Perfect bell nozzle parametric and optimization curves

Nozzle contour data for untruncated Bell nozzles with expansion area ratios to 6100 and a specific heat ratio of 1.2 are provided. Curves for optimization of nozzles for maximum thrust coefficient within a given length, surface area, or area ratio are included. The nozzles are two dimensional axisymmetric and calculations were performed using the method of characteristics. Drag due to wall friction was included in the final thrust coefficient

ASTP simulated lightning test report

A simulated lightning test was conducted on the backup spacecraft for the Apollo Soyuz Test Project mission (CSM-119) to determine the susceptibility of the Apollo spacecraft to damage from the indirect effects of lightning. It is demonstrated that induced lightning effects from low-level injected currents can be scaled linearly to those which are obtained in a full threat lightning stroke. Test results indicate that: (1) many of the power and signal critical circuits would fail if subjected to full-threat lightning, (2) pyrotechnic circuits are safe for full-threat lightning, and (3) common-mode voltages exceeded the failure criteria level for all but three of the circuits tested

The oxidative costs of reproduction are group-size dependent in a wild cooperative breeder.

Life-history theory assumes that reproduction entails a cost, and research on cooperatively breeding societies suggests that the cooperative sharing of workloads can reduce this cost. However, the physiological mechanisms that underpin both the costs of reproduction and the benefits of cooperation remain poorly understood. It has been hypothesized that reproductive costs may arise in part from oxidative stress, as reproductive investment may elevate exposure to reactive oxygen species, compromising survival and future reproduction and accelerating senescence. However, experimental evidence of oxidative costs of reproduction in the wild remains scarce. Here, we use a clutch-removal experiment to investigate the oxidative costs of reproduction in a wild cooperatively breeding bird, the white-browed sparrow weaver, Plocepasser mahali. Our results reveal costs of reproduction that are dependent on group size: relative to individuals in groups whose eggs were experimentally removed, individuals in groups that raised offspring experienced an associated cost (elevated oxidative damage and reduced body mass), but only if they were in small groups containing fewer or no helpers. Furthermore, during nestling provisioning, individuals that provisioned at higher rates showed greater within-individual declines in body mass and antioxidant protection. Our results provide rare experimental evidence that reproduction can negatively impact both oxidative status and body mass in the wild, and suggest that these costs can be mitigated in cooperative societies by the presence of additional helpers. These findings have implications for our understanding of the energetic and oxidative costs of reproduction, and the benefits of cooperation in animal societies.This study was funded by a BBSRC David Phillips Fellowship and a Royal Society Research Grant to A.J.Y. and an NERC studentship to D.L.C. J.D.B. was supported by a Royal Society University Research Fellowship.This is the final version of the article. It first appeared from Royal Society Publishing via http://dx.doi.org/10.1098/rspb.2015.203

Wellness in the Helping Professions: Historical Overview, Wellness Models, and Current Trends

