Search

Astromaterials, including neutron stars, have extraordinary properties in terms of very high densities, very large gravity, and magnetic field, and may have an incommensurate crystalline structure that could be composed of neutrons and protons. Neutron crystallization has been studied extensively, but the existence of Coulomb crystals in neutron stars is still to be studied to have a better idea of the crystallization of neutron stars and other types of astromaterials, such as black holes and white dwarfs (WD). Properties of Coulomb crystals in neutron stars are studied in this manuscript to have some idea of the structure of some hard astromaterials and their incommensurate nature. [ABSTRACT FROM AUTHOR]

Semi-empirical mass formulae are lagging in implementing quantum chromodynamics and electroweak interaction in understanding nuclear binding energy. In addition, they also fail in estimating absolute nuclear binding energy coefficients. In this context, considering Up and Down quarks and pions and weak bosons, we have presented a four-term nuclear binding energy relation with one common energy coefficient. [ABSTRACT FROM AUTHOR]

Nuclear charge radius is an important macroscopic variable that determines the magnitude and extent of the Coulomb potential within the boundaries of the atomic nucleus. An expression for the modified Coulomb potential valid for the atomic nucleus has been used to obtain an expression for the nuclear charge radius. The calculated values for the nuclear charge radius have been compared with the experimentally observed values for the nuclear charge radius. Excellent agreement between the calculated nuclear charge radius and the experimentally observed nuclear charge radius leads to a modified Coulomb potential relation that can be used to calculate more accurately the binding energy for the nucleus. The average deviation of nuclear charge radius is calculated for 957 nuclei to establish the better agreement between the calculated nuclear charge radius and the experimentally observed nuclear charge radius and the value of the average deviation is 0.30297fm, which is small. [ABSTRACT FROM AUTHOR]

A modified Coulomb energy equation has been derived and investigations on its role in the binding energy equation of the finite nuclei have been done. A comparison of the values of the Coulomb binding energy obtained using the modified Coulomb energy equation with other known Coulomb energy expressions was carried out. Owing to the fact that the calculated Coulomb energy values are not exact, we chose an exponential function as our correction term. Our calculations show that Coulomb energy is one of the major contributors of the nuclear binding energy in heavy nuclei due to the nuclear repulsion between the protons that increases with a corresponding increase in nuclear size. Proton-proton repulsion within the nucleus provides the long-range forces that multiply and permeates throughout the entire volume of the nucleus, hence contributing over 80%, of the Coulomb energy experienced at the nuclear surface. The Coulomb energy per nucleon, in this study, was found to increase exponentially with an increase in the mass number. Analysis of the results showed some slight variation among the modified Coulomb energy equations and this was attributed to the difference in the values of the nuclear radius parameters used. [ABSTRACT FROM AUTHOR]

In this paper, a new two-step approach for enhancing the accuracy of initial search center (ISC) prediction in h.264 has been proposed which improves the speed of motion estimation in video encoding. Previous methods for estimating the ISC worked in a single step by finding the mean/median of motion vectors (MVs) of neighboring blocks of the current and reference frames. The major drawback of all the existing ISC techniques is that they consider the participation of all the neighboring blocks with equal probability without taking into account their correlation with the current block. The blocks which have least correlation or no correlation at all affect the accuracy of prediction and hence increase the chances of trapping the search in local minima. Moreover, in the existing ISC prediction techniques, participation of MVs of restricted neighboring blocks is considered, which further limits the prediction accuracy. To elevate these drawbacks, a new two-step approach has been presented. The first step of the method works by identifying some candidate blocks for ISC and the second phase refines the search to obtain best possible ISC. Use of all the surrounding blocks from spatial and temporal frame along with the refinement stage has improved the accuracy. Simulation results clearly show the enhancement in accuracy of ISC prediction, improvement in video quality in terms of peak signal-to-noise ratio (PSNR) and reduction in the number of search steps. Most recent approach in ISC prediction has shown an improvement of 11.7% as compared to standard median predictor, whereas the proposed technique shows an improvement of almost 50%. The reduction in search points is nearly 40%–50% compared to standard median predictor for fast-motion sequences. Also the proposed technique works equally well for fast, medium, slow, cif, qcif and HD video sequences as indicated in the results. [ABSTRACT FROM PUBLISHER]

