Comparison of structural performance of one- and two-bay rotary joints for truss applications

The structural performance of one- and two-bay large-diameter discrete-bearing rotary joints was addressed for application to truss-beam structures such as the Space Station Freedom. Finite element analyses are performed to determine values for rotary joint parameters that give the same bending vibration frequency as the parent truss beam. The structural masses and maximum internal loads of these joints are compared to determine their relative structural efficiency. Results indicate that no significant difference exists in the masse of one- and two-bay rotary joints. This conclusion is reinforced with closed-form calculations of rotary joint structural efficiency in extension. Also, transition truss-member loads are higher in the one-bay rotary joint. However, because of the increased buckling strength of these members, the external load-carrying capability of the one-bay concept is higher than that of the two-bay concept

Modeling estuarine response to load reductions in a warmer climate: York River Estuary, Virginia, USA

The impact of climate warming on shallow tributary estuaries will be influenced by the complex cycling of nutrients and organic matter, diversity of primary producers, and enhanced benthic-pelagic coupling typical of these systems, along with advection of nutrients, organic matter, and hypoxic water from adjacent systems. This study utilized a parsimonious, reduced-complexity model that combines mechanistic equations with robust, data-driven, empirical formulations to predict how phytoplankton net primary production (NPP), net ecosystem metabolism (NEM), and hypoxia will change under a range of warmer conditions in the York River Estuary, VA, USA, a sub-estuary of Chesapeake Bay. Modeled NPP peaked earlier and responded positively to warming in the winter and spring throughout most of the system due to increased rates of nutrient remineralization; NPP remained elevated during summer and fall in the upper estuary under warming but decreased in the lower estuary. These changes caused the upper estuary to become more autotrophic, while NEM decreased in the lower estuary due to greater stimulation of respiration relative to NPP. Warming increased the predicted temporal and spatial extent of hypoxia, with the upper estuary experiencing a relatively constant increase in the number of hypoxic days with increasing temperature. Hypoxia in the lower estuary increased more rapidly with temperature. Offsetting this increase in hypoxia with climate warming will require additional nutrient and organic matter load reductions from the surrounding watershed and Chesapeake Bay in order to achieve the same level of improvement predicted in the absence of a warming climate

Southwest Border Violence: Issues in Identifying and Measuring Spillover Violence

[Excerpt] There has been a recent increase in the level of drug trafficking-related violence within and between the drug trafficking organizations in Mexico. This violence has generated concern among U.S. policy makers that the violence in Mexico might spill over into the United States. Currently, U.S. federal officials deny that the recent increase in drug trafficking-related violence in Mexico has resulted in a spillover into the United States, but they acknowledge that the prospect is a serious concern. Currently, no comprehensive, publicly available data exist that can definitively answer the question of whether there has been a significant spillover of drug trafficking-related violence into the United States. Although anecdotal reports have been mixed, U.S. government officials maintain that there has not yet been a significant spillover. In an examination of data that could provide insight into whether there has been a significant spillover in drug trafficking-related violence from Mexico into the United States, CRS analyzed violent crime data from the Federal Bureau of Investigation’s Uniform Crime Report program. The data, however, do not allow analysts to determine what proportion of the violent crime rate is related to drug trafficking or, even more specifically, what proportion of drug trafficking-related violent crimes can be attributed to spillover violence. In conclusion, because the trends in the overall violent crime rate may not be indicative of trends in drug trafficking-related violent crimes, CRS is unable to draw definitive claims about trends in drug trafficking-related violence spilling over from Mexico into the United States. This report will be updated as circumstances warrant

The versatility of a truss mounted mobile transporter for in-space construction

The Mobile Transporter (MT) evolution from early erectable structures assembly activities is detailed. The MT operational features which are required to support astronauts performing on-orbit structure construction or spacecraft assembly functions are presented and discussed. Use of the MT to perform a variety of assembly functions is presented. Estimated EVA assembly times for a precision segmented reflector approximately 20 m in diameter are presented. The EVA/MT technique under study for construction of the reflector (and the entire spacecraft) is illustrated. Finally, the current status of development activities and test results involving the MT and Space Station structural assembly are presented

