Fluctuation Dominated Josephson Tunneling with a Scanning Tunneling Microscope

We demonstrate Josephson tunneling in vacuum tunnel junctions formed between a superconducting scanning tunneling microscope tip and a Pb film, for junction resistances in the range 50-300 k$\Omega$. We show that the superconducting phase dynamics is dominated by thermal fluctuations, and that the Josephson current appears as a peak centered at small finite voltages. In the presence of microwave fields (f=15.0 GHz) the peak decreases in magnitude and shifts to higher voltages with increasing rf power, in agreement with theory.Comment: 4 pages, REVTeX, submitted to PR

Unique Thermal Properties of Clothing Materials.

Cloth wearing seems so natural that everyone is self-deemed knowledgeable and has some expert opinions about it. However, to clearly explain the physics involved, and hence to make predictions for clothing design or selection, it turns out to be quite challenging even for experts. Cloth is a multiphased, porous, and anisotropic material system and usually in multilayers. The human body acts as an internal heat source in a clothing situation, thus forming a temperature gradient between body and ambient. But unlike ordinary engineering heat transfer problems, the sign of this gradient often changes as the ambient temperature varies. The human body also perspires and the sweat evaporates, an effective body cooling process via phase change. To bring all the variables into analysis quickly escalates into a formidable task. This work attempts to unravel the problem from a physics perspective, focusing on a few rarely noticed yet critically important mechanisms involved so as to offer a clearer and more accurate depiction of the principles in clothing thermal comfort

Resolving singular forces in cavity flow: Multiscale modeling from atoms to millimeters

A multiscale approach for fluid flow is developed that retains an atomistic description in key regions. The method is applied to a classic problem where all scales contribute: The force on a moving wall bounding a fluid-filled cavity. Continuum equations predict an infinite force due to stress singularities. Following the stress over more than six decades in length in systems with characteristic scales of millimeters and milliseconds allows us to resolve the singularities and determine the force for the first time. The speedup over pure atomistic calculations is more than fourteen orders of magnitude. We find a universal dependence on the macroscopic Reynolds number, and large atomistic effects that depend on wall velocity and interactions.Comment: 4 pages,3 figure

Josephson scanning tunneling microscopy

We propose a set of scanning tunneling microscopy experiments in which the surface of superconductor is scanned by a superconducting tip. Potential capabilities of such experimental setup are discussed. Most important anticipated results of such an experiment include the position-resolved measurement of the superconducting order parameter and the possibility to determine the nature of the secondary component of the order parameter at the surface. The theoretical description based on the tunneling Hamiltonian formalism is presented.Comment: 6 pages, 7 figures, submitted to Phys. Rev.

Stress and its associated factors among medical students in a public medical faculty, Malaysia

Background: Stress is common among university students. Levels of stress vary between the students of different courses in the university and many factors are associated with it. As compared to other professional courses, medical students are more prone to get depressed because medical education is known to be stressful and very demanding. Materials and Methods: This is a cross-sectional study using a pretested, self-administered questionnaire involving all medical students in academic session 2013/2014. The questionnaire consists of 3 parts; socio-demographic information, family factors and personal factors; Depression, Anxiety and Stress Score 21 questionnaire (DASS 21) and Duke University Religion Index (DUREL). DUREL measures religiosity in 3 scales namely; organized religious activity (ORA), non-organized religious activity (NORA) and intrinsic religiosity (IR). The questionnaire was distributed to all medical students available in FMHS during the data collection period. Data collected were analyzed using IBM SPSS version 21. Result: Of 409 medical students, 329 (80.4%) responded. Most (50.5%) were aged 22 years and above, majority (62.3%) were female students. Respondents were mainly Malay (54.4%) and Muslims (56.8%). Stress prevalence in medical students were 19.8%. Stress prevalence was higher among students aged ≤ 21 years (22.1%), male (20.2%), Indian (24.0%) and Hindus (31.6%),among students with father of primary education level (21.4%), mother of tertiary education level (25%) and low income family (21.4%). Prevalence of stress among students in pre-clinical year (21.4%) and clinical year students (17.9%), p>0.05. Stress among students who did not undergo matriculation course and those who attended were 21.7% and 18.8%, respectively. Proportion of stress students who entered medical school not on their own choice and on their own choice were 24.3% and 18.5%, respectively, p>0.05. Medical students with poor ORA and NORA showed higher proportion of stress (20.2%, 20.6% respectively) however, students with good IR had higher proportion of stress compared to those with poor IR (20.0%, 19.5%, p>0.05). Conclusion: Stress is prevalent among almost one-fifth of medical students, especially those in their pre-clinical years of studies. Students’ involvement in religious activities could be beneficial to prevent stress. Further research is needed to assess the effect of medical training on stress and the effect of religiosity on stress coping

Orthotopic liver transplantation in dogs receiving FK-506.

Ten dogs that survived the perioperative events of liver transplantation were treated with 1 mg/kg/d oral FK. Eight of the recipients lived for at least 1 month postoperatively, and seven are still alive with normal hepatic function after 35 to 65 days. The consistency and good quality of results with this difficult transplant preparation using FK, in spite of its rumored great toxicity in dogs, have highlighted the importance of further developing the drug

Modular organization enhances the robustness of attractor network dynamics

Modular organization characterizes many complex networks occurring in nature, including the brain. In this paper we show that modular structure may be responsible for increasing the robustness of certain dynamical states of such systems. In a neural network model with threshold-activated binary elements, we observe that the basins of attractors, corresponding to patterns that have been embedded using a learning rule, occupy maximum volume in phase space at an optimal modularity. Simultaneously, the convergence time to these attractors decreases as a result of cooperative dynamics between the modules. The role of modularity in increasing global stability of certain desirable attractors of a system may provide a clue to its evolution and ubiquity in natural systems.Comment: 6 pages, 4 figure

Is There a Relationship Between the Concentration of Same-Sex Couples and Tobacco Retailer Density?

Tobacco use is markedly higher among lesbian, gay, and bisexual populations than heterosexuals. Higher density of tobacco retailers is found in neighborhoods with lower income and more racial/ethnic minorities. Same-sex couples tend to live in similar neighborhoods, but the association of this demographic with tobacco retailer density has not been examined

Probabilistic Quantum Logic Operations Using Polarizing Beam Splitters

It has previously been shown that probabilistic quantum logic operations can be performed using linear optical elements, additional photons (ancilla), and post-selection based on the output of single-photon detectors. Here we describe the operation of several quantum logic operations of an elementary nature, including a quantum parity check and a quantum encoder, and we show how they can be combined to implement a controlled-NOT (CNOT) gate. All of these gates can be constructed using polarizing beam splitters that completely transmit one state of polarization and totally reflect the orthogonal state of polarization, which allows a simple explanation of each operation. We also describe a polarizing beam splitter implementation of a CNOT gate that is closely analogous to the quantum teleportation technique previously suggested by Gottesman and Chuang [Nature 402, p.390 (1999)]. Finally, our approach has the interesting feature that it makes practical use of a quantum-eraser technique.Comment: 9 pages, RevTex; Submitted to Phys. Rev. A; additional references inlcude