Internally Isolated 12U Rail CubeSat Dispenser with Analyzable Boundary Conditions

CubeSats are growing in size, capability, and complexity. Along with these increases comes decreased acceptance of risk. Tyvak Nano-Satellite Systems’ 12U Dispenser incorporates significant upgrades to our flight-proven designs that mitigate the two key concerns for the developer designing a rail-type CubeSat. First, the dynamic environments experienced by rideshare payloads can be extreme. The Tyvak 12U dispenser incorporates a first-of-its-kind internal isolation system that reduces the CubeSat environment by 70-90% compared to the external launch vehicle environment. The CubeSat developer can therefore maximize the design for the space mission rather than to survive excessive launch loads. Secondly, developers have faced the challenge of modeling the dynamic response of their satellite due to the “floating” nonlinear boundary condition between it and the dispenser. The Tyvak 12U Dispenser solves this problem by incorporating movable rails that cradle the payload on all four corners. This mechanized rail interface provides an analyzable boundary condition and allows the developer to accurately predict isolated loads transmitted to the spacecraft. The design also provides a straightforward approach to structural design, analysis, manufacturing, test, and integration. The developer can then produce a satellite that is neither over-built nor over-tested

An Exact Solution to O(26) Sigma Model coupled to 2-D Gravity

By a mapping to the bosonic string theory, we present an exact solution to the O(26) sigma model coupled to 2-D quantum gravity. In particular, we obtain the exact gravitational dressing to the various matter operators classified by the irreducible representations of O(26). We also derive the exact form of the gravitationally modified beta function for the original coupling constant $e^2$. The relation between our exact solution and the asymptotic solution given in ref[3] is discussed in various aspects.Comment: 10 pages, pupt-144

Targeting the p53 Pathway in Ewing Sarcoma

The p53 tumour suppressor plays a pivotal role in the prevention of oncogenic transformation. Cancers frequently evade the potent antitumour surveillance mechanisms of p53 through mutation of the TP53 gene, with approximately 50% of all human malignancies expressing dysfunctional, mutated p53 proteins. Interestingly, genetic lesions in the TP53 gene are only observed in 10% of Ewing Sarcomas, with the majority of these sarcomas expressing a functional wild-type p53. In addition, the p53 downstream signaling pathways and DNA-damage cell cycle checkpoints remain functionally intact in these sarcomas. This paper summarizes recent insights into the functional capabilities and regulation of p53 in Ewing Sarcoma, with a particular focus on the cross-talk between p53 and the EWS-FLI1 gene rearrangement frequently associated with this disease. The development of several activators of p53 is discussed, with recent evidence demonstrating the potential of small molecule p53 activators as a promising systemic therapeutic approach for the treatment of Ewing Sarcomas with wild-type p53

Exchange Fluctuation Theorem for correlated quantum systems

We extend the Exchange Fluctuation Theorem for energy exchange between thermal quantum systems beyond the assumption of molecular chaos, and describe the non-equilibrium exchange dynamics of correlated quantum states. The relation quantifies how the tendency for systems to equilibrate is modified in high-correlation environments. Our results elucidate the role of measurement disturbance for such scenarios. We show a simple application by finding a semi-classical maximum work theorem in the presence of correlations.Comment: Lots of new material added, a figure, and a new author, 13 pages, 1 figure, comments welcom

Frequency and determinants of vitamin D deficiency among premenopausal and postmenopausal women in Karachi Pakistan

Background: Vitamin D deficiency is becoming a serious public health problem, even in sun-drenched cities like Karachi, Pakistan. We investigated the prevalence of vitamin D deficiency and its association with sociodemographic characteristics, anthropometric measures, and lifestyle factors among premenopausal and postmenopausal women (n = 784).Methods: Face-to-face interviews were conducted to collect information and serum concentrations of 25-hydroxyvitamin D were measured after the interviews.Results: A total of 57% of women were vitamin D deficient with higher vitamin D deficiency found among premenopausal women (64.7%) compared to postmenopausal women (49%). The median serum concentrations of 25-hydroxyvitamin D (IQR) were 16.7 ng/ml (IQR 9.8-30.0). Factors associated with vitamin D deficiency were lower socioeconomic status (OR 2.00; 95% CI 1.15-3.48), younger age with highest vitamin D deficiency found in \u3c 35 years of age group (OR 3.11; 95% CI 1.76-5.51), and winter season (OR 1.51, 95% CI 1.07-2.15) after adjusting for multiple confounders. The use of vitamin D supplement (OR 0.59, 95% CI 0.38-0.92) and vigorous exercise (OR 0.20, 95% CI 0.05-0.80) were protective against vitamin D deficiency.Conclusions: The study shows a high prevalence of vitamin D deficiency, with detrimental health effects, among younger women belonging to lower socioeconomic status and during the winter season. The use of vitamin D supplements and vigorous exercise were protective measures. Public health campaigns are needed for education and awareness about vitamin D deficiency to improve vitamin D status for younger women living in poor environments

A squeezed state source using radiation pressure induced rigidity

We propose an experiment to extract ponderomotive squeezing from an interferometer with high circulating power and low mass mirrors. In this interferometer, optical resonances of the arm cavities are detuned from the laser frequency, creating a mechanical rigidity that dramatically suppresses displacement noise. After taking into account imperfection of optical elements, laser noise, and other technical noise consistent with existing laser and optical technologies and typical laboratory environments, we expect the output light from the interferometer to have measurable squeezing of ~5 dB, with a frequency-independent squeeze angle for frequencies below 1 kHz. This squeeze source is well suited for injection into a gravitational-wave interferometer, leading to improved sensitivity from reduction in the quantum noise. Furthermore, this design provides an experimental test of quantum-limited radiation pressure effects, which have not previously been tested.Comment: 15 pages, 6 figures, submitted to Phys. Rev.

