1,843 research outputs found
One particle cross section in the target fragmentation region: an explicit calculation in (\phi^3)_6
One particle inclusive cross sections in the target fragmentation region are
considered and an explicit calculation is performed in (\phi^3)_6 model field
theory. The collinear divergences can be correctly absorbed into a parton
density and a fragmentation function but the renormalized cross section gets a
large logarithmic correction as expected in a two scale regime. We find that
the coefficient of such a correction is precisely the scalar DGLAP kernel.
Furthermore the consistency of this result with an extended factorization
hypothesis is investigated.Comment: latex, 16 pages including 8 postscript figure
Structure in Supersymmetric Yang-Mills Theory
We show that requiring sixteen supersymmetries in quantum mechanical gauge
theory implies the existence of a web of constrained interactions. Contrary to
conventional wisdom, these constraints extend to arbitrary orders in the
momentum expansion.Comment: 22 pages, LaTe
Generalized symmetries and invariant matter couplings in two-dimensional dilaton gravity
New features of the generalized symmetries of generic two-dimensional dilaton
models of gravity are presented and invariant gravity-matter couplings are
introduced. We show that there is a continuum set of Noether symmetries, which
contains half a de Witt algebra. Two of these symmetries are area-preserving
transformations. We show that gravity-matter couplings which are invariant
under area preserving transformations only contribute to the dynamics of the
dilaton-gravity sector with a reshaping of the dilaton potential. The
interaction with matter by means of invariant metrics is also considered. We
show in a constructive way that there are metrics which are invariant under two
of the symmetries. The most general metrics and minimal couplings that fulfil
this condition are found.Comment: LateX file, no macros, 14pp: minor changes have been made and some
misprints have been correcte
Effects of climate change on coastal fresh groundwater resources
This study evaluates the impacts of climate change on fresh groundwater resources specifically salinity intrusion in water resources stressed coastal aquifers. Our assessment used the Hadley Centre climate model, HadCM3 with high and low emission scenarios (SRES A2 and B2) for years 2000-2099. In both scenarios, the annual fresh groundwater resources losses indicate an increasing long-term trend in all stressed areas, except in the northern Africa/Sahara region. We also found that precipitation and temperature individually did not show good correlations with fresh groundwater loss. However, the relationship between the aridity index and fresh groundwater loss exhibited a strong negative correlation. We also discuss the impacts of loss of fresh groundwater resources on socio-economic activities, mainly population growth and per capita fresh groundwater resources
Neonatal lesions of orbital frontal areas 11/13 in monkeys alter goal-directed behavior but spare fear conditioning and safety signal learning
Recent studies in monkeys have demonstrated that damage to the lateral subfields of orbital frontal cortex (OFC areas 11/13) yields profound changes in flexible modulation of goal-directed behaviors and deficits in fear regulation. Yet, little consideration has been placed on its role in emotional and social development throughout life. The current study investigated the effects of neonatal lesions of the OFC on the flexible modulation of goal-directed behaviors and fear responses in monkeys. Infant monkeys received neonatal lesions of OFC areas 11/13 or sham-lesions during the first post-natal week. Modulation of goal-directed behaviors was measured with a devaluation task at 3â4 and 6â7 years. Modulation of fear reactivity by safety signals was assessed with the AX+/BXâ fear-potentiated-startle paradigm at 6â7 years. Similar to adult-onset OFC lesions, selective neonatal lesions of OFC areas 11/13 yielded a failure to modulate behavioral responses guided by changes in reward value, but spared the ability to modulate fear responses in the presence of safety signals. These results suggest that these areas play a critical role in the development of behavioral adaptation during goal-directed behaviors, but not or less so, in the development of the ability to process emotionally salient stimuli and to modulate emotional reactivity using environmental contexts, which could be supported by other OFC subfields, such as the most ventromedial subfields (i.e., areas 14/25). Given similar impaired decision-making abilities and spared modulation of fear after both neonatal lesions of either OFC areas 11 and 13 or amygdala (Kazama et al., 2012; Kazama and Bachevalier, 2013), the present results suggest that interactions between these two neural structures play a critical role in the development of behavioral adaptation; an ability essential for the self-regulation of emotion and behavior that assures the maintenance of successful social relationships
Effects of climate and land use changes on groundwater resources in coastal aquifers
To estimate the freshwater loss in coastal aquifers due to salinisation, a numerical model based on the sharp interface assumption has been introduced. The developed methodology will be useful in areas where limited hydrological data are available. This model will elaborate on the changes in fresh groundwater loss with respect to climate change, land use pattern and hydrologic soil condition. The aridity index has been introduced to represent the variations in precipitation and temperature. The interesting finding is that the deforestation leads to increase groundwater recharge in arid areas, because deforestation leads to reduce evapotranspiration even though it favors runoff. The combined climate and land use scenarios show that when the aridity index is less than 60, the agricultural lands give higher groundwater recharge than other land use patterns for all hydrologic soil conditions. The calculated recharge was then used to estimate the freshwaterâsaltwater interface and percentage of freshwater loss due to salinity intrusion. We found that in arid areas, the fresh groundwater loss increases as the percentage of forest cover increases. The combined effects of deforestation and aridity index on fresh groundwater loss show that deforestation causes an increase in the recharge and existing fresh groundwater resource in areas having low precipitation and high temperature (arid climates)
Fracture functions from cut vertices
Using a generalized cut vertex expansion we introduce the concept of an
extended fracture function for the description of semi-inclusive deep inelastic
processes in the target fragmentation region. Extended fracture functions are
shown to obey a standard homogeneous DGLAP-type equation which, upon
integration over t, becomes the usual inhomogeneous evolution equation for
ordinary fracture functions.Comment: latex, 15 pages including 7 postscript figure
Effect of sea level rise on the loss of fresh groundwater resources: case studies of Western American coast and Bay of Bengal
Effect of sea level fluctuations on the movement of the freshwater saltwater interface was analyzed bymeans of a sharp interface model. The simulation was carried out over 100 years period for two casestudies based on available data; western coast of America and the Bay of Bengal and adjacent continental shelf. The position of freshwater-saltwater interface was estimated and it reflects the effect of long term average sea level rise on the position of interface. Using the location of the interface, the related loss of freshwater resources was estimated in both areas and results show that volumetric freshwater losses due to sea level rise is 1%- 5% of the aquifer volume in western American coast and 1%-3% in Bay of Bengal. The effects and influences of the loss of fresh groundwater resources were discussed, considering the groundwater use and groundwater recharge and adaptation proposals were introduced for both areas
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