Showing papers by "Jagiellonian University published in 2009"

Fluorouracil, Leucovorin, and Oxaliplatin With and Without Cetuximab in the First-Line Treatment of Metastatic Colorectal Cancer

Abstract: Purpose This randomized study assessed whether the best overall response rate (ORR) of cetuximab combined with oxaliplatin, leucovorin, and fluorouracil (FOLFOX-4) was superior to that of FOLFOX-4 alone as first-line treatment for metastatic colorectal cancer. The influence of KRAS mutation status was investigated. Patients and Methods Patients received cetuximab (400 mg/m 2 initial dose followed by 250 mg/m 2 /wk thereafter) plus FOLFOX-4 (oxaliplatin 85 mg/m 2 on day 1, plus leucovorin 200 mg/m 2 and fluorouracil as a 400 mg/m 2 bolus followed by a 600 mg/m 2 infusion during 22 hours on days 1 and 2; n 169) or FOLFOX-4 alone (n 168). Treatment was continued until disease progression or unacceptable toxicity. KRAS mutation status was assessed in the subset of patients with assessable tumor samples (n 233). Results The confirmed ORR for cetuximab plus FOLFOX-4 was higher than with FOLFOX-4 alone (46% v 36%). A statistically significant increase in the odds for a response with the addition of cetuximab to FOLFOX-4 could not be established (odds ratio 1.52; P .064). In patients with KRAS wild-type tumors, the addition of cetuximab to FOLFOX-4 was associated with a clinically significant increased chance of response (ORR 61% v 37%; odds ratio 2.54; P .011) and a lower risk of disease progression (hazard ratio 0.57; P .0163) compared with FOLFOX-4 alone. Cetuximab plus FOLFOX-4 was generally well tolerated. Conclusion KRAS mutational status was shown to be a highly predictive selection criterion in relation to the treatment decision regarding the addition of cetuximab to FOLFOX-4 for previously untreated patients with metastatic colorectal cancer. J Clin Oncol 27:663-671. © 2008 by American Society of Clinical Oncology

Hydrodynamics with Triangle Anomalies

Abstract: We consider the hydrodynamic regime of theories with quantum anomalies for global currents. We show that a hitherto discarded term in the conserved current is not only allowed by symmetries, but is in fact required by triangle anomalies and the second law of thermodynamics. This term leads to a number of new effects, one of which is chiral separation in a rotating fluid at nonzero chemical potential. The new kinetic coefficients can be expressed, in a unique fashion, through the anomaly coefficients and the equation of state. We briefly discuss the relevance of this new hydrodynamic term for physical situations, including heavy-ion collisions.

Function of Mitochondrial Stat3 in Cellular Respiration

Abstract: Cytokines such as interleukin-6 induce tyrosine and serine phosphorylation of Stat3 that results in activation of Stat3-responsive genes. We provide evidence that Stat3 is present in the mitochondria of cultured cells and primary tissues, including the liver and heart. In Stat3(-/-) cells, the activities of complexes I and II of the electron transport chain (ETC) were significantly decreased. We identified Stat3 mutants that selectively restored the protein's function as a transcription factor or its functions within the ETC. In mice that do not express Stat3 in the heart, there were also selective defects in the activities of complexes I and II of the ETC. These data indicate that Stat3 is required for optimal function of the ETC, which may allow it to orchestrate responses to cellular homeostasis.

Ureases I. Functional, catalytic and kinetic properties: A review

Abstract: Ureases (urea amidohydrolases, EC 3.5.1.5) are a group of highly proficient enzymes, widely distributed in nature, whose catalytic function is to catalyze the hydrolysis of urea, its final products being carbonic acid and ammonia. The products and the resulting increase in pH of the reaction environment are consequential characteristics of the action of ureases. Apart from its natural significance, ureases-catalyzed hydrolysis of urea is important in that it has great potential for practical applications. In view of this importance, this article offers a review of the properties of the enzymes, where in addition to the established knowledge, the recent findings are presented. Special emphasis is put on the functional and practical properties of ureases that can be customized and exploited in a diversity of important applications, notably medical, analytical, environmental and engineering.

