Stress Investigation and Design Methods for Composite Beams Consisting of Concrete Slabs on Steel I-Beams

The term, reinforced concrete, as generally used, is applied to that type of construction in which steel rods are imbedded in concrete members. In these members the steel and concrete are considered to act as a unit and both are assumed to be effective in developing the resisting moment of the beam

Flight investigation of cockpit-displayed traffic information utilizing coded symbology in an advanced operational environment

Traffic symbology was encoded to provide additional information concerning the traffic, which was displayed on the pilot's electronic horizontal situation indicators (EHSI). A research airplane representing an advanced operational environment was used to assess the benefit of coded traffic symbology in a realistic work-load environment. Traffic scenarios, involving both conflict-free and conflict situations, were employed. Subjective pilot commentary was obtained through the use of a questionnaire and extensive pilot debriefings. These results grouped conveniently under two categories: display factors and task performance. A major item under the display factor category was the problem of display clutter. The primary contributors to clutter were the use of large map-scale factors, the use of traffic data blocks, and the presentation of more than a few airplanes. In terms of task performance, the cockpit-displayed traffic information was found to provide excellent overall situation awareness. Additionally, mile separation prescribed during these tests

Aerial survey and telemetry data analysis of a peripheral caribou calving area in northwestern Alaska

With industrial development expanding in the Arctic, there is increasing interest in quantifying the impacts of development projects on barren ground caribou (Rangifer tarandus granti). The primary data source to assess caribou distribution and predict impacts in remote areas of Alaska has shifted in recent decades from aerial survey data to telemetry data, but these techniques have different strengths and weaknesses. The ranges of two caribou herds, the Western Arctic Herd and the Teshekpuk Herd, overlap in northwest Alaska between Wainwright and Atqasuk, Alaska. Based on long-term telemetry data sets, this region was thought to be outside of the core calving ranges of both herds. Calving has long been reported to occur in this general area, but early reports assumed caribou were from the Western Arctic Herd and only one systematic aerial survey of caribou density and distribution during calving has been conducted in this area in recent decades. Following interest in industrial development in this area, we conducted aerial strip-transect surveys during early to mid-June 2013–2015 to directly assess the density and distribution of caribou in the area and we used existing telemetry data to compare our results to the seasonal distribution of both herds. Total caribou densities varied between 0.36 and 1.06 caribou/km² among years, and calf densities varied 0.04 and 0.25 calves/km² among years. Contrary to assumptions by early researchers in the area, telemetry data indicated that caribou in this area during early to mid-June were from the Teshekpuk Herd. The use of telemetry data alone underestimated the importance of this area for calving, but the combination of aerial surveys and telemetry data provided complementary information on caribou use of this area showing the importance of collecting the appropriate types of data for assessing potential impacts of development on caribou

Long-term outcome of noninvasive positive pressure ventilation for obesity hypoventilation syndrome

BACKGROUND: Few data are available on the long-term outcome of noninvasive positive pressure ventilation (NPPV) for obesity hypoventilation syndrome (OHS). This study was designed to determine long-term survival, treatment adherence, and prognostic factors in patients with OHS in whom NPPV was initiated in an acute setting vs under stable clinical conditions.METHODS: One hundred thirty consecutive patients with OHS (56 women) who started NPPV between January 1995 and December 2006 either under stable conditions (stable group, n = 92) or during ICU management of acute hypercapnic exacerbation (acute group, n = 38) were retrospectively analyzed. RESULTS: Arterial blood gases and the Epworth sleepiness scale were both significantly improved after 6 months of NPPV. With a mean follow-up of 4.1 +/- 2.9 years, 24 (18.5%) patients died and 24 (18.5%) discontinued NPPV. On Kaplan-Meier analysis, 1-, 2-, 3-, and 5-year survival probabilities were 97.5%, 93%, 88.3%, and 77.3%, respectively. Mortality was lower than that described in a previous series of patients with untreated OHS. Supplemental oxygen therapy was the only independent predictor of mortality. The probability of continuing NPPV was 80% at 3 years with a high rate of daily use ( > 7 h). Female sex was predictive of lower long-term adherence to NPPV. The acute and stable groups did not differ in terms of arterial blood gases and Epworth sleepiness scale at 6 months, long-term survival, and treatment adherence. CONCLUSIONS: The results of this study support long-term NPPV as an effective and well-tolerated treatment of OHS whether initiated in the acute or chronic setting

