Joint Spectral Radius and Path-Complete Graph Lyapunov Functions

We introduce the framework of path-complete graph Lyapunov functions for approximation of the joint spectral radius. The approach is based on the analysis of the underlying switched system via inequalities imposed among multiple Lyapunov functions associated to a labeled directed graph. Inspired by concepts in automata theory and symbolic dynamics, we define a class of graphs called path-complete graphs, and show that any such graph gives rise to a method for proving stability of the switched system. This enables us to derive several asymptotically tight hierarchies of semidefinite programming relaxations that unify and generalize many existing techniques such as common quadratic, common sum of squares, and maximum/minimum-of-quadratics Lyapunov functions. We compare the quality of approximation obtained by certain classes of path-complete graphs including a family of dual graphs and all path-complete graphs with two nodes on an alphabet of two matrices. We provide approximation guarantees for several families of path-complete graphs, such as the De Bruijn graphs, establishing as a byproduct a constructive converse Lyapunov theorem for maximum/minimum-of-quadratics Lyapunov functions.Comment: To appear in SIAM Journal on Control and Optimization. Version 2 has gone through two major rounds of revision. In particular, a section on the performance of our algorithm on application-motivated problems has been added and a more comprehensive literature review is presente

Efficient quantum processing of ideals in finite rings

Suppose we are given black-box access to a finite ring R, and a list of generators for an ideal I in R. We show how to find an additive basis representation for I in poly(log |R|) time. This generalizes a recent quantum algorithm of Arvind et al. which finds a basis representation for R itself. We then show that our algorithm is a useful primitive allowing quantum computers to rapidly solve a wide variety of problems regarding finite rings. In particular we show how to test whether two ideals are identical, find their intersection, find their quotient, prove whether a given ring element belongs to a given ideal, prove whether a given element is a unit, and if so find its inverse, find the additive and multiplicative identities, compute the order of an ideal, solve linear equations over rings, decide whether an ideal is maximal, find annihilators, and test the injectivity and surjectivity of ring homomorphisms. These problems appear to be hard classically.Comment: 5 page

Experimental investigation of optical atom traps with a frequency jump

We study the evolution of a trapped atomic cloud subject to a trapping frequency jump for two cases: stationary and moving center of mass. In the first case, the frequency jump initiates oscillations in the cloud's momentum and size. At certain times we find the temperature is significantly reduced. When the oscillation amplitude becomes large enough, local density increases induced by the anharmonicity of the trapping potential are observed. In the second case, the oscillations are coupled to the center of mass motion through the anharmonicity of the potential. This induces oscillations with even larger amplitudes, enhancing the temperature reduction effects and leading to nonisotropic expansion rates while expanding freely.Comment: 8 figures, Journal of Physics B: At. Mol. Op. Phy

Fermat's principle in quantum gravitational optics

Interactions incorporating the vacuum polarization effects in curved backgrounds modify the null cone structure in such a way that the photon trajectories would not be the space-time geodesics anymore. The gravitational birefringence introduced as a direct consequence of these effects, will allow shifts in the photon velocities leading to polarization dependent superluminal propagation. Taking these effects into account we study Fermat's principle in the context of the 1+3 (threading) formulation of the space-time decomposition. We find an expression for the modified spacetime refractive index and show it is proportional to the light cone correction to the first order. Consequences of this modification on polarization sum rules and spatial light paths are considered.Comment: 13 Pages, REVTex format, section on gravitomagnetic monopoles is removed along with its references, new references adde

Sensitivity or resistance to steroid therapy in children with idiopathic nephrotic syndrome is not associated with polymorphism of angiotensin converting enzyme (ACE)

It's about years that the relation between renin angiotensin aldosterone system (RAS) and involving enzymes such as angiotensin converting enzyme (ACE) with nephrotic syndrome is under the focus of researchers and also there are a lot of meta-analyses. However there were few studies investigated the relation of ACE polymorphism and sensitivity or resistance to steroid therapy in children. So we intend to do that. In the current study the sample size was 40 children. Among them, 22 patients were sensitive and 18 patients were resistant to steroid therapy. The samples were collected from Ali-Asghar pediatric hospital in Tehran, Iran. We used polymerase chain reaction (PCR) for the genotyping. After that, we used Chi-squared test for statistical analysis. The statistical analysis showed no significant correlation between ACE polymorphism and sensitivity or resistance to steroid therapy (P = 0.77). Although the frequency of DD genotype was higher in the resistant group, but this difference was not statistically significant. Finally we found that although based on previous studies, D allele and DD genotype are more frequent in children with idiopathic nephrotic syndrome in comparison to healthy children, but the resistance or sensitivity to steroid therapy in children is not associated with ACE polymorphism. Further meta-analysis on the studies done on children is suggested. � 2016 Parisadat Ahmadi et al

Relationship between physical activity during the first 20 weeks of gestation and hypertension in pregnancy