Diamonds with a high density of nitrogen-vacancy centers for magnetometry applications

Abstract: Nitrogen-vacancy (NV) centers in millimeter-scale diamond samples were produced by irradiation and subsequent annealing under varied conditions. The optical and spin-relaxation properties of these samples were characterized using confocal microscopy, visible and infrared absorption, and optically detected magnetic resonance. The sample with the highest ${\text{NV}}^{\ensuremath{-}}$ concentration, approximately 16 ppm $(2.8\ifmmode\times\else\texttimes\fi{}{10}^{18}\text{ }{\text{cm}}^{\ensuremath{-}3})$, was prepared with no observable traces of neutrally charged vacancy defects. The effective transverse spin-relaxation time for this sample was ${T}_{2}^{\ensuremath{\ast}}=118(48)\text{ }\text{ns}$, predominately limited by residual paramagnetic nitrogen which was determined to have a concentration of 49(7) ppm. Under ideal conditions, the shot-noise limited sensitivity is projected to be $\ensuremath{\sim}150\text{ }\text{fT}/\sqrt{\text{Hz}}$ for a $100\text{ }\ensuremath{\mu}\text{m}$-scale magnetometer based on this sample. Other samples with ${\text{NV}}^{\ensuremath{-}}$ concentrations from 0.007 to 12 ppm and effective relaxation times ranging from 27 to over 291 ns were prepared and characterized.

Probing the ATIC peak in the cosmic-ray electron spectrum with H.E.S.S.

Abstract: The measurement of an excess in the cosmic-ray electron spectrum between 300 and 800 GeV by the ATIC experiment has - together with the PAMELA detection of a rise in the positron fraction up to 100 GeV - motivated many interpretations in terms of dark matter scenarios; alternative explanations assume a nearby electron source like a pulsar or supernova remnant. Here we present a measurement of the cosmic-ray electron spectrum with H.E.S.S. starting at 340 GeV. The H.E.S.S. data with their lower statistical errors show no indication of a structure in the electron spectrum, but rather a power-law spectrum with spectral index of 3.0 +- 0.1 (stat.) +- 0.3 (syst.) which steepens at about 1 TeV.

Intracoronary infusion of bone marrow-derived selected CD34+CXCR4+ cells and non-selected mononuclear cells in patients with acute STEMI and reduced left ventricular ejection fraction: results of randomized, multicentre Myocardial Regeneration by Intracoronary Infusion of Selected Population of Stem Cells in Acute Myocardial Infarction (REGENT) Trial.

Abstract: Aims Comparison of intracoronary infusion of bone marrow (BM)-derived unselected mononuclear cells (UNSEL) and selected CD34+CXCR4+ cells (SEL) in patients with acute myocardial infarction (AMI) and reduced <40% left ventricular ejection fraction (LVEF). Methods and results Two hundred patients were randomized to intracoronary infusion of UNSEL ( n = 80) or SEL ( n = 80) BM cells or to the control (CTRL) group without BM cell treatment. Primary endpoint: change of LVEF and volumes measured by magnetic resonance imaging before and 6 months after the procedure. After 6 months, LVEF increased by 3% ( P = 0.01) in patients treated with UNSEL, 3% in patients receiving SEL ( P = 0.04) and remained unchanged in CTRL group ( P = 0.73). There were no significant differences in absolute changes of LVEF between the groups. Absolute changes of left ventricular end-systolic volume and left ventricular end-diastolic volume were not significantly different in all groups. Significant increase of LVEF was observed only in patients treated with BM cells who had baseline LVEF < median (37%). Baseline LVEF < median and time from the onset of symptoms to primary percutaneous coronary intervention ≥ median were predictors of LVEF improvement in patients receiving BM cells. There were no differences in major cardiovascular event (death, re-infarction, stroke, target vessel revascularization) between groups. Conclusion In patients with AMI and impaired LVEF, treatment with BM cells does not lead to a significant improvement of LVEF or volumes. There was however a trend in favour of cell therapy in patients with most severely impaired LVEF and longer delay between the symptoms and revascularization.