Pneumopathie médicamenteuse sous traitement par venlafaxine et propranolol

Introduction Venlafaxine and propranolol have rarely been identified as causes of pulmonary pathology. We describe a case of drug-induced pneumonitis occurring in a patient treated with these two medications. Case report A 55 years old woman with liver cirrhosis treated with venlafaxine for 1 year and propranolol for 1 month was admitted to the intensive care unit because of acute respiratory failure. A Mycoplasma pneumoniae pneumonitis was diagnosed. After initial improvement under antibiotics, a new deterioration of respiratory status was observed 4 days after the reintroduction of venlafaxine and propranolol. Spontaneous recovery occurred after these treatments were withheld. Co administration of venlafaxine and propranolol, 2 drugs with affinity for the same cytochrome P450 isoenzyme (CYP2D6), may have contributed to drug accumulation and pulmonary toxicity. The liver cirrhosis of our patient may also have contributed to decreased cytochrome P450 enzymatic activity. Conclusions Venlafaxine and propranolol share the same metabolic pathway and their co-administration may be complicated by drug induced pneumonitis

Distribution and Movements of the Teshekpuk Caribou Herd 1990–2005: Prior to Oil and Gas Development

Four caribou (Rangifer tarandus grantii) herds calve on the North Slope of Alaska, three of which have been exposed to little or no resource development. We present 15 years of baseline data on the distribution and movements of 72 satellite-collared and 10 GPS-collared caribou from the Teshekpuk caribou herd (TCH) that have had little to no exposure to oil and gas activities. Fixed-kernel home range analyses of collared caribou revealed that calving grounds were concentrated (i.e., 50% kernel utilization distribution) along the northeastern, eastern, and southeastern shores of Teshekpuk Lake. During the postcalving period, 51% and 35% of caribou moved through two constricted zones to the east and west of Teshekpuk Lake, respectively, and accessed insect-relief habitat along the Beaufort Sea coast. During late summer and early fall, TCH caribou were concentrated to the southeast and southwest of Teshekpuk Lake. Although 65% of the Teshekpuk caribou wintered in two areas on the central coastal plain around the village of Atqasuk and south of Teshekpuk Lake, other TCH animals wintered in a great variety of places, including the Seward Peninsula, the eastern and southern Brooks Range, and the Arctic National Wildlife Refuge. We detected an apparent emigration rate of 6.9%. One male and five female TCH caribou joined the breeding populations of the Western Arctic and Central Arctic herds. TCH caribou traveled an average distance of 2348 ± 190 km annually. Movement rates were at a maximum in midsummer, lowest in winter, and intermediate during spring and fall migrations. Restrictions on oil and gas leasing and surface occupancy have been in place to protect calving, migratory corridors, and insect-relief habitat for the TCH, but these protections are likely to be removed. These data will provide a good baseline that can be used to compare predevelopment distribution and movement patterns of TCH caribou to distribution and movement patterns during and after petroleum development.Quatre hardes de caribous (Rangifer tarandus grantii) vêlent sur la côte nord de l’Alaska, dont trois de ces hardes ont été exposées à peu ou pas d’aménagement des ressources. Nous présentons des données de base échelonnées sur 15 ans relativement à la répartition et aux déplacements de 72 caribous dotés d’un collier émetteur par satellite et de 10 caribous munis d’un collier émetteur GPS de la harde de caribous de Teshekpuk (HCT), caribous qui ont été peu ou pas du tout frottés aux activités pétrolières et gazières. L’analyse du noyau fixe des domaines vitaux des caribous à collier a révélé que les lieux de vêlage étaient concentrés (c’est-à-dire 50 % de la répartition de l’utilisation du noyau) le long des côtes nord-est, est et sud-est du lac Teshekpuk. Après la période de vêlage, 51 pour cent et 35 pour cent des caribous se déplaçaient au sein de deux zones de constriction à l’est et à l’ouest du lac Teshekpuk, respectivement, et accédaient un habitat où se trouvait moins d’insectes sur la côte de la mer de Beaufort. Vers la fin de l’été et le début de l’automne, les caribous de la HCT étaient concentrés au sud-est et au sud-ouest du lac Teshekpuk. Bien que 65 pour cent des caribous de Teshekpuk passaient l’hiver dans deux régions de la plaine côtière centrale autour du village d’Atqasuk et au sud du lac Teshekpuk, les autres bêtes de la HCT passaient l’hiver dans divers endroits, dont la péninsule de Seward, les versants est et sud des montagnes de Brooks et la Réserve faunique nationale de l’Arctique. Nous avons détecté un taux d’émigration apparent de 6,9 pour cent. Un caribou mâle et cinq caribous femelles de la HCT ont rejoint les populations de reproduction des hardes de l’ouest et du centre de l’Arctique. En moyenne, le caribou de la HCT parcourait une distance de 2348 ± 190 km annuellement. Les taux de déplacement étaient à leur point le plus élevé au milieu de l’été, tandis qu’ils étaient à leur niveau le plus bas l’hiver et à un niveau intermédiaire pendant les migrations du printemps et de l’automne. Il existe des restrictions en matière de location et d’occupation en surface pour le pétrole et le gaz afin de protéger le vêlage, les corridors de migration et les habitats à faible taux d’insectes pour la HCT, mais il est vraisemblable que ces restrictions soient éliminées. Ces données fourniront une bonne base pour comparer la répartition et les déplacements du caribou de la HCT avant la mise en valeur des ressources à la répartition et aux déplacements du caribou de la HCT pendant et après la mise en valeur pétrolière

