Projective representation of k-Galilei group

The projective representations of k-Galilei group G_k are found by contracting the relevant representations of k-Poincare group. The projective multiplier is found. It is shown that it is not possible to replace the projective representations of G_k by vector representations of some its extension.Comment: 15 pages Latex fil

Impossibility of spontaneously breaking local symmetries and the sign problem

Elitzur's theorem stating the impossibility of spontaneous breaking of local symmetries in a gauge theory is reexamined. The existing proofs of this theorem rely on gauge invariance as well as positivity of the weight in the Euclidean partition function. We examine the validity of Elitzur's theorem in gauge theories for which the Euclidean measure of the partition function is not positive definite. We find that Elitzur's theorem does not follow from gauge invariance alone. We formulate a general criterion under which spontaneous breaking of local symmetries in a gauge theory is excluded. Finally we illustrate the results in an exactly solvable two dimensional abelian gauge theory.Comment: Latex 6 page

A Path Integral Approach To Noncommutative Superspace

A path integral formula for the associative star-product of two superfields is proposed. It is a generalization of the Kontsevich-Cattaneo-Felder's formula for the star-product of functions of bosonic coordinates. The associativity of the star-product imposes certain conditions on the background of our sigma model. For generic background the action is not supersymmetric. The supersymmetry invariance of the action constrains the background and leads to a simple formula for the star-product.Comment: Latex 13 pages. v2: references and footnotes adde

The effects of hypoxic conditions on Dictyostelium mucoroides.

Previously a transcript corresponding to a gene in Dictyostelium mucoroides designated A-11 was found in amoebae during vegetative growth and macrocyst formation. The derived amino acid sequence of A-11 was used to search Genbank to find homologous proteins. The highest degree of homology was found with a hemoglobin from the bacterium Vitreoscilla. The Vitreoscilla hemoglobin protein showed greater than 65% similarity and 50% identity with the A-11 amino acid sequence. It was reported that hypoxic conditions could stimulate the expression of the gene corresponding to the Vitreoscilla hemoglobin when cloned in E. coli cells

A human colonic crypt culture system to study regulation of stem cell-driven tissue renewal and physiological function

The intestinal epithelium is one of the most rapidly renewing tissues in the human body and fulfils vital physiological roles such as barrier function and transport of nutrients and fluid. Investigation of gut epithelial physiology in health and disease has been hampered by the lack of ex vivo models of the native human intestinal epithelium. Recently, remarkable progress has been made in defining intestinal stem cells and in generating intestinal organoid cultures. In parallel, we have developed a 3D culture system of the native human colonic epithelium that recapitulates the topological hierarchy of stem cell-driven tissue renewal and permits the physiological study of native polarized epithelial cells. Here we describe methods to establish 3D cultures of intact human colonic crypts and conduct real-time imaging of intestinal tissue renewal, cellular signalling, and physiological function, in conjunction with manipulation of gene expression by lentiviral or adenoviral transduction. Visualization of mRNA- and protein-expression patterns in cultured human colonic crypts, and cross-validation with crypts derived from fixed mucosal biopsies, is also described. Alongside studies using intestinal organoids, the near-native human colonic crypt culture model will help to bridge the gap that exists between investigation of colon cancer cell lines and/or animal (tissue) studies, and progression to clinical trials. To this end, the near native human colonic crypt model provides a platform to aid the development of novel strategies for the prevention of inflammatory bowel disease and cancer

First in-human radiation dosimetry of (68)Ga-NODAGA-RGDyK.

