760 research outputs found

    An ecological study of the bacterial flora of Westhampton Lake

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    Most natural bodies of water which have been investigated have been shown to contain bacteria. Exceptions apparently occur where we find those waters which, due to their chemical constitution and physical makeup, are inimical even to the growth of bacteria . Since bacteria are virtually ubiquitous in waters, it would necessarily follow that biologists interested in this aspect of biology would have intensively studied bacteria and the part they play in the biology of water. Quite the contrary; instead of the study continuing along lines laid down by early scholars it has shifted to a study of bacteria which were not indigenous to water. Emphasis has been placed on the public health aspects of water and studies of pathogenic organisms, and manurial pollution have supplanted investigations largely taxonomic. Previous research has been concerned in some instances with an enumeration and identification of bacterial forms round in particular bodies or water. At other times work has dealt with environmental factors or chemical alterations affecting the numbers of bacteria. The purpose of the present investigation is a survey of environmental factors affecting the numbers of bacteria and a study of the species of bacteria found in a particular body of water

    The role of sediment supply in the adjustment of channel sinuosity across the Amazon Basin

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    © 2019 Geological Society of America. Sediment supplies are a fundamental component of alluvial river systems, but the importance of sustained supplies of externally derived sediments for the evolution of meandering planforms remains unclear. Here we demonstrate the importance of sediment supply in enhancing the growth of point bars that influence the rate of sinuosity increase through flow deflections in meander bends. We use an archive of Landsat images of 16 meandering reaches from across the Amazon Basin to show that rivers transporting larger sediment loads increase their sinuosity more rapidly than those carrying smaller loads. Sediment-rich rivers are dominated by downstream-rotating meanders that increase their sinuosity more rapidly than both extensional and upstream-rotating meanders. Downstream-rotating meanders appear to establish larger point bars that expand throughout the meander, in contrast to extensional meanders, which have smaller bars, and upstream rotating meanders, which are characterized by deposition over the bar head. These observations demonstrate that the size and position of point bars within meander bends influences flow routing and thus controls the dominant direction of meander growth. Rivers with low sediment supplies build smaller point bars, which reduces their capacity to increase meander curvature and the resulting sinuosity

    An addition to the Fogg Art Museum, Harvard University.

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    Thesis. 1977. M.Arch.--Massachusetts Institute of Technology. Dept. of Architecture.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH.Bibliography : leaf 23.M.Arch

    Surface Engineering for Phase Change Heat Transfer: A Review

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    Among numerous challenges to meet the rising global energy demand in a sustainable manner, improving phase change heat transfer has been at the forefront of engineering research for decades. The high heat transfer rates associated with phase change heat transfer are essential to energy and industry applications; but phase change is also inherently associated with poor thermodynamic efficiencies at low heat flux, and violent instabilities at high heat flux. Engineers have tried since the 1930's to fabricate solid surfaces that improve phase change heat transfer. The development of micro and nanotechnologies has made feasible the high-resolution control of surface texture and chemistry over length scales ranging from molecular levels to centimeters. This paper reviews the fabrication techniques available for metallic and silicon-based surfaces, considering sintered and polymeric coatings. The influence of such surfaces in multiphase processes of high practical interest, e.g., boiling, condensation, freezing, and the associated physical phenomena are reviewed. The case is made that while engineers are in principle able to manufacture surfaces with optimum nucleation or thermofluid transport characteristics, more theoretical and experimental efforts are needed to guide the design and cost-effective fabrication of surfaces that not only satisfy the existing technological needs, but also catalyze new discoveries

    Amino acids in the uterine luminal fluid reflects the temporal changes in transporter expression in the endometrium and conceptus during early pregnancy in cattle

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    In cattle, conceptus-maternal interactions are critical for the establishment and maintenance of pregnancy. A major component of this early interaction involves the transport of nutrients and secretion of key molecules by uterine epithelial cells to help support conceptus development during the peri-implantation period of pregnancy. Objectives were to: 1) analyze temporal changes in the amino acid (AA) content of uterine luminal fluid (ULF) during the bovine estrous cycle; 2) understand conceptus-induced alterations in AA content; 3) determine expression of AA transporters in the endometrium and conceptus; and 4) determine how these transporters are modulated by (Progesterone) P4. Concentrations of aspartic acid, arginine, glutamine, histidine, lysine, isoleucine, leucine, phenylalanine and tyrosine decreased on Day 16 of the estrous cycle but increased on Day 19 in pregnant heifers (P < 0.05). Glutamic acid only increased in pregnant heifers on Day 19 (P,0.001). Asparagine concentrations were greater in ULF of cyclic compared to pregnant heifers on Day 7 (P < 0.05) while valine concentrations were higher in pregnant heifers on Day 16 (P < 0.05). Temporal changes in expression of the cationic AA transporters SLC7A1 SLC7A4 and SLC7A6 occurred in the endometrium during the estrous cycle/early pregnancy coordinate with changes in conceptus expression of SLC7A4, SLC7A2 and SLC7A1 (P < 0.05). Only one acidic AA transporter (SLC1A5) increased in the endometrium while conceptus expression of SLC1A4 increased (P < 0.05). The neutral AA transporters SLC38A2 and SLC7A5 increased in the endometrium in a temporal manner while conceptus expression of SLC38A7, SLC43A2, SLC38A11 and SLC7A8 also increased (P < 0.05). P4 modified the expression of SLC1A1, -1A4, -1A5, -38A2 , -38A4, -38A7, -43A2, -6A14, -7A1, -7A5 and -7A7 in the endometrium. Results demonstrate that temporal changes in AA in the ULF reflect changes in transporter expression in the endometrium and conceptus during early pregnancy in cattle, some of which are modified by P4. © 2014 Forde et al

