1,960 research outputs found
The development of the head direction system before eye opening in the rat.
Head direction (HD) cells are neurons found in the hippocampal formation and connected areas that fire as a function of an animal's directional orientation relative to its environment. They integrate self-motion and environmental sensory information to update directional heading. Visual landmarks, in particular, exert strong control over the preferred direction of HD cell firing. The HD signal has previously been shown to appear adult-like as early as postnatal day 16 (P16) in the rat pup, just after eye opening and coinciding with the first spontaneous exploration of its environment. In order to determine whether the HD circuit can begin its organization prior to the onset of patterned vision, we recorded from the anterodorsal thalamic nucleus (ADN) and its postsynaptic target in the hippocampal formation, the dorsal pre-subiculum (PrSd), before and after eye opening in pre-weanling rats. We find that HD cells can be recorded at the earliest age sampled (P12), several days before eye opening. However, this early HD signal displays low directional information content and lacks stability both within and across trials. Following eye opening, the HD system matures rapidly, as more cells exhibit directional firing, and the quality and reliability of the directional signal improves dramatically. Cue-rotation experiments show that a prominent visual landmark is able to control HD responses within 24 hr of eye opening. Together, the results suggest that the directional network can be organized independently of visual spatial information while demonstrating the importance of patterned vision for accurate and reliable orientation in space
END OF IDEOLOGY? A TREND ANALYSIS OF COMMUNIST PARTY STRENGTH IN TEN ADVANCED INDUSTRIAL DEMOCRACIES
During the early 1960s, a number of prominent political and social theorists argued that one of the major results of the phenomenal economic growth of Western Europe after World War II was the "deradicalization" of politics. Ideology would cease to be a major' factor as the radical parties of the left and right responded to a breakdown in traditional class cleavages to pursue "pragmatic" programs of economic reforrn.! More recent studies focusing on value changes (Inglehart, 1971) and capital-labor confrontations (Hibbs, 1976) in these countries suggest, however, that ideological politics has not disappeared. This paper examines trends in strength of the communist parties in ten West European nations to determine whether their hypothesized decline as a result of economic development/ has occurred
Theta-modulated place-by-direction cells in the hippocampal formation in the rat
We report the spatial and temporal properties of a class of cells termed theta-modulated place-by-direction (TPD) cells recorded from the presubicular and parasubicular cortices of the rat. The firing characteristics of TPD cells in open-field enclosures were compared with those of the following two other well characterized cell classes in the hippocampal formation: place and head-direction cells. Unlike place cells, which code only for the animal's location, or head-direction cells, which code only for the animal's directional heading, TPD cells code for both the location and the head direction of the animal. Their firing is also strongly theta modulated, firing primarily at the negative-to-positive phase of the locally recorded theta wave. TPD theta modulation is significantly stronger than that of place cells. In contrast, the firing of head-direction cells is not modulated by theta at all. In repeated exposures to the same environment, the locational and directional signals of TPD cells are stable. When recorded in different environments, TPD locational and directional fields can uncouple, with the locational field shifting unpredictably ("remapping"), whereas the directional preference remains similar across environments
U.S. ARMS CONTROL POLICY: CONGRESSIONAL CONSTRAINT OR MIC BUSINESS AS USUAL?
