4,306 research outputs found
Selected Hydrogeologic and Water-quality Data from Jones Beach Island, Long Island, New York
A data-collection site was instrumented on Jones Beach Island, a barrier island south of Long Island, N.Y., to study local freshwater/ saltwater relations in the shallow ground-water system. A geologic test boring revealed about 88 feet of well-sorted glacial outwash sand above about 15 feet of Gardiners Clay, which directly overlies silty sand of the Magothy Formation. Tidal effects on water levels in Great South Bay, the upper glacial aquifer, and the Magothy aquifer were observed and quantified with a tidal gage in the bay and analog water-level recorders in the wells.Chloride concentrations in the upper Magothy aquifer were higher than expected--about 270 mg/L (milligrams per liter), and those in the upper glacial aquifer were 17,000 to 19,000 mg/L, about the same as in Great South Bay. Estimates of pressure and freshwater equivalent heads indicate that, at the data-collection site, freshwater is discharging upward from the Magothy aquifer into the salty upper glacial aquifer, but dilution by this freshwater is undetectable. The reason for the elevated chloride concentration in the Magothy aquifer cannot be determined from available hydrogeologic information
3.10 Bumble bee semi-field studies: choice and management of colonies to reduce variability in assessment endpoints
The publication of the proposed EFSA risk assessment for pollinators resulted in an increasing demand for experiments with non-Apis pollinators (EFSA 2013). However, no official guideline for the standardized semifield trials exists so far. To overcome this lack of guidance, the development of semi-field study designs are under way. The methodology is concurrently be developed by an ICPPR working group (non-Apis working group).A major challenge in higher tier studies is the variability of the different endpoints. Hive development and particularly the production of young queens are very variable (Cabrera et al. 2016). With the current knowledge it seemed crucial to select appropriate colonies for the tests to reduce variability. The aim was to evaluate different strategies for the selection of bumble bee colonies and to improve the data quality with regard to the most important endpoints in bumble bee semi-field studies.The publication of the proposed EFSA risk assessment for pollinators resulted in an increasing demand for experiments with non-Apis pollinators (EFSA 2013). However, no official guideline for the standardized semifield trials exists so far. To overcome this lack of guidance, the development of semi-field study designs are under way. The methodology is concurrently be developed by an ICPPR working group (non-Apis working group).A major challenge in higher tier studies is the variability of the different endpoints. Hive development and particularly the production of young queens are very variable (Cabrera et al. 2016). With the current knowledge it seemed crucial to select appropriate colonies for the tests to reduce variability. The aim was to evaluate different strategies for the selection of bumble bee colonies and to improve the data quality with regard to the most important endpoints in bumble bee semi-field studies
3.11 Bumble bee queen production in semi-field studies: assessment of endpoints and challenges
Bumble bees (Bombus terrestris L; Hymenoptera, Apidae) provide important pollination services and are commercially used, e.g. in greenhouse cultures. Consequently, the impacts of pesticides on bumble bees were already tested in the past. In the light of the newest EFSA guidance document on the risk assessment of plant protection products for pollinators standardized higher tier studies for pollinators are needed (EFSA 2013). For that reason a ringtest protocol for a bumble bee semi-field study design was developed in the ICPPR Non-Apis working group starting in 2015 to date.The central endpoint in a higher tier bumble bee study is the colony reproduction success (production of young queens, Cabrera et al. 2016). The endpoint is chosen because at the end of the annual life cycle of a bumble bee colony all workers die and only young queens overwinter. Queens that survive establish a new colony in the following year. However, assessing queen reproduction is challenging. Many variables can influence the number of produced queens, such as the right timing for the termination of the study or the condition of the colony at study start. Furthermore, young queen weights are measured. Weight is used as indicator of diapause survival. Literature values of average weight needed for survival before overwintering state 0.8 g for a young queen for successful overwintering (Beekman et al. 1998).Based on data from ring tests of 2016 and 2017 we tried to answer several open questions concerning queen reproduction, i.e. how can the experimental set-up influence queen weights and how high is the natural variation in queen numbers and queen weight/size?Bumble bees (Bombus terrestris L; Hymenoptera, Apidae) provide important pollination services and are commercially used, e.g. in greenhouse cultures. Consequently, the impacts of pesticides on bumble bees were already tested in the past. In the light of the newest EFSA guidance document on the risk assessment of plant protection products for pollinators standardized higher tier studies for pollinators are needed (EFSA 2013). For that reason a ringtest protocol for a bumble bee semi-field study design was developed in the ICPPR Non-Apis working group starting in 2015 to date.The central endpoint in a higher tier bumble bee study is the colony reproduction success (production of young queens, Cabrera et al. 2016). The endpoint is chosen because at the end of the annual life cycle of a bumble bee colony all workers die and only young queens overwinter. Queens that survive establish a new colony in the following year. However, assessing queen reproduction is challenging. Many variables can influence the number of produced queens, such as the right timing for the termination of the study or the condition of the colony at study start. Furthermore, young queen weights are measured. Weight is used as indicator of diapause survival. Literature values of average weight needed for survival before overwintering state 0.8 g for a young queen for successful overwintering (Beekman et al. 1998).Based on data from ring tests of 2016 and 2017 we tried to answer several open questions concerning queen reproduction, i.e. how can the experimental set-up influence queen weights and how high is the natural variation in queen numbers and queen weight/size
Phase-dependent light propagation in atomic vapors
Light propagation in an atomic medium whose coupled electronic levels form a
diamond-configuration exhibits a critical dependence on the input conditions.
