2,288 research outputs found
Systematic Status of the Fishes of Genus Campostoma (Cyprinidae) Inhabiting the Major Drainages of Northern Arkansas
A total of 6980 morphometric and meristic data points were analyzed from specimens previously identified as Campostoma anomalum pullum and Compostoma oligolepis from all areas of their Ozark ranges in Arkansas. Data were analyzed using the Statistical Analysis System (SAS) and IBM 370 Computer System (HASP II). An attempt was made to establish separation points through multivariate analysis (MANOVA) by taxon and watershed. Additional analyses included factor analysis and discriminant function analysis. Scale count frequencies were analyzed using computer program MINITAB. MANOVA revealed a lack of consistent separation points, and Ozark populations were shown to be distinct and highly variable from one watershed to another. Factor analysis revealed high correlation among morphometric characters (r\u3e.8), high correlation among meristic characters (r\u3e.8), and biologically insignificant correlation between the two sets of data. Discriminant function analysis classified 77.57% of all Ozark specimens as C. a. pullum, regardless of scale count. Frequency distribution analysis of scale counts for Ozark specimens revealed a normal distribution indicative of a single-species sample. Validity of subspecific status for taxon oligolepis in Arkansas Ozark populations is implied
Seismic Response to Injection Well Stimulation in a High-Temperature, High-Permeability Reservoir
Fluid injection into the Earth's crust can induce seismic events that cause damage to local infrastructure but also offer valuable insight into seismogenesis. The factors that influence the magnitude, location, and number of induced events remain poorly understood but include injection flow rate and pressure as well as reservoir temperature and permeability. The relationship between injection parameters and injection-induced seismicity in high-temperature, high-permeability reservoirs has not been extensively studied. Here we focus on the Ngatamariki geothermal field in the central TaupĆ Volcanic Zone, New Zealand, where three stimulation/injection tests have occurred since 2012. We present a catalog of seismicity from 2012 to 2015 created using a matched-filter detection technique. We analyze the stress state in the reservoir during the injection tests from first motion-derived focal mechanisms, yielding an average direction of maximum horizontal compressive stress (SHmax) consistent with the regional NE-SW trend. However, there is significant variation in the direction of maximum compressive stress (Ï1), which may reflect geological differences between wells. We use the ratio of injection flow rate to overpressure, referred to as injectivity index, as a proxy for near-well permeability and compare changes in injectivity index to spatiotemporal characteristics of seismicity accompanying each test. Observed increases in injectivity index are generally poorly correlated with seismicity, suggesting that the locations of microearthquakes are not coincident with the zone of stimulation (i.e., increased permeability). Our findings augment a growing body of work suggesting that aseismic opening or slip, rather than seismic shear, is the active process driving well stimulation in many environments
Dialectica Categories for the Lambek Calculus
We revisit the old work of de Paiva on the models of the Lambek Calculus in
dialectica models making sure that the syntactic details that were sketchy on
the first version got completed and verified. We extend the Lambek Calculus
with a \kappa modality, inspired by Yetter's work, which makes the calculus
commutative. Then we add the of-course modality !, as Girard did, to
re-introduce weakening and contraction for all formulas and get back the full
power of intuitionistic and classical logic. We also present the categorical
semantics, proved sound and complete. Finally we show the traditional
properties of type systems, like subject reduction, the Church-Rosser theorem
and normalization for the calculi of extended modalities, which we did not have
before
A microscopic model for Josephson currents
A microscopic model of a Josephson junction between two superconducting
plates is proposed and analysed. For this model, the nonequilibrium steady
state of the total system is explicitly constructed and its properties are
analysed. In particular, the Josephson current is rigorously computed as a
function of the phase difference of the two plates and the typical properties
of the Josephson current are recovered
The dynamic elastic response to impulse synchronisation of composite prosthetic energy storing and returning feet
In this research, it is proven that perfect synchronisation between the input impulse (human effort) and the ground reaction impulse/impact can result in a phenomenon called the dynamic elastic response to impulse synchronisation with favourable consequences to the behaviour of the energy storing and returning foot. An energy storing and returning composite prosthetic foot was first used in elite competition at the 1988 Paralympic Games. Since its introduction, the prostheses have proven to be a source of controversy. In 2008, it was concluded that the athletes who use such technology when running are in advantageous position when compared to able-bodied athletes. However, these findings have since been disputed. There still remain unanswered questions regarding the level of contribution of energy storing and returning feet in the performance of amputee athletes. A series of investigations have previously been conducted to study the dynamic characteristics of a number of energy storing and returning composite prosthetic feet. It was found that if a sinusoidal input impulse, with a frequency close to one of the energy storing and returning feetâs natural frequencies, could be applied, it can make the energy storing and returning foot susceptible to resonance, which, in the case of bending mode, if sustained can lead to a gain in height or increased velocity
