4,958 research outputs found
The hydrological regime of a forested tropical Andean catchment.
The hydrology of tropical mountain catchments plays a central role in ecological function, geochemical and biogeochemical cycles, erosion and sediment production, and water supply in globally important environments. There have been few studies quantifying the seasonal and annual water budgets in the montane tropics, particularly in cloud forests. We investigated the water balance and hydrologic regime of the Kosñipata catchment (basin area: 164.4 km2) over the period 2010–2011. The catchment spans over 2500 m in elevation in the eastern Peruvian Andes and is dominated by tropical montane cloud forest with some high-elevation puna grasslands. Catchment-wide rainfall was 3112 ± 414 mm yr−1, calculated by calibrating Tropical Rainfall Measuring Mission (TRMM) 3B43 rainfall with rainfall data from nine meteorological stations in the catchment. Cloud water input to streamflow was 316 ± 116 mm yr−1 (9.2% of total inputs), calculated from an isotopic mixing model using deuterium excess (Dxs) and δD of waters. Field streamflow was measured in 2010 by recording height and calibrating to discharge. River run-off was estimated to be 2796 ± 126 mm yr−1. Actual evapotranspiration (AET) was 688 ± 138 mm yr−1, determined using the Priestley and Taylor–Jet Propulsion Laboratory (PT-JPL) model. The overall water budget was balanced within 1.6 ± 13.7%. Relationships between monthly rainfall and river run-off follow an anticlockwise hysteresis through the year, with a persistence of high run-off after the end of the wet season. The size of the soil and shallow groundwater reservoir is most likely insufficient to explain sustained dry-season flow. Thus, the observed hysteresis in rainfall–run-off relationships is best explained by sustained groundwater flow in the dry season, which is consistent with the water isotope results that suggest persistent wet-season sources to streamflow throughout the year. These results demonstrate the importance of transient groundwater storage in stabilising the annual hydrograph in this region of the Andes
Implicit Beliefs About Change: A Theory-Grounded Measure Applied to Community Organizations Serving Children, Youth, and Families
The aim of this study was to design and evaluate a theory-grounded measure that taps staff beliefs about the possibility for change in an organization which serves children, youth and families at the community level. The rationale for measuring staff beliefs about change derived from a motivation theory that features two contrasting beliefs structures (entity vs. incremental), and the goals and behavioral dispositions associated with each (Dweck & Leggett, 1988). Twenty-nine individuals associated with the community-based organization completed the newly developed Implicit Beliefs About Change Scale (IBACS) and participatedi n a semi-structured interview. Quantitative analyses indicated that the IBACS has good internal consistency, and yields sufficient response variance. Content analysis of the semi-structured interviews, used to assess the scale\u27s construct validity, uncovered distinctive and theory-consistent behavioral dispositions among those staff members whose beliefs regarding change could be characterized as either incremental or entity in nature. Implications for staff development and future research are discussed
On the relation between virial coefficients and the close-packing of hard disks and hard spheres
The question of whether the known virial coefficients are enough to determine
the packing fraction at which the fluid equation of state of a
hard-sphere fluid diverges is addressed. It is found that the information
derived from the direct Pad\'e approximants to the compressibility factor
constructed with the virial coefficients is inconclusive. An alternative
approach is proposed which makes use of the same virial coefficients and of the
equation of state in a form where the packing fraction is explicitly given as a
function of the pressure. The results of this approach both for hard-disk and
hard-sphere fluids, which can straightforwardly accommodate higher virial
coefficients when available, lends support to the conjecture that
is equal to the maximum packing fraction corresponding to an ordered
crystalline structure.Comment: 10 pages, 6 figures; v2: discussion about hard-square and
hard-hexagon systems on a lattice added; five new reference
TBA for non-perturbative moduli spaces
Recently, an exact description of instanton corrections to the moduli spaces
of 4d N=2 supersymmetric gauge theories compactified on a circle and Calabi-Yau
compactifications of Type II superstring theories was found. The equations
determining the instanton contributions turn out to have the form of
Thermodynamic Bethe Ansatz. We explore further this relation and, in
particular, we identify the contact potential of quaternionic string moduli
space with the free energy of the integrable system and the Kahler potential of
the gauge theory moduli space with the Yang-Yang functional. We also show that
the corresponding S-matrix satisfies all usual constraints of 2d integrable
models, including crossing and bootstrap, and derive the associated Y-system.
