Blockspin Cluster Algorithms for Quantum Spin Systems

Cluster algorithms are developed for simulating quantum spin systems like the one- and two-dimensional Heisenberg ferro- and anti-ferromagnets. The corresponding two- and three-dimensional classical spin models with four-spin couplings are maped to blockspin models with two-blockspin interactions. Clusters of blockspins are updated collectively. The efficiency of the method is investigated in detail for one-dimensional spin chains. Then in most cases the new algorithms solve the problems of slowing down from which standard algorithms are suffering.Comment: 11 page

Testing the effect of purified lignocellulose on broilers for health status, production results and degree of histological and morphological changes in digestive tracts

Osnovni cilj istraživanja ove doktorske disertacije bio je da se ispita uticaj ishrane brojlera obrocima sa dodatkom različitih količina purifikovane lignoceluloze na zdravstveno stanje, proizvodne rezultate (tjelesna masa, prirast, konzumacija i konverzija hrane), fizičke karakteristike (težina digestivnog trakta), vlažnost stelje, mikrobiološke i morfološke karakteristike pojedinih segmenata crijeva, kao i opravdanost korištenja lignoceluloze u ishrani brojlera. Ogled je izveden na ukupno 400 brojlera provenijencije Cobb 500, podijeljenih u 4 grupe po 100 jedinki u svakoj. Sve jedinke hranjene su smješama standardnog sirovinskog i hemijskog sastava po preporuci proizvođača hibrida, s tim što su se grupe jedino razlikovale u tome što su ogledne grupe u starter i grover smješi za ishranu imale dodate različite količine purifikovane lignoceluloze ( O-I grupa je dobijala purifikovanu lignocelulozu u količini od 4 g/kg hrane, O-II grupa u količini od 6 g/kg purifikovane lignoceluloze , dok je u hranu za O-III grupu brojlera dodato 6 g/kg purifikovane lignoceluloze uz smanjenje učešća sojine sačme za 0,6%. Smješe za ishranu bile su formulisane tako da u potpunosti zadovolje potrebe brojlera u svim fazama tova. Za vrijeme trajanja ogleda praćeno je zdravstveno stanje i proizvodni parametri (tjelesna masa, prirast, konzumacija i konverzija hrane). Kontrolna mjerenja tjelesne mase i konzumacije hrane vršena su svakodnevno i na kraju svake nedelje tova. Na kraju tova brojleri su izmjereni, izračunata je potrošena količina hrane, a u klaonici je izvršeno mjerenje težine digestivnog trakta i uzimanje uzoraka crijeva za mikrobiološke i histološke analize. Korišćenjem purifikovane lignoceluloze postignuti su bolji proizvodni rezultati oglednih grupa u odnosu na kontrolnu grupu brojlera. Tjelesne mase brojlera oglednih grupa bile su veće od kontrolne grupe u svim fazama tova. U periodu tova od 1-21. dana utvrđena je statistički manja tjelesna masa brojlera kontrolne u odnosu na brojlere O-II grupe, s tim da je isti trend nastavljen i u drugoj fazi tova (22-42. dan) gdje su utvrđene statistički značajne razlike između O-II grupe u odnosu na kontrolnu, ali i ostale ogledne grupe. U svim fazama tova, kao i za cijeli period tova ogledne grupe brojlera ostvarile su veći prosiječni prirast od kontrolne grupe...The main goal of this doctoral dissertation was to investigate the effect of broiler’s nutrition on meals with the addition of various amounts of purified lignocelluloses on health condition, production results (body weight, growth, food consumption and conversion), physical characteristics (the weight of the digestive tract), litter moisture microbiological and morphological characteristics of certain segments of the intestine, as well as the justification for the use of lignocellulose in feeding of broilers. The experiment was performed on total of 400 broilers on provenance Cobb 500 divided into 4 groups with 100 individuals in each of them. All individuals were being fed with mixture of standard raw material and chemical composition as recommended by the hybrid manufacturer, the only thing was that groups differed in that the experimental groups in starter and grower mixture had different added amounts of purified lignocellulose (the OI group received purified lignocellulose in 4 g / kg of feed, O-II group in the amount of 6 g / kg of purified lignocellulose, while 6 g / kg of purified lignocellulose was added to the feed for O-III group of broilers with a 0.6% reduction in soybean meal content. Nutritional mixture were formulated to fully satisfy needs of borilers in all stages of fattening. During of the experiment health status and production parameters (body weight, growth, food consumption and conversion) were monitored daily and at the end of each week of fattening. At the end of fattening boilers were measured, the amount of consumed food was calculated and in the slaughterhouse the digestive tract weigh was measured and it was taken sample gut for microbiological and histological analysis. The use of purified lignocellulose achieved better production results of the experimental groups than the control group of broilers. The broiler body weights of experimental group were larger than the control group at all stages of fattening. In the fattening period 1-21 it was determined statistically lower body mass of control broiler than O-II group broilers. The same trend was continued in the second stage of fattening (22-42 days) where were determined statistically significant differences between O-II group compared to control, but also other experimental group. At all stages of fattening as for the whole fattening period experimental groups of broilers achieved higher average increment than control group..