This paper entertains the possibility that a military-industrial complex does in fact exist; that it is not constrained by Congress; that arms policy continues to serve this complex; and that in fact, Congress legitimates MIC activity through ritualistic conflict. Laurance's hypothesis that Congress has recently taken a more active role in the policy process is challenged. Using Yarmolinsky's broader conception ofarms policy, it is argued that arms policy has not significantly changed even though Congressional action has become more conflictual. Finally, it is argued that the changed Congressional role is best understood in terms ofEdelman's reversal ofsystems theory
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Predicting Climate Change Impacts on the Amount and Duration of Autumn Colors in a New England Forest
Climate change affects the phenology of many species. As temperature and precipitation are thought to control autumn color change in temperate deciduous trees, it is possible that climate change might also affect the phenology of autumn colors. Using long-term data for eight tree species in a New England hardwood forest, we show that the timing and cumulative amount of autumn color are correlated with variation in temperature and precipitation at specific times of the year. A phenological model driven by accumulated cold degree-days and photoperiod reproduces most of the interspecific and interannual variability in the timing of autumn colors. We use this process-oriented model to predict changes in the phenology of autumn colors to 2099, showing that, while responses vary among species, climate change under standard IPCC projections will lead to an overall increase in the amount of autumn colors for most species.Organismic and Evolutionary Biolog
A field-based study of alternative microbial indicator tests for drinking water quality in Northern Ghana
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering; and, (S.M. in Technology and Policy)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 81-87).Safe drinking water is essential for human survival, yet it is unavailable to over 1 billion of the world's people living in poverty (World Bank, 2009). The current methods used to identify drinking water sources are inadequate, with almost 40 percent of "safe" sources containing unsafe levels of microbial contamination (Joint Monitoring Programme (JMP) for Water Supply and Sanitation, 2010). Direct water testing is therefore necessary in order to accurately assess the safety of drinking water sources. The goals of this thesis are as follows: (1) To confirm the accuracy of the 20ml hydrogen sulfide (H2S) test as a single presence/absence (P/A) indicator for fecal coliforms; (2) To establish the accuracy of as a single enumerative test for fecal coliforms; (3) To verify the accuracy of the 20 ml H2S test used in conjunction with Easygel® as an improved method of quantifying contamination as compared with the individual tests; (4) To further confirm the accuracy of the EC-Kit as an improved method of quantifying contamination as compared with the individual tests; and (5) To use the results of an informal behavioral household interviews, and a performance review of the Community Water and Sanitation Agency (CWSA) to provide context and policy recommendations to improve access to potable water in Northern Ghana. Fieldwork for this research was completed in January 2011 in and around Tamale, Ghana. The author was hosted by Pure Home Water (PWH) and supported by the MIT Civil and Environmental Engineering Department. Overall, the 20 ml H2S presence/absence test was confirmed to be highly accurate for all types of water sources in Northern Ghana, as was the EC-Kit. The Easygel® and the H2S test combination is recommended solely for use when testing improved water sources. Additionally, field observations and a review of current policies of the CWSA demonstrate significant shortcomings in the ability of the Agency to supply rural areas with safe drinking water. Recommendations for improvement include more strict regulations of the levels and nature of foreign investment in Ghana's water sector.by Samantha F. O'Keefe.S.M.in Technology and PolicyS.M
DNA Methylation of the ABO Promoter Underlies Loss of ABO Allelic Expression in a Significant Proportion of Leukemic Patients
Background: Loss of A, B and H antigens from the red blood cells of patients with myeloid malignancies is a frequent occurrence. Previously, we have reported alterations in ABH antigens on the red blood cells of 55% of patients with myeloid malignancies. Methodology/Principal Findings: To determine the underlying molecular mechanisms of this loss, we assessed ABO allelic expression in 21 patients with ABH antigen loss previously identified by flow cytometric analysis as well as an additional 7 patients detected with ABH antigen changes by serology. When assessing ABO mRNA allelic expression, 6/12 (50%) patients with ABH antigen loss detected by flow cytometry and 5/7 (71%) of the patients with ABH antigen loss detected by serology had a corresponding ABO mRNA allelic loss of expression. We examined the ABO locus for copy number and DNA methylation alterations in 21 patients, 11 with loss of expression of one or both ABO alleles, and 10 patients with no detectable allelic loss of ABO mRNA expression. No loss of heterozygosity (LOH) at the ABO locus was observed in these patients. However in 8/11 (73%) patients with loss of ABO allelic expression, the ABO promoter was methylated compared with 2/10 (20%) of patients with no ABO allelic expression loss (P = 0.03). Conclusions/Significance: We have found that loss of ABH antigens in patients with hematological malignancies is associated with a corresponding loss of ABO allelic expression in a significant proportion of patients. Loss of ABO allelic expression was strongly associated with DNA methylation of the ABO promoter.Tina Bianco-Miotto, Damian J. Hussey, Tanya K. Day, Denise S. O'Keefe and Alexander Dobrovi
