An exploratory study of heavy domain wall fermions on the lattice

We report on an exploratory study of domain wall fermions (DWF) as a lattice regularisation for heavy quarks. Within the framework of quenched QCD with the tree-level improved Symanzik gauge action we identify the DWF parameters which minimise discretisation effects. We find the corresponding effective 4$d$ overlap operator to be exponentially local, independent of the quark mass. We determine a maximum bare heavy quark mass of $am_h\approx 0.4$, below which the approximate chiral symmetry and O(a)-improvement of DWF are sustained. This threshold appears to be largely independent of the lattice spacing. Based on these findings, we carried out a detailed scaling study for the heavy-strange meson dispersion relation and decay constant on four ensembles with lattice spacings in the range $2.0-5.7\,\mathrm{GeV}$. We observe very mild $a^2$ scaling towards the continuum limit. Our findings establish a sound basis for heavy DWF in dynamical simulations of lattice QCD with relevance to Standard Model phenomenology.Comment: 23 pages, 8 figure

Hemijski aspekt uticaja jona kobalta na aktivnost ATP-aza

The influence of Co2+ ions on the activities of Na+/K+-ATPase and Mg2+-ATPase, enzymes from rat brain synaptic plasma membrane, was studied. The aim of this study was to investigate the inhibition of both ATPases activities by exposure to cobalt ions as a function of experimentally added CoSO4. The "free" Co2+ concentrations in the reaction mixture were also calculated and discussed. CoSO4 induced a dose-dependent inhibition of both enzymes. The IC50 values of Co2+, as calculated from the experimental curves, were 168 mu M for Na+/K+-ATPase and 262 mu M for Mg2+-ATPase, and for the recalculated free Co2+ concentration 75.4 mu M for Na+/K+-ATPase and 136 mu M for Mg2+-ATPase. The obtained linear Dixon's plot for Na+/K+-ATPase implies equilibrium binding of cobalt with inhibitory sites on the enzyme. The kinetic parameters for both enzymes in presence and absence of CoSO4 were calculated from the experimental data. The results of the kinetic analysis show that inhibition of Na+/K+-ATPase induced by CoSO4 is non-competitive, and for Mg2+-ATPAse that there are two sites of different sensitivities or two different enzymes.Ispitan je uticaj Co2+ jona na aktivnost Na+/K+ -ATPaze i Mg2+ -ATP-aze, enzima sinaptozomalne membrane mozga pacova. Cilj rada je bio da se ispita inhibicija aktivnosti oba enzima izazvana izlaganjem jonima kobalta kao funkcija eksperimentalno dodatog CoSO4. Takođe je izračunata i diskutovana "slobodna" koncentracija Co2+ u reakcionoj smeši. Utvrđeno je da kobalt inhibira enzime u koncentraciono zavisnom smislu. Vrednosti IC50 izračunate iz eksperimentalnih krivih su: 168 μM za Na+/K+ -ATP-azu i 136 μM za Mg2+ -ATP-azu. Linearan Dixon-ov plot za Na+/K+ -ATP-azu ukazuje na ravnotežno vezivanje kobalta. Izračunati su kinetički parametri oba enzima u prisustvu i odsustvu CoSO4. Inhibicija Na+/K+-ATP-aze izazvana CoSO4 je nekompetitivna, dok Mg2+ -ATP-aza ima dva mesta vezivanja različitog afiniteta ili pak dva različita enzima

Genetic variability of mineral elements concentration in pepper varieties (Capsicum annuum L.)

