A doença de Alzheimer (DA) é caracterizada por déficit cognitivo, associada com prejuízos no metabolismo energético e na via de sinalização da insulina encefálicos. A injeção intracerebroventricular de baixas doses de estreptozotocina (STZ) tem sido utilizada como um modelo experimental da DA em ratos. Nesse sentido, tem sido demonstrada a participação do sistema canabinoide em processos neurodegenerativos e seus efeitos neuroprotetores e anti-inflamatórios. O objetivo deste trabalho foi caracterizar as alterações comportamentais e moleculares em modelos experimentais (in vivo e in vitro) expostos à STZ e avaliar a participação do sistema canabinoide. A STZ produziu prejuízo cognitivo, morte celular por apoptose, deficiência na resposta à insulina e alterações na via IR/PI3K, semelhantes às encontradas na DA. O agonista canabinoide ACEA foi capaz de reverter o prejuízo cognitivo, modificar as alterações proteicas da via IR/PI3K, e regular positivamente a via anti-apoptótica, gerando uma neuroproteção. / Alzheimer\'s disease (AD) is characterized by cognitive deficit associated with energy metabolism impairment and changes in insulin signaling. In this context, low doses of intracerebroventricular streptozotocin (STZ) injection has been used as an experimental model of AD in rats. Several studies have demonstrated the participation of the cannabinoid system in neurodegenerative processes and its neuroprotective and anti-inflammatory properties. Thus, the aim of this work was to characterize the molecular and behavior alterations in experimental models (in vitro and in vivo) produced by STZ exposure and evaluate the cannabinoid system participation in these models. STZ was able to induce cognitive impairment, apoptosis cell death, impaired insulin response and alterations in the IR/PI3K signaling pathway, similar to those found in AD. CB1 agonist, ACEA reversed cognitive impairment and modified some protein changes in IR/PI3K pathway caused by STZ, and positively regulate the anti-apoptotic pathway, generating neuroprotection.

This field study is the result of observations of stress and disquiet among educational administrators. Two survey instruments, one to a population of A.C.E.A. members in five states and two territories of Australia, and a refined survey to administrators in two Metropolitan West Inspectorates in N.S.W. were employed. An attempt was made to look at perceived deficits, in areas considered necessary skills for educational administrators, over variables of state, sex, age, level of institution, government/nongovernment systems, status, tenure and educational administration qualifications. From the outset it was realized that the nature of the study would have to be essentially to generate directions of future specific research since there was little Australian research in the areas being surveyed. This became more obvious as data was collected and possible causes for stress, perceived deficits, and the related poor morale multiplied with each set of comments received. The only conclusion that could be unequivocal was that the areas of administrator morale, training, selection, support, style and role perception are urgently in need of in-depth research as are the effects on educational institutions of policy processes, socio-political factors and community expectations. Even with a wider literature search it becomes obvious that there is a need for researchers to rethink theory in terms of social realities and human and socio-political possibilities rather than continue building theories which have little or no effect on the education received by an Australian student in the 1980's. It is equally evident that the solution for the obvious administrator malaise and powerlessness expressed by respondents is in their own hands via a quest for excellence in education, relevance to society and socio-political understanding.