Immunogenicity ofEscherichia coli O antigen in upper urinary tract infection
Immunogenicity ofEscherichia coli O antigen in upper urinary tract infection. The role of immunogenicity of the infecting organism (Escherichia coli) in the antibody response to O antigen in upper urinary tract infection was investigated Heat-killed vaccines were prepared from “immunogenic” organisms which had produced upper urinary tract infection associated with high titers of hemag-glutinating antibody to O antigen and “nonimmunogenic” organisms which had produced upper urinary tract infection without a rise in antibody titer. “Immunogenic” 06 vaccine produced high titers of antibody in patients regarded as possibly “poor producers” of antibody, but “nonimmunogenic” 011 vaccine was not associated with a rise in titer in patients previously regarded as “good producers”. These vaccines were significantly different in immunogenicity (P < 0.05). Five vaccines were tested in 50 rats. The difference in hemagglutinating titers to O antigen between 06 and 011 was highly significant (P < 0.001). Immunogenicity of the infecting organism appears to be a significant factor in determining antibody response to O antigen in upper urinary tract infection.Immunogénicité de l'antigène O d'Escherichia coli dans les infections du haut appareil urinaire. Le rôle de l'immunogénicité de l'organisme infectant (Escherichia coli) dans la réponse immune à l'antigène O au cours des infections du haut appareil urinaire a été étudié. Des vaccins tués par la chaleur ont été préparés à partir d'organismes “immunogéniques” qui ont été responsables d'infection du haut appareil urinaire associées à des titres élevés d'anticorps hémagglutinants contre l'antigène O et d'organismes “non immunogéniques” qui ont produit une infection du haut appareil sans augmentation du titre d'anticorps. Le vaccin “immunogénique” 06 produit des titres élevés d'anticorps chez des malades considérés comme de faibles producteurs d'anticorps et le vaccin “non immunogénique” 011 ne détermine pas d'augmentation du titre chez des malades antérieurement considérés comme de “bons producteurs”. Ces vaccins diffèrent significativement en “immunogénicité” (P < 0, 05). Cinq vaccins ont été essayés chez 50 rats. La différence dans les titres d'hémmaglutination vis à vis de l'antigène O est très significative entre 06 et 011 (P < 0, 001). L'immunogénicité de l'organisme infectant parait être un facteur important dans la détermination de la réponse immune à l'antigène O au cours des infections du haut appareil urinaire
Variations in Old-Growth Structure and Definitions: Forest Dynamics on Wachusett Mountain, Massachusetts
Are non-invasive or minimally invasive autopsy techniques for detecting cause of death in prenates, neonates and infants accurate? A systematic review of diagnostic test accuracy
Objectives: To assess the diagnostic accuracy of non-invasive or minimally invasive autopsy techniques in deaths under 1 year of age. Design: This is a systematic review of diagnostic test accuracy. The protocol is registered on PROSPERO. Participants: Deaths from conception to one adjusted year of age. Search methods: MEDLINE (Ovid), EMBASE (Ovid), CINAHL (EBSCO), the Cochrane Library, Scopus and grey literature sources were searched from inception to November 2021. Diagnostic tests: Non-invasive or minimally invasive diagnostic tests as an alternative to traditional autopsy. Data collection and analysis: Studies were included if participants were under one adjusted year of age, with index tests conducted prior to the reference standard. Data were extracted from eligible studies using piloted forms. Risk of bias was assessed using Quality Assessment of Diagnostic Accuracy Studies-2. A narrative synthesis was conducted following the Synthesis without Meta-Analysis guidelines. Vote counting was used to assess the direction of effect. Main outcome measures: Direction of effect was expressed as percentage of patients per study. Findings: We included 54 direct evidence studies (68 articles/trials), encompassing 3268 cases and eight index tests. The direction of effect was positive for postmortem ultrasound and antenatal echography, although with varying levels of success. Conversely, the direction of effect was against virtual autopsy. For the remaining tests, the direction of effect was inconclusive. A further 134 indirect evidence studies (135 articles/trials) were included, encompassing 6242 perinatal cases. The addition of these results had minimal impact on the direct findings yet did reveal other techniques, which may be favourable alternatives to autopsy. Seven trial registrations were included but yielded no results. Conclusions: Current evidence is insufficient to make firm conclusions about the generalised use of non-invasive or minimally invasive autopsy techniques in relation to all perinatal population groups. PROSPERO registration number CRD42021223254
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