867 research outputs found
Time evolution of the Luttinger model with nonuniform temperature profile
No full textWe study the time evolution of a one-dimensional interacting fermion system described by the Luttinger model starting from a nonequilibrium state defined by a smooth temperature profile T (x). As a specific example we consider the case when T (x) is equal to T-L (T-R) far to the left (right). Using a series expansion in epsilon = 2(T-R -T-L)/(T-L + T-R), we compute the energy density, the heat current density, and the fermion two-point correlation function for all times t >= 0. For local (delta-function) interactions, the first two are computed to all orders, giving simple exact expressions involving the Schwarzian derivative of the integral of T (x). For nonlocal interactions, breaking scale invariance, we compute the nonequilibrium steady state (NESS) to all orders and the evolution to first order in epsilon. The heat current in the NESS is universal even when conformal invariance is broken by the interactions, and its dependence on T-L,T-R agrees with numerical results for the XXZ spin chain. Moreover, our analytical formulas predict peaks at short times in the transition region between different temperatures and show dispersion effects that, even if nonuniversal, are qualitatively similar to ones observed in numerical simulations for related models, such as spin chains and interacting lattice fermions
Steady States and Universal Conductance in a Quenched Luttinger Model
No full textWe obtain exact analytical results for the evolution of a 1+1-dimensional Luttinger model prepared in a domain wall initial state, i.e., a state with different densities on its left and right sides. Such an initial state is modeled as the ground state of a translation invariant Luttinger Hamiltonian Hλ with short range non-local interaction and different chemical potentials to the left and right of the origin. The system evolves for time t > 0 via a Hamiltonian Hλ′ which differs from Hλ by the strength of the interaction. Asymptotically in time, as t→ ∞, after taking the thermodynamic limit, the system approaches a translation invariant steady state. This final steady state carries a current I and has an effective chemical potential difference μ+- μ- between right- (+) and left- (−) moving fermions obtained from the two-point correlation function. Both I and μ+- μ- depend on λ and λ′. Only for the case λ= λ′= 0 does μ+- μ- equal the difference in the initial left and right chemical potentials. Nevertheless, the Landauer conductance for the final state, G= I/ (μ+- μ-) , has a universal value equal to the conductance quantum e2/ h for the spinless case
A Fast Scheme for Blind Identification of Channel Codes
No full textWe present a fast mechanism for determining which channel code that was used on a communication link. In the proposed scheme, the receiver does not need to receive the entire data to determine the actual code. Moreover, the proposed scheme can also be used to determine the interleaving/scrambling sequence that was used at the transmitter. We investigate the performance of the scheme for some standard convolutional codes.©2011 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. Reza Moosavi and Erik G. Larsson, A Fast Scheme for Blind Identification of Channel Codes, 2011, accepted The 54th IEEE Global Communications Conference (GLOBECOM).</p
JCB887358 Supplementary material - Supplemental material for Low-level carbon monoxide exposure affects BOLD fMRI response
No full textSupplemental material, JCB887358 Supplementary material for Low-level carbon monoxide exposure affects BOLD fMRI response by Caroline Bendell, Shakeeb H Moosavi and Mari Herigstad in Journal of Cerebral Blood Flow & Metabolism</p
Reducing Downlink Signaling Traffic in Wireless Systems Using Mobile-Assisted Scheduling
No full textWe present an idea to reduce the part of the downlink signaling traffic in wireless multiple access systems that contains scheduling information. The theoretical basis of the scheme is that the scheduling decisions made by the base station are correlated with the CSI reports from the mobiles. This correlation can be exploited by the source coding scheme that is used to compress the scheduling maps before they are sent to the mobiles. In the proposed scheme, this idea is implemented by letting the mobiles make tentative scheduling decisions themselves, and then letting the base station transmit "agreement maps" instead of raw scheduling maps to the mobiles. The agreement maps have lower entropy and they require less resources to be transmitted than the original scheduling maps do. The improvement can be substantial.©2010 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.: Reza Moosavi and Erik G. Larsson, Reducing Downlink Signaling Traffic in Wireless Systems Using Mobile-Assisted Scheduling, 2010, Proceedings of the IEEE Global Communications Conference 2010 (GLOBECOM 2010).</p
A note on sensitivity analysis for post-machine learning causal inference
No full textIn Moosavi et al. (2022) a sensitivity analysis method to unobserved confounding was proposed when estimating an average causal effect with a double robust estimator in high dimensional situations. For this purpose, it was assumed that linear models could sparselyapproximate the nuisance functions (treatment assignment and outcome models). In this note, we relax these assumptions making the sensitivity analysis more generally applicable, for instance when nuisance functions are (weakly) consistently estimated with machine learning algorithms. Simulations and a case study illustrate the performance and use of the method.</p
Is the existence of a mutualistic relationship between Lobesia botrana and Botrytis cinerea well-founded?