Numerical tests of fast reconnection in weakly stochastic magnetic fields

Abstract: We study the effects of turbulence on magnetic reconnection using three-dimensional direct numerical simulations. This is the first attempt to test a model of fast magnetic reconnection in the presence of weak turbulence proposed by Lazarian & Vishniac. This model predicts that weak turbulence, which is generically present in most astrophysical systems, enhances the rate of reconnection by reducing the transverse scale for reconnection events and by allowing many independent flux reconnection events to occur simultaneously. As a result, the reconnection speed becomes independent of Ohmic resistivity and is determined by the magnetic field wandering induced by turbulence. We test the dependence of the reconnection speed on turbulent power, the energy injection scale, and resistivity. We apply the open and experiment with the outflow boundary conditions in our numerical model and discuss the advantages and drawbacks of various setups. To test our results, we also perform simulations of turbulence with the same outflow boundaries but without a large-scale field reversal, thus without large-scale reconnection. To quantify the reconnection speed we use both an intuitive definition, i.e., the speed of the reconnected flux inflow, and a more sophisticated definition based on a formally derived analytical expression. Our results confirm the predictions of the Lazarian and Vishniac model. In particular, we find that the reconnection speed is proportional to the square root of the injected power, as predicted by the model. The dependence on the injection scale for some of our models is a bit weaker than expected, i.e., l 3/4 inj, compared to the predicted linear dependence on the injection scale, which may require some refinement of the model or may be due to effects such as the finite size of the excitation region, which are not a part of the model. The reconnection speed was found to depend on the expected rate of magnetic field wandering and not on the magnitude of the guide field. In our models, we see no dependence on the guide field when its strength is comparable to the reconnected component. More importantly, while in the absence of turbulence we successfully reproduce the Sweet-Parker scaling of reconnection, in the presence of turbulence we do not observe any dependence on Ohmic resistivity, confirming that the reconnection of the weakly stochastic field is fast. We also do not observe a dependence on anomalous resistivity, which suggests that the presence of anomalous effects, e.g., Hall MHD effects, may be irrelevant for astrophysical systems with weakly stochastic magnetic fields.

Constraining emission models of luminous blazar sources

Abstract: Many luminous blazars which are associated with quasar-type active galactic nuclei display broadband spectra characterized by a large luminosity ratio of their high-energy (γ-ray) and low-energy (synchrotron) spectral components This large ratio, reaching values up to 100, challenges the standard synchrotron self-Compton models by means of substantial departures from the minimum power condition Luminous blazars also typically have very hard X-ray spectra, and those in turn seem to challenge hadronic scenarios for the high-energy blazar emission As shown in this paper, no such problems are faced by the models which involve Comptonization of radiation provided by a broad-line region, or dusty molecular torus The lack or weakness of bulk-Compton and Klein-Nishina features indicated by the presently available data favors the production of γ-rays via upscattering of infrared photons from hot dust This implies that the blazar emission zone is located at parsec-scale distances from the nucleus, and as such is possibly associated with the extended, quasi-stationary reconfinement shocks formed in relativistic outflows This scenario predicts characteristic timescales for flux changes in luminous blazars to be days/weeks, consistent with the variability patterns observed in such systems at infrared, optical, and γ-ray frequencies We also propose that the parsec-scale blazar activity can be occasionally accompanied by dissipative events taking place at sub-parsec distances and powered by internal shocks and/or reconnection of magnetic fields These could account for the multiwavelength intraday flares occasionally observed in powerful blazar sources

Randomized clinical trial of visualization versus neuromonitoring of recurrent laryngeal nerves during thyroidectomy

