Comprehensive evaluation of the IEEE 802.15.4 MAC layer performance with retransmissions

Supported by IEEE 802.15.4 standardization activities, embedded networks have been gaining popularity in recent years. The focus of this paper is to quantify the behavior of key networking metrics of IEEE 802.15.4 beacon-enabled nodes under typical operating conditions, with the inclusion of packet retransmissions. We corrected and extended previous analyses by scrutinizing the assumptions on which the prevalent Markovian modeling is generally based. By means of a comparative study, we singled out which of the assumptions impact each of the performance metrics (throughput, delay, power consumption, collision probability, and packet-discard probability). In particular, we showed that - unlike what is usually assumed - the probability that a node senses the channel busy is not constant for all the stages of the backoff procedure and that these differences have a noticeable impact on backoff delay, packet-discard probability, and power consumption. Similarly, we showed that - again contrary to common assumption - the probability of obtaining transmission access to the channel depends on the number of nodes that is simultaneously sensing it. We evidenced that ignoring this dependence has a significant impact on the calculated values of throughput and collision probability. Circumventing these and other assumptions, we rigorously characterize, through a semianalytical approach, the key metrics in a beacon-enabled IEEE 802.15.4 system with retransmissions.

Effets des usages différenciés de l'activité physique sur des enfants en classe enfantine : étude pluridisciplinaire et comparative

La thèse traite de projets de classes enfantines avec de l'activité physique, projets pilotes ayant entre autres le but d'évaluer les effets d'un apport d'activité physique auprès d'enfants de 4 à 6 ans. Le projet de recherche saisit l'opportunité de pouvoir observer les effets de l'AP sur de jeunes enfants (n=86, classes AP=40, classes contrôles=46) et ceci par trois regards distincts : une quantification de l'activité physique, l'influence de cette dernière sur certaines composantes cognitives (créativité, intelligence et concentration) des jeunes enfants et, enfin, l'influence de l'activité physique au niveau psychosocial (microsystèmes familial et scolaire). La méthodologie mélange des méthodes qualitatives (entretiens, observations) et quantitatives (accéléromètres (GT1M), tests de créativité (Krampen, 1996), d'intelligence (Cattell, Weiss & Osterland, 1997), de concentration (Krampen, 2007)). Les principaux résultats démontrent que ce type de projet permet d'augmenter l'AP durant le temps scolaire et les résultats sont plus contrastés en extrascolaire. Un temps supérieur consacré à l'AP ne démontre aucune diminution des capacités cognitives dans cette tranche d'âge-là. L'analyse du microsystème familial nous informe sur le fait que les parents qui ont placé leurs enfants dans ce type de classes sont eux-mêmes plus actifs que la moyenne de la population suisse (Lamprecht, Fischer, & Stamm, 2008a). Enfin, un apport d'AP ne permet pas d'augmenter le nombre de feedbacks tournés vers l'autonomie et le style contrôlant est même renforcé. Nos résultats sont discutés sur la base des études de Kriemler et al. (2010) qui démontrent toute la difficulté d'une intervention scolaire pour modifier les comportements familiaux en extrascolaire. La fonction exécutive (Tomporowski et al., 2008) offre un regard neurophysiologique éclairant les effets de l'AP sur les différentes capacités étudiées. Enfin, il semble que la pression générée par la mise en place de projets liés à un apport d'AP en école enfantine va dans le sens d'une augmentation d'un style contrôlant (Tessier, 2006). Ce choix d'approcher les observations selon plusieurs angles d'étude est audacieux car il se situe en situation écologique mais il représente en même temps le seul moyen d'observer les effets en tenant davantage compte de la complexité des conduites des interactions entre différents facteurs. - The aim of the study is to evaluate the effect of physical activity (PA) in kindergartens with children aged from 4 to 6 years old. The project seizes the opportunity to observe the effects of PA on young children (n=86, classes AP=40, control classes=46) with three different axes: a quantification of PA, the influence of PA on cognitive functions (creativity, intelligence and concentration), and the influence on the family and the climate in the class. The methodology is based on a mix of qualitative (interviews, observations) and quantitative (accelerometer (GT1M), creativity test (Krampen, 1996), intelligence test (Cattell, Weiss & Osterland, 1997), concentration test (Krampen, 2007)) methods. The main results show that PA during the schooltime increased and the results outside of the school present more contrasts. More time spent for PA doesn't influence negatively the evolution of the cognitive functions at this age. The parents, who have interest for this kind of kindergartens for their children move significantly more than the Swiss population (Lamprecht, et al., 2008a). More PA during the lessons doesn't increase the feedbacks given with autonomy and more control is even observed. The results show the difficulty of changing the behaviors of a family linked to PA outside of the school (Kriemler et al., 2010). The discussion of the results of the cognitive functions is based on the executive function, which seems to be linked to PA (Tomporowski et al., 2008). Finally, it seems that the pressure occurred by those projects with PA tend to foster a climate with more control (Tessier, 2006). The choice of structuring the thesis with three different axes represents a risk because it is established in ecological conditions, but it also allows to observe the effects of PA taking into consideration the interactions between the different factors.

