Global constants in (2+1)--dimensional gravity

The extended conformal algebra (so)(2,3) of global, quantum, constants of motion in 2+1 dimensional gravity with topology R x T^2 and negative cosmological constant is reviewed. It is shown that the 10 global constants form a complete set by expressing them in terms of two commuting spinors and the Dirac gamma matrices. The spinor components are the globally constant holonomy parameters, and their respective spinor norms are their quantum commutators.Comment: 14 pages, to appear in Classical and Quantum Gravity, Spacetime Safari: Essays in Honor of Vincent Moncrief on the Classical Physics of Strong Gravitational Field

Expansion-induced contribution to the precession of binary orbits

We point out the existence of new effects of global spacetime expansion on local binary systems. In addition to a possible change of orbital size, there is a contribution to the precession of elliptic orbits, to be added to the well-known general relativistic effect in static spacetimes, and the eccentricity can change. Our model calculations are done using geodesics in a McVittie metric, representing a localized system in an asymptotically Robertson-Walker spacetime; we give a few numerical estimates for that case, and indicate ways in which the model should be improved.Comment: revtex, 7 pages, no figures; revised for publication in Classical and Quantum Gravity, with minor changes in response to referees' comment

Hamiltonian structure of 2+1 dimensional gravity

A summary is given of some results and perspectives of the hamiltonian ADM approach to 2+1 dimensional gravity. After recalling the classical results for closed universes in absence of matter we go over the the case in which matter is present in the form of point spinless particles. Here the maximally slicing gauge proves most effective by relating 2+1 dimensional gravity to the Riemann- Hilbert problem. It is possible to solve the gravitational field in terms of the particle degrees of freedom thus reaching a reduced dynamics which involves only the particle positions and momenta. Such a dynamics is proven to be hamiltonian and the hamiltonian is given by the boundary term in the gravitational action. As an illustration the two body hamiltonian is used to provide the canonical quantization of the two particle system.Comment: 13 pages,2 figures,latex, Plenary talk at SIGRAV2000 Conferenc

Xanthogranulomatous Cystitis Presenting as Urinary Incontinence and a Vesicovaginal Fistula: A Case Report and Review of the Literature

Abstract Anthogranulomatous cystitis (XC) is an inflammatory condition of the urinary bladder that is benign and rarely seen. XC is a unique disease in which there have been only 26 cases described in the literature, including our case. Patients with XC often present with lower urinary tract symptoms, hematuria, abdominal pain, or abdominal mass. We present the unusual case of an 81 year old female who presents with urinary incontinence, which was later diagnosed as a vesicovaginal fistula. After describing the treatment of this patient, a review of the literature is detailed including presentation, possible etiologies, and treatment of XC

A case of iliac crest avulsion with peritoneal disruption and bowel herniation after blunt trauma

Pelvic fractures account for approximately 3% of all blunt traumatic skeletal injuries. Pelvic fractures are most commonly caused by motor vehicle accidents (60%), falls from a height (30%), and crush injuries (10%). Pelvic fractures are a marker for high-energy trauma and are often associated with other life-threatening injuries. Over 80% of patients with unstable pelvic fractures will be found to have additional musculoskeletal injuries. Although the mortality rate in patients with pelvic fractures has been declining in recent years due to the robustness of the US trauma system, the incidence is increasing due to the higher rate of high-speed motor vehicle collisions

