Contributions from Dilatonic Strings to the Flat Behaviour of the Rotational Curves in Galaxies

We analyse the flat behaviour of the rotational curves in some galaxies in the framework of a dilatonic, current-carrying string. We determine the expression of the tangential velocity of test objects following a stable circular equatorial orbit in this spacetime.Comment: This version to be published in the Int. Journal of Modern Phys.

Developmental regulation of expression of the lactate dehydrogenase (LDH) multigene family during mouse spermatogenesis

Expression of the Lactate Dehydrogenase (LDH) genes during various stages of spermatogenesis was studied by using a combination of Northern blot analyses and in situ hybridization techniques. These studies have indicated that developmentally programmed expression of all three functional LDH genes occurs during differentiation of germ cells. The LDH/C (ldh-3) gene was expressed exclusively during meiosis and spermiogenesis, beginning in leptotene/zygotene spermatocytes and continuing through to the elongated spermatids. LDH/C (ldh-3) gene expression was accompanied by transient expression of the LDH/A (ldh-1) gene in pachytene spermatocytes and round spermatids. The LDH/B (ldh-2) gene was expressed mainly in Sertoli and spermatogonial cells. By using somatic cell hybrids, the LDH/C (ldh-3) gene has been mapped to mouse chromosome 7, establishing that it is syntenic with the LDH/A (ldh-1) gene locus. Experimental observations made in this study provide new insight into the order and sequence of events involved in the regulation of gene expression of the LDH gene family during spermatogenesis

Miller's (2009) WACC model: An extension

Miller (2009a) presents an analysis of the weighted average cost of capital WACC model. The paper attracts debate which uses a variety of repayment schedules to support the arguments raised. We present an extension of Miller's (2009a) WACC model in a world where interest is tax deductible and debt principal is paid at maturity. We also present the corresponding model for the required rate of return on levered equity which is a vital input to the WACC model. Since these models are unwieldy, we explore an alternative definition of the WACC. These models provide insights into the debate on Miller's (2009a) paper

Tillage and crop rotation effects on subsurface drainage response to rainfall

A field study was conducted to determine if tillage and crop rotation affected subsurface drainage response to rainfall. An instrumentation system collected subsurface drain flow data from thirty-six, 0.4 ha plots during the 1993, 1994 and 1995 growing seasons. Response time, time-to-peak drain flow rate, drainage volume, peak drain flow rate and percent preferential flow were compared between two tillage systems (no-till and chisel plow) and two crop rotations (continuous corn and corn-soybean) for 23 drainage events over the three-year study. The influence of preferential flow was estimated for each drainage event using a hydrograph separation procedure based on subsurface drain flow rate changes

A note resolving the debate on “The weighted average cost of capital is not quite right”

Miller (2009a) derives a weighted average cost of capital for the special case where the cash flows to equity and the cashflows to debt are annuities. The paper attracts debate. We show that the weighted average cost of capital is redundant in a world where interest paid is not tax deductible. The required rate of return on unlevered equity will consistently and reliably estimate the net present value of any project no matter the idiocyncratic beliefs of the analyst as to the year-by-year leverage of the project, or of the firm. We recommend that the weighted average cost of capital method is discarded. Our recommendation also applies to a world where interest paid is tax deductible

Seasonal changes in flow and nitrate-N loss from subsurface drains

Subsurface drainage from thirty-six, 0.4-ha plots was monitored for three years (1990 to 1992) from chisel plow, moldboard plow, ridge till, and no-till systems with continuous corn and corn-soybean rotations. Data were analyzed in four seasonal stages to determine variations in drain flows and nitrate-N contents in drain effluent. The hypothesis of this study was that differences among tillage systems would change during the monitoring season as rainfall patterns varied and as plots were fertilized and cultivated

Effects of Selective Deletion of Tyrosine Hydroxylase from Kisspeptin Cells on Puberty and Reproduction in Male and Female Mice.

The neuropeptide kisspeptin, encoded by Kiss1, regulates reproduction by stimulating GnRH secretion. Kiss1-syntheizing neurons reside primarily in the hypothalamic anteroventral periventricular (AVPV/PeN) and arcuate (ARC) nuclei. AVPV/PeN Kiss1 neurons are sexually dimorphic, with females expressing more Kiss1 than males, and participate in estradiol (E2)-induced positive feedback control of GnRH secretion. In mice, most AVPV/PeN Kiss1 cells coexpress tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamine synthesis (in this case, dopamine). Dopamine treatment can inhibit GnRH neurons, but the function of dopamine signaling arising specifically from AVPV/PeN Kiss1 cells is unknown. We generated a novel TH flox mouse and used Cre-Lox technology to selectively ablate TH specifically from Kiss1 cells. We then examined the effects of selective TH knock-out on puberty and reproduction in both sexes. In control mice, 90% of AVPV/PeN Kiss1 neurons coexpressed TH, whereas in mice lacking TH exclusively in Kiss1 cells (termed Kiss THKOs), TH was successfully absent from virtually all Kiss1 cells. Despite this absence of TH, both female and male Kiss THKOs displayed normal body weights, puberty onset, and basal gonadotropin levels in adulthood, although testosterone (T) was significantly elevated in adult male Kiss THKOs. The E2-induced LH surge was unaffected in Kiss THKO females, and neuronal activation status of kisspeptin and GnRH cells was also normal. Supporting this, fertility and fecundity were normal in Kiss THKOs of both sexes. Thus, despite high colocalization of TH and Kiss1 in the AVPV/PeN, dopamine produced in these cells is not required for puberty or reproduction, and its function remains unknown

Cluster-based network proximities for arbitrary nodal subsets

The concept of a cluster or community in a network context has been of considerable interest in a variety of settings in recent years. In this paper, employing random walks and geodesic distance, we introduce a unified measure of cluster-based proximity between nodes, relative to a given subset of interest. The inherent simplicity and informativeness of the approach could make it of value to researchers in a variety of scientific fields. Applicability is demonstrated via application to clustering for a number of existent data sets (including multipartite networks). We view community detection (i.e. when the full set of network nodes is considered) as simply the limiting instance of clustering (for arbitrary subsets). This perspective should add to the dialogue on what constitutes a cluster or community within a network. In regards to health-relevant attributes in social networks, identification of clusters of individuals with similar attributes can support targeting of collective interventions. The method performs well in comparisons with other approaches, based on comparative measures such as NMI and ARI

Direct genetic demonstration of Gα13 coupling to the orphan G protein-coupled receptor G2A leading to RhoA-dependent actin rearrangement

G2A is an orphan G protein-coupled receptor (GPCR), expressed predominantly in T and B cells and homologous to a small group of GPCRs of unknown function expressed in lymphoid tissues. G2A is transcriptionally induced in response to diverse stimuli, and its ectopic expression suppresses transformation of B lymphoid precursors by BCR-ABL. G2A induces morphological transformation of NIH 3T3 fibroblasts. Microinjection of constructs encoding G2A into Swiss 3T3 fibroblasts induces actin reorganization into stress fibers that depends on RhoA, but not CDC42 or RAC. G2A elicits RhoA-dependent transcriptional activation of serum response factor. Direct evaluation of RhoA activity demonstrates elevated levels of RhoA-GTP in G2A-expressing cells. Microinjection of embryonic fibroblasts derived from various Galpha knockout mice establishes a requirement for Galpha 13 but not Galpha 12 or Galpha q/11 in G2A-induced actin rearrangement. In conclusion, G2A represents a family of GPCRs expressed in lymphocytes that may link diverse stimuli to cytoskeletal reorganization and transcriptional activation through a pathway involving Galpha 13 and RhoA