Jalkaterapian asiakkaiden jalkojen omahoitotottumukset vuosina 2003-2005

Tutkimuksen tavoitteena oli kartoittaa Helsingin ammattikorkeakoulu Stadian jalkapisteessä hoidossa käyneiden eri-ikäisten asiakkaiden (n=346) jalkojen omahoitotottumukset ja niiden tarkoituksenmukaisuus sekä jalkaterien terveyden taso. Tutkimukseen osallistuneiden ikäjakauma oli 6-96 ja keski-ikä 60 vuotta. Kysely toteutettiin Kunto-Stadian jalkapisteessä opiskelijoiden harjoittelujaksoilla vuosina 2003-2005. Tutkimusstrategia oli kvantitatiivinen ja tiedonhankintamenetelmänä oli strukturoitu kyselylomake. Tulokset on esitetty käyttäen frekvenssejä ja prosenttiosuuksia. Tulosten mukaan suurin osa vastanneista pesi jalat päivittäin ja kuivasi varvasvälit joka pesun yhteydessä. Vajaa puolet rasvasi jalat harvemmin kuin kerran viikossa tai ei lainkaan. Noin puolet käytti jalkojen ihon hoidossa raspia. Noin puolet käytti luonnonkuitusukkia. Yksi kymmenestä liikkui sisätiloissa sukkasillaan. Hieman yli puolelle kenkien löytyminen oli vaikeata. Alle kolmasosa harrasti yhtä tai kahta liikuntalajia. Yleisimmin harrastettiin kävelyä. Alle puolet harrasti liikuntaa 3-4 kertaa viikossa. Alle puolet ei toteuttanut jalkavoimistelua. Johtopäätöksenä voidaan todeta, että jalkahygienian taso on huono, koska jalkojen omahoitotietoudessa on puutteita. Tässä tutkimuksessa sukat ja kengät tukevat jalkojen terveyttä melko huonosti. Tutkimustulosten mukaan sukkia vaihdetaan liian harvoin, jonka seurauksena jalkahygienia kärsii. Kenkätottumukset eivät tue pystyasentoa ja liikkumista. Tutkimukseen osallistuneet harrastavat yksipuolista liikuntaa, koska tutkimustuloksista ilmenee, että suurin osa harrastaa yhtä tai kahta liikuntalajia. Jalkavoimistelua harrastettiin liian vähän, jonka seurauksena jalkaterän ja säären alueen lihastasapaino häiriintyy ja nivelten toiminta kärsii. Suomessa ja ulkomailla ei ole aiemmin tehty näin laajaa tutkimusta jalkojen omahoitotottumuksista. Ammattikuntamme ja muu terveydenhuoltohenkilöstö saavat ajankohtaista ja syventävää tietoa, jolloin jalkaongelmien syntymistä voidaan ehkäistä puuttumalla ajoissa opetuksen ja ohjauksen avulla puutteellisiin jalkojen omahoitotottumuksiin. Toivomme tämän tutkimuksen kannustavan jalkojenhoitajia ja jalkaterapeutteja panostamaan jatkossa yksilölliseen asiakkaan opetukseen ja ohjaukseen sekä kehittämisehdotusten perusteella muokatun jalkojen omahoitolomakeen motivoivan entistä enemmän keräämään tietoja asiakkaiden jalkojen omahoitotottumuksista. Kysymykset on muokattu tutkimustulosten ja opinnäytetyön tekovaiheessa ilmenneiden kehitystarpeiden perusteella.