A mathematical model is developed to describe the steady state creep in a rotating Al-SiCp disc having a non-linear thickness profile and distribution of SiC particles along the radial direction. The model is used to investigate the effect of imposing three different kinds of radial temperature profiles viz. linear, parabolic and exponential with fixed values of inner and outer surface temperatures, on the creep stresses and strain rates. It is noticed that by increasing the temperature exponent (nT ), the radial stress (over the entire radius) and tangential stress (near the inner radius) increase in the disc. However, the tangential stress decreases near the outer radius. The radial and tangential strain rates in the functionally graded (FG) disc reduce significantly with the increase in exponent nT . Besides reduction in the magnitude, the distribution of strain rates also become relatively more uniform throughout with the increase in nT . It is concluded that FG disc operating under exponential temperature profile performs better. It is also revealed that amongst several FG discs operating under radial thermal gradients, with different values of temperature exponent (nT ) but having the same average and fixed outer surface temperature, the FGM disc with lower value of nT exhibits the maximum creep life. [ABSTRACT FROM AUTHOR]

Cholera gastroenteritis amongst 3595 children under twelve years suffering from acute watery diarrhea was studied for a period of five years (1982-86). V. cholerae 01 could be isolated from 31.7% of total specimens studied. Distribution in different age groups out of total gastroenteritis cases was 7.5% in less than 2 years, 13.1% in 2-5 years and 11.1% in greater than 5-12 years. Out of total cholera cases (1141 isolate) 23.4% occurred in the age group less than 2 yrs., 41.4% in 2-5 yrs. and 35.1% in greater than 5-12 yrs. Infection occurred more often in males in all the age groups. Throughout the study, cholera was observed during summer monsoon season with Ogawa being predominant serotype. [ABSTRACT FROM AUTHOR]

Background Despite its obvious pathophysiological relevance, the clinical utility of measures of esophagogastric junction ( EGJ) contractility is unsubstantiated. High-resolution manometry ( HRM) may improve upon this with its inherent ability to integrate the magnitude of contractility over time and length of the EGJ. This study aimed to develop a novel HRM metric summarizing EGJ contractility and test its ability distinguish among subgroups of proton pump inhibitor non-responders ( PPI- NRs). Methods 75 normal controls and 88 PPI- NRs were studied. All underwent HRM. PPI- NRs underwent pH-impedance monitoring on PPI therapy scored in terms of acid exposure, number of reflux events, and reflux-symptom correlation and grouped as meeting all criteria, some criteria, or no criteria of abnormality. Control HRM studies were used to establish normal values for candidate EGJ contractility metrics, which were then compared in their ability to differentiate among PPI- NR subgroups. Key Results The EGJ contractile integral ( EGJ- CI), a metric integrating contractility across the EGJ for three respiratory cycles, best distinguished the All Criteria PPI- NR subgroup from controls and other PPI- NR subgroups. Normal values (median, [ IQR]) for this measure were 39 mmHg-cm [25-55 mmHg-cm]. The correlation between the EGJ- CI and a previously proposed metric, the lower esophageal sphincter-pressure integral, that used a fixed 10 s time frame and an atmospheric as opposed to gastric pressure reference was weak. Conclusions & Inferences Among HRM metrics tested, the EGJ- CI was best in distinguishing PPI- NRs meeting all criteria of abnormality on pH-impedance testing. Future prospective studies are required to explore its utility in management of broader groups of gastroesophageal reflux disease patients. [ABSTRACT FROM AUTHOR]

Mutations of p53 in cancer can result in a gain of function associated with tumour progression and metastasis. We show that inducible expression of several p53 'hotspot' mutants promote a range of centrosome abnormalities, including centrosome amplification, increased centrosome size and loss of cohesion, which lead to mitotic defects and multinucleation. These mutant p53-expressing cells also show a change in morphology and enhanced invasive capabilities. Consequently, we sought for a means to specifically target the function of mutant p53 in cancer cells. This study has identified ANKRD11 as a key regulator of the oncogenic potential of mutant p53. Loss of ANKRD11 expression with p53 mutation defines breast cancer patients with poor prognosis. ANKRD11 alleviates the mitotic defects driven by mutant p53 and suppresses mutant p53-mediated mesenchymal-like transformation and invasion. Mechanistically, we show that ANKRD11 restores a native conformation to the mutant p53 protein and causes dissociation of the mutant p53-p63 complex. This represents the first evidence of an endogenous protein with the capacity to suppress the oncogenic properties of mutant p53. [ABSTRACT FROM AUTHOR]