O sistema endocanabinóide (eCB) tem sido reconhecido como um importante modulador da homeostase energética e recentemente estudos o apontam como um possível integrador da homeostase hidroeletrolítica. Estudos recentes do nosso laboratório demonstraram a participação do receptor canabinóide do tipo 1 (CB1R) no controle da secreção neurohipofisária em resposta a expansão hipertônica do volume extracelular. Dessa forma, o presente trabalho visou esclarecer a participação do sistema eCB, particularmente do CB1R, nas respostas neuronais, neuroendócrinas e comportamentais induzidas pela sobrecarga salina de 4 dias (SS). Uma vez que os animais em SS apresentam hipofagia induzida pela hiperosmolalidade, buscou-se avaliar as vias de integração do controle da homeostase energética e do balanço hidroeletrolítico por meio da introdução de um grupo em dieta pareada (pair fed, PF). De forma a investigar a hipótese acima, utilizou-se como ferramenta farmacológica o agonista seletivo CB1R, araquidonil-2-cloroetilamida (ACEA - 0,1g/5L), administrado por via intracerebroventricular (icv). Inicialmente, nosso trabalho mostrou que a SS promoveu aumento da expressão de CB1R tanto nos núcleos supra-óptico (NSO) e paraventricular (NPV) do hipotálamo quanto em estruturas da lâmina terminal [órgão subfornicial (SFO), o órgão vasculoso da lâmina terminal (OVLT) e o núcleo pré-óptico mediano (MnPO)]. Tais observações foram reforçadas pela análise microscópica destas regiões cerebrais por imunofluorescência, que evidenciou aumento da imunomarcação para CB1R no NPV, NSO e SFO em animais submetidos a SS. Estes resultados também mostraram que a maioria dos terminais pré-sinápticos CB1R-positivos estão localizados predominantemente na porção ventral do NSO, na qual predominam neurônios vasopressinérgicos. Os dados mostram ainda que todas as respostas induzidas pela SS foram revertidas após a reintrodução dos líquidos (RL, água e NaCl 0,3M). Já no grupo PF, não foram observadas alterações na expressão de CB1R em nenhuma das áreas avaliadas. No entanto, após a RL, os animais PF apresentaram hipoosmolalidade plasmática e aumento da expressão de CB1R na LT, sendo este último efeito aparentemente mediado por um aumento da expressão deste receptor no SFO. Em animais normoidratados, a administração central de ACEA produziu um aumento significativo na ingestão alimentar, sendo esta resposta ausente nos animais submetidos a SS, apesar do aumento da expressão de CB1R no hipotálamo verificada neste grupo. Entretanto, o pré-tratamento com ACEA foi capaz de potencializar a ingestão de água induzida pela SS, não produzindo efeitos significativos sobre este parâmetro no grupo PF. Este estudo demonstrou ainda que a SS não alterou as concentrações plasmáticas de angiotensina II (ANGII), porém promoveu aumento signficativo nas concentrações plasmáticas de corticosterona, vasopressina (AVP) e ocitocina (OT), além de diminuir a secreção de peptídeo natriurético atrial (ANP). Em animais submetidos a SS, o prétratamento com ACEA potencializou a secreção de corticosterona e preveniu o aumento da secreção de AVP e OT. Por outro lado, não foram observados efeitos da administração de ACEA sobre a secreção de ANP e ANGII induzida pela SS. Após a RL, o grupo SS apresentou normalização das concentrações plasmáticas hormonais, não sendo observados quaisquer efeitos da administração de ACEA nestas condições experimentais. No grupo PF, por sua vez, após a RL foi observada diminuição na secreção de OT e aumento nas concentrações plasmáticas de ANGII, efeitos estes não alterados pelo pré-tratamento com ACEA. Em conjunto, nossos dados sugerem que o CB1R participa ativamente das respostas homeostáticas comportamentais e neuroendócrinas desencadeadas pela SS, sendo estas respostas especificamente relacionadas ao controle da homeostase hidrossalina e não secundárias à hipofagia induzida pela hiperosmolalidade. Desta forma, conclui-se que a participação do CB1R na homeostase hidroeletrolítica ocorre em paralelo e independentemente da modulação exercida por este receptor sobre a homeostase energética. / The endocannabinoid system (eCB) has been recognized as an important modulator of energy homeostasis and recent studies suggest that this system may play a possible integrator role on hydromineral homeostasis. Recent studies from our laboratory demonstrated the involvement of the type 1 cannabinoid receptor (CB1R) in the control of neurohypophyseal secretion in response to hypertonic extracellular volume expansion. Therefore, the present study aimed to clarify the involvement of the ECB system, particularly of CB1Rs, in neuronal, neuroendocrine and behavioral responses induced by 4 days of salt load (SS). Since the animals submitted to SS exhibit a well known state of hyperosmolality-induced hypophagia, we attempted to evaluate the integrated control of energy homeostasis and hydroelectrolytic balance through the introduction of a paired diet group (pair fed, PF). In order to achieve these goals, this study employed as a pharmacological tool the CB1R selective agonist, arachidonoyl-2\'-chloroethylamide (ACEA-0.1g/5L), administered intracerebroventricularly (icv). Initially, our work showed that SS increased the expression of CB1R in both supraoptic (SON) and paraventricular (PVN) nuclei of the hypothalamus, as well as in the structures