No full textSome studies have highlighted benefits for Lobesia botrana by adding Botrytis cinerea mycelium to an artificial larval diet and have suggested a mutualistic relationship between the two organisms on grapevine, hypothesizing that fungal sterols were the nutritional factor involved. Because the nutritional quality of an artificial diet should be similar to grapes to allow extrapolation of the results to the field conditions, in the current study L. botrana larval performance was compared when larvae were fed on grapes (berries) or two artificial diets either with or without enrichment with B. cinerea. Based on sterol analysis, the two artificial diets had high cholesterol content, but relative to berries showed comparable and low phytosterol contents, respectively (high- and low-phytosterol, HPh, and LPh). While larval fitness on the HPh diet was similar to berries, the LPh diet led to higher mortality and worse larval performance. The addition of the fungus compensated for the shortage in the LPh diet but did not improve the HPh diet. Supplementing the LPh diet with linoleic acid, which is supplied also from B. cinerea, partially improved larval performance. In a field experiment, females did not show any egg-laying preferences towards naturally botrytized bunches. The positive effect of B. cinerea on the moth's next generation that is reported in the literature could be a consequence of fungus developed inside berry tunnels bored by larvae. Therefore, based on our data and previous reports the existence of a mutualistic relationship between L. botrana and B. cinerea is not well-founded
Prevalence of celiac disease in patients with irritable bowel syndrome in Ardabil-Iran (2009-10)
No full textBackground and Objective: Irritable bowel syndrome (IBS) is the most prevalent gastrointestinal disorder and is one the common conditions seen by gastroenterologists in their daily practice. This study was done to determine the prevalence of celiac disease in patients with irritable bowel syndrome in Ardabil-Iran. Materials and Methods: This descriptive study was conducted on 105 patients with IBS whome referred to the gastroenterology unit in Ardabil-Iran during 2009-10. Serum IgA anti tTG were measured all patients with positive for antibodies against tTG were candidated for upper endoscopy and biopsy. Data were analyzed using SPSS-16, t-test, Chi-Square and Fisher’s exact tests. Results: The average age of IBS subjects were 31.4±10.14 years (range 16-63 years). Celiac disease was diagnosed in 14 subjects (13.5%). The celiac patient age were 22-55 years with mean of 34.93±9.47. Among celiac afflicted patients IBS type D and M observed among 10 and 4 patients, respectivley. Celiac affected female constituted 12 (85.7%) of all patients (P<0.05). 10 of these patients were IBS-D and 4 with IBS-M. From 14 celiac patient 4 (28.57%) were family related, but this rate among IBS patient was 3.3%, this difference was significant (P<0.05). Conclusion: This study showed that the prevalence of celiac in patients with IBS is found to be 13.5% which seem is more than ther studies in other parts of Iran
Quantification of dyspnoea using descriptors: development and initial testing of the Dyspnoea-12
No full textRationale: Dyspnoea is a debilitating and distressing symptom that is reflected in different verbal descriptors. Evidence suggests that dyspnoea, like pain perception, consists of sensory quality and affective components. The objective of this study was to develop an instrument that measures overall dyspnoea severity using descriptors that reflect its different aspects. Methods: 81 dyspnoea descriptors were administered to 123 patients with chronic obstructive pulmonary disease (COPD), 129 with interstitial lung disease and 106 with chronic heart failure. These were reduced to 34 items using hierarchical methods. Rasch analysis informed decisions regarding further item removal and fit to the unidimensional model. Principal component analysis (PCA) explored the underlying structure of the final item set. Validity and reliability of the new instrument were further assessed in a separate group of 53 patients with COPD. Results: After removal of items with hierarchical methods (n = 47) and items that failed to fit the Rasch model (n = 22), 12 were retained. The "Dyspnoea-12" had good internal reliability (Cronbach's alpha = 0.9) and fit to the Rasch model (χ2 p = 0.08). Items patterned into two groups called "physical"(n = 7) and "affective"(n = 5). In the separate validation study, Dyspnoea-12 correlated with the Hospital Anxiety and Depression Scale (anxiety r = 0.51; depression r = 0.44,
5-Oxohexahydroquinolines bearing 4-pyridyl methyl carboxylate as P-glycoprotein inhibitors and multidrug resistance reversal agents in cancer cells
No full textMultidrug resistance (MDR) limits the therapeutic effect of conventional chemotherapeutic agents as well as novel targeted anticancer drugs. An important mechanism of MDR is the overexpression of ATP-binding cassette (ABC) transporters in cancer cells, among which P-glycoprotein (P-gp) has one of the highest contributions to drug resistance. In this study, 10 novel 5-oxo-hexahydroquinoline (5-oxo-HHQ) derivatives bearing 4-pyridyl methyl carboxylate moiety (G1-G10) were synthesized and examined for their MDR reversal activity in P-gp overexpressing MES-SA-DX5 cells. Moreover, all synthesized compounds were evaluated for their cell growth inhibitory effect in several cancer cell lines. Most of the tested compounds significantly enhanced the intracellular accumulation of rhodamine 123, a P-gp substrate, in MDR cells, some of them showing better results than verapamil, a well-established P-gp inhibitor. Moreover, most compounds, especially G2, G3, G7, and G8, bearing 2-chlorophenyl, 3-bromophenyl, 3-nitrophenyl and pyridin-4-yl moieties were effective in reversing resistance to doxorubicin when co-incubated with this chemotherapeutic agent in MES-SA-DX5 cells. Our results also showed that compounds G3 and G7 exhibited considerable cytotoxic effects against leukemia and colon cancer cells. In silico docking analysis also confirmed the interaction of compounds G2, G3, G7, and G8 with the drug-substrate binding site of P-gp. Molecular dynamic simulation study was performed to gain insight into the binding mode of compound G3 with P-gp. According to the results, hydrophobic interactions played a more prominent role than hydrogen-binding interactions. Taken together, our findings showed that designed 5-oxo-HHQ compounds are promising MDR reversal agent
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