Introduction Wellness and the concept of holism have rich histories throughout the helping professions. However, Westernized medical models often promote the concept of treatment rather than prevention, limiting the helper’s ability to focus on wellness when working with clients/patients. Therefore, in order to support a re-integration to holistic wellness and the prevention of illness, and re-focus on a wellness ideology, we conducted a thorough theoretical overview of wellness in the helping professions to: (a) provide a historical overview of wellness in helping professions, (b) discuss prominent wellness models, (c) review wellness assessments, (d) present wellness supervision models, and (e) offer implications for helping professionals, helping educators, and helping-professionals-in-training (HPITs) who would like to implement or re-integrate wellness techniques across occupational and personal realms. Discussion The history of healthcare is rich with wellness undertones and holistic foundations for practice. However, the helping professions have been shifting away from traditional wellness ideologies with the emphasis on current healthcare trends and the philosophical struggle of balancing both wellness tenets and a popular medical model for practice. Following a thorough discussion of historical implications of wellness, wellness models, wellness assessments, and wellness supervision, implications for a re-integration of a wellness ideology are highlighted for (a) helping professionals, (b) healthcare educators, and (c) HPITs. In regard to practicing healthcare providers, helping professionals are only as helpful as they are well. We suggest that helping professionals refocus their practice to include wellness and integrate such practices into their daily routine to combat compassion fatigue and/or burnout (which are common occurrences among helpers). Wellness practices may include meditation; breathing exercises; reflection; journaling; and other avenues to reflect, respond, and re-center throughout the day to remain within their own window of tolerance, reducing potential for burnout. Helping professional educators, on the other hand, are tasked with training the next wave of helpers. As such, they are responsible for assessing personal levels of wellness in order to ensure they are modeling wellness-behaviors for their HPITs. Regarding healthcare training programs and curriculums, administrators may introduce wellness courses or infuse wellness throughout the life of the program/training experience so HPITs are learning about wellness education and how to implement it across diverse situations. Furthermore, consistent wellness infusion in curricula could promote wellness behaviors and practices beyond the training experience. Finally, HPITs (similar to practicing professionals and healthcare educators) are not insulated from the effects of unwellness. As such, HPITs are encouraged during their clinical experiences to assess their own wellness and partake in activities to increase their wellness awareness. HPITs can formally (see the section on wellness assessments) or informally assess (refer to the wellness models section) their current levels of functioning and learn of potential wellness discrepancies early on in their careers, which in turn can help mitigate negative effects of being a helper in the future. Conclusion With the influence of Westernized viewpoints and a medical model symptom-reduction focus, a re-orientation to wellness could benefit helpers. Furthermore, as helpers continue to face heavy caseloads, high stress environments, and increased propensity for burnout and related issues, increasing wellness and wellness awareness can serve as a protective factor against the deleterious effects of helping for both helpers and the individuals they serve. By reviewing the literature on wellness (e.g., models, assessments, supervision) in the helping professions and applying wellness perspectives in personal and professional endeavors, helping can once again be at the fore-front of wellness-based treatment, training, and living

The Sexual Values and Behaviors Discrepancy Model

Founded in theory and empirical research, we developed the Sexual Values and Behaviors Discrepancy Model (SVBDM) as reflective model for counselors to follow in order to assist their clients in safely reducing discrepancies between their ideal and practiced sexual beliefs, values, and behaviors. The SVBDM is a wellness-informed and sex-positive approach to working with clients and is comprised of three steps: Identification and Operationalization of Potential Sexual Issues, Counselor’s Self-Assessment, and Reducing Discrepancies and Maintaining Safety. We note practical implications and potential limitations of this model as well as recommendations for future research

Immune response in a wild bird is predicted by oxidative status, but does not cause oxidative stress.

The immune system provides vital protection against pathogens, but extensive evidence suggests that mounting immune responses can entail survival and fecundity costs. The physiological mechanisms that underpin these costs remain poorly understood, despite their potentially important role in shaping life-histories. Recent studies involving laboratory models highlight the possibility that oxidative stress could mediate these costs, as immune-activation can increase the production of reactive oxygen species leading to oxidative stress. However, this hypothesis has rarely been tested in free-ranging wild populations, where natural oxidative statuses and compensatory strategies may moderate immune responses and their impacts on oxidative status. Furthermore, the possibility that individuals scale their immune responses according to their oxidative status, conceivably to mitigate such costs, remains virtually unexplored. Here, we experimentally investigate the effects of a phytohaemagglutinin (PHA) immune-challenge on oxidative status in wild male and female white-browed sparrow weavers, Plocepasser mahali. We also establish whether baseline oxidative status prior to challenge predicts the scale of the immune responses. Contrary to previous work on captive animals, our findings suggest that PHA-induced immune-activation does not elicit oxidative stress. Compared with controls (n = 25 birds), PHA-injected birds (n = 27 birds) showed no evidence of a differential change in markers of oxidative damage or enzymatic and non-enzymatic antioxidant protection 24 hours after challenge. We did, however, find that the activity of a key antioxidant enzyme (superoxide dismutase, SOD) prior to immune-activation predicted the scale of the resulting swelling: birds with stronger initial SOD activity subsequently produced smaller swellings. Our findings (i) suggest that wild birds can mount immune responses without suffering from systemic oxidative stress, and (ii) lend support to biomedical evidence that baseline oxidative status can impact the scale of immune responses; a possibility not yet recognised in ecological studies of immunity