Pepper (Capsicum annuum L.) is one of the major members of the vegetable kingdom. The differences between the individual varieties in mineral nutrition and the uptake of mineral elements have provoked our interest for the investigations of their genotype specificity. The chemical composition of pepper leaves at flowering and at the end of the growing season was analyzed. On the average, the content of total ash was app. 22%, namely 19-20% (soluble) and 2-3% (insoluble) at both stages. The highest accumulation values were obtained with nitrogen, then potassium, calcium and phosphorus, whereas the lowest with sodium. The most remarkable genotypic differences were recorded at the end of the growing season. The results obtained clearly demonstrate the chemical heterogeneity of pepper varieties. This crop may be grown successfully only if specificity of its mineral nutrition is known

A stochastic model of Min oscillations in Escherichia coli and Min protein segregation during cell division

The Min system in Escherichia coli directs division to the centre of the cell through pole-to-pole oscillations of the MinCDE proteins. We present a one dimensional stochastic model of these oscillations which incorporates membrane polymerisation of MinD into linear chains. This model reproduces much of the observed phenomenology of the Min system, including pole-to-pole oscillations of the Min proteins. We then apply this model to investigate the Min system during cell division. Oscillations continue initially unaffected by the closing septum, before cutting off rapidly. The fractions of Min proteins in the daughter cells vary widely, from 50%-50% up to 85%-15% of the total from the parent cell, suggesting that there may be another mechanism for regulating these levels in vivo.Comment: 19 pages, 12 figures (25 figure files); published at http://www.iop.org/EJ/journal/physbi

Reproduction of symbolic boundaries through family practices in Serbia

Predmet doktorske disertacije predstavlja analiza reprodukcije simboličkih granica kroz porodične prakse smeštene u porodičnom polju i porodičnom prostoru. Prvi nivo porodične dinamike, porodično polje, obuhvata pitanja odnosa između porodica različitog društvenog položaja, dok drugi nivo porodične dinamike, porodični prostor, obuhvata pitanja unutarporodičnih odnosa. Cilj istraživanja je lociranje oblasti porodičnih praksi u kojima su simboličke granice prisutne i relevantne, kao i analiza tipova i karakteristika granica koje se uspostavljaju između članova porodice i između različitih porodica. Takođe, jedan od ciljeva istraživanja je da se kritički razmotren i proširen koncept simboličkih granica primeni u oblasti porodičnih praksi, tj. da se testiraju njegove eksplorativne i eksplanatorne mogućnosti. Kako bi se postigli postavljeni ciljevi, u istraživanju je korišćen kombinovani istraživački nacrt (mixed methods research design). Kvantitativni podaci su poslužili u skiciranju osnovne dimenzije porodičnog prostora, konstituisanju tipova strategijskog delanja porodica i istraživanju sklonosti i stavova opšte populacije prema digitalnim i rodnim praksama, kao i porodičnoj formi. Metod dubinskog intervjua, je na drugoj strani, pružio kvalitativni materijal na osnovu kojeg su pronađene glavne oblasti razgraničavanja i lična perspektiva procesa identifikacije i isključivanja. Kombinovani metod istraživanja je omogućio da se kvalitativnim podacima da dimenzija opšte rasprostranjenosti, dok su kvalitativni podaci dobijali dimenziju konkretnosti kroz situiranje opštih pravilnosti ili trendova u složen sklop pojedinačnog slučaja. Pored toga, dubinskim intervjuima su dobijeni slojevi lične intepretacije smisla određenog delanja, i grupnog (porodičnog) i pojedinačnog. Analiza intervjua je svakako bila usmerena i na aspekte narativa koji u sebi sadrže čistu reprodukciju postojećih društvenih oblika delanja, kao što je i produkovala i objašnjenja koja učesnici istraživanja nisu eksplicirali..

