Investigation of the preparation of materials in space. Task 4 - Field management for weightless containerless processing Quarterly progress report, 22 Aug. - 31 Oct. 1969

Weightless containerless processing for space, electromagnetic position control, force measurements and techniques, and hydrodynamic

Talking a team into being in online workplace collaborations: the discourse of virtual work

Digital communication technologies led to a revolution in how people interact at work: relying on computer-mediated communication technologies is now a must, rather than an alternative. This empirical study investigates how colleagues in a virtual team use synchronous online communication platform in the workplace. Inspired by the conceptualisation of web-based communication platforms as tool, place or context of social construction, we explore the discursive strategies that contribute to the construction of the team’s shared sense of purpose and identity, a collegial atmosphere and consequently lead to effective collaboration. The close analyses of real-life data from a multinational workplace provide insights into the everyday communication practices of virtual team members. Our findings supplement organisational literature based on etic observations of the effectiveness of virtual work and provide a basis for further theorisations about how communication technologies affect the ecology of and discourse practices in computer-mediated communication at work

Effect of Enalapril on erythropoiesis recovery in murine anemia

La presencia de receptores de Angiotensina en células eritropoyéticas y estromales medulares muestra claramenteun mecanismo de regulación de la eritropoyesis mediado por el Sistema Renina-Angiotensina. El objetivo fueestudiar los efectos de Inhibidores de la Enzima Convertidora de Angiotensina (IECA) como Enalapril (E) sobrela respuesta eritropoyética en ratones anémicos tratados con Fenilhidrazina (FHZ), a través de estudios hematológicose histológicos. Tanto los ratones tratados con FHZ como los tratados con E y FHZ mostraron hemólisis eldía 14. Sin embargo, la recuperación del estado anémico fue el día 16 en ratones tratados con FHZ y el día 20 enratones tratados con E y FHZ. Se observó actividad eritropoyética en el bazo (día 16) y en el riñón (día 20) deratones tratados con E y FHZ. En ratones tratados con FHZ, se observó actividad eritropoyética en bazo y riñónel día 16. Concluimos que la inhibición de la ECA con Enalapril retarda la recuperación eritropoyética en ratonestratados con E y FHZ. La actividad eritropoyética en el bazo y riñón sugiere la participación de estos órganos enla recuperación del eritrón.The presence of Angiotensin receptors in erythropoietic bone marrow and marrow stromal cells clearly shows a mechanism forRennin-Angiotensin System-mediated regulation of erythropoiesis. The aim was to study the effects of Angiotensin-ConvertingEnzyme inhibition (ACEI) as Enalapril(E) on erythropoietic response in anemic mice treated with Phenylhydrazine (PHZ) bymeans of hematological and histological studies. Both PHZ and E-PHZ-treated mice showed hemolysis on day 14. Howeverthe restoration of anemic state occurred on day 16 in PHZ-treated mice and on day 20 in E-PHZ-treated mice. Erythropoieticactivity was observed in spleen (day16) and kidney (day20) of E-PHZ-treated mice. In PHZ-treated mice erythropoietic activitywas seen in spleen and kidney on day 16. We conclude that Inhibition of ACE with Enalapril delays the erythropoietic recoveryof hemolytic anemia in E-PHZ-treated mice. Erythropoietic activity in spleen and kidney suggest an involvement of theseorgans in the erythron recovery

Intra- and inter-individual genetic differences in gene expression

Genetic variation is known to influence the amount of mRNA produced by a gene. Given that the molecular machines control mRNA levels of multiple genes, we expect genetic variation in the components of these machines would influence multiple genes in a similar fashion. In this study we show that this assumption is correct by using correlation of mRNA levels measured independently in the brain, kidney or liver of multiple, genetically typed, mice strains to detect shared genetic influences. These correlating groups of genes (CGG) have collective properties that account for 40-90% of the variability of their constituent genes and in some cases, but not all, contain genes encoding functionally related proteins. Critically, we show that the genetic influences are essentially tissue specific and consequently the same genetic variations in the one animal may up-regulate a CGG in one tissue but down-regulate the same CGG in a second tissue. We further show similarly paradoxical behaviour of CGGs within the same tissues of different individuals. The implication of this study is that this class of genetic variation can result in complex inter- and intra-individual and tissue differences and that this will create substantial challenges to the investigation of phenotypic outcomes, particularly in humans where multiple tissues are not readily available.