KOMBINIRANO DJELOVANJE BITURATA I EKSTRAKTA YUCCA SCHIDIGERI NA GASTROINTESTINALNI SUSTAV SVINJA OKO ODBIJANJA

After the banning of antibiotics as growth promoters, animal production in the EU faced the problem of increased post-weaning disorders, and several solutions were proposed (acidifiers, probiotics, herb extracts, enzyme cocktails, etc.). Short chain fatty acids (SCFA) are the main end product of bacterial fermentation in the hind gut in monogastric animals and can be used as energy supply for the epithelial cells of gut mucosa. Thus the aim of the study was to test the usefulness of novel microencapsulated sodium butyrate and Yucca Schidigera extract (encourages friendly bacteria growth, reduces ammonia) preparation on pig performance and small intestine development in the critical weaning period. Microencapsulation helps to avoid stomach degradation and provides better distribution of the compounds along the small intestine. Suckling piglets, 14-day old, were divided into 2 groups, control and with butyrate addition. Control pigs received a standard feed supplemented with a microencapsulated acidifier (0.3%). Butyrate pigs received the same feed and acidifier, as controls, supplemented with butyrate/yucca preparation (0.3%). At days 28 (weaning), 35 and 56 of life, 6 pigs from each group were killed and the gastrointestinal tract was harvested and measured. The initial body weight (14 d) of pigs from the control group was higher than that of the experimental, but at day 56 it did not differ significantly (P=0.48). The relative stomach and pancreas weights in the experimental group showed a tendency toward higher values in all time points, and the small intestine relative weight in day 35 was higher as compared to the controls. The growth rate of the pigs at day 35 decreased significantly in the control (P=0.007), but did not in the experimental (P=0.058) group compared to day 31. Measurements of the small intestine sections revealed increased mucosa thickness in butyrate treated pigs. This was due to both villi and crypt enlargement. In conclusion, our results demonstrated the effectiveness sodium butyrate and Yucca Shidigera extract in the prevention of weaning problems in pigs, however further research on the novel preparation is needed.Nakon zabrane antibiotika kao promotora rasta, proizvodnja životinja u EU suočila se sa sve više poremećaja nakon odbijanja pa je predloženo nekoliko rješenja (acidifikatori, probiotici, biljni ekstrakti, kokteli enzima, itd.). Kratkolančane masne kiseline glavni su krajnji proizvod bakterijske fermentacije u stražnjem crijevu u monogastričnih životinja pa se mogu upotrijebiti za snabdijevanje energijom epitelnih stanica crijevne sluznice /mukoze. Stoga je cilj ovog rada bio testirati korisnost novog natrijevog biturata u mikrokapsuli i pripravka ekstrakta Yucca Schidigera (potiče rast dobročudnih bakterija, smanjuje amonijak) na performansu svinja i razvoj tankog crijeva u kritičnom razdoblju odbijanja. Mikrokapsule pomažu da se izbjegne oštećenje želuca i pruža bolju razdiobu spojeva duž tankog crijeva. Praščići na sisi, u dobi od 14 dana, bili su podijeljeni u dvije skupine, kontrolnu i skupinu s dodavanjem biturata. Kontrolni praščići dobivali su standardnu hranu s dodatkom acidifikatora/zakiseljivača u mikrokapsuli (0.03%). Praščići na bituratima dobivali su istu hranu i acidifikator/zakiseljivač s dodatkom biturata/yucca pripravka (0.03%). U dobi od 28 (odbijanje), 35 i 56 dana žrtvovano je 6 svinja iz svake skupine te je pregledan i izmjeren gastrointestinalni sustav. Početna tjelesna masa (14. dan) svinja iz kontrolne skupine bila je veća od mase svinja pokusne skupine ali 56. dan nije se značajno razlikovala (P=0.48). Relativne mase želuca i gušterače u pokusnoj skupini pokazale su tendenciju viših vrijednosti u svim razdobljima, a relativna masa tankog crijeva 35. dana bila je viša u usporedbi s kontrolnom skupinom. Stopa rasta svinja 35. dana znatno se smanjila u kontrolnoj skupini (P=0.007) ali ne u kontrolnoj skupini (P=0.058) u usporedbi s 31. danom. Mjere tankog crijeva pokazale su povećanu debljinu sluznice u svinja tretiranih bituratom. To se pripisuje povećanju dlačica i udubina (villi i crypt). U zaključku, naši su rezultati pokazali djelotvornost natrijevog biturata i ekstrakta Yucca Schidigeri u prevenciji problema odbijanja u svinja, međutim, potrebna su dalja istraživanja novih pripravaka