In particular, the relative phase of the input fields gives rise to
interference phenomena in the electronic excitation whose interplay with
relaxation processes determines the stationary state. We integrate numerically
the Maxwell-Bloch equations and observe two metastable behaviors for the
relative phase of the propagating fields corresponding to two possible
interference phenomena. These phenomena are associated to separate types of
response along propagation, minimize dissipation, and are due to atomic
coherence. These behaviors could be studied in gases of isotopes of
alkali-earth atoms with zero nuclear spin, and offer new perspectives in
control techniques in quantum electronics.Comment: 16 pages, 11 figures, v2: typos corrected, v3: final version, to
appear in Phys. Rev.
Frictional quantum decoherence
The dynamics associated with a measurement-based master equation for quantum
Brownian motion are investigated. A scheme for obtaining time evolution from
general initial conditions is derived. This is applied to analyze dissipation
and decoherence in the evolution of both a Gaussian and a Schr\"{o}dinger cat
initial state. Dependence on the diffusive terms present in the master equation
is discussed with reference to both the coordinate and momentum
representations.Comment: 18 pages, 7 figure
About direct Dark Matter detection in Next-to-Minimal Supersymmetric Standard Model
Direct dark matter detection is considered in the Next-to-Minimal
Supersymmetric Standard Model (NMSSM). The effective neutralino-quark
Lagrangian is obtained and event rates are calculated for the Ge-73 isotope.
Accelerator and cosmological constraints on the NMSSM parameter space are
included. By means of scanning the parameter space at the Fermi scale we show
that the lightest neutralino could be detected in dark matter experiments with
sizable event rate.Comment: latex, 12 pages, 2 ps-figures; extra LEP constraint is included,
extra figure is added, recorrected version, resubmitted to Phys.Rev.
Targeted analysis of polymorphic loci from low-coverage shotgun sequence data allows accurate genotyping of HLA genes in historical human populations
The highly polymorphic human leukocyte antigen (HLA) plays a crucial role in adaptive immunity and is associated with various complex diseases. Accurate analysis of HLA genes using ancient DNA (aDNA) data is crucial for understanding their role in human adaptation to pathogens. Here, we describe the TARGT pipeline for targeted analysis of polymorphic loci from low-coverage shotgun sequence data. The pipeline was successfully applied to medieval aDNA samples and validated using both simulated aDNA and modern empirical sequence data from the 1000 Genomes Project. Thus the TARGT pipeline enables accurate analysis of HLA polymorphisms in historical (and modern) human populations
The Origins of Phase Transitions in Small Systems
The identification and classification of phases in small systems, e.g.
nuclei, social and financial networks, clusters, and biological systems, where
the traditional definitions of phase transitions are not applicable, is
important to obtain a deeper understanding of the phenomena observed in such
systems. Within a simple statistical model we investigate the validity and
applicability of different classification schemes for phase transtions in small
systems. We show that the whole complex temperature plane contains necessary
information in order to give a distinct classification.Comment: 3 pages, 4 figures, revtex 4 beta 5, for further information see
http://www.smallsystems.d
Statistical Mechanics of Canonical-Dissipative Systems and Applications to Swarm Dynamics
We develop the theory of canonical-dissipative systems, based on the
assumption that both the conservative and the dissipative elements of the
dynamics are determined by invariants of motion. In this case, known solutions
for conservative systems can be used for an extension of the dynamics, which
also includes elements such as the take-up/dissipation of energy. This way, a
rather complex dynamics can be mapped to an analytically tractable model, while
still covering important features of non-equilibrium systems. In our paper,
this approach is used to derive a rather general swarm model that considers (a)
the energetic conditions of swarming, i.e. for active motion, (b) interactions
between the particles based on global couplings. We derive analytical
expressions for the non-equilibrium velocity distribution and the mean squared
displacement of the swarm. Further, we investigate the influence of different
global couplings on the overall behavior of the swarm by means of
particle-based computer simulations and compare them with the analytical
estimations.Comment: 14 pages incl. 13 figures. v2: misprints in Eq. (40) corrected, ref.
updated. For related work see also:
http://summa.physik.hu-berlin.de/~frank/active.htm
High permeability explains the vulnerability of the carbon store in drained tropical peatlands
Tropical peatlands are an important global carbon (C) store but are threatened by drainage for palm oil and wood pulp production. The store's stability depends on the dynamics of the peatland water table, which in turn depend on peat permeability. We found that an example of the most abundant type of tropical peatland—ombrotrophic domes—has an unexpectedly high permeability similar to that of gravel. Using computer simulations of a natural peat dome (NPD) and a ditch-drained peat dome (DPD) we explored how such high permeability affects water tables and peat decay. High permeability has little effect on NPD water tables because of low hydraulic gradients from the center to the margin of the peatland. In contrast, DPD water tables are consistently deep, leaving the upper meter of peat exposed to rapid decay. Our results reveal why ditch drainage precipitates a rapid destabilization of the tropical peatland C store
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