چکیده: زمینه و هدف: اختلالات فشارخون بارداری از عوارض خطرناک بارداری است که علت آن شناخته نشده است. تلاش های اخیر برای کنترل و پیشگیری از آن بر روی عوامل مؤثر بر افزایش توان بدن برای مقابله با استرس اکسیداتیو بنا شده است. با توجه به اثرات آنتی اکسیدانت فعالیت فیزیکی، این تحقیق با هدف بررسی ارتباط بین مدت و شدت فعالیت فیزیکی با اختلالات فشارخون بارداری انجام گرفت. روش بررسی: این مطالعه از نوع مورد –شاهدی است که بر روی دو گروه 97 نفره زنان حامله با فشارخون بارداری و بدون فشارخون بارداری بستری در بیمارستانهای شهید بهشتی، الزهرا(س) و شهید صدوقی اصفهان انجام شد. میزان و مدت فعالیت فیزیکی بر حسب شدت و نوع فعالیت در بیست هفته اول بارداری در دو گروه با استفاده از پرسشنامه استاندارد فعالیت فیزیکی (MET) در دوران بارداری سنجیده شد. برای مقایسه متغیرهای کمی از آزمون t و برای متغیرهای کیفی آزمون من ویتنی استفاده شد. یافته ها: دو گروه از نظر سن، میانگین شاخص توده بدنی (BMI)، سطح تحصیلات، سن حاملگی و وضعیت اشتغال اختلاف معنی داری نداشتند. نتایج نشان داد که میزان فعالیت فیزیکی بر اساس پرسشنامه استاندارد فعالیت فیزیکی در زنان بدون فشارخون بارداری (89/14±38/30) به طور معنی داری بیشتر از گروه دارای فشارخون بالاتر (24/12±63/14) بود (001/0

Response variability in balanced cortical networks

We study the spike statistics of neurons in a network with dynamically balanced excitation and inhibition. Our model, intended to represent a generic cortical column, comprises randomly connected excitatory and inhibitory leaky integrate-and-fire neurons, driven by excitatory input from an external population. The high connectivity permits a mean-field description in which synaptic currents can be treated as Gaussian noise, the mean and autocorrelation function of which are calculated self-consistently from the firing statistics of single model neurons. Within this description, we find that the irregularity of spike trains is controlled mainly by the strength of the synapses relative to the difference between the firing threshold and the post-firing reset level of the membrane potential. For moderately strong synapses we find spike statistics very similar to those observed in primary visual cortex.Comment: 22 pages, 7 figures, submitted to Neural Computatio

Incidence of branch block of the heart and its related factors in patients with myocardial infarction hospitalized in Hajar hospital, Shahrekord

زمینه و هدف: با وجود پیشرفت های وسیع تشخیصی و درمانی، هنوز یک سوم بیمارانی که دچار انفارکتوس حاد میوکارد می شوند، فوت می کنند.آریتمی های قلبی شایع­ترین علت مرگ در جریان انفارکتوس حاد میوکارد و بلوک­های قلبی دسته مهمی از این آریتمی ها هستند. هدف از این مطالعه، تعیین بروز بلوک های شاخه ای قلب و عوامل خطر دموگرافیک و سوابق بالینی مرتبط با آن در بیماران انفارکتوس قلبی می باشد. روش بررسی: در این مطالعه توصیفی تحلیلی مقطعی پرونده 263 بیمار مبتلا به انفارکتوس حاد میوکارد بستری شده در بخش مراقبت ویژه قلب مورد بررسی قرار گرفت و اطلاعات دموگرافیک و سوابق بالینی بیماران جمع آوری شد. اطلاعات به­دست آمده با استفاده از شاخص های مرکزی و پراکندگی و آزمون های تی مستقل، کای اسکور و آنالیز واریانس یک­طرفه در نرم­افزار STATA مورد تجزیه و تحلیل آماری قرار گرفت. یافته ها: فراوانی نسبی بروز بلوک شاخه ای کامل 97/15 (42 بیمار) بود. 23/45 بیماران بلوک شاخه راست کامل و 76/54 بلوک شاخه چپ کامل داشتند. بروز بلوک شاخه راست و چپ در کل جمعیت مورد مطالعه به­ترتیب 22/7 و 75/8 بود. بروز بلوک شاخه ای چپ و راست قلبی با متغیرهای جنسیت، سن، محل سکونت افراد، فشارخون بالا و سابقه بیماری ایسکمیک ارتباط معنی­داری نداشت (05/0<P)؛ ولی با سابقه ابتلا به دیابت رابطه معنی داری داشت (05/0>P). نتیجه گیری: در این مطالعه بروز بلوک های شاخه ای قلب در بیماران بستری گزارش شد. با توجه به بروز بالای پیامد مورد بررسی، توصیه می شود بیماران با انفارکتوس حاد میوکارد قلب به­طور جدی از­نظر عوامل مساعد کننده نظیر دیابت و آریتمی های بطنی مانند وجود اختلالات الکتریکی بررسی شوند. در نهایت اقدامات درمانی مناسب، از ایجاد آریتمی های خطرناک جلوگیری نمایند

Energy inputs and outputs in a chickpea production system in Kurdistan, Iran

Chickpea (Cicer arietinum L.) is one of the most important grain legumes which traditionally cultivated in marginal areas and saline soils. In this study, chickpea production in Kurdistan, Iran and the energy equivalencesof input used in production were investigated. The aims of this study were to determine the amount of input–output energy used in chickpea production, to investigate the efficiency of energy consumption, to make an economic analysis of chickpea production, and to establish a relation between energy inputs and yield. Data were collected through a survey using a face-to-face questionnaire. Diesel energy engrossed 37.9% of total energy, followed by chemical fertiliser 29.6% during production period. Energy efficiency was 1.04, and energy productivity was 0.07 kg MJ-1. The profit-cost ratio of the farms was 1.17. Calculated net return was 42.2 $ ha-1 in the investigated farms. The Cobb–Douglas function,, and the linear function, , were selected to establish the best fitness relations between the production and various energy inputs. Whereas the R squares in both models are close, but it has shown that the Cobb–Douglas model was better than linear model