Tests of an alternate mobile transporter and extravehicular activity assembly procedure for the Space Station Freedom truss

Results are presented from a ground test program of an alternate mobile transporter (MT) concept and extravehicular activity (EVA) assembly procedure for the Space Station Freedom (SSF) truss keel. A three-bay orthogonal tetrahedral truss beam consisting of 44 2-in-diameter struts and 16 nodes was assembled repeatedly in neutral buoyancy by pairs of pressure-suited test subjects working from astronaut positioning devices (APD's) on the MT. The truss bays were cubic with edges 15 ft long. All the truss joint hardware was found to be EVA compatible. The average unit assembly time for a single pair of experienced test subjects was 27.6 sec/strut, which is about half the time derived from other SSF truss assembly tests. A concept for integration of utility trays during truss assembly is introduced and demonstrated in the assembly tests. The concept, which requires minimal EVA handling of the trays, is shown to have little impact on overall assembly time. The results of these tests indicate that by using an MT equipped with APD's, rapid EVA assembly of a space station-size truss structure can be expected

A Preliminary Assessment of Mental Health Needs Faced in Religious Leaders in Eastern Europe

Enormous sociopolitical changes in Eastern Europe in the last decade have had a profound impact on the psychological functioning of the citizens of these nations. In order to assess and intervene in the mental health realm in Eastern Europe, a brief survey was sent to various Christian leaders in Eastern Europe. Common mental health problems identified across the various Eastern European countries and cultures include depression, relationship difficulties, alcohol abuse, and anxiety disorders. Christians in Eastern Europe tend to turn to family and friends for help with these problems first, pastors second, and almost never to mental health professionals. Clergy and laypersons have little training in mental health issues. A promising direction for future service is training those who can, in turn, train Eastern European laypersons in basic listening and support skills. Cultural awareness and sensitivity will be of paramount importance in such an endeavor

Using Videography to Quantify Landscape-Level Availability of Habitat for Grazers: An Example with Emperor Geese in Western Alaska

We present a videography approach to estimating large-scale availability of grazing lawns, an important food resource used by broods of emperor geese (Chen canagica) on the Yukon-Kuskokwim Delta, Alaska. Sampling was conducted in 1999, 2003, and 2004 at six locations that encompassed ~40% of the North American population of breeding emperor geese. We conducted ground truthing in 2003 and 2004 to estimate how accurately grazing lawn was classified. Overall, classification accuracy for grazing lawn and non-grazing lawn habitat was greater than 91%. Availability of grazing lawns was stable among years, but varied both among and within locations. Some locations have up to three times as much available grazing lawn, which in combination with densities of geese, likely represents dramatic variation in per capita food availability. Our results suggest that videography is a useful way to sample quickly across a large region and accurately identify fine-scale habitats. We present its use for estimating the availability of a preferred food resource for emperor geese, but the method could be applied to many other cases.Nous présentons une méthode vidéographique pour évaluer, à grande échelle, la disponibilité des pâturages, une importante ressource alimentaire pour les couvées d’oies empereurs (Chen canagica) du delta Yukon-Kuskokwim, en Alaska. Des échantillonnages ont été effectués en 1999, 2003 et 2004 à six emplacements visant environ 40 % de la population nord-américaine d’oies empereurs nicheuses. Nous avons réalisé des vérifications au sol en 2003 et en 2004 dans le but d’estimer dans quelle mesure les pâturages étaient bien classés. Dans l’ensemble, l’exactitude du classement des habitats destinés au pâturage et de ceux qui ne sont pas destinés au pâturage dépassait les 91 %. La disponibilité des pâturages était stable au fil des ans, mais variait d’un emplacement à l’autre et au sein de ceux-ci. Certains emplacements ont trois fois plus de pâturages disponibles que d’autres. Cela, allié aux densités d’oies, représente vraisemblablement des écarts remarquables pour ce qui est de la disponibilité de nourriture par tête. Nos résultats laissent supposer que la vidéographie représente une bonne manière de faire des échantillonnages rapides dans de grandes régions et de repérer avec prévision les habitats à petite échelle. Nous présentons l’emploi de cette méthode pour évaluer la disponibilité d’une source alimentaire préférée de l’oie empereur, méthode qui pourrait être employée dans bien d’autres cas

