Investigating optical atom traps for Bose-Einstein condensate

Scope and Method of Study: The purpose of this research was to make a Bose Einstein condensate (BEC) of Rb87 atoms using an all optical method. Specific attention was given to replacing the traditional magnetic traps with dipole traps created by high power, far off resonant CO2 laser beams (FORT) for trapping and evaporative cooling.Findings and Conclusions. Three major steps where identified necessary to realize a BEC: (a)preparing a source of cold atoms (magneto optical trap (MOT)), b) loading atoms from the MOT to the FORT, (c)evaporative cooling the atoms in the FORT to nanoKelvin temperatures. Successful accomplishment of these steps lead us to create BEC. While investigating step (b), we found that the power in the CO2 laser does not affect the FORT population after a certain power is achieved. Also a strong correlation between the CO2 beam waist and the loading efficiency was observed. These findings led us to employ the concept of a time averaged potential to increase the trap's population. The basic idea was to sweep a tightly focused CO2 beam while it was overlapped with the MOT. By sweeping the CO2 beam rapidly, atoms could not react to the beam movement and therefore felt a time-averaged potential. These ideas were supported with the observation of lower temperatures for the trapped atoms in the time-averaged FORTs compared to the atoms trapped in the stationary FORT. By adiabatically damping the sweeping amplitude most of the atoms could be forced to accumulate into a non-time averaged trap with a tight waist. Using this technique a 100% increase in the loading efficiency of the FORT was observed.Our numerical simulations showed that spherical aberration creates local intensity maxima along the CO2 beam propagation direction which are capable of trapping atoms. This prediction was confirmed by the experimental observation of well separated micro-optical traps. We found that the separation of the micro-optical traps could be changed making them a suitable system for the study of quantum computation with neutral atoms

MnO2 nanorods modified screen-printed electrode for the electrochemical determination of Sudan dye in food sample

A novel MnO2 nanorods modified screen-printed electrode was fabricated and used as a voltammetric sensor for Sudan determination. MnO2 nanorods were characterized using Field emission-scanning electron microscopy (FE-SEM). Electrochemical measurements were performed using cyclic voltammetry (CV), linear sweep voltammetry (LSV), differential pulse voltammetry (DPV), and chronoammperometry (CA). The MnO2 nanorods on the electrode surface act as an excellent catalyst for the Sudan oxidation reaction. Our modified electrode presents good electrocatalytic activity toward Sudan, a short response time of <10 s, a low detection limit of around 0.08 µM, and linear detection range from 0.25 to 300.0 µM

Ultracold Fermionic Feshbach Molecules of 23^{23}Na40^{40}K

We report on the formation of ultracold fermionic Feshbach molecules of $^{23}$Na$^{40}$K, the first fermionic molecule that is chemically stable in its ground state. The lifetime of the nearly degenerate molecular gas exceeds 100 ms in the vicinity of the Feshbach resonance. The measured dependence of the molecular binding energy on the magnetic field demonstrates the open-channel character of the molecules over a wide field range and implies significant singlet admixture. This will enable efficient transfer into the singlet vibrational ground state, resulting in a stable molecular Fermi gas with strong dipolar interactions.Comment: 5 pages, 4 figure

The Prevalence of Accommodative Insufficiency among Students of an Iranian Medical School

Purpose: To evaluate the prevalence of accommodative insufficiency in a student population from Iran.Patients and Methods: This cross-sectional study was performed on 596 eyes from 298 participants (157 males, 141 females) in age range of 18 to 29 years among students from Iran University of Medical Sciences, Tehran, Iran, between 2014 and 2015. The amplitude of accommodation among volunteers in this study was evaluated using the Donder's push up method. Then, the minimum normal amplitude of accommodation for a given age was estimated by Hofstetter formula (15 - 0.25 * age in years), and then the prevalence of accommodative insufficiency among the study population was determined according to this calculations. Results: We found the prevalence of accommodative insufficiency to be 7.2% in the study population. The prevalence of accommodative insufficiency was 4.1% and 7.25% among males and females respectively (P &lt; 0.001). Conclusion: The prevalence of accommodative insufficiency in our study population was less than previous studies among children, which might be explained by the role of natural selection (people with accommodative disorders might have less chance of excelling in education and entering higher education institutes than patients without this disorder). We also found a statistically significant higher prevalence of accommodative insufficiency among female college aged students compared to male students.Keywords: Accommodation, insufficiency, prevalence, eye, Iran

