The 2006-2007 Active Phase Of Anomalous X-Ray Pulsar 4U 0142+61: Radiative and Timing Changes, Bursts, and Burst Spectral Features

After at least 6 years of quiescence, Anomalous X-ray Pulsar (AXP) 4U 0142+61 entered an active phase in 2006 March that lasted several months and included six X-ray bursts as well as many changes in the persistent X-ray emission. The bursts, the first seen from this AXP in >11 years of Rossi X-ray Timing Explorer monitoring, all occurred in the interval between 2006 April 6 and 2007 February 7. The burst durations ranged from 8-3x10(exp 3)s. The first five burst spectra are well modeled by blackbodies, with temperatures kT approx. 2 - 6 keV. However, the sixth burst had a complicated spectrum that is well characterized by a blackbody plus three emission features whose amplitude varied throughout the burst. The most prominent feature was at 14.0 keV. Upon entry into the active phase the pulsar showed a significant change in pulse morphology and a likely timing glitch. The glitch had a total frequency jump of (1.9+/-0.4)x10(exp -7) Hz, which recovered with a decay time of 17+/-2 days by more than the initial jump, implying a net spin-down of the pulsar. We discuss these events in the context of the magnetar model

An extremal effective survey about extremal effective cycles in moduli spaces of curves

We survey recent developments and open problems about extremal effective divisors and higher codimension cycles in moduli spaces of curves.Comment: Submitted to the Proceedings of the Abel Symposium 2017. Comments are welcom

Laparoscopic treatment of the hepatic cysts

Sectia Chirugie, Spitalul Municipal de Urgență, Moinesti, Al XI-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” din Republica Moldova și cea de-a XXXIII-a Reuniune a Chirurgilor din Moldova „Iacomi-Răzeșu” 27-30 septembrie 2011Scop. Prezentarea avantajelor metodei laparoscopice în tratamentul chisturilor hepatice. Material şi metodă. Acest studiu prezintă experienţa noastră în tratamentul laparoscopic pentru 57 de cazuri de chisturi hepatice (42 de cazuri de chisturi seroase şi 15 cazuri de chisturi hidatice selectionate: univezicular, necomplicat, localizat în segmentele hepatice laparoscopice) reprezentând 1,89% din 3010 operații laparoscopice efectuate în perioada “2006-2010”. În 49 de cazuri (85,97%), chistul hepatic a fost unic. Indicația de tratament laparoscopic a fost pusă pe criterii clinice, biologice, imagistice și antecedentele bolnavului. În 45 de cazuri (78,95%), chisturile hepatice au fost localizate în lobul drept, dimensiunile fiind de 6-16 cm. Rezultate. Nu au fost înregistrate cazuri de conversie. Complicaţii postoperatorii au fost la 3 dintre pacienţi (5,26%): supurative - 2 abcese şi o fistula biliara. Durata medie de spitalizare a fost de 4,8 zile, iar perioada postoperatorie a fost fără recidive. La toate cazurile s-a practicat și colecistectomia. Pentru chisturile seroase a fost utilizataă tehnica Lin. Cele 12 cazuri de chisturi hidatice au fost rezolvate prin tehnica Lagrot (după inactivarea cu ser hiperton 20%), iar alte 3 cazuri prin chistectomie ideală. Rezultatele sunt argumente care ne determină să recomandăm această cale de abordare laparoscopică pentru tratamentul chistului hepatic. Pentru cele 15 cazuri profilaxia recidivelor postoperatorii a fost efectuată prin administrare de Albendazol. Concluzie. Chirurgia laparoscopică este o metodă sigură şi eficientă de tratare a pacienților cu chisturi hepatice seroase, iar pentru cazurile selectate de chisturi hidatice este o alternativă la chirurgia clasică. Aceasta respecta principiile chirurgiei deschise, beneficiind de avantajele chirurgiei minim invazive: confort postoperator, dureri minime, spitalizare scurtă, reinsertie socială rapidă.Aim. The evaluation of the advantages of the laparoscopic method in surgery of hepatic cysts. Material and method. This study presents our experience in laparoscopic solution of 57 cases of hepatic cysts (42 cases of serous cysts and 15 selected cases of hydatid cysts: univesicular, uncomplicated, localized in laparoscopic hepatic segments) presenting 1,89 % from one 3010 laparoscopic interventions performed between “2006-2010”. In 49 of cases (85,97%) the hepatic cyst was unique. Laparoscopic treatment of the hepatic cysts was attempted in all patients who had clinical, biological, imaging, and following the patient history. In 45 cases (78,95%) the hepatic cysts were located in the right lobe, with dimensions between 6-16 cm. Results. There weren’t any cases of conversion. In 3 of patients (5,26%) postoperative complications were recorded: suppurative – 2 abscesses and one biliary fistula. The mean hospital stay was 4,8 days, and the postoperative period to a year was without recurrences. In all cases, we performed the cholecystectomy, too. For the serious cysts was used the Lin technique was. In 12 cases of hydatid cysts were performed the Lagrot technique (after inactivation with hypertonic saline 20%), and the other 3 cases were performed by ideal cystectomy. The results are arguments for us to recommend this way of laparoscopic approach for the treatment of hepatic cyst. For the 15 cases, prophylaxis of postoperative recurrence was performed by administration of Albendazole. Conclusions. Laparoscopic surgery is a safe and effective method of treating patients with hepatic serous cysts, and for the selected cases of hydatids cysts, it is an alternative to classic surgery. It respects the principles of open surgery, with all the benefits of laparoscopic surgery: postoperative comfort, minimal pain, short hospital stay, rapid social reintegration