Abstract: Background: The aim of this study was to test the hypothesis that identification of the recurrent laryngeal nerve (RLN) during thyroid surgery reduces injury, and that intraoperative nerve monitoring may be of additional benefit. Methods: One thousand consenting patients scheduled to have bilateral thyroid surgery were randomized to standard protection or additional nerve monitoring. The primary outcome measure was prevalence of RLN injury. Results: Of 1000 nerves at risk in each group, transient and permanent RLN injuries were found respectively in 38 and 12 nerves without RLN monitoring (P = 0·011) and 19 and eight nerves with RLN monitoring (P = 0·368). The prevalence of transient RLN paresis was lower in patients who had RLN monitoring by 2·9 per cent in high-risk patients (P = 0·011) and 0·9 per cent in low-risk patients (P = 0·249). The negative and positive predictive values of RLN monitoring in predicting postoperative vocal cord function were 98·9 and 37-8 per cent respectively. Conclusion: Nerve monitoring decreased the incidence of transient but not permanent RLN paresis compared with visualization alone, particularly in high-risk patients. Registration number: NCT00661024 (http://www.clinicaltrials.gov).

Perceptions of aging across 26 cultures and their culture-level associates.

Abstract: College students (N=3,435) in 26 cultures reported their perceptions of age-related changes in physical, cognitive, and socioemotional areas of functioning and rated societal views of aging within their culture. There was widespread cross-cultural consensus regarding the expected direction of aging trajectories with (a) perceived declines in societal views of aging, physical attractiveness, the ability to perform everyday tasks, and new learning; (b) perceived increases in wisdom, knowledge, and received respect; and (c) perceived stability in family authority and life satisfaction. Cross-cultural variations in aging perceptions were associated with culture-level indicators of population aging, education levels, values, and national character stereotypes. These associations were stronger for societal views on aging and perceptions of socioemotional changes than for perceptions of physical and cognitive changes. A consideration of culture-level variables also suggested that previously reported differences in aging perceptions between Asian and Western countries may be related to differences in population structure.

Genome-wide association study identifies 19p13.3 (UNC13A) and 9p21.2 as susceptibility loci for sporadic amyotrophic lateral sclerosis.

Abstract: We conducted a genome-wide association study among 2,323 individuals with sporadic amyotrophic lateral sclerosis (ALS) and 9,013 control subjects and evaluated all SNPs with P < 1.0 x 10(-4) in a second, independent cohort of 2,532 affected individuals and 5,940 controls. Analysis of the genome-wide data revealed genome-wide significance for one SNP, rs12608932, with P = 1.30 x 10(-9). This SNP showed robust replication in the second cohort (P = 1.86 x 10(-6)), and a combined analysis over the two stages yielded P = 2.53 x 10(-14). The rs12608932 SNP is located at 19p13.3 and maps to a haplotype block within the boundaries of UNC13A, which regulates the release of neurotransmitters such as glutamate at neuromuscular synapses. Follow-up of additional SNPs showed genome-wide significance for two further SNPs (rs2814707, with P = 7.45 x 10(-9), and rs3849942, with P = 1.01 x 10(-8)) in the combined analysis of both stages. These SNPs are located at chromosome 9p21.2, in a linkage region for familial ALS with frontotemporal dementia found previously in several large pedigrees.

Advantages of Volunteer-Based Biodiversity Monitoring in Europe

Abstract: Without robust and unbiased systems for monitoring, changes in natural systems will remain enigmatic for policy makers, leaving them without a clear idea of the consequences of any environmental policies they might adopt. Generally, biodiversity-monitoring activities are not integrated or evaluated across any large geographic region. The EuMon project conducted the first large-scale evaluation of monitoring practices inEuropethroughanon-linequestionnaireandisreportingontheresultsofthissurvey.InSeptember 2007 the EuMon project had documented 395 monitoring schemes for species, which represents a total annual cost of about €4 million, involving more than 46,000 persons devoting over 148,000 person-days/year to biodiversity-monitoring activities. Here we focused on the analysis of variations of monitoring practices across a set of taxonomic groups (birds, amphibians and reptiles, mammals, butterflies, plants, and other insects) and across 5 European countries (France, Germany, Hungary, Lithuania, and Poland). Our results suggest that the overall sampling effort of a scheme is linked with the proportion of volunteers involved in that scheme. Because precision is a function of the number of monitored sites and the number of sites is maximized by volunteer involvement, our results do not support the common belief that volunteer-based schemes are too noisy to be informative. Just the opposite, we believe volunteer-based schemes provide relatively reliable data,

