SEISMIC: A Self-Exciting Point Process Model for Predicting Tweet Popularity

Social networking websites allow users to create and share content. Big information cascades of post resharing can form as users of these sites reshare others' posts with their friends and followers. One of the central challenges in understanding such cascading behaviors is in forecasting information outbreaks, where a single post becomes widely popular by being reshared by many users. In this paper, we focus on predicting the final number of reshares of a given post. We build on the theory of self-exciting point processes to develop a statistical model that allows us to make accurate predictions. Our model requires no training or expensive feature engineering. It results in a simple and efficiently computable formula that allows us to answer questions, in real-time, such as: Given a post's resharing history so far, what is our current estimate of its final number of reshares? Is the post resharing cascade past the initial stage of explosive growth? And, which posts will be the most reshared in the future? We validate our model using one month of complete Twitter data and demonstrate a strong improvement in predictive accuracy over existing approaches. Our model gives only 15% relative error in predicting final size of an average information cascade after observing it for just one hour.Comment: 10 pages, published in KDD 201

Early affective changes and increased connectivity in preclinical Alzheimer's disease.

IntroductionAffective changes precede cognitive decline in mild Alzheimer's disease and may relate to increased connectivity in a "salience network" attuned to emotionally significant stimuli. The trajectory of affective changes in preclinical Alzheimer's disease, and its relationship to this network, is unknown.MethodsOne hundred one cognitively normal older adults received longitudinal assessments of affective symptoms, then amyloid-PET. We hypothesized amyloid-positive individuals would show enhanced emotional reactivity associated with salience network connectivity. We tested whether increased global connectivity in key regions significantly related to affective changes.ResultsIn participants later found to be amyloid positive, emotional reactivity increased with age, and interpersonal warmth declined in women. These individuals showed higher global connectivity within the right insula and superior temporal sulcus; higher superior temporal sulcus connectivity predicted increasing emotional reactivity and decreasing interpersonal warmth.ConclusionsAffective changes should be considered an early preclinical feature of Alzheimer's disease. These changes may relate to higher functional connectivity in regions critical for social-emotional processing

Symmetric Teleparallel Gravity: Some exact solutions and spinor couplings

In this paper we elaborate on the symmetric teleparallel gravity (STPG) written in a non-Riemannian spacetime with nonzero nonmetricity, but zero torsion and zero curvature. Firstly we give a prescription for obtaining the nonmetricity from the metric in a peculiar gauge. Then we state that under a novel prescription of parallel transportation of a tangent vector in this non-Riemannian geometry the autoparallel curves coincides with those of the Riemannian spacetimes. Subsequently we represent the symmetric teleparallel theory of gravity by the most general quadratic and parity conserving lagrangian with lagrange multipliers for vanishing torsion and curvature. We show that our lagrangian is equivalent to the Einstein-Hilbert lagrangian for certain values of coupling coefficients. Thus we arrive at calculating the field equations via independent variations. Then we obtain in turn conformal, spherically symmetric static, cosmological and pp-wave solutions exactly. Finally we discuss a minimal coupling of a spin-1/2 field to STPG.Comment: Accepted for publication in the International Journal of Modern Physics

Phi_0 - Periodic Aharonov-Bohm Oscillations Survive Ensemble Averaging

We have demonstrated that Phi_0 periodic Aharonov--Bohm oscillations measured in a ensemble of rings may survive after ensemble averaging procedure. The central point is the difference between the preparation stage of the ensemble and the subsequent measurement stage. The robustness of the effect under finite temperature and non--zero charging energy of rings is discussed.Comment: 11 pages, 2 figures, RevTex 3.0,WIS-93/84/Aug.-P

Ekspresija E-selektina u mišjem sjemeniku nakon njegove pokusne torzije (ishemije/reperfuzije).