Factors associated with mammographic breast density among women in Karachi Pakistan

Background: There are no studies done to evaluate the distribution of mammographic breast density and factors associated with it among Pakistani women.Methods: Participants included 477 women, who had received either diagnostic or screening mammography at two hospitals in Karachi Pakistan. Mammographic breast density was assessed using the Breast Imaging Reporting and Data System. In person interviews were conducted using a detailed questionnaire, to assess risk factors of interest, and venous blood was collected to measure serum vitamin D level at the end of the interview. To determine the association of potential factors with mammographic breast density, multivariable polytomous logistic regression was used.Results: High-density mammographic breast density (heterogeneously and dense categories) was high and found in 62.4% of women. There was a significant association of both heterogeneously dense and dense breasts with women of a younger age group \u3c 45 years (OR 2.68, 95% CI 1.60-4.49) and (OR 4.83, 95% CI 2.54-9.16) respectively. Women with heterogeneously dense and dense breasts versus fatty and fibroglandular breasts had a higher history of benign breast disease (OR 1.90, 95% CI 1.14-3.17) and (OR 3.61, 95% CI 1.90-6.86) respectively. There was an inverse relationship between breast density and body mass index. Women with dense breasts and heterogeneously dense breasts had lower body mass index (OR 0.94 95% CI 0.90-0.99) and (OR 0.81, 95% CI 0.76-0.87) respectively. There was no association of mammographic breast density with serum vitamin D levels, diet, and breast cancer.Conclusions: The findings of a positive association of higher mammographic density with younger age and benign breast disease and a negative association between body mass index and breast density are important findings that need to be considered in developing screening guidelines for the Pakistani population

Patient delay in breast cancer diagnosis in two hospitals in Karachi, Pakistan: Preventive and life-saving measures needed

Purpose: Patients with breast cancer in Pakistan commonly present with advanced disease. The objectives of this study were to evaluate the frequency and length of delays in seeking medical consultation and to assess the factors associated with them.Methods: Four hundred ninety-nine patients with newly diagnosed breast cancer were enrolled and interviewed over the period from February 2015 to August 2017. Information on sociodemographic factors, delay to medical consultation, stage of breast cancer at presentation, and tumor characteristics of the breast cancer were collected through face-to-face interviews and medical file review.Results: The mean (standard deviation) age of patients with breast cancer was 48.0 (12.3) years. The mean (standard deviation) patient delay was 15.7 (25.9) months, with 55.2% of women detecting a breast lump but not seeking a medical consultation because of a lack of awareness about the significance of the lump. A total of 9.4% of the women decided to seek treatment initially using complementary and alternative medicine and traditional treatment; 9.4% of the women presented to a health care provider with a breast lump but no action was taken, and they were wrongly reassured about the lump without mammography or biopsy. For 26% of the women, the delay in presentation was caused by anxiety, fears and misconceptions regarding diagnosis and treatment, and other social factors including possible adverse effects on their relationship with their husband. Multivariable analysis showed a strong association of lower socioeconomic status (odds ratio [OR], 8.11 [95% CI, 2.46 to 26.69]) and late stage of breast cancer (OR, 4.83 [95% CI, 1.74 to 13.39]) with a patient delay of ≥ 3 months.Conclusion: Patient delay is a serious problem in Pakistan. There is an urgent need for intensive and comprehensive breast cancer education that addresses the myths and misconceptions related to breast cancer

A multicenter case control study of association of vitamin D with breast cancer among women in Karachi, Pakistan

Background: The prevalence of vitamin D inadequacy and breast cancer are both high among women living in Karachi, Pakistan. Methods: A matched case control study was conducted in two hospitals of Karachi, Pakistan to evaluate the association of vitamin D (serum 25-hydroxyvitamin D) concentrations, vitamin D supplementation and sun exposure with breast cancer among Pakistani women. A total of 411 newly diagnosed histologically confirmed primary breast cancer cases were enrolled and 784 controls, free of breast and any other cancers, were matched by age (year of birth ± 5 years), residence in the same geographic area and study site. Information was collected on sociodemographic history, history of vitamin D supplementation, past medical and obstetrical history, family history of breast cancer, sun exposure history, histopathology reports and anthropometric measurement and venous blood was collected to measure serum 25-hydroxyvitamin D (25(OH)D) concentration. Results: Compared to patients with sufficient serum vitamin D (\u3e30 ng/ml), women with serum vitamin D deficiency (\u3c20ng/ml), had a higher risk of breast cancer (OR = 1.65, 95%CI: 1.10, 2.50). Women with history of vitamin D supplementation one year prior to enrollment, had significant protective effect against breast cancer (OR = 0.32, 95% CI: 0.24, 0.43). Conclusions and Recommendation: Serum vitamin D deficiency was associated with increased risk of breast cancer, while vitamin D supplementation was associated with decreased risk of breast cancer. In Pakistani women, where vitamin D deficiency is common, raising and maintaining serum vitamin D at population level is a safe and affordable strategy. It may play a role in reducing the incidence of both vitamin D deficiency and breast cancer, particularly among poor women where the breast cancer mortality is highest due to limited resources for early detection, diagnosis, and treatment. The effects of vitamin D with regard to breast cancer risk in Karachi Pakistan should be further evaluated