A variational method based on weighted graph states

In a recent article [Phys. Rev. Lett. 97 (2006), 107206], we have presented a class of states which is suitable as a variational set to find ground states in spin systems of arbitrary spatial dimension and with long-range entanglement. Here, we continue the exposition of our technique, extend from spin 1/2 to higher spins and use the boson Hubbard model as a non-trivial example to demonstrate our scheme.Comment: 36 pages, 13 figure

BRAHMA ATPase of the SWI/SNF Chromatin Remodeling Complex Acts as a Positive Regulator of Gibberellin-Mediated Responses in Arabidopsis

SWI/SNF chromatin remodeling complexes perform a pivotal function in the regulation of eukaryotic gene expression. Arabidopsis (Arabidopsis thaliana) mutants in major SWI/SNF subunits display embryo-lethal or dwarf phenotypes, indicating their critical role in molecular pathways controlling development and growth. As gibberellins (GA) are major positive regulators of plant growth, we wanted to establish whether there is a link between SWI/SNF and GA signaling in Arabidopsis. This study revealed that in brm-1 plants, depleted in SWI/SNF BRAHMA (BRM) ATPase, a number of GA-related phenotypic traits are GA-sensitive and that the loss of BRM results in markedly decreased level of endogenous bioactive GA. Transcriptional profiling of brm-1 and the GA biosynthesis mutant ga1-3, as well as the ga1-3/brm-1 double mutant demonstrated that BRM affects the expression of a large set of GA-responsive genes including genes responsible for GA biosynthesis and signaling. Furthermore, we found that BRM acts as an activator and directly associates with promoters of GA3ox1, a GA biosynthetic gene, and SCL3, implicated in positive regulation of the GA pathway. Many GA-responsive gene expression alterations in the brm-1 mutant are likely due to depleted levels of active GAs. However, the analysis of genetic interactions between BRM and the DELLA GA pathway repressors, revealed that BRM also acts on GA-responsive genes independently of its effect on GA level. Given the central position occupied by SWI/SNF complexes within regulatory networks controlling fundamental biological processes, the identification of diverse functional intersections of BRM with GA-dependent processes in this study suggests a role for SWI/SNF in facilitating crosstalk between GA-mediated regulation and other cellular pathways

Ponzano-Regge model revisited I: Gauge fixing, observables and interacting spinning particles

We show how to properly gauge fix all the symmetries of the Ponzano-Regge model for 3D quantum gravity. This amounts to do explicit finite computations for transition amplitudes. We give the construction of the transition amplitudes in the presence of interacting quantum spinning particles. We introduce a notion of operators whose expectation value gives rise to either gauge fixing, introduction of time, or insertion of particles, according to the choice. We give the link between the spin foam quantization and the hamiltonian quantization. We finally show the link between Ponzano-Regge model and the quantization of Chern-Simons theory based on the double quantum group of SU(2)Comment: 48 pages, 15 figure

Diagnosing collaboration in practice-based learning: Equality and intra-individual variability of physical interactivity

Collaborative problem solving (CPS), as a teaching and learning approach, is considered to have the potential to improve some of the most important skills to prepare students for their future. CPS often differs in its nature, practice, and learning outcomes from other kinds of peer learning approaches, including peer tutoring and cooperation; and it is important to establish what identifies collaboration in problem-solving situations. The identification of indicators of collaboration is a challenging task. However, students physical interactivity can hold clues of such indicators. In this paper, we investigate two non-verbal indexes of student physical interactivity to interpret collaboration in practice-based learning environments: equality and intra-individual variability. Our data was generated from twelve groups of three Engineering students working on open-ended tasks using a learning analytics system. The results show that high collaboration groups have member students who present high and equal amounts of physical interactivity and low and equal amounts of intra-individual variability