629 research outputs found
Quantum Otto cycle with inner friction: finite-time and disorder effects
The concept of inner friction, by which a quantum heat engine is unable to
follow adiabatically its strokes and thus dissipates useful energy, is
illustrated in an exact physical model where the working substance consists of
an ensemble of misaligned spins interacting with a magnetic field and
performing the Otto cycle. The effect of this static disorder under a
finite-time cycle gives a new perspective of the concept of inner friction
under realistic settings. We investigate the efficiency and power of this
engine and relate its performance to the amount of friction from misalignment
and to the temperature difference between heat baths. Finally we propose an
alternative experimental implementation of the cycle where the spin is encoded
in the degree of polarization of photons.Comment: Published version in the Focus Issue on "Quantum Thermodynamics
Structural change of vortex patterns in anisotropic Bose-Einstein condensates
We study the changes in the spatial distribution of vortices in a rotating
Bose-Einstein condensate due to an increasing anisotropy of the trapping
potential. Once the rotational symmetry is broken, we find that the vortex
system undergoes a rich variety of structural changes, including the formation
of zig-zag and linear configurations. These spatial re-arrangements are well
signaled by the change in the behavior of the vortex-pattern eigenmodes against
the anisotropy parameter. The existence of such structural changes opens up
possibilities for the coherent exploitation of effective many-body systems
based on vortex patterns.Comment: 5 pages, 4 figure
Halogen-bonded architectures of multivalent calix[4]arenes
A small family of novel halogen-bonded crystalline supramolecular architectures of calixarenes was obtained by the co-crystallization of cone (1) and 1,3-alternate tetrakis(3-iodopropargyloxy)calix[4]arene (4) as tetradentate halogen donors with different multidentate acceptors. Particularly interesting is the interpenetrated diamondoid network of 4 with DABCO, which represents the first example of a 2D network of calixarene macrocycles where halogen bonding is the key interaction for self-organization
Making an impression @UTampaSpeech: A case study using Instagram at The University of Tampa’s Center for Public Speaking
Instagram is one of the most widely used social networking sites for college students (Smith & Anderson, 2018). But using a medium because it is popular does not equate to effective use. During 2018-2019, The University of Tampa’s Center for Public Speaking performed an 11-month case study to assess our use of Instagram to examine whether it was the right platform for our communication center. We determined it was, and we offer “best practices” to use in the future and suggest other communication centers consider performing case studies of their own to assess their use of social media.
Critical assessment of two-qubit post-Markovian master equations
A post-Markovian master equation has been recently proposed as a tool to
describe the evolution of a system coupled to a memory-keeping environment [A.
Shabani and D. A. Lidar, Phys. Rev. A 71, 020101 (R) (2005)]. For a single
qubit affected by appropriately chosen environmental conditions, the
corresponding dynamics is always legitimate and physical. Here we extend such
situation to the case of two qubits, only one of which experiences the
environmental effects. We show how, despite the innocence of such an extension,
the introduction of the second qubit should be done cum grano salis to avoid
consequences such as the breaking of the positivity of the associated dynamical
map. This hints at the necessity of using care when adopting phenomenologically
derived models for evolutions occurring outside the Markovian framework.Comment: 7 pages, 1 figure, RevTeX4. Close to published versio
A Disease-Based Approach to the Vertical and Horizontal Integration of a Medical Curriculum
As medical disciplines have become increasingly interdisciplinary and evidenced-based medicine is widely practiced, there is a need for curricula that reflect these changes. The newly revised LCME standards 1.1 Strategic Planning and Continuous Quality Improvement and 8.3 Curricular Design, Review, Revision/Content Monitoring require ongoing curricular review to assure accreditation compliancy. We have completed a comprehensive review of our curriculum and have moved from a discipline-based curriculum to that of one that focuses on a systems/disease-based model. The approach allows for a more horizontally integrated curriculum in the preclinical years, while the use of 115 distinct disease and eight themes creates a quality assurance mechanism that allows for tracking of vertical integration across the entire curriculum. The first step in the development of this quality assurance model was to establish and empower a newly formed integration subcommittee. This subcommittee was tasked with developing a model to review, track and improve the horizontal and vertical integration of the curriculum. Our integrated curriculum is now in its second year having completed the initial identification of gaps and redundancies through a process that relies on the mapping of diseases and themes throughout the courses. This ongoing review and evaluation process has created a dynamic quality assurance process that allows our faculty to address issues of both horizontal and vertical integration of our curriculum at the course level
Predicting Medical Student Success on Licensure Exams
Many schools seek to predict performance on national exams required for medical school graduation using prematriculation and medical school performance data. The need for targeted intervention strategies for at-risk students has led much of this interest. Assumptions that preadmission data and high stakes in-house medical exams correlate strongly with national standardized exam performance needs to be examined. Looking at prematriculation data for predicting USMLE Step 1 performance, we found that MCAT exam totals and math-science GPA had the best prediction from a set of prematriculation values (adjusted R 2 = 11.7 %) for step 1. The addition of scores from the first medical school exam improved our predictive capabilities with a linear model to 27.9 %. As we added data to the model, we increased our predictive values as expected. However, it was not until we added data from year 2 exams that we started to get step 1 prediction values that exceeded 50 %. Stepwise addition of more exams in year two resulted in much higher predictive values but also led to the exclusion of many early variables. Therefore, our best step 1 predictive value of around 76.7 % consisted of three variables from a total of 37. These data suggest that the preadmission information is a relatively poor predictor of licensure exam performance and that including class exam scores allows for much more accurate determination of students who ultimately proved to be at risk for performance on their licensure exams. The continuous use of this data, as it becomes available, for assisting at-risk students is discussed (251)
Virtually Augmented Self-Hypnosis in Peripheral Vascular Intervention: A Randomized Controlled Trial.