Neurotoxicant-induced inflammatory response in three-dimensional brain cell cultures.

Brain inflammatory response is triggered by the activation of microglial cells and astrocytes in response to various types of CNS injury, including neurotoxic insults. Its outcome is determined by cellular interactions, inflammatory mediators, as well as trophic and/or cytotoxic signals, and depends on many additional factors such as the intensity and duration of the insult, the extent of both the primary neuronal damage and glial reactivity and the developmental stage of the brain. Depending on particular circumstances, the brain inflammatory response can promote neuroprotection, regeneration or neurodegeneration. Glial reactivity, regarded as the central phenomenon of brain inflammation, has also been used as an early marker of neurotoxicity. To study the mechanisms underlying the glial reactivity, serum-free aggregating brain cell cultures were used as an in vitro model to test the effects of conventional neurotoxicants such as organophosphate pesticides, heavy metals, excitotoxins and mycotoxins. This approach was found to be relevant and justified by the complex cell-cell interactions involved in the brain inflammatory response, the variability of the glial reactions and the multitude of mediators involved. All these variables need to be considered for the elucidation of the specific cellular and molecular reactions and their consequences caused by a given chemical insult.

O primeiro centro urbano colonial nos trópicos: Ribeira Grande (Cabo Verde), séculos XV-XVII.

A cidade da Ribeira Grande não resulta de uma selecção natural das populações ao longo dos tempos, atraídas por um local que apresente as várias condições favoráveis à evolução da vida comunitária. Ela é fundada por decisão administrativa num vazio populacional, de clima adverso, por razões exógenas ao território. Quando esses condicionalismos externos se alteram e a retaguarda se povoa, a cidade decai e a população ruraliza-se. A ilha de Santiago e designadamente o porto da Ribeira Grande tornaram-se, no 3º quartel do séc. XV, objecto de atenções por parte da política ultramarina da Coroa portuguesa devido à sua possível função de “fortaleza feitoria insular” da Costa da Guiné.1 Efectivamente, por razões estratégicas os portugueses inventaram um pólo de atracção tão intenso, quanto nele confluíam todas as linhas que estabeleciam a ligação entre a ilha e o extenso litoral fronteiro. O porto insular foi um litoral fabricado, para ocupação sem resistências, dispondo de uma retaguarda passiva, utilizável a qualquer momento.2

Predictive factors of adrenal insufficiency in patients admitted to acute medical wards: a case control study.