Efficacy of human C1 esterase inhibitor concentrate compared with placebo in acute hereditary angioedema attacks

Abstract: Background Hereditary angioedema caused by C1 esterase inhibitor deficiency is a rare disorder. Objective To compare the efficacy of pasteurized C1 esterase inhibitor concentrate (Berinert, CSL Behring) at intravenous doses of 10 or 20 U/kg body weight with placebo in the treatment of single, acute abdominal or facial attacks in patients with hereditary angioedema. Methods This was a randomized, double-blind, placebo-controlled study in 125 patients with type I or II hereditary angioedema. The primary outcome was time from start of treatment to onset of symptom relief. Secondary outcomes were time to complete resolution, proportion of patients with worsened intensity of angioedema symptoms between 2 and 4hours after treatment, and number of vomiting episodes within 4 hours. Results Median time to onset of relief was significantly shorter with C1 esterase inhibitor concentrate at a dose of 20 U/kg than with placebo (0.5 vs 1.5 hours; P = .0025), whereas with 10 U/kg, the time to onset of relief was only slightly shorter than with placebo (1.2 vs 1.5 hours; P = .2731). Compared with placebo, the reduction in time to onset of relief was greatest for severe attacks (0.5 vs 13.5 hours). The secondary outcomes consistently supported the efficacy of the 20 U/kg dose. C1 esterase inhibitor concentrate was safe and well tolerated. No seroconversions were observed for HIV, hepatitis virus, or human B19 virus. Conclusion C1 esterase inhibitor concentrate given intravenously at a dose of 20 U/kg is an effective and safe treatment for acute abdominal and facial attacks in patients with hereditary angioedema, with a rapid onset of relief.

The high-acceptance dielectron spectrometer HADES

Abstract: HADES is a versatile magnetic spectrometer aimed at studying dielectron production in pion, proton and heavy-ion-induced collisions. Its main features include a ring imaging gas Cherenkov detector for electron-hadron discrimination, a tracking system consisting of a set of 6 superconducting coils producing a toroidal field and drift chambers and a multiplicity and electron trigger array for additional electron-hadron discrimination and event characterization. A two-stage trigger system enhances events containing electrons. The physics program is focused on the investigation of hadron properties in nuclei and in the hot and dense hadronic matter. The detector system is characterized by an 85% azimuthal coverage over a polar angle interval from 18° to 85°, a single electron efficiency of 50% and a vector meson mass resolution of 2.5%. Identification of pions, kaons and protons is achieved combining time-of-flight and energy loss measurements over a large momentum range (0.1 < p < 1.0 GeV/c). This paper describes the main features and the performance of the detector system. © Societa Italiana di Fisica / Springer-Verlag 2009.

Clinical impact of thrombectomy in acute ST-elevation myocardial infarction: an individual patient-data pooled analysis of 11 trials

Abstract: Aims Thrombectomy in patients with ST-elevation myocardial infarction (STEMI) undergoing percutaneous coronary intervention (PCI) is associated to better myocardial reperfusion. However, no single trial was adequately powered to asses the impact of thrombectomy on long-term clinical outcome and to identify patients at higher benefit. Thus, we sought to assess these issues in a collaborative individual patient-data pooled analysis of randomized studies (study acronym: ATTEMPT, number of registration: NCT00766740). Methods and results Individual data of 2686 patients enrolled in 11 trials entered the pooled analysis. Primary endpoint of the study was all-cause mortality. Major adverse cardiac events (MACE) were considered as the occurrence of all-cause death and/or target lesion/vessel revascularization and/or myocardial infarction (MI). Subgroups analysis was planned according to type of thrombectomy device (manual or non-manual), diabetic status, IIb/IIIa-inhibitor therapy, ischaemic time, infarct-related artery, pre-PCI TIMI flow. Clinical follow-up was available in 2674 (99.6%) patients at a median of 365 days. Kaplan–Meier analysis showed that allocation to thrombectomy was associated with significantly lower all-cause mortality ( P = 0.049). Thrombectomy was also associated with significantly reduced MACE ( P = 0.011) and death + MI rate during the follow-up ( P = 0.015). Subgroups analysis showed that thrombectomy is associated to improved survival in patients treated with IIb/IIIa-inhibitors ( P = 0.045) and that the survival benefit is confined to patients treated in manual thrombectomy trials ( P = 0.011). Conclusion The present large pooled analysis of randomized trials suggests that thrombectomy (in particular manual thrombectomy) significantly improves the clinical outcome in patients with STEMI undergoing mechanical reperfusion and that its effect may be additional to that of IIb/IIIa-inhibitors.

