877 research outputs found
Relationship of Alexithymia Ratings to Dopamine D2-type Receptors in Anterior Cingulate and Insula of Healthy Control Subjects but Not Methamphetamine-Dependent Individuals.
BackgroundIndividuals with substance-use disorders exhibit emotional problems, including deficits in emotion recognition and processing, and this class of disorders also has been linked to deficits in dopaminergic markers in the brain. Because associations between these phenomena have not been explored, we compared a group of recently abstinent methamphetamine-dependent individuals (n=23) with a healthy-control group (n=17) on dopamine D2-type receptor availability, measured using positron emission tomography with [(18)F]fallypride.MethodsThe anterior cingulate and anterior insular cortices were selected as the brain regions of interest, because they receive dopaminergic innervation and are thought to be involved in emotion awareness and processing. The Toronto Alexithymia Scale, which includes items that assess difficulty in identifying and describing feelings as well as externally oriented thinking, was administered, and the scores were tested for association with D2-type receptor availability.ResultsRelative to controls, methamphetamine-dependent individuals showed higher alexithymia scores, reporting difficulty in identifying feelings. The groups did not differ in D2-type receptor availability in the anterior cingulate or anterior insular cortices, but a significant interaction between group and D2-type receptor availability in both regions, on self-report score, reflected significant positive correlations in the control group (higher receptor availability linked to higher alexithymia) but nonsignificant, negative correlations (lower receptor availability linked to higher alexithymia) in methamphetamine-dependent subjects.ConclusionsThe results suggest that neurotransmission through D2-type receptors in the anterior cingulate and anterior insular cortices influences capacity of emotion processing in healthy people but that this association is absent in individuals with methamphetamine dependence
Probing the phase diagram of CeRu_2Ge_2 by thermopower at high pressure
The temperature dependence of the thermoelectric power, S(T), and the
electrical resistivity of the magnetically ordered CeRu_2Ge_2 (T_N=8.55 K and
T_C=7.40 K) were measured for pressures p < 16 GPa in the temperature range 1.2
K < T < 300 K. Long-range magnetic order is suppressed at a p_c of
approximately 6.4 GPa. Pressure drives S(T) through a sequence of temperature
dependences, ranging from a behaviour characteristic for magnetically ordered
heavy fermion compounds to a typical behaviour of intermediate-valent systems.
At intermediate pressures a large positive maximum develops above 10 K in S(T).
Its origin is attributed to the Kondo effect and its position is assumed to
reflect the Kondo temperature T_K. The pressure dependence of T_K is discussed
in a revised and extended (T,p) phase diagram of CeRu_2Ge_2.Comment: 7 pages, 6 figure
High-pressure transport properties of CeRu_2Ge_2
The pressure-induced changes in the temperature-dependent thermopower S(T)
and electrical resistivity \rho(T) of CeRu_2Ge_2 are described within the
single-site Anderson model. The Ce-ions are treated as impurities and the
coherent scattering on different Ce-sites is neglected. Changing the
hybridisation \Gamma between the 4f-states and the conduction band accounts for
the pressure effect. The transport coefficients are calculated in the
non-crossing approximation above the phase boundary line. The theoretical S(T)
and \rho(T) curves show many features of the experimental data. The seemingly
complicated temperature dependence of S(T) and \rho(T), and their evolution as
a function of pressure, is related to the crossovers between various fixed
points of the model.Comment: 9 pages, 10 figure
Metalografía de puntas de flecha de base hierro de los ejércitos musulmán y cristiano en la Batalla de las Navas de Tolosa (Santa Elena, Jaén)
Phase diagram of heavy fermion systems
The Meccano of heavy fermion systems is shown on different cases going from
anomalous monochalcogenides to cerium intermetallic compounds with special
focus on the ideal case of the CeRu2Si2 series. Discussion is made in the frame
of the interplay between valence, electronic structure (Fermi surface), and
magnetism. The nice tools given by the temperature, the pressure, and the
magnetic field allow to explore different ground states as well as the slow
downhill ''race'' before reaching a Fermi liquid finish line at very low
temperature. Experimentally, the Gr"uneisen parameter i.e. the ratio of the
thermal expansion by the specific heat is a coloured magic number; its
temperature, pressure, and magnetic field dependence is a deep disclosure of
competing hierarchies and the conversion of this adaptive matter to external
responses.Comment: submitted ICM200
Estimate of Production By a Population of Fathead Minnows, Pimpephales promelas, In a South Dakota Prairie Wetland
Estimates of production and population densities were obtained for an autochthonous population of fathead minnows, Pimephales promelas Rafinesque, in a South Dakota prairie wetland. The study was conducted from May to September of 1976. Population estimates were obtained using a Schnabel-type mark and recapture model. Fish were marked either by fin clipping or granular fluorescent pigments driven into the dermal tissue. Production estimates were derived both arithmetically and graphically. The estimated population of adult fathead minnows declined from 194 in May and June to 26 in July. Production by adults was estimated at 0.10 kg, or 0.0007 gm/m²/yr. The population of young-of-the-year fathead minnows was estimated at 21,020 in July; 126,505 in August; and 105,297 in September. Production by young-of-the-year was estimated at 174.99 kg, or 1.75 gm/m²/yr. Young-of-the-year contributed more than ninety-nine percent of the total net production, which was estimated at 175.09 kg, or 1.75 gm/m²/yr. Chapman (1967) reported that lentic waters in temperate regions have produced 2 to 15 gm/m²/yr. where a single species predominated. Production by fathead minnows in Pickering Slough was probably underestimated as a result of: 1) low initial brood stock density (less than five per acre); 2) receding water levels through the study period; 3) exclusion of sexual products form the estimate of net production; 4) exclusion of production by fry not surviving to be censused; and 5) exclusion of production in September and October