of the lamina terminalis [subfornical organ (SFO), organum vasculosum of the lamina terminalis (OVLT) and median preoptic nucleus (MnPO)]. These observations were reinforced by the microscopic analysis of these brain regions by immunofluorescence, which showed increased immunostaining for CB1R in the PVN, SON and SFO in animals submitted to SS. These results also showed that most of the presynaptic CB1R-positive terminals are located predominantly in the ventral part of the SON, which is characterized by the presence of vasopressinergic neurons. The data also showed that all SS-induced responses were reversed after reintroduction of fluids (RF, water and 0,3M NaCl). On the other hand, no changes in the expression of CB1R in any of the evaluated areas were observed in the PF group. However, after RF, PF animals showed hypoosmolality and increased expression of CB1R in the LT, being the latter effect apparently mediated by increased expression of this receptor in SFO. In euhydrated animals, the central administration of ACEA produced a significant increase in food intake, being this response absent in animals submitted to SS, despite the increased expression of CB1R in the hypothalamus observed in this group. However, pretreatment with ACEA was able to potentiate SS-induced water intake, producing no significant effect on this parameter in the PF group. This study also demonstrated that SS did not alter plasma concentrations of angiotensin II (ANG II), but significantly increased plasma concentrations of corticosterone, vasopressin (AVP) and oxytocin (OT), and decreased the secretion of atrial natriuretic peptide (ANP). In animals submitted to SS, pretreatment with ACEA enhanced the secretion of corticosterone and prevented the increased secretion of AVP and OT. Moreover, no effect of ACEA was observed on the SS-induced ANG II and ANP secretion. After RF, the SS group showed normalization of hormonal plasma concentrations, and no effects of ACEA administration were verified under these experimental conditions. After RF, the PF group exhibited a decrease in OT secretion and increased plasma concentrations of ANG II, effects that were not altered by pretreatment with ACEA. Taken together, our data suggest that CB1Rs actively participate in behavioral and neuroendocrine homeostatic responses triggered by SS, and that these responses were specifically related to the control of hydromineral homeostasis and not secondary to the hyperosmolality-induced hypophagia. Therefore, we conclude that the involvement of CB1R in electrolyte homeostasis occurs in parallel and independently of the modulation exerted by this receptor on energy homeostasis.

O sistema endocanabinóide (eCB) tem sido reconhecido como um importante modulador da homeostase energética e recentemente estudos o apontam como um possível integrador da homeostase hidroeletrolítica. Estudos recentes do nosso laboratório demonstraram a participação do receptor canabinóide do tipo 1 (CB1R) no controle da secreção neurohipofisária em resposta a expansão hipertônica do volume extracelular. Dessa forma, o presente trabalho visou esclarecer a participação do sistema eCB, particularmente do CB1R, nas respostas neuronais, neuroendócrinas e comportamentais induzidas pela sobrecarga salina de 4 dias (SS). Uma vez que os animais em SS apresentam hipofagia induzida pela hiperosmolalidade, buscou-se avaliar as vias de integração do controle da homeostase energética e do balanço hidroeletrolítico por meio da introdução de um grupo em dieta pareada (pair fed, PF). De forma a investigar a hipótese acima, utilizou-se como ferramenta farmacológica o agonista seletivo CB1R, araquidonil-2-cloroetilamida (ACEA - 0,1g/5L), administrado por via intracerebroventricular (icv). Inicialmente, nosso trabalho mostrou que a SS promoveu aumento da expressão de CB1R tanto nos núcleos supra-óptico (NSO) e paraventricular (NPV) do hipotálamo quanto em estruturas da lâmina terminal [órgão subfornicial (SFO), o órgão vasculoso da lâmina terminal (OVLT) e o núcleo pré-óptico mediano (MnPO)]. Tais observações foram reforçadas pela análise microscópica destas regiões cerebrais por imunofluorescência, que evidenciou aumento da imunomarcação para CB1R no NPV, NSO e SFO em animais submetidos a SS. Estes resultados também mostraram que a maioria dos terminais pré-sinápticos CB1R-positivos estão localizados predominantemente na porção ventral do NSO, na qual predominam neurônios vasopressinérgicos. Os dados mostram ainda que todas as respostas induzidas pela SS foram revertidas após a reintrodução dos líquidos (RL, água e NaCl 0,3M). Já no grupo PF, não foram observadas alterações na expressão de CB1R em nenhuma das áreas avaliadas. No entanto, após a RL, os animais PF apresentaram hipoosmolalidade plasmática e aumento da expressão de CB1R na LT, sendo este último efeito aparentemente mediado por um aumento da expressão deste receptor no SFO. Em animais normoidratados, a administração central de ACEA produziu um aumento significativo na ingestão alimentar, sendo esta resposta ausente nos animais submetidos a SS, apesar do aumento da expressão de CB1R no hipotálamo verificada neste grupo. Entretanto, o pré-tratamento com ACEA foi capaz de potencializar a ingestão de água induzida pela SS, não produzindo efeitos significativos sobre este parâmetro no grupo