Radio Imaging of the Very-High-Energy gamma-Ray Emission Region in the Central Engine of a Radio Galaxy

Abstract: The accretion of matter onto a massive black hole is believed to feed the relativistic plasma jets found in many active galactic nuclei (AGN). Although some AGN accelerate particles to energies exceeding 10(12) electron volts and are bright sources of very-high-energy (VHE) gamma-ray emission, it is not yet known where the VHE emission originates. Here we report on radio and VHE observations of the radio galaxy Messier 87, revealing a period of extremely strong VHE gamma-ray flares accompanied by a strong increase of the radio flux from its nucleus. These results imply that charged particles are accelerated to very high energies in the immediate vicinity of the black hole.

Corruption of innate immunity by bacterial proteases.

Abstract: The innate immune system of the human body has developed numerous mechanisms to control endogenous and exogenous bacteria and thus prevent infections by these microorganisms. These mechanisms range fr

Heterochromatin protein 1 is recruited to various types of DNA damage

Abstract: Heterochromatin protein 1 (HP1) family members are chromatin-associated proteins involved in transcription, replication, and chromatin organization. We show that HP1 isoforms HP1-α, HP1-β, and HP1-γ are recruited to ultraviolet (UV)-induced DNA damage and double-strand breaks (DSBs) in human cells. This response to DNA damage requires the chromo shadow domain of HP1 and is independent of H3K9 trimethylation and proteins that detect UV damage and DSBs. Loss of HP1 results in high sensitivity to UV light and ionizing radiation in the nematode Caenorhabditis elegans, indicating that HP1 proteins are essential components of DNA damage response (DDR) systems. Analysis of single and double HP1 mutants in nematodes suggests that HP1 homologues have both unique and overlapping functions in the DDR. Our results show that HP1 proteins are important for DNA repair and may function to reorganize chromatin in response to damage.

The Vimos VLT deep survey - stellar mass segregation and large-scale galaxy environment in the redshift range 0.2 < z < 1.4

Abstract: Context. Hierarchical models of galaxy formation predict that the properties of a dark matter halo depend on the large-scale environment surrounding the halo. As a result of this correlation, we expect massive haloes to be present in larger number in overdense regions than in underdense ones. Given that a correlation exists between a galaxy stellar mass and the hosting dark matter halo mass, the segregation in dark matter halo mass should then result in a segregation in the distribution of stellar mass in the galaxy population. Aims. In this work we study the distribution of galaxy stellar mass and rest-frame optical color as a function of the large-scale galaxy distribution using the VLT VIMOS Deep Survey sample, in order to verify the presence of segregation in the properties of the galaxy population. Methods. We use VVDS redshift measurements and multi-band photometric data to derive estimates of the stellar mass, rest-frame optical color, and of the large-scale galaxy density, on a scale of approximately 8 Mpc, for a sample of 5619 galaxies in the redshift range 0.2 0.7. However, when we consider only galaxies in narrow bins of stellar mass, in order to exclude the effects of stellar mass segregation on galaxy properties, we no longer observe any significant color segregation.