Hypnosis is useful for diminishing distress during medical procedures. This study investigated the efficacy of virtually augmented self-hypnosis as an adjunctive non-pharmacological method for procedural pain and anxiety relief during endovascular interventions (EVI).
We compared an immersive distraction experience (clinicaltrials.gov identifier NCT04561596) featuring virtual reality (VR) using a head-mounted display versus treatment as usual (TAU). Patients followed the "Aqua" module (Oncomfort™) consisting of a scuba dive and breathing exercises. They experienced a self-induced dissociative state similar to clinical hypnosis without direct intervention of a professional. Enrollment followed a 1:1 randomized open study (VR or TAU). Patients' feelings were evaluated just before and after the procedure, and 3 months following intervention. Anxiety was evaluated using the State Trait Anxiety Inventory (STAI) and pain (sensory, emotional, and memory) with a visual analogue scale (VAS).
This study included 100 patients. Mean anxiety (pre-post) was significantly reduced within groups and between groups (difference of 4.2 points, p = 0.016). The percentage of responders to anxiety lowering were 76 and 46% for VR and TAU, respectively (p = 0.004). The two groups did not significantly differ in mean sensory-intensity and affective emotional pain (pre-post) using VAS, in negative memories concerning remembered pain at 3 months (difference > 1 from immediate post-procedural reported pain intensity), mean procedural time, or the need for analgesic or sedative drugs.
VR self-hypnosis has the potential to improve the management of patients' distress during radiological procedures. It is safe and effective for reducing anxiety during EVI
Ca2+ signaling modulates cytolytic T lymphocyte effector functions
Cytolytic T cells use two mechanisms to kill virally infected cells, tumor cells, or other potentially autoreactive T cells in short-term in vitro assays. The perforin/granule exocytosis mechanism uses preformed cytolytic granules that are delivered to the target cell to induce apoptosis and eventual lysis. FasL/Fas (CD95 ligand/CD95)–mediated cytolysis requires de novo protein synthesis of FasL by the CTL and the presence of the death receptor Fas on the target cell to induce apoptosis. Using a CD8+ CTL clone that kills via both the perforin/granule exocytosis and FasL/Fas mechanisms, and a clone that kills via the FasL/Fas mechanism only, we have examined the requirement of intra- and extracellular Ca2+ in TCR-triggered cytolytic effector function. These two clones, a panel of Ca2+ antagonists, and agonists were used to determine that a large biphasic increase in intracellular calcium concentration, characterized by release of Ca2+ from intracellular stores followed by a sustained influx of extracellular Ca2+, is required for perforin/granule exocytosis. Only the sustained influx of extracellular Ca2+ is required for FasL induction and killing. Thapsigargin, at low concentrations, induces this small but sustained increase in [Ca2+]i and selectively induces FasL/Fas-mediated cytolysis but not granule exocytosis. These results further define the role of Ca2+ in perforin and FasL/Fas killing and demonstrate that differential Ca2+ signaling can modulate T cell effector functions
Virtually Augmented Self-Hypnosis applied to endovascular interventions (VA-HYPO): Randomized Controlled Trial Protocol.
Endovascular interventions (EVI) are increasingly performed as minimally-invasive alternatives to surgery and have many advantages, including a decreased need for general anesthesia. However, EVI can be stressful for patients and often lead to anxiety and pain related to the procedure. The use of local anesthetics, anxiolytics, and analgesic drugs can help avoid general anesthesia. Nevertheless, these drugs have potential side effects. Alternative nonpharmacological therapies can improve patients' experience during conscious interventions and reduce the need for additional medications. The added value of virtually augmented self-hypnosis (VA-HYPO) and its potential to reduce pain and anxiety during peripheral and visceral arterial and venous EVI is unknown. This is a prospective two-arm trial designed to randomize 100 patients in two groups according to the use or not of VA-HYPO during peripheral EVI as a complementary nonpharmacological technique to improve patient comfort. The main objective is to compare per-procedural anxiety, and the secondary aim is to compare the rated per-procedural pain in both groups. The potential significance is that VA-HYPO may improve patients' experience during peripheral and visceral arterial and venous EVI and other minimally invasive interventions performed under local anesthesia. Trial registration: Our study is registered on clinicaltrials.gov, with trial registration number: NCT04561596
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