Precise Localization of the Soft Gamma Repeater SGR 1627-41 and the Anomalous X-ray Pulsar AXP 1E1841-045 with Chandra

We present precise localizations of AXP 1E1841-045 and SGR 1627-41 with Chandra. We obtained new infrared observations of SGR 1627-41 and reanalyzed archival observations of AXP 1E1841-045 in order to refine their positions and search for infrared counterparts. A faint source is detected inside the error circle of AXP 1E1841-045. In the case of SGR 1627-41, several sources are located within the error radius of the X-ray position and we discuss the likelihood of one of them being the counterpart. We compare the properties of our candidates to those of other known AXP and SGR counterparts. We find that the counterpart candidates for SGR 1627-41 and SGR 1806-20 would have to be intrinsically much brighter than AXPs to have detectable counterparts with the observational limits currently available for these sources. To confirm the reported counterpart of SGR 1806-20, we obtained new IR observations during the July 2003 burst activation of the source. No brightening of the suggested counterpart is detected, implying that the counterpart of SGR 1806-20 remains yet to be identified.Comment: 29 pages, 4 figures, accepted for publication in Ap

7‑hydroxymitragynine is an active metabolite of mitragynine and a key mediator of its analgesic effects

Mitragynina speciosa, more commonly known as kratom, is a plant native to Southeast Asia, the leaves of which have been used traditionally as a stimulant, analgesic, and treatment for opioid addiction. Recently, growing use of the plant in the United States and concerns that kratom represents an uncontrolled drug with potential abuse liability, have highlighted the need for more careful study of its pharmacological activity. The major active alkaloid found in kratom, mitragynine, has been reported to have opioid agonist and analgesic activity in vitro and in animal models, consistent with the purported effects of kratom leaf in humans. However, preliminary research has provided some evidence that mitragynine and related compounds may act as atypical opioid agonists, inducing therapeutic effects such as analgesia, while limiting the negative side effects typical of classical opioids. Here we report evidence that an active metabolite plays an important role in mediating the analgesic effects of mitragynine. We find that mitragynine is converted in vitro in both mouse and human liver preparations to the much more potent mu-opioid receptor agonist 7-hydroxymitragynine, and that this conversion is mediated by cytochrome P450 3A isoforms. Further, we show that 7-hydroxymitragynine is formed from mitragynine in mice and that brain concentrations of this metabolite are sufficient to explain most or all of the opioid-receptor-mediated analgesic activity of mitragynine. At the same time, mitragynine is found in the brains of mice at very high concentrations relative to its opioid receptor binding affinity, suggesting that it does not directly activate opioid receptors. The results presented here provide a metabolism-dependent mechanism for the analgesic effects of mitragynine and clarify the importance of route of administration for determining the activity of this compound. Further, they raise important questions about the interpretation of existing data on mitragynine and highlight critical areas for further research in animals and humans.</p

