Structural and dynamic analysis of the Apollo AFT heat shield Final report, Sep. 12, 1964 - Mar. 1, 1966

Structural and dynamic analysis of Apollo aft heat shiel

Influence of truck driver eye position on effectiveness of retroreflective traffic signs

The amount of light reflected from a retroreflective traffic sign decreases with an increase in the observation angle—the angle between the headlamp, the sign, and the eyes of the driver. Mainly because of the increased seated eye height of truck drivers, the actual observation angles are greater for them than they are for car drivers. Consequently, there is concern about the impaired night-time detection and legibility of retroreflective signs for truck drivers. The present study evaluated the relative amount of light reaching drivers of different types of vehicle by using survey data collected in 1989 by the Transport and Road Research Laboratory (TRRL) in England. The TRRL data included driver eye heights and headlamp mounting heights for 445 vehicles. The present analysis considered three sign locations on a straight roadway: left shoulder, centre, and right shoulder. Two viewing distances were included: 152 m (500 feet) (typical of a sign-legibility distance), and 305 m (1000 feet) (typical of a sign-detection distance). The analysis considered both the differential amount of illumination impinging on the signs from headlamps of trucks and cars, as well as the differential amount of the light reflected from the signs in the direction of truck drivers and car drivers. The main results are that for the viewing distance of 152 m, the amount of light reaching a truck driver can be as low as 25% of the light reaching a car driver; the corresponding percentages for the viewing distance of 305 m are as low as 68%. These reductions were then related to the expected effects on sign legibility and detection. The results imply that the increased eye height of truck drivers could have a major effect on the legibility of retroreflective traffic signs, but only a modest effect on their detection.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68794/2/10.1177_096032719302500105.pd

Recent variations of Ghiacciaio del Calderone, Abruzzi, Italy

AbstractResults of a detailed topographic survey of Ghiacciaio del Calderone, Italy, the southernmost in Europe, are described and compared with those of surveys made in earlier years. Recession and thinning, much affected by micro-climate, have been the predominant state of health during the 20th century. Between 1916 and 1990, volume is estimated to have been reduced by about 90% and area by about 68%

Rockfalls and glacier contraction: Cirque de Troumouse, French Pyrenees

The incidence of rockfalls within the Cirque de Troumouse appears to have been triggered by ice wastage and the resultant geomorphological pattern of rockfall deposits affords an insight into the migration of headwall weathering zones. Observations of the rockfall deposits indicate clear geological controls which maybe directly related to the exposure of the headwall zone during phases of glacier wastage[es] Las caldas de piedras en el Circo de Troumouse parecen haber sido desencadenadas por la acción del hielo, y el modelo geomorfológico de depósitos de bloques resultante proporciona una idea sobre la migración de las zonas de meteorización en las paredes. Las observaciones de tales depósitos indican la existencia de claros controles geológicos que pueden relacionarse directamente con la exposición de la pared durante las fases de fusión glaciar. [fr] Les chutes des pierres dans le cirque de Troumouse paraissent avoir été déclenchées par l'action de la glace, et le modèle géomorphologique des dépôts de blocs résultant donne une idée de la migration des zones de météorisation dans les parois. Les observations de ces dépôts indiquent l'existence de contrôles géologiques très clairs qui peuvent être directement liés à l'exposition de la paroi durant les phases de fusion glaciaire

Stress transmission in granular matter

The transmission of forces through a disordered granular system is studied by means of a geometrical-topological approach that reduces the granular packing into a set of layers. This layered structure constitutes the skeleton through which the force chains set up. Given the granular packing, and the region where the force is applied, such a skeleton is uniquely defined. Within this framework, we write an equation for the transmission of the vertical forces that can be solved recursively layer by layer. We find that a special class of analytical solutions for this equation are L\'evi-stable distributions. We discuss the link between criticality and fragility and we show how the disordered packing naturally induces the formation of force-chains and arches. We point out that critical regimes, with power law distributions, are associated with the roughness of the topological layers. Whereas, fragility is associated with local changes in the force network induced by local granular rearrangements or by changes in the applied force. The results are compared with recent experimental observations in particulate matter and with computer simulations.Comment: 14 pages, Latex, 5 EPS figure

Expansion of the Knockdown Resistance Frequency Map for Human Head Lice (Phthiraptera: Pediculidae) in the United States Using Quantitative Sequencing