Integrating transposable elements in the 3D genome
Chromosome organisation is increasingly recognised as an essential component of genome regulation, cell fate and cell health. Within the realm of transposable elements (TEs) however, the spatial information of how genomes are folded is still only rarely integrated in experimental studies or accounted for in modelling. Whilst polymer physics is recognised as an important tool to understand the mechanisms of genome folding, in this commentary we discuss its potential applicability to aspects of TE biology. Based on recent works on the relationship between genome organisation and TE integration, we argue that existing polymer models may be extended to create a predictive framework for the study of TE integration patterns. We suggest that these models may offer orthogonal and generic insights into the integration profiles (or "topography") of TEs across organisms. In addition, we provide simple polymer physics arguments and preliminary molecular dynamics simulations of TEs inserting into heterogeneously flexible polymers. By considering this simple model, we show how polymer folding and local flexibility may generically affect TE integration patterns. The preliminary discussion reported in this commentary is aimed to lay the foundations for a large-scale analysis of TE integration dynamics and topography as a function of the three-dimensional host genome
Loving to Straighten Out Development: Sexuality and ‘Ethnodevelopment’ in the World Bank’s Ecuadorian Lending
Gender staff in the World Bank -- the world's largest and most influential development institution -- have a policy problem. Having prioritised efforts to get women into paid employment as the "cure-all" for gender inequality they must deal with the work that women already do -- the unpaid labour of caring, socialisation, and human needs fulfilment. This article explores the most prominent policy solution enacted by the Bank to this tension between paid and unpaid work: the restructuring of normative heterosexuality to encourage a two-partner model of love and labour wherein women work more and men care better. Through a case study of Bank gender lending in Ecuador I argue that staff are trying to (re)forge normative arrangements of intimacy, a policy preference that remains invisible unless sexuality is taken seriously as a category of analysis in development studies. Specifically, I focus on four themes that emerge from the attempt to restructure heteronormativity in the loan: (1) the definition of good gender analysis as requiring complementary sharing and dichotomous sex; (2) the Bank's attempt to inculcate limited rationality in women such that they operate as better workers while retaining altruistic attachments to loved ones; (3) the Bank's attempt to inculcate better loving in men, such that they pick up the slack of caring labour when their (partially) rational wives move into productive work, and; (4) the invocation of a racialised hierarchy resting on the extent to which communities approximate ideals of sharing monogamous partnership. Aside from providing clear evidence that the world's largest development institution is involved in micro-processes of sexuality adjustment alongside macro-processes of economic restructuring, I also critique the Bank's sexualised policy interventions and suggest that they warrant contestation
Kondo engineering : from single Kondo impurity to the Kondo lattice
In the first step, experiments on a single cerium or ytterbium Kondo impurity
reveal the importance of the Kondo temperature by comparison to other type of
couplings like the hyperfine interaction, the crystal field and the intersite
coupling. The extension to a lattice is discussed. Emphasis is given on the
fact that the occupation number of the trivalent configuration may be the
implicit key variable even for the Kondo lattice. Three phase
diagrams are discussed: CeRuSi, CeRhIn and SmS
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Atmospheric Peroxyacetyl Nitrate (PAN): A Global Budget and Source Attribution
Peroxyacetyl nitrate (PAN) formed in the atmospheric oxidation of non-methane volatile organic compounds (NMVOCs) is the principal tropospheric reservoir for nitrogen oxide radicals . PAN enables the transport and release of to the remote troposphere with major implications for the global distributions of ozone and OH, the main tropospheric oxidants. Simulation of PAN is a challenge for global models because of the dependence of PAN on vertical transport as well as complex and uncertain NMVOC sources and chemistry. Here we use an improved representation of NMVOCs in a global 3-D chemical transport model (GEOS-Chem) and show that it can simulate PAN observations from aircraft campaigns worldwide. The immediate carbonyl precursors for PAN formation include acetaldehyde (44% of the global source), methylglyoxal (30%), acetone (7%), and a suite of other isoprene and terpene oxidation products (19%). A diversity of NMVOC emissions is responsible for PAN formation globally including isoprene (37%) and alkanes (14%). Anthropogenic sources are dominant in the extratropical Northern Hemisphere outside the growing season. Open fires appear to play little role except at high northern latitudes in spring, although results are very sensitive to plume chemistry and plume rise. Lightning is the dominant contributor to the observed PAN maximum in the free troposphere over the South Atlantic.Engineering and Applied Science
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