Frequency of Injuries from Line Entanglements, Killer Whales, and Ship Strikes on Bering-Chukchi-Beaufort Seas Bowhead Whales

We analyzed scarring data for Bering-Chukchi-Beaufort (BCB) Seas bowhead whales (Balaena mysticetus) harvested by Alaska Native hunters to quantify the frequency of line entanglement, ship strikes, and killer whale-inflicted injuries. We had 904 records in our database for whales landed between 1990 and 2012, and after data quality screening, we found 521 records containing information on scarring. Logistic regression was used to evaluate different combinations of explanatory variables (i.e., body length, sex, year, year-group) to develop a prediction model for each scar type. We also list bowhead whales that were harvested, found dead, or observed alive entangled in commercial line/fishing gear. Our findings suggest that about 12% of harvested bowheads show entanglement scars. Their frequency is highly correlated with body length and sex: about 50% of very large bowheads (> 17 m) show such scars, while whales under 9 m rarely do, and males show a significantly higher rate than females. Scars associated with ship strikes are infrequent and occur on ~2% of all harvested whales; body length, sex, and year were not significant factors. Scarring from attempted killer whale predation was evident on ~8% of landed whales. As with entanglement injuries, the frequency of killer whale scars was much higher (> 40%) on whales more than 16 m in length and statistically more frequent in the second half of the study (2002 – 12). Increased killer whale injuries in the recent decade are consistent with studies conducted on bowheads of the Eastern Canada-West Greenland population. The findings presented here reflect the most thorough analysis of injury rates from entanglement, ships, and killer whales for the BCB bowheads conducted to date. They indicate that (1) entanglement rates primarily from pot fishing gear (crab or cod or both) are relatively high for very large and presumably older bowheads, (2) collisions with ships are infrequent at present, and (3) scarring from killer whales is frequent on very large adult whales (> 17 m). Considering that bowhead habitat is changing rapidly (e.g., sea ice reduction), industrial ship traffic in the Arctic is increasing, and commercial fishing operations are expanding to the north, we strongly recommend that monitoring of scarring and injuries on harvested bowheads continue into the future as a means of documenting change.Nous avons analysé les données sur les cicatrices que portent les baleines boréales (Balaena mysticetus) des mers de Béring, des Tchouktches et de Beaufort capturées par des chasseurs autochtones de l’Alaska afin de quantifier la fréquence d’emmêlements dans des filets de pêche, de collisions avec des navires et de blessures infligées par des épaulards. Notre base de données contenait 904 enregistrements portant sur des baleines prises entre 1990 et 2012 et, après une sélection des données selon leur qualité, nous avons trouvé 521 enregistrements comptant de l’information sur des cicatrices. Une méthode de régression logistique a été utilisée pour évaluer différentes combinaisons de variables explicatives (longueur corporelle, sexe, année et année-groupe, par exemple) afin de concevoir un modèle prédictif pour chaque type de cicatrice. Nous énumérons également les baleines boréales retrouvées emmêlées dans des engins ou des filets de pêche commerciale qui ont été capturées, trouvées mortes ou observées vivantes. Nos découvertes suggèrent qu’environ 12 % des baleines boréales capturées portent des cicatrices causées par l’emmêlement. La fréquence des cicatrices est étroitement liée à la longueur corporelle et au sexe : environ 