A priori Wannier functions from modified Hartree-Fock and Kohn-Sham equations

The Hartree-Fock equations are modified to directly yield Wannier functions following a proposal of Shukla et al. [Chem. Phys. Lett. 262, 213-218 (1996)]. This approach circumvents the a posteriori application of the Wannier transformation to Bloch functions. I give a novel and rigorous derivation of the relevant equations by introducing an orthogonalizing potential to ensure the orthogonality among the resulting functions. The properties of these, so-called a priori Wannier functions, are analyzed and the relation of the modified Hartree-Fock equations to the conventional, Bloch-function-based equations is elucidated. It is pointed out that the modified equations offer a different route to maximally localized Wannier functions. Their computational solution is found to involve an effort that is comparable to the effort for the solution of the conventional equations. Above all, I show how a priori Wannier functions can be obtained by a modification of the Kohn-Sham equations of density-functional theory.Comment: 7 pages, RevTeX4, revise

Conserved Spin and Orbital Angular Momentum Hall Current in a Two-Dimensional Electron System with Rashba and Dresselhaus Spin-orbit Coupling

We study theoretically the spin and orbital angular momentum (OAM) Hall effect in a high mobility two-dimensional electron system with Rashba and Dresselhuas spin-orbit coupling by introducing both the spin and OAM torque corrections, respectively, to the spin and OAM currents. We find that when both bands are occupied, the spin Hall conductivity is still a constant (i.e., independent of the carrier density) which, however, has an opposite sign to the previous value. The spin Hall conductivity in general would not be cancelled by the OAM Hall conductivity. The OAM Hall conductivity is also independent of the carrier density but depends on the strength ratio of the Rashba to Dresselhaus spin-orbit coupling, suggesting that one can manipulate the total Hall current through tuning the Rashba coupling by a gate voltage. We note that in a pure Rashba system, though the spin Hall conductivity is exactly cancelled by the OAM Hall conductivity due to the angular momentum conservation, the spin Hall effect could still manifest itself as nonzero magnetization Hall current and finite magnetization at the sample edges because the magnetic dipole moment associated with the spin of an electron is twice as large as that of the OAM. We also evaluate the electric field-induced OAM and discuss the origin of the OAM Hall current. Finally, we find that the spin and OAM Hall conductivities are closely related to the Berry vector (or gauge) potential.Comment: latest revised version; Accepted for publication in Physical Review

The Role of Tobacco, Alcohol, and Obesity in Neoplastic Progression to Esophageal Adenocarcinoma: A Prospective Study of Barrett's Esophagus

Background: Esophageal adenocarcinoma (EA) incidence in many developed countries has increased dramatically over four decades, while survival remains poor. Persons with Barrett's esophagus (BE), who experience substantially elevated EA risk, are typically followed in surveillance involving periodic endoscopy with biopsies, although few progress to EA. No medical, surgical or lifestyle interventions have been proven to safely lower EA risk. Design: We investigated whether smoking, obesity or alcohol could predict progression to EA in a prospective cohort of 411 BE patients. Data were collected during personal interview. Adjusted hazard ratios (HR) were estimated using Cox regression. Results: 39% had body mass index (BMI) over 30 and 64% had smoked cigarettes. Main analyses focused on those with at least 5 months of follow-up (33,635 person-months), in whom 45 developed EA. Risk increased by 3% per year of age (trend p-value 0.02), with approximate doubling of risk among males. EA risk increased with smoking pack-years (trend p-value 0.04) and duration (p-value 0.05). Compared to never-smokers, the HR for those in the highest pack-year tertile was 2.29 (95%CI 1.04–5.07). No association was found with alcohol or BMI, whereas a suggestion of increased risk was observed in those with higher waist-hip ratio, especially among males. Conclusion: EA risk significantly increased with increasing age and cigarette exposure. Abdominal obesity, but not BMI, was associated with a modest increased risk. Continued follow-up of this and other cohorts is needed to precisely define these relationships so as to inform risk stratification and preventive interventions