-based	Health care delivery and	Monitoring and surveillance of disease outbreaks for
	data gathering	logistics	more timely reporting of symptoms and containment
		Crisis mapping	of epidemics
		Resource allocation	Crisis mapping after natural disasters
			Reporting of urgent health needs
			Real-time provision with information on available
			health facilities and resources
			Supply chain management
			Access to health emergency services and rapid
			response systems
	Provision of health care to	Remote provision of health	Medical advice, reminders counseling, monitoring,
	remote and difficult-to-serve	care services	simple diagnoses
	locations	Extending the reach of	Focusing on areas where only limited physical
		health care	infrastructure is available, such as remote and rural
		Complementing traditional	areas, including telenursing, teleradiology,
		face-to-face health care	telepsychiatry, and tele-education.
		services
	Fostering learning and	Medical knowledge repositories	Retrieving best practices, international standards,
	knowledge exchange among	Virtual communities	and patient histories from other health care
	health professionals	Event and conference	professionals
		organization	Local communities
			Expert crowdsourcing for health information wikis
			Virtual classrooms, webinars, and the like
	Promoting public health	Delivery of health information	Games, quizzes, and other nontraditional
		Awareness building and	mechanisms
		campaigning	Conventional mHealth prevention and education
		(Mass-oriented) tele-education	campaigns
			Medication reminders
	Improving accountability	Transparency for usage of funds	Public health fund flow tracking
		Feedback systems	Interactive portals for comments and complaints
	Self-management of patient	Enabling better self-help and	Patients obtain accurate information
	health	limiting transactions	Patients can better understand their diagnoses, for
		Lowering health care costs	example, by checking medical records
		(shifting tasks to the patient)	Mainly focused on noncommunicable diseases and
		Patient empowerment	may deal with health indicators such as weight and
			blood pressure

Table 2

 2 Selected mobile health deployments in Africa[START_REF]GSMA/PwC Report: touching lives through mobile health: assessment of the global market opportunity[END_REF].

	Country	Provider	Project	Outline
	Mali	Medic Mobile	FrontlineSMS	An SMS platform that is used for patient management. The services
				include accessing of Electronic Health Records through mobile
				phones, low cost diagnostics and mapping of health services.
	Ghana	Vodafone, Ghana	MDNet	A free voice and sms services that promotes transfer of knowledge
		Medical Association		among physicians. This service helps to send bulk SMS during national
				emergencies and contact doctors with particular speciality.
	Nigeria	We Care Solar	WE CARE Solar	WE CARE Solar's project attempts to promote safe motherhood and
				reduce maternal mortality in developing regions. This project
				provide health workers with reliable lighting, mobile
				communication, and blood bank refrigeration using solar electricity.
				The provision of mobile phones allows labor and delivery nurses to
				quickly notify on-call physicians of emergencies, and ask for advice.
	Kenya	Dimagi	Weltel	SMS service to support antiretroviral medication adherence. It helps
				health worker assist HIV patients and provides health information to
				the public. It also includes support for remote data collection and
				logistics of moving healthcare related products.
	Mozambique Canadian International	AED Satellite	CHWs use PDAs and mobile phones for data collection and access to
		Development Agency		up to date health information
	Botswana	American Academy of	Africa Tele-	Telemedicine for dermatology. Provides dermatology support to local
		Dermatology	dermatology	physicians, dermatologists, and health care workers in hospitals and
			Project	clinics throughout Africa. This support is provided through
				Teledermatology consultation services, discussion pertaining to
				diagnosis and management of patients with skin diseases, links to
				educational resources, and access to a dermatologic curriculum
				created specifically for African sites.

Funding

This research was not supported by any funding.

Competing interests

None declared.