PF. Este estudo demonstrou ainda que a SS não alterou as concentrações plasmáticas de angiotensina II (ANGII), porém promoveu aumento signficativo nas concentrações plasmáticas de corticosterona, vasopressina (AVP) e ocitocina (OT), além de diminuir a secreção de peptídeo natriurético atrial (ANP). Em animais submetidos a SS, o prétratamento com ACEA potencializou a secreção de corticosterona e preveniu o aumento da secreção de AVP e OT. Por outro lado, não foram observados efeitos da administração de ACEA sobre a secreção de ANP e ANGII induzida pela SS. Após a RL, o grupo SS apresentou normalização das concentrações plasmáticas hormonais, não sendo observados quaisquer efeitos da administração de ACEA nestas condições experimentais. No grupo PF, por sua vez, após a RL foi observada diminuição na secreção de OT e aumento nas concentrações plasmáticas de ANGII, efeitos estes não alterados pelo pré-tratamento com ACEA. Em conjunto, nossos dados sugerem que o CB1R participa ativamente das respostas homeostáticas comportamentais e neuroendócrinas desencadeadas pela SS, sendo estas respostas especificamente relacionadas ao controle da homeostase hidrossalina e não secundárias à hipofagia induzida pela hiperosmolalidade. Desta forma, conclui-se que a participação do CB1R na homeostase hidroeletrolítica ocorre em paralelo e independentemente da modulação exercida por este receptor sobre a homeostase energética. / The endocannabinoid system (eCB) has been recognized as an important modulator of energy homeostasis and recent studies suggest that this system may play a possible integrator role on hydromineral homeostasis. Recent studies from our laboratory demonstrated the involvement of the type 1 cannabinoid receptor (CB1R) in the control of neurohypophyseal secretion in response to hypertonic extracellular volume expansion. Therefore, the present study aimed to clarify the involvement of the ECB system, particularly of CB1Rs, in neuronal, neuroendocrine and behavioral responses induced by 4 days of salt load (SS). Since the animals submitted to SS exhibit a well known state of hyperosmolality-induced hypophagia, we attempted to evaluate the integrated control of energy homeostasis and hydroelectrolytic balance through the introduction of a paired diet group (pair fed, PF). In order to achieve these goals, this study employed as a pharmacological tool the CB1R selective agonist, arachidonoyl-2\'-chloroethylamide (ACEA-0.1g/5L), administered intracerebroventricularly (icv). Initially, our work showed that SS increased the expression of CB1R in both supraoptic (SON) and paraventricular (PVN) nuclei of the hypothalamus, as well as in the structures of the lamina terminalis [subfornical organ (SFO), organum vasculosum of the lamina terminalis (OVLT) and median preoptic nucleus (MnPO)]. These observations were reinforced by the microscopic analysis of these brain regions by immunofluorescence, which showed increased immunostaining for CB1R in the PVN, SON and SFO in animals submitted to SS. These results also showed that most of the presynaptic CB1R-positive terminals are located predominantly in the ventral part of the SON, which is characterized by the presence of vasopressinergic neurons. The data also showed that all SS-induced responses were reversed after reintroduction of fluids (RF, water and 0,3M NaCl). On the other hand, no changes in the expression of CB1R in any of the evaluated areas were observed in the PF group. However, after RF, PF animals showed hypoosmolality and increased expression of CB1R in the LT, being the latter effect apparently mediated by increased expression of this receptor in SFO. In euhydrated animals, the central administration of ACEA produced a significant increase in food intake, being this response absent in animals submitted to SS, despite the increased expression of CB1R in the hypothalamus observed in this group. However, pretreatment with ACEA was able to potentiate SS-induced water intake, producing no significant effect on this parameter in the PF group. This study also demonstrated that SS did not alter plasma concentrations of angiotensin II (ANG II), but significantly increased plasma concentrations of corticosterone, vasopressin (AVP) and oxytocin (OT), and decreased the secretion of atrial natriuretic peptide (ANP). In animals submitted to SS, pretreatment with ACEA enhanced the secretion of corticosterone and prevented the increased secretion of AVP and OT. Moreover, no effect of ACEA was observed on the SS-induced ANG II and ANP secretion. After RF, the SS group showed normalization of hormonal plasma concentrations, and no effects of ACEA administration were verified under these experimental conditions. After RF, the PF group exhibited a decrease in OT secretion and increased plasma concentrations of ANG II, effects that were not altered by pretreatment with ACEA. Taken together, our data suggest that CB1Rs actively participate in behavioral and neuroendocrine homeostatic responses triggered by SS, and that these responses were specifically related to the control of hydromineral homeostasis and not secondary to the hyperosmolality-induced hypophagia. Therefore, we conclude that the involvement of CB1R in electrolyte homeostasis occurs in parallel and independently of the modulation exerted by this receptor on energy homeostasis.