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Unmasking Chaotic Attributes in Time Series of Living Cell Populations

. Such complicated dynamics are generally the result of a combination of stochastic events and deterministic regulation. Assessing the role, if any, of chaotic regulation is difficult. However, unmasking chaotic dynamics is essential for analysis of cellular processes related to proliferation rate, including metabolic activity, telomere homeostasis, gene expression, and tumor growth.Using a simple, original, nonlinear method based on return maps, we previously found a geometrical deterministic structure coordinating such fluctuations in populations of various cell types. However, nonlinearity and determinism are only necessary conditions for chaos; they do not by themselves constitute a proof of chaotic dynamics. Therefore, we used the same analytical method to analyze the oscillations of four well-known, low-dimensional, chaotic oscillators, originally designed in diverse settings and all possibly well-adapted to model the fluctuations of cell populations: the Lorenz, Rössler, Verhulst and Duffing oscillators. All four systems also display this geometrical structure, coordinating the oscillations of one or two variables of the oscillator. No such structure could be observed in periodic or stochastic fluctuations.Theoretical models predict various cell population dynamics, from stable through periodically oscillating to a chaotic regime. Periodic and stochastic fluctuations were first described long ago in various mammalian cells, but by contrast, chaotic regulation had not previously been evidenced. The findings with our nonlinear geometrical approach are entirely consistent with the notion that fluctuations of cell populations can be chaotically controlled

An agent based decentralized matching macroeconomic model

In this paper we present a macroeconomic microfounded framework with heterogeneous agents-individuals, firms, banks-which interact through a decentralized matching process presenting common features across four markets-goods, labor, credit and deposit. We study the dynamics of the model by means of computer simulation. Some macroeconomic properties emerge such as endogenous business cycles, nominal GDP growth, unemployment rate fluctuations, the Phillips curve, leverage cycles and credit constraints, bank defaults and financial instability, and the importance of government as an acyclical sector which stabilize the economy. The model highlights that even extended crises can endogenously emerge. In these cases, the system may remain trapped in a large unemployment status, without the possibility to quickly recover unless an exogenous intervention takes place

Cellular Radiosensitivity: How much better do we understand it?

Purpose: Ionizing radiation exposure gives rise to a variety of lesions in DNA that result in genetic instability and potentially tumorigenesis or cell death. Radiation extends its effects on DNA by direct interaction or by radiolysis of H2O that generates free radicals or aqueous electrons capable of interacting with and causing indirect damage to DNA. While the various lesions arising in DNA after radiation exposure can contribute to the mutagenising effects of this agent, the potentially most damaging lesion is the DNA double strand break (DSB) that contributes to genome instability and/or cell death. Thus in many cases failure to recognise and/or repair this lesion determines the radiosensitivity status of the cell. DNA repair mechanisms including homologous recombination (HR) and non-homologous end-joining (NHEJ) have evolved to protect cells against DNA DSB. Mutations in proteins that constitute these repair pathways are characterised by radiosensitivity and genome instability. Defects in a number of these proteins also give rise to genetic disorders that feature not only genetic instability but also immunodeficiency, cancer predisposition, neurodegeneration and other pathologies. Conclusions: In the past fifty years our understanding of the cellular response to radiation damage has advanced enormously with insight being gained from a wide range of approaches extending from more basic early studies to the sophisticated approaches used today. In this review we discuss our current understanding of the impact of radiation on the cell and the organism gained from the array of past and present studies and attempt to provide an explanation for what it is that determines the response to radiation

Linkage disequilibrium pattern of the ATM gene in breast cancer patients and controls; association of SNPs and haplotypes to radio-sensitivity and post-lumpectomy local recurrence

<p>Abstract</p> <p>Background</p> <p>The ATM protein is activated as a result of ionizing radiation, and genetic variants of the <it>ATM </it>gene may therefore affect the level of radiation-induced damage. Individuals heterozygous for <it>ATM </it>mutations have been reported to have an increased risk of malignancy, especially breast cancer.</p> <p>Materials and methods</p> <p>Norwegian breast cancer patients (272) treated with radiation (252 of which were evaluated for radiation-induced adverse side effects), 95 Norwegian women with no known history of cancer and 95 American breast cancer patients treated with radiation (44 of which developed ipsilateral breast tumour recurrence, IBTR) were screened for sequence variations in all exons of the <it>ATM </it>gene as well as known intronic variants by denaturating high performance liquid chromatography (dHPLC) followed by sequencing to determine the nature of the variant.</p> <p>Results and Conclusion</p> <p>A total of 56 variants were identified in the three materials combined. A borderline significant association with breast cancer risk was found for the 1229 T>C (Val>Ala) substitution in exon 11 (P-value 0.055) between the Norwegian controls and breast cancer patients as well as a borderline significant difference in haplotype distribution (P-value 0.06). Adverse side effects, such as: development of costal fractures and telangiectasias, subcutaneous and lung fibrosis, pleural thickening and atrophy were evaluated in the Norwegian patients. Significant associations were found for several of the identified variants such as rs1800058 (Leu > Phe) where a decrease in minor allele frequency was found with increasing level of adverse side effects for the clinical end-points pleural thickening and lung fibrosis, thus giving a protective effect. Overall our results indicate a role for variation in the <it>ATM </it>gene both for risk of developing breast cancer, and in radiation induced adverse side effects. No association could be found between risk of developing ipsilateral breast tumour recurrence and any of the sequence variants found in the American patient material.</p