    Modelling aspects of oviduct fluid formation in vitro

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    © 2017 Society for Reproduction and Fertility. Oviduct fluid is the microenvironment that supports early reproductive processes including fertilisation, embryo cleavage and genome activation. However, the composition and regulation of this critical environment remain rather poorly defined. This study uses an in vitro preparation of the bovine oviduct epithelium to investigate the formation and composition of in vitro-derived oviduct fluid (ivDOF) within a controlled environment. We confirm the presence of oviduct-specific glycoprotein 1 in ivDOF and show that the amino acid and carbohydrate content resembles that of previously reported in vivo data. In parallel, using a different culture system, a panel of oviduct epithelial solute carrier genes and the corresponding flux of amino acids within ivDOF in response to steroid hormones were investigated. We next incorporated fibroblasts directly beneath the epithelium. This dual culture arrangement represents more faithfully the in vivo environment and impacts on ivDOF composition. Lastly, physiological and pathophysiological endocrine states were modelled and their impact on the in vitro oviduct preparation was evaluated. These experiments help clarify the dynamic function of the oviduct in vitro and suggest a number of future research avenues, such as investigating epithelial-fibroblast interactions, probing the molecular aetiologies of subfertility and optimising embryo culture media

    A uvbyCaHβ CCD Analysis of the Open Cluster Standard NGC 752*

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    Precision uvbyCaHβ photometry of the nearby old open cluster, NGC 752, is presented. The mosaic of CCD fields covers an area ~42' on a side with internal precision at the 0.005–0.010 mag level for the majority of stars down to V ~ 15. The CCD photometry is tied to the standard system using an extensive set of published photoelectric observations adopted as secondary standards within the cluster. Multicolor indices are used to eliminate as nonmembers a large fraction of the low probability proper-motion members near the faint end of the main sequence, while identifying 24 potential dwarf members between V = 15.0 and 16.5, eight of which have been noted before from Vilnius photometry. From 68 highly probable F dwarf members, we derive a reddening estimate of E(b − y) = 0.025 ± 0.003 (E(B − V) = 0.034 ± 0.004), where the error includes the internal photometric uncertainty and the systematic error arising from the choice of the standard (b − y, Hβ) relation. With reddening fixed, [Fe/H] is derived from the F dwarf members using both m1 and hk, leading to [Fe/H] = −0.071 ± 0.014 (sem) and −0.017 ± 0.008 (sem), respectively. Taking the internal precision and possible systematics in the standard relations into account, [Fe/H] for NGC 752 becomes −0.03 ± 0.02. With the reddening and metallicity defined, we use the Victoria-Regina isochrones on the Strömgren system and find an excellent match for (m − M) = 8.30 ± 0.05 and an age of 1.45 ± 0.05 Gyr at the appropriate metallicity

    NR3C1 (nuclear receptor subfamily 3, group C, member 1/glucocorticoid receptor)

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    NR3C1 gene encodes the human glucocorticoid receptor(hGR), which is a ligand-dependent transcription factor and activates transcription of glucocorticoid-responsive genes through binding directly to glucocorticoid response elements(GREs) in their promoter region, or modulating transcriptional activity of other transcription factors through protein-protein interactions. hGR is implicated in a broad spectrum of biochemical physiologic functions, which are essential for life, and has also a key role in the maintenance of basal and stress-related homeostasis. Almost 20% of the genes expressed in human leukocytes are regulated positively or negatively by the hGR. Approximately every cellular, molecular and other physiologic network in the human body are influenced by this receptor and more specifically growth, reproduction, intermediary metabolism, immune and inflammatory reactions, as well as central nervous system and cardiovascular functions and lymphoproliferative disorders, cellular proliferation and differentiation in target tissues and normal renal tubular function and thus water and electrolyte homeostasis are only some of the examples where hGR is implicated(Nicolaides, Galata, Kino, Chrousos, and Charmandari, 2010)

    Epididymal Adenomatoid Tumor: A Very Rare Paratesticular Tumor of Childhood

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    Adenomatoid tumor is an uncommon benign mesothelial neoplasm, usually localized in the epididymis. It is the most common paratesticular tumor of middle-aged patients (average age of clinical presentation: 36 years). However, these tumors in pediatric and pubertal patients are extremely rare. Due to their rarity, we present a case of adenomatoid tumor of the tail of the epididymis in a 16-year-old patient. After systematic research of the current literature, we did not find another case report of epididymal adenomatoid tumor in a male patient aged 16 years old or less. This notice and our concern, as well, about the patient’s surveillance protocol during the postoperative period were the motive for this case study
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