Inherited mutations are known to cause familial cancers. However, the cause of sporadic cancers, which likely represent the majority of cancers, is yet to be elucidated. Sporadic cancers contain somatic mutations (including oncogenic mutations); however, the origin of these mutations is unclear. An intriguing possibility is that a stable alteration occurs in somatic cells prior to oncogenic mutations and promotes the subsequent accumulation of oncogenic mutations. This review explores the possible role of prions and protein-only inheritance in cancer. Genetic studies using lower eukaryotes, primarily yeast, have identified a large number of proteins as prions that confer dominant phenotypes with cytoplasmic (non-Mendelian) inheritance. Many of these have mammalian functional homologs. The human prion protein (PrP) is known to cause neurodegenerative diseases and has now been found to be upregulated in multiple cancers. PrP expression in cancer cells contributes to cancer progression and resistance to various cancer therapies. Epigenetic changes in the gene expression and hyperactivation of MAP kinase signaling, processes that in lower eukaryotes are affected by prions, play important roles in oncogenesis in humans. Prion phenomena in yeast appear to be influenced by stresses, and there is considerable evidence of the association of some amyloids with biologically positive functions. This suggests that if protein-only somatic inheritance exists in mammalian cells, it might contribute to cancer phenotypes. Here, we highlight evidence in the literature for an involvement of prion or prion-like mechanisms in cancer and how they may in the future be viewed as diagnostic markers and potential therapeutic targets. [ABSTRACT FROM AUTHOR]

n N-ethyl- N-nitrosourea random mutation screen was used to identify recessive modifiers of gene silencing in the mouse using an epigenetically sensitive reporter transgene. One of the mutant lines, MommeR1, was identified as a suppressor of variegation and it showed female-specific age-associated infertility in homozygotes. Linkage analysis identified a region on chromosome 10, containing the Foxo3a gene, previously shown to play a critical role in female gametogenesis. Foxo3a is a transcription factor with roles in cell cycle control, apoptosis, neural and hematopoietic cell differentiation, and DNA repair. Sequencing of the Foxo3a gene in MommeR1 mice revealed a point mutation that causes an amino acid substitution in the highly conserved Forkhead DNA-binding domain. In vitro transcription assays showed that the point mutation causes loss of FOXO3a transactivation activity. Compound heterozygotes made with Foxo3a-null mice (carrying the targeted deletion of exon 2) displayed complementation with respect to both the activation of the reporter transgene and defects in folliculogenesis similar to those seen in MommeR1 homozygotes, supporting the conclusion that this is the causative mutation. Approximately one in six female MommeR1 homozygotes develop teratomas, a phenotype not reported in Foxo3a-null mice. Ovulated oocytes from MommeR1 homozygotes display a number of abnormalities. The MommeR1 mice provide a novel platform to investigate teratocarcinogenesis and link Foxo3a with parthenogenesis and ovarian cancer. The finding of Foxo3a as a modifier of epigenetic reprogramming is discussed. [ABSTRACT FROM AUTHOR]

The DNA-damage response (DDR) pathways consist of interconnected components that respond to DNA damage to allow repair and promote cell survival. The DNA repair pathways and downstream cellular responses have diverged in cancer cells compared with normal cells because of genetic alterations that underlie drug resistance, disabled repair and resistance to apoptosis. Consequently, abrogating DDR pathways represents an important mechanism for enhancing the therapeutic index of DNA-damaging anticancer agents. In this review, we discuss the DDR pathways that determine antitumor effects of DNA-damaging agents with a specific focus on treatment outcomes in tumors carrying a defective p53 pathway. Finely tuned survival and death pathways govern the cellular responses downstream of the cytotoxic insults inherent in anticancer treatment. The significance and relative contributions of cellular responses including apoptosis, mitotic catastrophe and senescence are discussed in relation to the web of molecular interactions that affect such outcomes. We propose that promising combinations of DNA-damaging anticancer treatments with DDR-pathway inhibition would be further enhanced by activating downstream apoptotic pathways. The proposed rationale ensures that actual cell death is the preferred outcome of cancer treatment instead of other responses, including reversible cell cycle arrest, autophagy or senescence. Finally, to better measure the contribution of different cellular responses to anticancer treatments, multiplex in vivo assessments of therapy-induced response pathways such as cell death, senescence and mitotic catastrophe is desirable rather than the current reliance on the measurement of a single response pathway such as apoptosis. [ABSTRACT FROM AUTHOR]