Biomechanical locomotion adaptations on uneven surfaces can be simulated with a randomly deforming shoe midsole

Background: A shoe with unsystematic perturbations, similar to natural uneven terrain, may offer an enhanced training stimulus over current unstable footwear technologies. This study compared the instability of a shoe with unpredictably random midsole deformations, an irregular surface and a control shoe-surface whilst treadmill walking and running. Methods: Three-dimensional kinematics and electromyography were recorded of the lower limb in 18 active males. Gait cycle characteristics, joint angles at initial ground contact and maximum values during stance, and muscle activations prior to initial contact and during loading were analysed. Perceived stability, injury-risk and energy consumption were evaluated. Instability was assessed by movement variability, muscular activations and subjective ratings. Results: Posture alterations at initial contact revealed active adaptations in the irregular midsole and irregular surface to maintain stability whilst walking and running. Variability of the gait cycle and lower limb kinematics increased on the irregular surface compared to the control across locomotion types. Similarly increased variability (coefficient of variation) were found in the irregular midsole compared to the control for frontal ankle motion (walk: 31.1 and 14.9, run: 28.1 and 11.6), maximum sagittal knee angle (walk: 7.6 and 4.8, run: 2.8 and 2.4), and global gait characteristics during walking only (2.1 ± 0.5 and 1.6 ± 0.3). Tibialis anterior pre-activation reduced and gastrocnemius activation increased in the irregular midsole compared to the control across locomotion types. During running, peroneus longus activation increased in the irregular midsole and irregular surface. Conclusions: Results indicate random shoe midsole deformations enhanced instability relative to the control and simulated certain locomotion adaptations of the irregular surface, although less pronounced. Thus, a shoe with unpredictable instability revealed potential as a novel instability-training device

Polygenic mechanisms underpinning the response to exercise-induced muscle damage in humans:In vivo and in vitro evidence

We investigated whether 20 candidate single nucleotide polymorphisms (SNPs) were associated with in vivo exercise-induced muscle damage (EIMD), and with an in vitro skeletal muscle stem cell wound healing assay. Sixty-five young, untrained Caucasian adults performed 120 maximal eccentric knee-extensions on an isokinetic dynamometer to induce EIMD. Maximal voluntary isometric/isokinetic knee-extensor torque, knee joint range of motion (ROM), muscle soreness, serum creatine kinase activity and interleukin-6 concentration were assessed before, directly after and 48 h after EIMD. Muscle stem cells were cultured from vastus lateralis biopsies from a separate cohort (n = 12), and markers of repair were measured in vitro. Participants were genotyped for all 20 SNPs using real-time PCR. Seven SNPs were associated with the response to EIMD, and these were used to calculate a total genotype score, which enabled participants to be segregated into three polygenic groups: ‘preferential’ (more ‘protective’ alleles), ‘moderate’, and ‘non-preferential’. The non-preferential group was consistently weaker than the preferential group (1.93 ± 0.81 vs. 2.73 ± 0.59 N ∙ m/kg; P = 9.51 × 10−4) and demonstrated more muscle soreness (p = 0.011) and a larger decrease in knee joint ROM (p = 0.006) following EIMD. Two TTN-AS1 SNPs in linkage disequilibrium were associated with in vivo EIMD (rs3731749, p ≤ 0.005) and accelerated muscle stem cell migration into the artificial wound in vitro (rs1001238, p ≤ 0.006). Thus, we have identified a polygenic profile, linked with both muscle weakness and poorer recovery following EIMD. Moreover, we provide evidence for a novel TTN gene-cell-skeletal muscle mechanism that may help explain some of the interindividual variability in the response to EIMD.</p