2-Approximation for Prize-Collecting Steiner Forest

Approximation algorithms for the prize-collecting Steiner forest problem (PCSF) have been a subject of research for over three decades, starting with the seminal works of Agrawal, Klein, and Ravi and Goemans and Williamson on Steiner forest and prize-collecting problems. In this paper, we propose and analyze a natural deterministic algorithm for PCSF that achieves a $2$-approximate solution in polynomial time. This represents a significant improvement compared to the previously best known algorithm with a $2.54$-approximation factor developed by Hajiaghayi and Jain in 2006. Furthermore, K{\"{o}}nemann, Olver, Pashkovich, Ravi, Swamy, and Vygen have established an integrality gap of at least $9/4$ for the natural LP relaxation for PCSF. However, we surpass this gap through the utilization of a combinatorial algorithm and a novel analysis technique. Since $2$ is the best known approximation guarantee for Steiner forest problem, which is a special case of PCSF, our result matches this factor and closes the gap between the Steiner forest problem and its generalized version, PCSF

Determination of some nutritional value and organoleptic properties in fruity teas

Fruity teas are popular due to variety in sensory properties as well as their nutritional and therapeutical characteristics. Recently, the worldwide researches related to fruity teas have been considerably developed. In this work, effects of fruit type (apple, quince and pear) and brewing time (10 or 20 min) on some nutritional properties (Mg, Fe and Ca contents, sugars and protein percent) as well as on the sensory attributes of final products were investigated. No chemical preservative, flavoring gents and colorants were added for preparation of the samples. At the end of 10 min brewing, the highest extraction rates of Mg and protein, Fe and sugars, and Ca were observed for pear, apple, and quince, respectively. At the end of 20 min brewing, the greatest extraction rates of Mg and protein, sugars, and Ca were related to the pear, apple, and quince, respectively. Increasing the time of brewing up to 10 min although did not noticeably affect the extraction rate of nutrients from dried fruits (especially for protein content), significantly influence the sensory characteristics (flavor and color) of final products; so that those prepared by 20 min brewing had higher acceptability. Among the fruity teas produced by 20 min brewing, apple had the best sensory acceptability from flavor and color points of view. After that, pear tea from taste and quince tea from color standpoints were realized as the best samples

Prevalence of Rare and Common Bleeding Disorders in Kurdistan Province of Iran

Background: Congenital bleeding disorders (CBD) are a group of coagulopathies with different clinical and laboratory features. The prevalence of these disorders in different parts of the world is variable. Iran as a country with a high rate of parental consanguinity has a high rate of CBDs. This study was to report the prevalence of these disorders in Kurdistan province, west of Iran.Methods and materials: This descriptive study was conducted on patients suspected of a congenital bleeding disorder referred to hemophilia center of this province for evaluation of underlying bleeding diathesis. Diagnosis and classification of disorders were made by routine and specific laboratory tests.Results: Out of 107 patients, 65.4% affected by common bleeding disorders (hemophilia A and B), 23.4% affected by rare bleeding disorders (RBDs) and 11.2% had inherited platelet disorders. Factor VII deficiency (64%) was the most common RBDs and 9 patients had von Willebrand disease. Out of three patients with inherited platelet disorders, two had Glanzmann thrombasthenia.Conclusion: CBD pattern though has similar patterns with total pattern of the country, some of the inherited platelet disorders are more common in Kurdish province. Determination of prevalence and distribution of these disorders can improve health system planning and resource allocation.Keywords: Congenital bleeding disorders, Rare bleeding disorders, Common bleeding disorders, inherited platelet disorder

Quantum degenerate Bose-Fermi mixture of chemically different atomic species with widely tunable interactions

We have created a quantum degenerate Bose-Fermi mixture of 23Na and 40K with widely tunable interactions via broad interspecies Feshbach resonances. Twenty Feshbach resonances between 23Na and 40K were identified. The large and negative triplet background scattering length between 23Na and 40K causes a sharp enhancement of the fermion density in the presence of a Bose condensate. As explained via the asymptotic bound-state model (ABM), this strong background scattering leads to a series of wide Feshbach resonances observed at low magnetic fields. Our work opens up the prospect to create chemically stable, fermionic ground state molecules of 23Na-40K where strong, long-range dipolar interactions will set the dominant energy scale