No description available.

An operating vehicle requires energy to oppose the subjected driving resistances. This energy is supplied via the fuel combustion in the engine. Decreasing the opposing driving resistances for an operating vehicle increases its fuel efficiency: an effect which is highly valued in today’s industry, both from an environmental and economical point of view. Therefore a lot of progress has been made during recent years in the area of fuel efficient vehicles, even though some driving resistances still rises perplexity. These resistances are the air drag Fd generated by the viscous air opposing the vehicles propulsion and the rolling resistance Frr generated mainly by the hysteresis caused by the deformation cycle of the viscoelastic pneumatic tires. The energy losses associated with the air drag and rolling resistance account for the majority of the driving resistances facing an operating vehicle, and depends on numerous stochastic and ambient parameters, some of which are highly correlated both within and between the two resistances. To increase the understanding of the driving mechanics behind the energy losses associated with the complexity that is rolling resistance, a set of complete vehicle tests has been carried out. These tests were carried out on the test track Malmby Fairground, using a Scania CV AB developed R440 truck equipped with various sensors connected in one measurement system. Under certain conditions, these parameters can allow for an investigation of the rolling resistance, and a separation of the rolling resistance and air drag via explicit subtraction of the air drag from the measured traction force. This method is possible since the aerodynamic property AHDVCd(β) to some extent can be generated from wind tunnel tests and CFD simulations. Two measurement series that enable the above formulated method of separation were designed and carried out, using two separate measurement methods. One which enables the investigation of the transient nature of rolling resistance as it strives for stationarity, where the vehicle is operated under constant velocities i.e. no acceleration, and one using the well established method of coastdown, where no driving torque is applied. The drive cycles spanned a range of velocities, which allowed for dynamic and stationary analyses of both the tire temperature- and the velocity dependence of rolling resistance. When analysing the results of the transient analysis, a strong dependence upon tire temperature for given constant low velocity i.e. v ≤ 60 kmh−1 was clearly visible. The indicated dependency showed that the rolling resistance decreased as the tire temperature increased over time at a given velocity, and vice versa, towards a stationary temperature and thereby rolling resistance. The tire temperature evolution from one constant velocity to another, took place well within 50 min to a somewhat stationary value. However, even though the tire temperature had reached stationarity, rolling resistance did not; there seemed to be a delay between stationary tire temperature, and rolling resistance. The results did not indicate any clear trends for v ≥ 60 kmh−1, where the results at v = 80 kmh−1 were chaotic. This suggests that some additional forces were uncompensated for, or that the compensation for air drag was somehow wrongly treated at higher velocities. Several factors ruled out any attempts at proposing a new rolling resistance model. These included: the chaotic results for v = 80 kmh−1, the delayed rolling resistance response upon tire temperature stabilization, and the lack of literature support for the observed tendency. The results from the coastdown series on the other hand, showed good agreement with a dynamical model suggested in literature. The stationary temperature behaviour for the considered velocity range at assumed constant condition is also supported in literature. Finally, an investigation of the aerodynamic property AHDVCd inspired by ongoing work in ACEA (European Automobile Manufacturers’ Association), was carried out assuming both zero and non-zero air drag at low velocities. The results indicated surprisingly good agreement with wind tunnel measurements, especially when neglecting air drag at low velocities: as suggested by