Pediculosis is a prevalent parasitic infestation of humans, which is increasing due, in part, to the selection of lice resistant to either the pyrethrins or pyrethroid insecticides by the knockdown resistance (kdr) mechanism. To determine the extent and magnitude of thekdr-type mutations responsible for this resistance, lice were collected from 138 collection sites in 48 U.S. states from 22 July 2013 to 11 May 2015 and analyzed by quantitative sequencing. Previously published data were used for comparisons of the changes in the frequency of thekdr-type mutations over time. Mean percent resistance allele frequency (mean % RAF) values across the three mutation loci were determined from each collection site. The overall mean % RAF (+/-SD) for all analyzed lice was 98.3 +/- 10%. 132/138 sites (95.6%) had a mean % RAF of 100%, five sites (3.7%) had intermediate values, and only a single site had no mutations (0.0%). Forty-two states (88%) had a mean % RAF of 100%. The frequencies ofkdr-type mutations did not differ regardless of the human population size that the lice were collected from, indicating a uniformly high level of resistant alleles. The loss of efficacy of the Nix formulation (Prestige Brand, Tarrytown, NY) from 1998 to 2013 was correlated to the increase inkdr-type mutations. These data provide a plausible reason for the decrease in the effectiveness of permethrin in the Nix formulation, which is the parallel increase ofkdr-type mutations in lice over time

Male Attitudes towards Infertility:Results from a Global Questionnaire

PURPOSE: In general, men are less likely to seek health care than women. Infertility is a global disease that afflicts approximately 15% of reproductive age couples and the male contributes to 40% of the diagnosable cause. Remarkably, no large or multi-national population data exist regarding men’s perceptions about their infertility. The purpose of this study was to advance our knowledge about the infertile male’s social experience regarding: (1) how they feel about their infertility, (2) what motivated them to seek health care, (3) how likely are they to talk with others about their infertility, (4) their awareness of male infertility support groups, and (5) what their primary source for information is regarding male infertility? Based on the results from this study, these simple questions now have clearer definition. MATERIALS AND METHODS: An Institutional Review Board-approved, male-directed, anonymous questionnaire translated into 20 languages was made globally available through the Fertility Europe website (https://fertilityeurope.eu). Males (n=1,171) age 20–49 years were invited to complete the online survey after informed consent. RESULTS: Most respondents were European (86%). Of European men, <15.8% were self-motivated to seek medical help. Further, their physician was not the primary source of information regarding their infertility. While most men (59%) viewed their infertility positively, a large majority were not very likely (73%) to talk about it. Most respondents indicated a lack of awareness or absence of male infertility support groups. CONCLUSIONS: These are the first multi-national population data revealing men’s feelings about their infertility, what motivates them to seek help and their awareness of resources for peer support and information. These findings also serve to highlight significant gaps that exist in the provision of male reproductive health care and in supportive resources for men suffering from infertility. We offer recommendations on how to address the problem(s)

Looming motion primes the visuomotor system

A wealth of evidence now shows that human and animal observers display greater sensitivity to objects that move toward them than to objects that remain static or move away. Increased sensitivity in humans is often evidenced by reaction times that increase in rank order from looming, to receding, to static targets. However, it is not clear whether the processing advantage enjoyed by looming motion is mediated by the attention system or the motor system. The present study investigated this by first examining whether sensitivity is to looming motion per se or to certain monocular or binocular cues that constitute stereoscopic motion in depth. None of the cues accounted for the looming advantage. A perceptual measure was then used to examine performance with minimal involvement of the motor system. Results showed that looming and receding motion were equivalent in attracting attention, suggesting that the looming advantage is indeed mediated by the motor system. These findings suggest that although motion itself is sufficient for attentional capture, motion direction can prime motor responses

An atlas of cell types in the mouse epididymis and vas deferens

Following testicular spermatogenesis, mammalian sperm continue to mature in a long epithelial tube known as the epididymis, which plays key roles in remodeling sperm protein, lipid, and RNA composition. To understand the roles for the epididymis in reproductive biology, we generated a single-cell atlas of the murine epididymis and vas deferens. We recovered key epithelial cell types including principal cells, clear cells, and basal cells, along with associated support cells that include fibroblasts, smooth muscle, macrophages and other immune cells. Moreover, our data illuminate extensive regional specialization of principal cell populations across the length of the epididymis. In addition to region-specific specialization of principal cells, we find evidence for functionally specialized subpopulations of stromal cells, and, most notably, two distinct populations of clear cells. Our dataset extends on existing knowledge of epididymal biology, and provides a wealth of information on potential regulatory and signaling factors that bear future investigation