The proper function of the spindle is crucial to the high fidelity of chromosome segregation and is indispensable for tumor suppression in humans. Centrobin is a recently identified centrosomal protein that has a role in stabilizing the microtubule structure. Here we functionally characterize the defects in centrosome integrity and spindle assembly in Centrobin-depleted cells. Centrobin-depleted cells show a range of spindle abnormalities including unfocused poles that are not associated with centrosomes, S-shaped spindles and mini spindles. These cells undergo mitotic arrest and subsequently often die by apoptosis, as determined by live cell imaging. Co-depletion of Mad2 relieves the mitotic arrest, indicating that cells arrest due to a failure to silence the spindle checkpoint in metaphase. Consistent with this, Centrobin-depleted metaphase cells stained positive for BubR1 and BubR1 S676. Staining with a panel of centrosome markers showed a loss of centrosome anchoring to the mitotic spindle. Furthermore, these cells show less cold-stable microtubules and a shorter distance between kinetochore pairs. These results show a requirement of Centrobin in maintaining centrosome integrity, which in turn promotes anchoring of mitotic spindle to the centrosomes. Furthermore, this anchoring is required for the stability of microtubule–kinetochore attachments and biogenesis of tension-ridden and properly functioning mitotic spindle. [ABSTRACT FROM AUTHOR]

The thermal conductivity of a system consisting of square-well particles has been determined by the extension of the Enskog formula of the hard-sphere model to square-well fluid. The approach is the same as applied for the diffusion coefficients and shear viscosity of square-well fluid. The addition of an attractive part in the hard-sphere potential such as square-well potential remains insensitive to influence the thermal conductivity. The results obtained are in a good agreement with the molecular dynamics results. [ABSTRACT FROM AUTHOR]

A new coordination number model is proposed for square-well fluids at λ = 1.5. The model modifies the theory previously developed for the coordination number of square-well fluids derived on the basis of the generalized Van der Waals theory by Largo and Solana. The present work proposes a new formula for the maximum reduced density and a new method to solve the integral corresponding to coordination number of hard sphere fluids. Thermodynamic quantities such as pair correlation function at contact, excess internal energy and constant volume excess heat capacity are determined employing the model. Good agreement is achieved between theoretical results and Monte Carlo (M.C.) data. As expected, the results of the excess heat capacity are poor at low temperatures. [ABSTRACT FROM AUTHOR]

A protein-truncating variant of CHEK2, 1100delC, is associated with a moderate increase in breast cancer risk. We have determined the prevalence of this allele in index cases from 300 Australian multiple-case breast cancer families, 95%of which had been found to be negative for mutations in BRCA1 and BRCA2. Only two (0.6%) index cases heterozygous for the CHEK2 mutation were identified. All available relatives in these two families were genotyped, but there was no evidence of co-segregation between the CHEK2 variant and breast cancer. Lymphoblastoid cell lines established from a heterozygous carrier contained approximately 20%of the CHEK2 1100delC mRNA relative to wild-type CHEK2 transcript. However, no truncated CHK2 protein was detectable. Analyses of expression and phosphorylation of wild-type CHK2 suggest that the variant is likely to act by haploinsufficiency. Analysis of CDC25A degradation, a downstream target of CHK2, suggests that some compensation occurs to allow normal degradation of CDC25A. Such compensation of the 1100delC defect in CHEK2 might explain the rather low breast cancer risk associated with the CHEK2 variant, compared to that associated with truncating mutations in BRCA1 or BRCA2.British Journal of Cancer (2005) 92, 784-790. doi:10.1038/sj.bjc.6602381 www.bjcancer.com Published online 8 February 2005 [ABSTRACT FROM AUTHOR]