BACKGROUND: Adrenal insufficiency is a rare and potentially lethal disease if untreated. Several clinical signs and biological markers are associated with glucocorticoid failure but the importance of these factors for diagnosing adrenal insufficiency is not known. In this study, we aimed to assess the prevalence of and the factors associated with adrenal insufficiency among patients admitted to an acute internal medicine ward. METHODS: Retrospective, case-control study including all patients with high-dose (250 μg) ACTH-stimulation tests for suspected adrenal insufficiency performed between 2008 and 2010 in an acute internal medicine ward (n = 281). Cortisol values <550 nmol/l upon ACTH-stimulation test were considered diagnostic for adrenal insufficiency. Area under the ROC curve (AROC), sensitivity, specificity, negative and positive predictive values for adrenal insufficiency were assessed for thirteen symptoms, signs and biological variables. RESULTS: 32 patients (11.4%) presented adrenal insufficiency; the others served as controls. Among all clinical and biological parameters studied, history of glucocorticoid withdrawal was the only independent factor significantly associated with patients with adrenal insufficiency (Odds Ratio: 6.71, 95% CI: 3.08 -14.62). Using a logistic regression, a model with four significant and independent variable was obtained, regrouping history of glucocorticoid withdrawal (OR 7.38, 95% CI [3.18 ; 17.11], p-value <0.001), nausea (OR 3.37, 95% CI [1.03 ; 11.00], p-value 0.044), eosinophilia (OR 17.6, 95% CI [1.02; 302.3], p-value 0.048) and hyperkalemia (OR 2.41, 95% CI [0.87; 6.69], p-value 0.092). The AROC (95% CI) was 0.75 (0.70; 0.80) for this model, with 6.3 (0.8 - 20.8) for sensitivity and 99.2 (97.1 - 99.9) for specificity. CONCLUSIONS: 11.4% of patients with suspected adrenal insufficient admitted to acute medical ward actually do present with adrenal insufficiency, defined by an abnormal response to high-dose (250 μg) ACTH-stimulation test. A history of glucocorticoid withdrawal was the strongest factor predicting the potential adrenal failure. The combination of a history of glucocorticoid withdrawal, nausea, eosinophilia and hyperkaliemia might be of interest to suspect adrenal insufficiency.

Quality assurance of the EORTC 22043-30041 trial in post-operative radiotherapy in prostate cancer: Results of the Dummy Run procedure.

BACKGROUND AND PURPOSE: The EORTC 22043-30041 trial investigates the role of the addition of androgen suppression to post-operative radiotherapy in patients who have undergone radical prostatectomy. As part of the quality assurance of radiotherapy (QART) a Dummy Run (DR) procedure was performed. MATERIALS AND METHOD: The protocol included detailed and published delineation guidelines. Participating institutions digitally submitted radiotherapy treatment volumes and a treatment plan for a standard clinical case. Submissions were centrally reviewed using the VODCA software platform. RESULTS: Thirty-eight submissions from thirty-one institutions were reviewed. Six were accepted without comments. Twenty-three were accepted with comments on one or more items: target volume delineation (22), OAR delineation (23), planning and dosimetry (3) or treatment verification (1). Nine submissions were rejected requiring resubmission, seven for target volume delineation reasons alone. Intervention to highlight the importance of delineation guidelines was made prior to the entry of the first patient in the trial. After this, a lower percentage of resubmissions was required. CONCLUSIONS: The EORTC 22043-30041 Dummy Run highlights the need for timely and effective QART in clinical trials. The variation in target volume and OAR definition demonstrates that clinical guidelines and radiotherapy protocols are not a substitute for QART procedures. Early intervention in response to the Dummy Run improved protocol understanding.

Padrão atípico de secreção de cortisol em profissionais de Enfermagem

RESUMO Objetivo Descrever a frequência de profissionais de enfermagem de unidades hospitalares com alteração no padrão diurno de secreção de cortisol. Método Foram incluídos 56 profissionais de enfermagem randomicamente selecionados, alocados nas unidades ambulatório, clínica médica, clínica cirúrgica, centro cirúrgico, pronto socorro infantil e adulto, unidade de terapia intensiva adulto e pediátrica de um hospital universitário. Para avaliação do padrão diurno de secreção de cortisol foram coletadas amostras de saliva em dois dias úteis consecutivos de trabalho. Resultados 42,5% dos profissionais de enfermagem apresentaram padrão atípico de secreção de cortisol. Além disso, quanto maior o tempo de trabalho na profissão, maior a concentração de cortisol (r=0,346; p=0,020). Conclusão Mais de um terço da amostra de profissionais de enfermagem apresentou padrões atípicos de secreção de cortisol, sugerindo que estes profissionais podem estar expostos a uma sobrecarga não apenas mental, mas biológica, estando expostos ao risco para o adoecimento por doenças relacionadas ao estresse.

Professori L.A. Puntila 20/10 1960

Kirje 20.10.1960