Kosterlitz-Thouless transition of quantum XY model in two dimensions

The two-dimensional $S=1/2$ XY model is investigated with an extensive quantum Monte Carlo simulation. The helicity modulus is precisely estimated through a continuous-time loop algorithm for systems up to $128 \times 128$ near and below the critical temperature. The critical temperature is estimated as $T_{\rm KT} = 0.3427(2)J$. The obtained estimates for the helicity modulus are well fitted by a scaling form derived from the Kosterlitz renormalization group equation. The validity of the Kosterlitz-Thouless theory for this model is confirmed.Comment: 8 pages, 2 tables, 6 figure

Two-dimensional Superfluidity and Localization in the Hard-Core Boson Model: a Quantum Monte Carlo Study

Quantum Monte Carlo simulations are used to investigate the two-dimensional superfluid properties of the hard-core boson model, which show a strong dependence on particle density and disorder. We obtain further evidence that a half-filled clean system becomes superfluid via a finite temperature Kosterlitz-Thouless transition. The relationship between low temperature superfluid density and particle density is symmetric and appears parabolic about the half filling point. Disorder appears to break the superfluid phase up into two distinct localized states, depending on the particle density. We find that these results strongly correlate with the results of several experiments on high-$T_c$ superconductors.Comment: 10 pages, 3 figures upon request, RevTeX version 3, (accepted for Phys. Rev. B

Performances, Heal and Cecal Microbial Populations and Histological Characteristics in Broilers Fed Diets Supplemented with Lignocellulose

The effect of dietary lignocellulose on broilers performance, intestinal microbiota and morphology, pH of digesta and litter humidity after 28 and 42 days of the experiment was evaluated. A total of 384 Cobb500 chickens (initial weight: 41.88 +/- 1.56 g) were divided into 4 groups with 24 replications and fed with control diet (C), a control diet with added 0.4% of lignocellulose (T1), a diet with added 0.6% of lignocellulose at the expense of soybean meal and maize (T2), and a diet supplemented with 0.6% of lignocellulose at the expense of soybean meal (T3). T2 treatment significantly influenced body weight, weight gain (WG), feed intake (FI) and feed conversion ratio (FCR). T2 and T3 treatment increased average LAB and Bifidobacterium spp. count, and decreased the number of Escherichia coil in the ileum and cecum, while differences in cecal Clostridium perfringens count among 0.4% and 0.6% treatments were not observed. Feeding the lignocellulose diet did not affect the relative weights of empty proventriculus, gizzard or intestines, but led to a decrease in pHs. T3 treatment caused an increase of the villi heights and significantly lower moisture content in the litter. Even though the addition of lignocellulose into broilers diet positively influenced performances, changes in intestinal microbiota and villi heights, based on the results of the present study, supplementation with 0.6% lignocellulose is recommended

