Space trajectories optimization using variable-chromosome-length genetic algorithms

The problem of optimal design of a multi-gravity-assist space trajectories, with free number of deep space maneuvers (MGADSM) poses multi-modal cost functions. In the general form of the problem, the number of design variables is solution dependent. To handle global optimization problems where the number of design variables varies from one solution to another, two novel genetic-based techniques are introduced: hidden genes genetic algorithm (HGGA) and dynamic-size multiple population genetic algorithm (DSMPGA). In HGGA, a fixed length for the design variables is assigned for all solutions. Independent variables of each solution are divided into effective and ineffective (hidden) genes. Hidden genes are excluded in cost function evaluations. Full-length solutions undergo standard genetic operations. In DSMPGA, sub-populations of fixed size design spaces are randomly initialized. Standard genetic operations are carried out for a stage of generations. A new population is then created by reproduction from all members based on their relative fitness. The resulting sub-populations have different sizes from their initial sizes. The process repeats, leading to increasing the size of sub-populations of more fit solutions. Both techniques are applied to several MGADSM problems. They have the capability to determine the number of swing-bys, the planets to swing by, launch and arrival dates, and the number of deep space maneuvers as well as their locations, magnitudes, and directions in an optimal sense. The results show that solutions obtained using the developed tools match known solutions for complex case studies. The HGGA is also used to obtain the asteroids sequence and the mission structure in the global trajectory optimization competition (GTOC) problem. As an application of GA optimization to Earth orbits, the problem of visiting a set of ground sites within a constrained time frame is solved. The J2 perturbation and zonal coverage are considered to design repeated Sun-synchronous orbits. Finally, a new set of orbits, the repeated shadow track orbits (RSTO), is introduced. The orbit parameters are optimized such that the shadow of a spacecraft on the Earth visits the same locations periodically every desired number of days

Cavity optomechanics with stoichiometric SiN films

We study high-stress SiN films for reaching the quantum regime with mesoscopic oscillators connected to a room-temperature thermal bath, for which there are stringent requirements on the oscillators' quality factors and frequencies. Our SiN films support mechanical modes with unprecedented products of mechanical quality factor $Q_m$ and frequency $\nu_m$ reaching $Q_{m} \nu_m \simeq2 \times 10^{13}$ Hz. The SiN membranes exhibit a low optical absorption characterized by Im$(n) \lesssim 10^{-5}$ at 935 nm, representing a 15 times reduction for SiN membranes. We have developed an apparatus to simultaneously cool the motion of multiple mechanical modes based on a short, high-finesse Fabry-Perot cavity and present initial cooling results along with future possibilities.Comment: 4 pages, 5 figure

Investigation of Diffuse Hair Fall Case Due to Vitamin D Deficiency: A Case Report and Literature Review

A 45-year-old female from northern Sudan presented a complaint of diffuse hair loss from her scalp for 4 years. The condition started when she was in Saudi Arabia, where she resided for five years with her husband and children. The condition is associated with fatigability and easily falling asleep. The condition is static with no known relieving or aggravating factors. She looks well, not pale, jaundiced or cyanosed, regular pulse, no lymph node enlargement; thyroid is central with normal size and no lower limb edema. Scalp: looks normal, no scales or erosions. Hair: hair is dry with normal texture; loss is diffuse, no apparent patch of alopecia. Axillary and pubic hair is normal. All investigations were within normal values except serum vitamin D that was found to be very low: 9 (average value 30–300). Management plans to correct the deficiency for three months, and then a daily maintenance dose is to be prescribed. The monitoring of vitamin D serum level is to be assessed to avoid hyper vitaminosis. Vitamin D supplement was prescribed as oral tabs of 50,000 IU weekly for three months. Daily maintenance dose of 1000 IU was prescribed. Improvement was noticed starting from the first month, and excellent result was achieved after three months of daily supplementation; daily maintenance dose was then prescribed with an advice of being outdoors to enhance endogenous synthesis. Conclusion: Serum vitamin D level should be assessed in patients with hair loss, especially those at a risk because of being indoors