ACEA. / För att övervinna de motstånd som ett fordon utsätts för under drift krävs energi, vilket levereras genom förbränningen av bränsle. Genom att minska de körmotstånd som ett fordon utsätts för under drift, kan man öka dess energieffektivitet. Denna potential är idag högt värderad i fordonsindustrin, både ur ett miljömässigt och ekonomiskt perspektiv. På senare år har stora framsteg gjorts inom området energieffektiva fordon, men fortfarande råder det förvirring kring de energiförluster som förknippas med luftmotstånd Fd och rullmotstånd Frr, där luftmotståndet skapas av den omkringliggande viskösa luften, medan rullmotståndet genereras av hysteresen som uppstår när fordonets viskoelastiska pneumatiska däck utsätts för deformation. De energiförluster som förknippas med luft- och rullmotstånd motsvarar den största delen av de motstånd som ett fordon påverkas av, och beror på en mängd stokastiska och yttre parametrar, varav vissa är starkt korrelerade både inom och mellan nämnda motstånd. För att förbättra förståelsen kring dessa energiförluster, med fokus på förståelsen av rullmotstånd, har ett antal helfordonstest genomförts. Dessa genomfördes på provbanan Malmby Fairground med en R440 lastbil från Scania CV AB, utrustad med en mängd sensorer sammankopplade i ett mätsystem. Det uppbyggda mätsystemet möjliggjorde samtida mätningar av bl.a. drivande moment, motorvarv, fordonshastighet, däcktemperatur, omkringliggande lufts hastighet och dess riktning. Under specifika förhållanden kunde dessa parametrar möjliggöra analys av rullmotstånd genom en explicit subtraktion av luftmotstånd från den uppmätta drivande kraften. Denna metod är möjlig tack vare en förhållandevis bra modell av ekipagets aerodynamiska egenskap AHDVCd(β), som generats från vindtunneltest och CFD simuleringar. Två körcykler som möjliggjorde ovan formulerade separation designades och genomfördes. Dessa använder två skilda mätmetoder, varav den ena möjliggör analys av rullmotståndets övergående förlopp från dynamiskt till stationärt genom att hålla konstant hastighet. Den andra studerade det dynamiska förloppet genom den väletablerade metoden utrullning, dvs. utan något drivande moment. Dessa körcyklar genomfördes, för ett antal hastigheter, vilket möjliggjorde analys av både hastighets- och däcktemperaturberoendet hos rullmotstånd, under dynamiska såväl som stationära förlopp. Analysen av rullmotståndets dynamik i strävan mot stationära förhållanden visade på ett starkt temperaturberoende vid låga hastigheter dvs. v ≤ 60 kmh−1. Beroendet visade på att rullmotståndet avtog med ökande däcktemperatur och vice versa, tills dess att en någorlunda stationär temperatur för given hastighet uppnåtts. Däcktemperaturen stabiliserades till ett nytt stationärt värde inom 50 min från att hastigheten ändrats. Resultaten tyder dock på att även om stationär däcktemperatur uppnåtts finns det en fördröjning i rullmotståndets tidsspann innan rullmotståndet stabiliserat sig. För högre hastigheter, dvs. v ≥ 60 kmh-1, var dock inga klara trender synliga, varken i hastighet eller temperatur och resultaten vid v = 80 kmh-1 var kaotiska. Detta antyder att man missat att kompensera för någon kraft vid höga hastigheter, alternativt att man på något sätt kompenserar fel för luftmotståndet vid högre hastigheter. Flera faktorer hindrade försök att föreslå någon ny rullmotståndsmodell. Dessa faktorer inkluderar det kaotiska resultatet vid v = 80 kmh-1, tidsfördröjningen mellan stationärt rullmotstånd och däcktemperatur samt att resultatet för antagna stationära värden inte finner stöd i litteraturen. Resultatet från utrullningsprovet överstämmer dock bra med tidigare föreslagen dynamisk modell, samt att resultaten av beteendet hos stationär temperatur för olika hastigheter även de överensstämmer med och finner stöd i litteraturen. Slutligen har en studie kring den aerodynamiska egenskapen AHDVCd, inspirerad av pågående arbete inom ACEA (European Automobile Manufacturers’ Association) utförts både med antagandet av ett noll- skilt och med ett försumbart luftmotstånd vid låga hastigheter. Resultatet visar på en överraskande god överensstämmelse med vindtunnelmätningar, framför allt under antagandet av försumbart luftmotstånd vid låga hastigheter i enlighet med förslagen metod från ACEA.