The reoperations after reconstructive operations on the arteries of the plevis and inferior extremities

U toku dvije godine na Odsjeku za vaskularnu kirurgiju Odjela za kirurgiju Opće bolnice u Osijeku izvedeno je 95 rekonstruktivnih kirurških zahvata na arterijama zdjelice i donjih ekstremiteta. Autori opisuju vrste i broj reoperacija, analiziraju uzroke koji su do njih doveli i prikazuju rezultate reoperativnih zahvata. Posebno ukazuju na značaj operativnih indikacija i prefinjenost operativne tehnike kao bitnih elemenata u prevenciji postoperativnih komplikacija.In the course of two years 95 reconstructive operations on the arteries of the pelvis and the inferior extremities were performed at the Department of the Vascular Surgery, General Hospital Osijek. The authors describe the types and the number of reoperations. The various reasons for chosen techniques are analysed and their results reported. As essential parts of the prevention of the postoperative complications, the importance of indications for the surgery as well as fine operative technique are pointed out

Postoperative infections in vascular surgery of infereior extramities

Autori su u toku jedne godine pratili razvoj postoperativno nastale infekcije u 173 bolesnika. Ukazuju na benigni tok ekstrafascijalne i opasan razvoj subfascijalne infekcije, razrađuju mogućnost preventivnih mjera, kao i terapijske postupke kod nastalih komplikacija. Svoje rezultate dovode u znatnu ovisnost o uvjete rada na kirurškim odjelima gdje nedostaje adekvatan suvremeni medicinski komfor.The authors were interested in the evolution of postoperative infections in 173 patients during one year. They point at the benign course of extrafascial infections, and the dangereous development of the subfascial ones. Preventive procedures and therapeutic treatment in the cases with complications are presented. The effect in the treatment of postoperative infections is highly dependent on working conditions in the surgery department, since there are no adequate medical conveniences at disposal

Disorder Induced Phase Transition in a Random Quantum Antiferromagnet

A two-dimensional Heisenberg model with random antiferromagnetic nearest-neighbor exchange is studied using quantum Monte Carlo techniques. As the strength of the randomness is increased, the system undergoes a transition from an antiferromagnetically ordered ground state to a gapless disordered state. The finite-size scaling of the staggered structure factor and susceptibility is consistent with a dynamic exponent $z = 2$.Comment: Revtex 3.0, 10 pages + 5 postscript figures available upon request, UCSBTH-94-1

Temperature behavior of the magnon modes of the square lattice antiferromagnet

A spin-wave theory of short-range order in the square lattice Heisenberg antiferromagnet is formulated. With growing temperature from T=0 a gapless mode is shown to arise simultaneously with opening a gap in the conventional spin-wave mode. The spectral intensity is redistributed from the latter mode to the former. For low temperatures the theory reproduces results of the modified spin-wave theory by M.Takahashi, J.E.Hirsch et al. and without fitting parameters gives values of observables in good agreement with Monte Carlo results in the temperature range 0 <= T < 0.8J where J is the exchange constant.Comment: 12 pages, 2 figure

Toward a Unified Magnetic Phase Diagram of the Cuprate Superconductors

We propose a unified magnetic phase diagram of cuprate superconductors. A new feature of this phase diagram is a broad intermediate doping region of quantum-critical, $z=1$, behavior, characterized by temperature independent $T_1T/T_{\rm 2G}$ and linear $T_1T$, where the spin waves are not completely absorbed by the electron-hole continuum. The spin gap in the moderately doped materials is related to the suppression of the low-energy spectral weight in the quantum disordered, $z=1$, regime. The crossover to the $z=2$ regime, where T_1T/T_{\rm 2G}^2 \simeq \mbox{const}, occurs only in the fully doped materials.Comment: 14 pages, REVTeX v2.1, PostScript file for 3 figures attached, UIUC-P-93-06-04