Surprisingly, in the simplest case the Y-system is described by the MacMahon
function relevant for crystal melting and topological strings.Comment: 25 pages, 1 figur
S-duality in Twistor Space
In type IIB string compactifications on a Calabi-Yau threefold, the
hypermultiplet moduli space must carry an isometric action of the modular
group SL(2,Z), inherited from the S-duality symmetry of type IIB string theory
in ten dimensions. We investigate how this modular symmetry is realized at the
level of the twistor space of , and construct a general class of
SL(2,Z)-invariant quaternion-Kahler metrics with two commuting isometries,
parametrized by a suitably covariant family of holomorphic transition
functions. This family should include corrected by D3-D1-D(-1)-instantons
(with fivebrane corrections ignored) and, after taking a suitable rigid limit,
the Coulomb branch of five-dimensional N=2 gauge theories compactified on a
torus, including monopole string instantons. These results allow us to
considerably simplify the derivation of the mirror map between type IIA and IIB
fields in the sector where only D1-D(-1)-instantons are retained.Comment: 29 pages, 1 figur
D3-instantons, Mock Theta Series and Twistors
The D-instanton corrected hypermultiplet moduli space of type II string
theory compactified on a Calabi-Yau threefold is known in the type IIA picture
to be determined in terms of the generalized Donaldson-Thomas invariants,
through a twistorial construction. At the same time, in the mirror type IIB
picture, and in the limit where only D3-D1-D(-1)-instanton corrections are
retained, it should carry an isometric action of the S-duality group SL(2,Z).
We prove that this is the case in the one-instanton approximation, by
constructing a holomorphic action of SL(2,Z) on the linearized twistor space.
Using the modular invariance of the D4-D2-D0 black hole partition function, we
show that the standard Darboux coordinates in twistor space have modular
anomalies controlled by period integrals of a Siegel-Narain theta series, which
can be canceled by a contact transformation generated by a holomorphic mock
theta series.Comment: 42 pages; discussion of isometries is amended; misprints correcte
Completeness in supergravity constructions
We prove that the supergravity r- and c-maps preserve completeness. As a
consequence, any component H of a hypersurface {h=1} defined by a homogeneous
cubic polynomial such that -d^2 h is a complete Riemannian metric on H defines
a complete projective special Kahler manifold and any complete projective
special Kahler manifold defines a complete quaternionic Kahler manifold of
negative scalar curvature. We classify all complete quaternionic Kahler
manifolds of dimension less or equal to 12 which are obtained in this way and
describe some complete examples in 16 dimensions.Comment: 29 page
Carrying capacity and goat botanical diet composition in an arid ecosystem, Lavalle, Argentina
8 págs, 1 tabla.-- Comunicación presentada a la XLV Reunión Científica de la Sociedad Española para el Estudio de los Pastos: "Producciones agroganaderas: gestión eficiente y conservación del medio natural" (Gijón, 28 de mayo al 3 de junio de 2005).[ES] El trabajo se llevó a cabo en el departamento de Lavalle, Mendoza, Argentina. Las unidades de pastos, más importantes desde el punto de vista forrajero son: Algarrobal de Prosopis flexuosa; Matorral con Atriplex lampa (zampal); Matorral con Tricomaria usillo
(usillar); Matorral degradado con Larrea cuneifolia (jarillal) y Medanal. Los objetivos del estudio fueron estimar la capacidad sustentadora de las diferentes unidades y la composición botánica de la ingesta de los caprinos. La estimación de dicha capacidad, expresada en hectáreas por Unidades Ganadera Caprinas (ha UGC–1), se realizó mediante el método de Point Quadrat modificado para el Monte. Y por medio del análisis microhistológico de heces se determinó la composición estacional de la ingesta.Los valores medios anuales de capacidad sustentadora fueron: Algarrobal, 1,2;
Zampal, 1,7; Usillar, 3,5; Jarillal, 5,8 y Médanos, 4,3 ha UGC-1. La composición de la