Integrin-targeting radiopharmaceuticals have potential broad applications, spanning from cancer theranostics to cardiovascular diseases. We have previously reported preclinical dosimetry results of (68)Ga-NODAGA-RGDyK in mice. This study presents the first human dosimetry of (68)Ga-NODAGA-RGDyK in the five consecutive patients included in a clinical imaging protocol of carotid atherosclerotic plaques. Five male patients underwent whole-body time-of-flight (TOF) PET/CT scans 10, 60 and 120 min after tracer injection (200 MBq). Quantification of (68)Ga activity concentration was first validated by a phantom study. To be used as input in OLINDA/EXM, time-activity curves were derived from manually drawn regions of interest over the following organs: brain, thyroid, lungs, heart, liver, spleen, stomach, kidneys, red marrow, pancreas, small intestine, colon, urinary bladder and whole body. A separate dosimetric analysis was performed for the choroid plexuses. Female dosimetry was extrapolated from male data. Effective doses (EDs) were estimated according to both ICRP60 and ICRP103 assuming 30-min and 1-h voiding cycles. The body regions receiving the highest dose were urinary bladder, kidneys and choroid plexuses. For a 30-min voiding cycle, the EDs were 15.7 and 16.5 μSv/MBq according to ICRP60 and ICRP103, respectively. The extrapolation to female dosimetry resulted in organ absorbed doses 17% higher than those of male patients, on average. The 1-h voiding cycle extrapolation resulted in EDs of 19.3 and 19.8 μSv/MBq according to ICRP60 and ICRP103, respectively. A comparison is made with previous mouse dosimetry and with other human studies employing different RGD-based radiopharmaceuticals. According to ICRP60/ICRP103 recommendations, an injection of 200 MBq (68)Ga-NODAGA-RGDyK leads to an ED in man of 3.86/3.92 mSv. For future therapeutic applications, specific attention should be directed to delivered dose to kidneys and potentially also to the choroid plexuses. Clinical trial.gov, NCT01608516

Ponzano-Regge model revisited III: Feynman diagrams and Effective field theory

We study the no gravity limit G_{N}-> 0 of the Ponzano-Regge amplitudes with massive particles and show that we recover in this limit Feynman graph amplitudes (with Hadamard propagator) expressed as an abelian spin foam model. We show how the G_{N} expansion of the Ponzano-Regge amplitudes can be resummed. This leads to the conclusion that the dynamics of quantum particles coupled to quantum 3d gravity can be expressed in terms of an effective new non commutative field theory which respects the principles of doubly special relativity. We discuss the construction of Lorentzian spin foam models including Feynman propagatorsComment: 46 pages, the wrong file was first submitte

Living in the past, present, and future: measuring temporal orientation with language

OBJECTIVE: Temporal orientation refers to individual differences in the relative emphasis one places on the past, present, or future, and is related to academic, financial, and health outcomes. We propose and evaluate a method for automatically measuring temporal orientation through language expressed on social media. METHOD: Judges rated the temporal orientation of 4,302 social media messages. We trained a classifier based on these ratings, which could accurately predict the temporal orientation of new messages in a separate validation set (accuracy/mean sensitivity = .72; mean specificity = .77). We used the classifier to automatically classify 1.3 million messages written by 5,372 participants (50% female, aged 13-48). Finally, we tested whether individual differences in past, present, and future orientation differentially related to gender, age, Big Five personality, satisfaction with life, and depressive symptoms. RESULTS: Temporal orientations exhibit several expected correlations with age, gender, and Big Five personality. More future-oriented people were older, more likely to be female, more conscientious, less impulsive, less depressed, and more satisfied with life; present orientation showed the opposite pattern. CONCLUSION: Language-based assessments can complement and extend existing measures of temporal orientation, providing an alternative approach and additional insights into language and personality relationships. This article is protected by copyright. All rights reserved.Support for this article was provided by grant #63597 from the Robert Wood Johnson Foundation (M. E. P. Seligman, PI) and by a grant from the Templeton Religion Trust (M.E.P. Seligman, H. A. Schwartz, L. H. Ungar, co-PIs)

Entropic Gravity, Phase-Space Noncommutativity and the Equivalence Principle

We generalize E. Verlinde's entropic gravity reasoning to a phase-space noncommutativity set-up. This allow us to impose a bound on the product of the noncommutative parameters based on the Equivalence Principle. The key feature of our analysis is an effective Planck's constant that naturally arises when accounting for the noncommutative features of the phase-space.Comment: 12 pages. Version to appear at the Classical and Quantum Gravit