Cellular-level versus receptor-level response threshold hierarchies in T-Cell activation
Peptide-MHC (pMHC) ligand engagement by T-cell receptors (TCRs) elicits a variety of cellular responses, some of which require substantially more TCR-mediated stimulation than others. This threshold hierarchy could reside at the receptor level, where different response pathways branch off at different stages of the TCR/CD3 triggering cascade, or at the cellular level, where the cumulative TCR signal registered by the T-cell is compared to different threshold values. Alternatively, dual-level thresholds could exist. In this study, we show that the cellular hypothesis provides the most parsimonious explanation consistent with data obtained from an in-depth analysis of distinct functional responses elicited in a clonal T-cell system by a spectrum of biophysically defined altered peptide ligands across a range of concentrations. Further, we derive a mathematical model that describes how ligand density, affinity, and off-rate all affect signaling in distinct ways. However, under the kinetic regime prevailing in the experiments reported here, the TCR/pMHC class I (pMHCI) dissociation rate was found to be the main governing factor. The CD8 coreceptor modulated the TCR/pMHCI interaction and altered peptide ligand potency. Collectively, these findings elucidate the relationship between TCR/pMHCI kinetics and cellular function, thereby providing an integrated mechanistic understanding of T-cell response profiles
The Measurement Process in Local Quantum Theory and the EPR Paradox
We describe in a qualitative way a possible picture of the Measurement
Process in Quantum Mechanics, which takes into account: 1. the finite and non
zero time duration T of the interaction between the observed system and the
microscopic part of the measurement apparatus; 2. the finite space size R of
that apparatus; 3. the fact that the macroscopic part of the measurement
apparatus, having the role of amplifying the effect of that interaction to a
macroscopic scale, is composed by a very large but finite number N of
particles. The conventional picture of the measurement, as an instantaneous
action turning a pure state into a mixture, arises only in the limit in which N
and R tend to infinity, and T tends to 0. We sketch here a proposed scheme,
which still ought to be made mathematically precise in order to analyse its
implications and to test it in specific models, where we argue that in Quantum
Field Theory this picture should apply to the unique time evolution expressing
the dynamics of a given theory, and should comply with the Principle of
Locality. We comment on the Einstein Podolski Rosen thought experiment (partly
modifying the discussion on this point in an earlier version of this note),
reformulated here only in terms of local observables (rather than global ones,
as one particle or polarisation observables). The local picture of the
measurement process helps to make it clear that there is no conflict with the
Principle of Locality.Comment: 18 page
Termination Casts: A Flexible Approach to Termination with General Recursion
This paper proposes a type-and-effect system called Teqt, which distinguishes
terminating terms and total functions from possibly diverging terms and partial
functions, for a lambda calculus with general recursion and equality types. The
central idea is to include a primitive type-form "Terminates t", expressing
that term t is terminating; and then allow terms t to be coerced from possibly
diverging to total, using a proof of Terminates t. We call such coercions
termination casts, and show how to implement terminating recursion using them.
For the meta-theory of the system, we describe a translation from Teqt to a
logical theory of termination for general recursive, simply typed functions.
Every typing judgment of Teqt is translated to a theorem expressing the
appropriate termination property of the computational part of the Teqt term.Comment: In Proceedings PAR 2010, arXiv:1012.455
Girlsâ and womenâs education within Unesco and the World Bank, 1945â2000
By 2000, girlsâ and womenâs education was a priority for international development organisations. While studies have examined the impact of recent campaigns and programmes, there has been less exploration of ideas about girlsâ and womenâs education within development thought in the immediate post?colonial period, and the political mechanisms through which this came to be a global concern. Through a study of policy documents, this paper investigates how the education of girls and women came to be prioritised within the two principle UN agencies involved with education since 1945, the World Bank and Unesco. A shift in priorities is evident, from ensuring formal rights and improving the status of women, to expanding the productive capacities of women, fertility control and poverty reduction. While the ascendance of human capital theory provided a space for a new perception of the role of womenâs education in development, in other policy arenas womenâs education was central to exploring more substantive, rights?based notions of gender equality. Ultimately, the goal of improving girlsâ and womenâs education fitted into diverse development agendas, paving the way for it to become a global development priority
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