50 % des baleines boréales de très grande taille (> 17 m) montrent de telles cicatrices, tandis que les baleines mesurant moins de 9 m portent rarement de telles cicatrices. Par ailleurs, les mâles affichent beaucoup plus de cicatrices que les femelles. Les cicatrices reliées à des collisions avec des navires sont rares et n’apparaissent que sur environ 2 % de toutes les baleines capturées; la longueur corporelle, le sexe et l’année n’étaient pas des facteurs importants. Les cicatrices causées par des tentatives de prédation par les épaulards étaient apparentes sur environ 8 % des baleines prises. Comme pour les blessures causées par l’emmêlement, la fréquence des cicatrices causées par des épaulards était beaucoup plus élevée(> 40 %) sur les baleines mesurant plus de 16 m de longueur et statistiquement plus fréquente dans la deuxième partie de l’étude (2002–2012). L’augmentation des blessures causées par des épaulards au cours de la dernière décennie concorde avec les études réalisées sur la population des baleines boréales de l’est du Canada et de l’ouest du Groenland. Les résultats présentés dans cette étude reflètent l’analyse la plus profonde du taux de blessures causées par l’emmêlement, les navires et les épaulards sur les baleines boréales des mers de Béring, des Tchouktches et de Beaufort à avoir été réalisée jusqu’à présent. Les observations indiquent que : 1) le taux d’emmêlement découlant principalement des engins ou casiers de pêche (crabe ou morue ou les deux) est relativement élevé chez les baleines boréales de très grande taille et probablement plus vieilles, 2) les collisions avec les navires sont rares en ce moment, et 3) les cicatrices causées par des épaulards sont fréquentes chez les baleines adultes de très grande taille (> 17 m). Étant donné le changement rapide de l’habitat de la baleine boréale (diminution des glaces marines, par exemple), l’augmentation de la circulation maritime industrielle dans l’Arctique et l’intensification des opérations de pêche commerciale au nord, nous recommandons fortement de continuer de surveiller les cicatrices et les blessures des baleines boréales capturées afin de documenter les changements

Dynamics of Electric Field Domains and Oscillations of the Photocurrent in a Simple Superlattice Model

A discrete model is introduced to account for the time-periodic oscillations of the photocurrent in a superlattice observed by Kwok et al, in an undoped 40 period AlAs/GaAs superlattice. Basic ingredients are an effective negative differential resistance due to the sequential resonant tunneling of the photoexcited carriers through the potential barriers, and a rate equation for the holes that incorporates photogeneration and recombination. The photoexciting laser acts as a damping factor ending the oscillations when its power is large enough. The model explains: (i) the known oscillatory static I-V characteristic curve through the formation of a domain wall connecting high and low electric field domains, and (ii) the photocurrent and photoluminescence time-dependent oscillations after the domain wall is formed. In our model, they arise from the combined motion of the wall and the shift of the values of the electric field at the domains. Up to a certain value of the photoexcitation, the non-uniform field profile with two domains turns out to be metastable: after the photocurrent oscillations have ceased, the field profile slowly relaxes toward the uniform stationary solution (which is reached on a much longer time scale). Multiple stability of stationary states and hysteresis are also found. An interpretation of the oscillations in the photoluminescence spectrum is also given.Comment: 34 pages, REVTeX 3.0, 10 figures upon request, MA/UC3M/07/9