Germ cell-specific apoptosis occurs after ischemia/reperfusion of the testis and is dependent on E-selectin expression. The aim of the study was to determine differences in E-selectin expression in testes tissues of control, sham and treatment groups after ischemia/reperfusion in mice. Mice were subjected to 720° testicular torsion for 1 h or 2 h duration (ischemia) followed by detorsion (reperfusion). After 2 h of reperfusion, the testes were fixed in Bouin fixative and immunohistochemical analysis performed for E-Selectin expression. E-selectin expression increased in the ischemic testis and contralateral testis after 2 h of reperfusion in mice. This increase in E-selectin expression may confirm that E-selectins play a key role in mediating of apoptosis in germ cells after ischemia/reperfusion. Thus, the blockage of E-selectins might be a strategy for rescue of post-ischemic testes.Apoptoza germinativnih stanica javlja se nakon ishemije i reperfuzije sjemenika, a ovisna je o ekspresiji E-selektina. Cilj ovog istraživanja bio je odrediti razlike u ekspresiji E-selektina u tkivu sjemenika kontrolne, placebo i pokusne skupine nakon ishemije/reperfuzije u miševa. Miševi su bili podvrgnuti torziji sjemenika od 7200 tijekom jednog ili dva sata (ishemija), nakon čega je slijedila detorzija (reperfuzija). Nakon dva sata reperfuzije tkivo sjemenika bilo je fiksirano u Bouinovom fiksativu i pretraženo imunohistokemijski na ekspresiju E-selektina. Ekspresija E-selektina povećala se u ishemičnih sjemenika nakon dva sata reperfuzije. Može se reći da povećanje ekspresije E-selektina potvrđuje njhovu ključnu ulogu u nastanku apoptoze germinativnih stanica nakon ishemije/reperfuzije pa bi blokada E-selektina mogla biti od važnosti za spašavanje sjemenika nakon ishemije

Self contamination effects in the TAUVEX UV Telescope: Ground testing and computer simulation

The contamination effects due to outgassing from construction materials of the TAUVEX (Tel Aviv University UV Telescope) were evaluated using a combination of ground testing and computer simulations. Tests were performed from the material level of the system level including: (1) High sensitivity CVCM(10(exp -3 percent) measurements of critical materials. (2) Optical degradation measurements of samples specially contaminated by outgassing products at different contamination levels. (3) FTIR studies of chemical composition of outgassed products on above samples. (4) High resolution AFM studies of surface morphology of contaminated surfaces. The expected degradation of TAUVEX performance in mission was evaluated applying a computer simulation code using input parameters determined experimentally in the above tests. The results have served as guidelines for the proper selection of materials, cleanliness requirements, determination of the thermal conditions of the system and bakeout processes

Finite difference schemes for the symmetric Keyfitz-Kranzer system

We are concerned with the convergence of numerical schemes for the initial value problem associated to the Keyfitz-Kranzer system of equations. This system is a toy model for several important models such as in elasticity theory, magnetohydrodynamics, and enhanced oil recovery. In this paper we prove the convergence of three difference schemes. Two of these schemes is shown to converge to the unique entropy solution. Finally, the convergence is illustrated by several examples.Comment: 31 page

Fenofibrate Treatment Enhances Antioxidant Status and Attenuates Endothelial Dysfunction in Streptozotocin-Induced Diabetic Rats

Diabetic endothelial dysfunction is accompanied by increased oxidative stress and upregulated proinflammatory and inflammatory mediators in the vasculature. Activation of peroxisome proliferator-activated receptor-alpha (PPAR-α) results in antioxidant and anti-inflammatory effects. This study was designed to investigate the effect of fenofibrate, a PPAR-α activator, on the endothelial dysfunction, oxidative stress, and inflammation in streptozotocin diabetic rats. Diabetic rats received fenofibrate (150 mg kg−1 day−1) for 4 weeks. Fenofibrate treatment restored the impaired endothelium-dependent relaxation and increased basal nitric oxide availability in diabetic aorta, enhanced erythrocyte/liver superoxide dismutase and catalase levels, ameliorated the abnormal serum/aortic thiobarbituric acid reactive substances, and prevented the increased aortic myeloperoxidase without a significant change in serum total cholesterol and triglyceride levels. It did not affect the decreased total homocysteine level and the increased tumor necrosis factor-α level in the serum of diabetic rats. Fenofibrate-induced prevention of the endothelial function seems to be related to its potential antioxidant and antiinflammatory activity

Modern Diagnostics of Sepsis and Septic Shock in Children

Sepsis is still one of the leading causes of child mortality worldwide, despite advances in its diagnosis and treatment. Difficulties in recognizing the transition of a localized infectious-inflammatory process to a generalized one lead to a belated diagnosis and the beginning of therapy. Meanwhile, the earlier treatment is started, the higher the patients’ chances of life. Early diagnosis of sepsis, which corresponds to modern ideas about this condition, is one of the main tasks for both scientists and practitioners. The aim of this review is to study modern recommendations for the diagnosis of sepsis and septic shock in children. The article reflects the epidemiology, etiological features, modern definitions, and methods of diagnosis of pediatric sepsis

Exact norm-conserving stochastic time-dependent Hartree-Fock

We derive an exact single-body decomposition of the time-dependent Schroedinger equation for N pairwise-interacting fermions. Each fermion obeys a stochastic time-dependent norm-preserving wave equation. As a first test of the method we calculate the low energy spectrum of Helium. An extension of the method to bosons is outlined.Comment: 21 pages, 3 figures, LaTeX fil