De la profondeursur 2 sites en Guadeloupe pendant la saison sèche et la saison humide (Chapitre 3). A u cours de cette étude,les genres Ostreopsis et Prorocentrum étaient les plus abondants. Aucune influence de la profondeur n'a é;étrouvée sur l'abondance totale des dinoflagellés benthiques ; cependant les genres Ostreopsis et GambiericLscusétaient principalement abondants en surface, alors que le genre Coolia était présent plus en profondeur.L'approche d'écologie trophique concernait le lien trophique entre dinoflagellés benthiques toxiqueset méiofaune (Chapitre 1). Les transferts au sein des réseaux trophiques de phycotoxines synthétisées par lesdinoflagellés benthiques toxiques sont généralement étudiés chez les organismes de grande taille, délaissantles organismes de μeLile Laille qui sulll pourtant en contact direct avec les microalgues. Au cours de cetteétude, une attention particulière a été portée aux copépodes harpacticoïdes qui composent ia méiofaune.Cette étude expérimentale, par marquage des microalgues aux isotopes stables, s'est focalisée sur lescopépodes harpacticoïdes et a permis de mesurer le taux d'ingestion d'Amphidinium sp. et d'Ostreopsis sp ..Cette étude démontre que les organismes de la méiofaune peuvent constituer une voie d'entrée des toxinessynthétisées par les dinoflagellés benthiques dans les réseaux trophiques. / The distribution of benthic toxiï rlinofüeefü1tes is 1111known in (Juadeloupe and Martinique even if at theCaribbean basin spatial scale, those microalgae are responsible for serious poisoning such as ciguatera.During this thesis, the ecology of benthic toxic dinoflagellates μreseul was sLudieJ using: spatio-temporalstudies (Chapters 1, 2, 3) and a trophic ecology approach (Chapter 4).First, 27 sites were explored to describe the spatial distribution of benthic dinoflagellatf's prPsf'nt inGuadeloupe and Martinique (Chapter 1). Only the most abundant macrophytes (biological substrates ofbenthic dinoflagellates) at the different sites were considered. ln this study, 161 samples were analyzed and 7times more taxie benthic dinoflagellates were found in Guadeloupe than in Martinique. The genus Ostreopsisdominated the benthic dinoflagellate community in both islands, although this trend has only rarely beenfound in the Caribbean basin.Then, 3 sites per department were chosen in order to set up a monthly monitoring of benthicdinoflagellates abundances duringl8 months (Chapter 2). The sites selected i) had a high abundance ofbenthic toxic dinoflagellates and ii) were identified as potentially dangerous by the Agence Régionale de laSanté. During this study, 927 samples of macrophytes were analyzed and 5 times more benthic toxicdinoflagellates were found in Guadeloupe than in Martinique. Ostreopsis and Prorocentrum genera dominatedrespectively in Guadeloupe and in Martinique. Two times more Gambierdiscus were found in Martinique thanin Guadeloupe even if Guadeloupe is located in the high prevalence area and this genus being responsible forciguatera. This result suggested that species with different toxicities structured the benthic toxicdinoflagellates community in this area. The abundances of benthic dinoflagellates were little influenced byabiotic parameters (temperature and salinity) but structured by biotic parameters (host macrophytes).Halophila stipulacea an invasive angiosperm in the Lesser Antilles has been identified as promoting thedevelopment of the genus Gambierdiscus.. The distribution of benthic toxic dinoflagellates was also studied according to the depth at 2 sites inGuadeloupe during the dry and the wet seasons (Chapter 3). ln order to avoid bias due to the presence ofdifferent macrophytes, this experiment was conducted only on H. stipulacea constituting mono-specificmeadows along a strong depth gradient. ln this study, the Ostreopsis and Prorocentrum genera were the mostabundant. No influence of the depth was found on total abundance of benthic dinoflagellates; however,Ostreopsis and Gambierdiscus genera were mainly abundant near the surface while the genus Coolia was presentdeeper.The trophic ecology approach focused on the trophic link between taxie benthic dinoflagellates andmeiofauna (Chapter 4). Transfers within the food webs of phycotoxins synthesized by benthic dinoflagellatesare mainly studied in large organisms neglecting smaller ones in direct contact with microalgae. Thisexperimental study, by labeling the microalgae with stable isotopes, focused on harpacticoides copepod andmeasured for the first time their ingestion rates of Amphidinium sp. and Ostreopsis sp.. This studydemonstrated that meiofauna organisms can constitute an input channel of phycotoxins from benthicdinoflagellates in food webs.