Detection of Gamma Rays from a Starburst Galaxy

Abstract: Starburst galaxies exhibit in their central regions a highly increased rate of supernovae, the remnants of which are thought to accelerate energetic cosmic rays up to energies of ~ 10^15 eV. We report the detection of gamma rays -- tracers of such cosmic rays -- from the starburst galaxy NGC 253 using the H.E.S.S. array of imaging atmospheric Cherenkov telescopes. The gamma-ray flux above 220 GeV is F = (5.5 +/- 1.0stat +/- 2.8sys) x 10^-13 ph. s-1 cm-2, implying a cosmic-ray density about three orders of magnitude larger than that in the center of the Milky Way. The fraction of cosmic-ray energy channeled into gamma rays in this starburst environment is 5 times larger than that in our Galaxy.

Density studies of mhd interstellar turbulence : statistical moments, correlations and bispectrum

Abstract: We present a number of statistical tools that show promise for obtaining information on turbulence in molecular clouds (MCs) and diffuse interstellar medium (ISM). For our tests we make use of three-dimensional 5123 compressible MHD isothermal simulations performed for different sonic, i.e., , where VL is the injection velocity, Vs is the sound velocity, and Alfvenic , where VA is the Alfven velocity, Mach numbers. We introduce the bispectrum, a new tool for statistical studies of the interstellar medium which, unlike an ordinary power spectrum of turbulence, preserves the phase information of the stochastic field. We show that the bispectra of the three-dimensional stochastic density field and of column densities, available from observations, are similar. This opens good prospects for studies of MCs and diffuse media with the new tool. We use the bispectrum technique to define the role of nonlinear wave-wave interactions in the turbulent energy cascade. We also obtained the bispectrum function for density and column densities with varying magnetic field strength. As expected, a strong correlation is obtained for wave modes k 1 = k 2 for all models. Larger values of result in increased correlations for modes with k 1 ≠ k 2. This effect becomes more evident with increasing magnetic field intensity. We believe that the different MHD wave modes, e.g., Alfven and magneto-acoustic, which arise in strongly magnetized turbulence, may be responsible for the increased correlations compared to purely hydrodynamical perturbations. In addition to the bispectrum, we calculated the third and fourth statistical moments of density and column density, namely, skewness and kurtosis, respectively. We found a strong dependence of skewness and kurtosis with . In particular, as increases, so does the Gaussian asymmetry of the density distribution. We also studied the correlations of two-dimensional column density with dispersion of velocities and magnetic field, as well as the correlations of three-dimensional density with magnetic and kinetic energy and for comparison. Our results show that column density is linearly correlated with magnetic field for high . This trend is independent of the turbulent kinetic energy and can be used to characterize inhomogeneities of physical properties in low density clumps in the ISM.

What are melanocytes really doing all day long

Abstract: Everyone knows and seems to agree that melanocytes are there to generate melanin - an intriguing, but underestimated multipurpose molecule that is capable of doing far more than providing pigment and UV protection to skin (1). What about the cell that generates melanin, then? Is this dendritic, neural crest-derived cell still serving useful (or even important) functions when no-one looks at the pigmentation of our skin and its appendages and when there is essentially no UV exposure? In other words, what do epidermal and hair follicle melanocytes do in their spare time - at night, under your bedcover? How much of the full portfolio of physiological melanocyte functions in mammalian skin has really been elucidated already? Does the presence or absence of melanocytes matter for normal epidermal and/or hair follicle functions (beyond pigmentation and UV protection), and for skin immune responses? Do melanocytes even deserve as much credit for UV protection as conventional wisdom attributes to them? In which interactions do these promiscuous cells engage with their immediate epithelial environment and who is controlling whom? What lessons might be distilled from looking at lower vertebrate melanophores and at extracutaneous melanocytes in the endeavour to reveal the 'secret identity' of melanocytes? The current Controversies feature explores these far too infrequently posed, biologically and clinically important questions. Complementing a companion viewpoint essay on malignant melanocytes (2), this critical re-examination of melanocyte biology provides a cornucopia of old, but under-appreciated concepts and novel ideas on the slowly emerging complexity of physiological melanocyte functions, and delineates important, thought-provoking questions that remain to be definitively answered by future research.