488 research outputs found
The conditional tunneling time for reflection using the WKB wave-function
We derive an expression for the conditional time for the reflection of a wave
from an arbitrary potential barrier using the WKB wavefunction in the barrier
region. Our result indicates that the conditional times for transmission and
reflection are equal for a symmetric barrier within the validity of the WKB
approach.Comment: 4 pages RevTeX, 1 eps figure include
Time for pulse traversal through slabs of dispersive and negative (, ) materials
The traversal times for an electromagnetic pulse traversing a slab of
dispersive and dissipative material with negative dielectric permittivity
() and magnetic permeability () have been calculated by using
the average flow of electromagnetic energy in the medium. The effects of
bandwidth of the pulse and dissipation in the medium have been investigated.
While both large bandwidth and large dissipation have similar effects in
smoothening out the resonant features that appear due to Fabry-P\'{e}rot
resonances, large dissipation can result in very small or even negative
traversal times near the resonant frequencies. We have also investigated the
traversal times and Wigner delay times for obliquely incident pulses and
evanescent pulses. The coupling to slab plasmon polariton modes in frequency
ranges with negative or is shown to result in large traversal
times at the resonant conditions. We also find that the group velocity mainly
contributes to the delay times for pulse propagating across a slab with n=-1.
We have checked that the traversal times are positive and subluminal for pulses
with sufficiently large bandwidths.Comment: 9 pages, 9 figures, Submitted to Phys. Rev.
Two variable fragment of Term Modal Logic
Term modal logics (TML) are modal logics with unboundedly many modalities, with quantification over modal indices, so that we can have formulas of the form Exists y Forall x (Box_x P(x,y) implies Diamond_y P(y,x)). Like First order modal logic, TML is also "notoriously" undecidable, in the sense that even very simple fragments are undecidable. In this paper, we show the decidability of one interesting fragment, that of two variable TML. This is in contrast to two-variable First order modal logic, which is undecidable
Prevalence of pulmonary tuberculosis in retroviral positive chest symptomatics in a tertiary care hospital, South India
Background: Human immunodeficiency virus (HIV) associated tuberculosis (TB) remains a major global public health challenge. As this co-infection results in high mortality among retroviral positive patients, we undertook this study to find its prevalence in our region.Methods: Sputum smears from all retroviral positive patients who attended the ART clinic from April 2015 to February 2016 were examined for the presence of Mycobacterium tuberculosis bacilli by fluorescent staining technique. CD4 lymphocyte counting was also done by using BD FACS count instrument.Results: 65 patients were retroviral positive among the 180 patients who came to ART clinic. Of them 43 (66%) were males and 22 (34%) were females. 30 (46%) of retroviral positive patients were sputum positive indicating HIV-TB co-infection. 60% of co-infected patients belong to productive age group of 16-45 years. 93.4% of the co-infected patients had CD4 counts below 350 cells/µl. sputum negative retroviral positive patients had more than 250 CD4 cells/ µl.Conclusions: Our study highlights the fact that HIV-TB co-infection is more prevalent in productive age group and has a positive correlation with lower CD4 counts
The circumventricular organs form a potential neural pathway for lactate sensitivity: implications for panic disorder
Patients with panic disorder experience panic attacks after intravenous sodium lactate infusions by an as yet unexplained mechanism. Lactate elicits a panic-like response in rats with chronic dysfunction of GABA neurotransmission in the dorsomedial hypothalamus (DMH). The circumventricular organs, organum vasculosum lamina terminalis (OVLT) and subfornical organ (SFO), are potential sites that could detect increases in plasma lactate levels and activate the DMH. To test this, we obtained baseline heart rate (HR) and blood pressure (BP) responses to lactate infusions in rats fit with femoral arterial and venous catheters. Next, unilateral chronic injection cannulae connected to an Alzet infusion pump filled with the GABA synthesis inhibitor L-allylglycine (L-AG) were implanted into the DMH. Another chronic injection cannula was implanted into the region of the OVLT, SFO, or an adjacent control site, the median preoptic area (MePOA). These rats were tested once again with lactate infusions after injection of either artificial cerebrospinal fluid (ACSF) or tetrodotoxin (TTX) into the CVO sites. Injecting TTX into the OVLT completely blocked the lactate-induced response, whereas TTX injections into the SFO or MePOA did not. Also, direct injections of lactate (100 or 500 nl) into the OVLT elicited robust anxiety-like responses in these rats. These results suggest that the OVLT may be the primary site that detects lactate infusions, activating an anxiety-like response in a compromised DMH, and provide the first neuroanatomical basis for lactate response in panic disorder
Enhancing and Sustaining Pulse Production and Farmer Incomes in the TRFA Statess: Issues of Stray Animal Grazing and Value Chain Integration for Small and Marginal Farmers
Pulses are an integral component of a sustainable crop-production system, as these crops are capable of biological nitrogen fixation and have low water requirements and a high capacity to withstand changing weather conditions. Pulses are widely grown and consumed in India owing to their high nutritional value, especially as a source of protein. While India contributes 25 percent of the world’s pulse production, its domestic demand far exceeds the available supply. This has led to increasing pressure on prices, accessibility across different income strata, and the country importing pulses for domestic consumption
Bundled Fragments of First-Order Modal Logic: (Un)Decidability
Quantified modal logic is notorious for being undecidable, with very few known decidable fragments such as the monodic ones. For instance, even the two-variable fragment over unary predicates is undecidable. In this paper, we study a particular fragment, namely the bundled fragment, where a first-order quantifier is always followed by a modality when occurring in the formula, inspired by the proposal of [Yanjing Wang, 2017] in the context of non-standard epistemic logics of know-what, know-how, know-why, and so on.
As always with quantified modal logics, it makes a significant difference whether the domain stays the same across possible worlds. In particular, we show that the predicate logic with the bundle "forall Box" alone is undecidable over constant domain interpretations, even with only monadic predicates, whereas having the "exists Box" bundle instead gives us a decidable logic. On the other hand, over increasing domain interpretations, we get decidability with both "forall Box" and "exists Box" bundles with unrestricted predicates, where we obtain tableau based procedures that run in PSPACE. We further show that the "exists Box" bundle cannot distinguish between constant domain and variable domain interpretations
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