ingesta varió durante las estaciones, observándose una predominancia de las especies arbustivas, las gramíneas perennes aparecieron en muy baja frecuencia en todas las estaciones. El Algarrobal y el Zampal son las unidades de mayor importancia forrajera, presentando receptividades ganaderas más altas y una oferta forrajera más estable a lo largo del año, respecto del resto de las unidades de pastos analizadas.[EN] The work was carried out in the department of Lavalle, Mendoza, Argentina. The units of pastures, more important from the forage matter are: Algarrobal of Prosopis flexuosa; Shrubland with Atriplex lampa (zampal); Shrubland with Tricomaria usillo (usillar); Shrubland degraded with Larrea cuneifolia (jarillal) and Dunes. The aims of the study were to estimate the carrying capacity of the different units and the botanical composition of goat diets. The carrying capacity, expressed in hectares by Units Goat (ha UG-1), was measured by the method of Point Quadrat modified for Monte and the seasonal
botanical composition of goat diets, was determined by microhistological analysis of
faeces. The annual average values of carrying capacity were: Algarrobal, 1.2; Zampal, 1.7; Usillar, 3.5; Jarillal, 5.8 and Dunes, 4.3 ha UG-1. The composition of the diet varied during the seasons, the predominance of the shrubs species were observed, the perennial grass appeared in low frequency in all the seasons. The Algarrobal and the Zampal are the units
of greater forage importance, where forage receptivity are higher and with more stable
production throughout the year, respect to the others units of pastures analyzed.Peer reviewe
Heterotic-Type II duality in the hypermultiplet sector
We revisit the duality between heterotic string theory compactified on K3 x
T^2 and type IIA compactified on a Calabi-Yau threefold X in the hypermultiplet
sector. We derive an explicit map between the field variables of the respective
moduli spaces at the level of the classical effective actions. We determine the
parametrization of the K3 moduli space consistent with the Ferrara-Sabharwal
form. From the expression of the holomorphic prepotential we are led to
conjecture that both X and its mirror must be K3 fibrations in order for the
type IIA theory to have an heterotic dual. We then focus on the region of the
moduli space where the metric is expressed in terms of a prepotential on both
sides of the duality. Applying the duality we derive the heterotic
hypermultiplet metric for a gauge bundle which is reduced to 24 point-like
instantons. This result is confirmed by using the duality between the heterotic
theory on T^3 and M-theory on K3. We finally study the hyper-Kaehler metric on
the moduli space of an SU(2) bundle on K3.Comment: 27 pages; references added, typos correcte
The pitfalls of electronic health orders: Development of an enhanced institutional protocol after a preventable patient death
BACKGROUND: Continuous bladder irrigation (CBI) is a long-standing treatment used in the setting of gross hematuria and other acute bladder issues. Its use has traditionally been reserved for patients under direct urologic care, but with the constraints of modern large-hospital healthcare, many patients have CBI administered by providers unfamiliar with its use and potential complications. FINDINGS: There were 136 CBI orders placed in 2013 by non-urologic providers. The biggest hazard found in our analysis was the requirement for entering a rate of irrigation administration. Nurses with no experience with CBI viewed this order as an indication to administer via an infusion pump, which can easily exceed the mechanical integrity of the bladder and increase the risk of bladder perforation. Our panel also found that due to lack of experience by nurses and non-urologic providers, that signs and symptoms of CBI dysfunction were not common knowledge. Also we found that non-urologic providers were unfamiliar with administration and dosing of medications for CBI patients to help with the intrinsic discomfort with CBI administration. CONCLUSIONS: In our revised order set we found that removing the requirement for an infusion rate, along with placing warnings in the CPOE, helped staff better understand this possible complication. We created a best practice alert in our CPOE to strongly recommend the urology service be consulted. Communication text boxes were added to the order set to help staff be aware of the signs and symptoms of CBI dysfunction, along with a guide for trouble shooting
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