Electrical characteristics of female and male human skin

Bioimpedance spectroscopy (BIS) is a popular method for characterizing the electrical properties of biological tissues. In this study, BIS measurement data of female and male human skin were analyzed and compared. The electrical characteristics of tissue were followed according to four-parameters of the Cole-Cole model: low frequency resistance R0; high frequency resistance R∞; relaxation time t and parameter a. Individual electrical characteristics of human skin were determined for 30 women and 30 men. The distribution and one-way analysis of variance (one-way ANOVA) of the Cole-Cole parameters R0, R∞, t, a within the human population indicated their different dependence on gender. Parameter a, which is higher in the female subjects (a =0.83±0.03) than in the male subjects (a=0.7±0.05), is strongly dependent on gender (p=0). Parameter R∞ also significantly depends on gender (p=0.002), while t and R0 seem to be slightly related to gender (p>0.05)

Chemical heterogeneity of tomato inbred lines

Compositional characteristics of seven lines of tomatoes have been determined. The following parameters were evaluated: dry matter, acidity (citric acid equivalent), Ca-pectate, ash, cellulose, sugars (total, reducing sugars, sucrose), mineral substances (N, P, K, Ca, Na), surface color and carotenoid content. From a compositional viewpoint, there were no significant differences between lines, but in cellulose, sucrose, mineral substances, carotenoid content, and surface colour parameters, a*, b*, L and h°.

Dimension of the Torelli group for Out(F_n)

Let T_n be the kernel of the natural map from Out(F_n) to GL(n,Z). We use combinatorial Morse theory to prove that T_n has an Eilenberg-MacLane space which is (2n-4)-dimensional and that H_{2n-4}(T_n,Z) is not finitely generated (n at least 3). In particular, this recovers the result of Krstic-McCool that T_3 is not finitely presented. We also give a new proof of the fact, due to Magnus, that T_n is finitely generated.Comment: 27 pages, 9 figure

ZnTiO3 Ceramic Nanopowder Microstructure Changes During Compaction

ZnTiO3 nanopowder as a constitutive component in compact production was primarily characterised. Scanning electron micrographs of as received powder were recorded. Mercury porosimetry and nitrogen adsorption were also performed on loose powder. Particle size distribution in a water powder suspension was determined with a laser particle size analyser. Compaction was performed on different pressures in a range from 100 to 400 MPa using the uniaxial double sided compaction technique without binder and lubricant. Micrographs of compacted specimens were obtained using scanning electron microscopy and atomic force microscopy. Pore size distribution was also determined by mercury porosimetry and nitrogen adsorption. Results revealed that with increasing pressure during compaction interagglomerate pores diminish in size until they reach some critical diameter related to the intra-agglomerate pore size

Homeostatic Modulation of Stimulation-Dependent Plasticity in Human Motor Cortex

Since recently, it is possible, using noninvasive cortical stimulation, such as the protocol of paired associative stimulation (PAS), to induce the plastic changes in the motor cortex, in humans that mimic Hebb's model of learning. Application of TMS conjugated with peripheral electrical stimulation at strictly coherent temporal manner lead to convergence of inputs in the sensory-motor cortex, with the consequent synaptic potentiation or weakening, if applied repetitively. However, when optimal interstimulus interval (ISI) for induction of LTP-like effects is applied as a single pair, Motor evoked potential (MEP) amplitude inhibition is observed, the paradigm known as short-latency afferent inhibition (SLAI). Aiming to resolve this paradox, PAS protocols were applied, with 200 repetitions of TMS pulses paired with median nerve electrical stimulation, at ISI equal to individual latencies of evoked response of somatosensory cortex (N-20) (PASLTP), and at ISI of N-20 shortened for 5 msec (PASLTD) protocols that mimic LTP-like changes in the human motor cortex. MEP amplitudes before, during and after interventions were measured as an indicator based on output signals originating from the motor system. Post-intervention MEP amplitudes following the TMS protocols of PASLTP and PASLTD were facilitated and depressed, respectively, contrary to MEP amplitudes during intervention. During PASLTP MEP amplitudes were significantly decreased in case of PASLTP, while in the case of PASLTD an upward trend was observed. In conclusions, a possible explanation for the seemingly paradoxical effect of PAS can be found in the mechanism of homeostatic modulation of plasticity. Those findings indicate the existence of complex relationships in the development of plasticity induced by stimulation, depending on the level of the previous motor cortex excitability