Independent Set Reconfiguration in Cographs

We study the following independent set reconfiguration problem, called TAR-Reachability: given two independent sets $I$ and $J$ of a graph $G$, both of size at least $k$, is it possible to transform $I$ into $J$ by adding and removing vertices one-by-one, while maintaining an independent set of size at least $k$ throughout? This problem is known to be PSPACE-hard in general. For the case that $G$ is a cograph (i.e. $P_4$-free graph) on $n$ vertices, we show that it can be solved in time $O(n^2)$, and that the length of a shortest reconfiguration sequence from $I$ to $J$ is bounded by $4n-2k$, if such a sequence exists. More generally, we show that if $X$ is a graph class for which (i) TAR-Reachability can be solved efficiently, (ii) maximum independent sets can be computed efficiently, and which satisfies a certain additional property, then the problem can be solved efficiently for any graph that can be obtained from a collection of graphs in $X$ using disjoint union and complete join operations. Chordal graphs are given as an example of such a class $X$

On the complexity of color-avoiding site and bond percolation

The mathematical analysis of robustness and error-tolerance of complex networks has been in the center of research interest. On the other hand, little work has been done when the attack-tolerance of the vertices or edges are not independent but certain classes of vertices or edges share a mutual vulnerability. In this study, we consider a graph and we assign colors to the vertices or edges, where the color-classes correspond to the shared vulnerabilities. An important problem is to find robustly connected vertex sets: nodes that remain connected to each other by paths providing any type of error (i.e. erasing any vertices or edges of the given color). This is also known as color-avoiding percolation. In this paper, we study various possible modeling approaches of shared vulnerabilities, we analyze the computational complexity of finding the robustly (color-avoiding) connected components. We find that the presented approaches differ significantly regarding their complexity.Comment: 14 page

Preparation and Characterisation of Alumina Template Obtained by OneStep Anodization Method

The goal of this study was to obtain an alumina template (AAO) by one-step anodization method and to evaluate its optical properties correlated with the annealing temperature. AAO was obtained from two different media: sulphuric acid (1.5 M H2SO4) and oxalic acid (0.4 M H2C2O4) at a potential of 15 V and 40 V, respectively. AAO morphology and chemical composition had been investigated by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The average pore diameters such as 20 nm for AAO obtained from H2SO4 and 40 nm from H2C2O4 were measured. The crystalline structures of AAO samples annealed at three different temperatures of 150 ºC, 300 ºC and 350 ºC were studied by Xray diffractometry (XRD). The effect of annealing temperature on the optical properties of AAO was studied by UV-VIS spectrophotometry

Syzygies of torsion bundles and the geometry of the level l modular variety over M_g

We formulate, and in some cases prove, three statements concerning the purity or, more generally the naturality of the resolution of various rings one can attach to a generic curve of genus g and a torsion point of order l in its Jacobian. These statements can be viewed an analogues of Green's Conjecture and we verify them computationally for bounded genus. We then compute the cohomology class of the corresponding non-vanishing locus in the moduli space R_{g,l} of twisted level l curves of genus g and use this to derive results about the birational geometry of R_{g, l}. For instance, we prove that R_{g,3} is a variety of general type when g>11 and the Kodaira dimension of R_{11,3} is greater than or equal to 19. In the last section we explain probabilistically the unexpected failure of the Prym-Green conjecture in genus 8 and level 2.Comment: 35 pages, appeared in Invent Math. We correct an inaccuracy in the statement of Prop 2.