An equation of state for long chain molecules has been proposed using statistical associating fluid theory (SAFT). The formalism derived here is based on the assumption that the chain is formed by the pairs of trimers. The equations of state for 48-mers and 192-mers are formulated and compared with Monte Carlo results. The theory has been developed to treat hard sphere molecules with two attraction sites to form a ring molecule. The equations of state for trimer, hexamer and 12-mer ring molecules have been formulated. There is excellent agreement with available Monte Carlo results. Second virial coefficients of tangent chain molecules and ring molecules have been determined numerically and compared with simulation results. [ABSTRACT FROM AUTHOR]

A set of density dependent nucleon-nucleon (N-N) interactions has been examined in nuclear matter calculations by varying spin-isospin contributions. Two sets of potentials have been considered. One having a density dependent σ-function type short range part followed by one term long range Gaussian part while the other having a density dependent σ-function part followed by two Gaussian terms. The strength parameters of the potential have been fitted to the saturation properties of nuclear matter, i.e. binding energy per particle of 15.5 MeV at k F=1.35 fm−1. Several sets of these two potentials have been generated by varying the strength parameter M of Majorana exchange operator P M. It is seen that M indirectly controls the spin, iso-spin contribution to the interaction potential and thus affects the nuclear matter properties such as compressibility and symmetry energy considerably, while variation of these quantities with the range parameter μ for given M is moderate at low M values while at higher M values it is quite large. [ABSTRACT FROM AUTHOR]

Purpose: The product of the gene ATM mutated in the human genetic disorder ataxia-telangiectasia (A-T) is predominantly present in the nucleus compatible with a role in DNA-damage recognition and cell-cycle control. However, ATM is also present outside the nucleus in cytoplasmic and membrane associated vesicles, which may explain the more general signalling defect in A-T. This led us to investigate signalling events initiated by ionizing radiation, remote from the nucleus. Materials and Methods: A-T and control lymphoblastoid cells were employed to study radiation-induced signalling at the level of protein activation using immunoprecipitation and immunoblotting. Flow cytometry was used to determine mobilization of intracellular Ca[sup 2]. Results: Lymphoblastoid cells from A-T patients were found to be defective in the radiation-induced activation of protein tyrosine kinase p53/p56lyn. In control cells Ca[sup 2] was mobilized in response to gamma-radiation largely from internal stores, and increased significantly over a 20 min period. This mobilization of Ca2 was either absent or increased very slowly in A-T cells post-irradiation. The same pattern of release was observed after treatment with the radiometric agent, streptonigrin. In addition the phospatidylinositol 3-kinase (PI3-kinase) inhibitor wortmannin suppressed the release of Ca[sup 2]. Conclusion: These data demonstrate that ionizing radiation activates lyn kinase and leads to the release of Ca[sup 2], and-for the first time-that these steps are ATM-dependent. [ABSTRACT FROM AUTHOR]

SAFT-dimer (SAFT-D) theory is reformulated to yield an improved equation of state for the hard sphere chain fluid. Two sets of the equation of state are proposed by employing Chiew's expressions for the contact values of the m hard sphere site-site correlation function g ( sigma) . Comparison with molecular simulation data shows that the improved SAFT-D equation of state predicts the compressibility factor more accurately than Ghonasgi and Chapman's equation of state. It has been shown that SAFT-dimer theory can be applied readily to fused hard sphere chain fluids by considering the correct value of the effective chain length (m). SAFTdimer theory is also extended to the 2-dimensional tangent and fused hard disc chain fluids. For the fused hard disc dimer fluid, the SAFT equation of state is found to be more accurate than the Boublik hard disc dimer equation of state. For tangent hard disc chain fluids, the results obtained from SAFT-dimer theory are compared with Monte Carlo results for 5-mers and with GFD theory for 4-mers, 8-mers and 16-mers. [ABSTRACT FROM AUTHOR]

Effect of organic amendments on the microbial population of rhizosphere and non-rhizosphere soils was studied taking a number of dry and green plant materials. All the amendments had marked stimulatory/inhibitory effects on the population of fungi and bacteria in the rhizosphere but the magnitude varied with the amendment as well as variety and age of the plant. They also affected the relative population of different fungi in the rhizosphere. A number of them suppressed the population of Fusaria and stimulated that of Aspergilli. [ABSTRACT FROM AUTHOR]