Self-consistent treatment of the self-energy in nuclear matter

The influence of hole-hole propagation in addition to the conventional particle-particle propagation, on the energy per nucleon and the momentum distribution is investigated. The results are compared to the Brueckner-Hartree-Fock (BHF) calculations with a continuous choice and conventional choice for the single-particle spectrum. The Bethe-Goldstone equation has been solved using realistic $NN$ interactions. Also, the structure of nucleon self-energy in nuclear matter is evaluated. All the self-energies are calculated self-consistently. Starting from the BHF approximation without the usual angle-average approximation, the effects of hole-hole contributions and a self-consistent treatment within the framework of the Green function approach are investigated. Using the self-consistent self-energy, the hole and particle self-consistent spectral functions including the particle-particle and hole-hole ladder contributions in nuclear matter are calculated using realistic $NN$ interactions. We found that, the difference in binding energy between both results, i.e. BHF and self-consistent Green function, is not large. This explains why is the BHF ignored the 2h1p contribution.Comment: Preprint 20 pages including 15 figures and one tabl

Assessment of Serum Copper Level among Sudanese Patients with vitiligo

Background: Vitiligo is a common skin disease of unknown etiology characterized clinically by depigmented patches, which can be localized or generalized; it usually runs a chronic course with an un predictable outcome and failure of complete cure in many affected individuals. Many communities consider it a contagious disease which leads to a great psychological and social stigma for patients; previous studies showed that copper might be associated with the pathogenesis of vitiligo. The aim of this study was to assess copper level in Sudanese vitiligo patients. Methods: This is a case-control study conducted in dermatology clinics in Khartoum state during the period from November 2018 to February 2019. Blood samples were obtained from 100 participants, 50 from vitiligo patients and 50 from non-vitiligo subjects representing a control  group. Serum copper was measured by mind-ray (automation). Results: A highly significant increase (P-value = 0.000) in the copper level was seen in vitiligo patients compared with the control group. Of the total number of patients, 17 (34%) were females and 33 (66%) were males. According to the duration of the disease, the copper level was significantly increased in patient group with a disease duration of > one year compared to the patient group six months–one year and patient group < 6 months; we found no significance of the family history, 18% of the case group had a family history while 42 (82%) had no family history. Discussion: The relationship between the serum level of copper and vitiligo has been assessed by many studies. Copper is one of the trace elements that was found to be important for tyrosinase enzyme that catalyzes the first steps in melanin synthesis in the skin. Some studies showed that the disease was associated with low serum levels of copper and since vitiligo is a disease that is characterized clinically by white areas of skin with no melanin, these studies seem to be logical. However, in this study, the serum level of copper was found to be high in vitiligo patients which might be justified by the release of copper from the destroyed melanocytes. Another justification might be a defect in the carrier protein for copper. Conclusion: The study found that the serum copper was significantly increased in vitiligo patients compared to the control and it is recommended that serum copper level and copper profile should be assessed routinely in vitiligo patients. Keywords: vitiligo, depigmentation, copper, Sudanes

Absolute Measurements for Uranium Verification Content in Radiographic Containers

Depleted Uranium (DU) is used for its very high density in civilian uses include radiation shielding in medical radiation therapy, industrial radiography equipment, containers used to transport radioactive materials. Absolute measurements have been performed for verification of uranium mass content in gamma radiography by using detector’s model developed with MCNP in nuclear safeguard inspection for these samples. Both the experimental results obtained as well as MCNP results are used to estimate the 238U mass content. The determined and the declared 238U masses values are found in an agreement with accuracy from -1.74 % to 1.80 %

Scalar FCNC and rare top decays in a two Higgs doublet model "for the top"

In the so called two Higgs doublet model for the top-quark (T2HDM), first suggested by Das and Kao, the top quark receives a special status, which endows it with a naturally large mass, and also potentially gives rise to large flavor changing neutral currents (FCNC) only in the up-quark sector. In this paper we calculate the branching ratio (BR) for the rare decays t->ch and h->tc (h is a neutral Higgs) in the T2HDM, at tree level and at 1-loop when it exceeds the tree-level. We compare our results to predictions from other versions of 2HDM's and find that the scalar FCNC in the T2HDM can play a significant role in these decays. In particular, the 1-loop mediated decays can be significantly enhanced in the T2HDM compared to the 2HDM of types I and II, in some instances reaching BR~10^-4 which is within the detectable level at the LHC.Comment: added two references. 15 pages, 14 figure