1,313 research outputs found
Quantum affine Cartan matrices, Poincare series of binary polyhedral groups, and reflection representations
We first review some invariant theoretic results about the finite subgroups
of SU(2) in a quick algebraic way by using the McKay correspondence and quantum
affine Cartan matrices. By the way it turns out that some parameters
(a,b,h;p,q,r) that one usually associates with such a group and hence with a
simply-laced Coxeter-Dynkin diagram have a meaningful definition for the
non-simply-laced diagrams, too, and as a byproduct we extend Saito's formula
for the determinant of the Cartan matrix to all cases. Returning to invariant
theory we show that for each irreducible representation i of a binary
tetrahedral, octahedral, or icosahedral group one can find a homomorphism into
a finite complex reflection group whose defining reflection representation
restricts to i.Comment: 19 page
Water requirements and footprint of a super intensive olive grove under Mediterranean climate
Abstract
The water footprint of a product can be described as the volume of
freshwater used to produce it, associated to a geographic and temporal resolution. For crops, the water footprint relates crop water requirements and yield. The components of water footprint, blue, green and grey water footprints, refer to the volumes of respectively, surface and groundwater, rainfall, and water required to assimilate pollution, used to produce the crop yield. The global standard for crop water footprint assessment relies on evapotranspiration models to estimate green and blue water evapotranspiration. This approach has been used in the present study to estimate the water footprint of a very high density drip irrigated olive grove and further compared with data obtained from evapotranspiration measurements or from its components: the eddy covariance method to quantify latent heat flux, a heat dissipation sap flow technique to determine transpiration and microlysimeters to evaluate soil evaporation. The eddy covariance technique was used for short periods in 2011 and 2012, while sap flow measurements were performed continuously, hence allowing the extension of the data series. Measurements of evapotranspiration with the eddy covariance method provided an average close to 3.4 mm d-1 (2011) and 2.5 mm d-1 (2012). The ratio of evapotranspiration to reference evapotranspiration approached 0.6 and 0.4 for the respective periods. The water footprint of the olive crop under study, calculated with field data, was higher than the water footprint simulated using the global standard assessment and was lower than that reported in literature for olives. Lower values are probably related to differences in cultural practices, e.g., the density of plantation, harvesting techniques and irrigation management. The irrigated high-density olive grove under study had a high yield, which compensates for high water consumption, thus leading to a water footprint lower than the ones of rainfed or less dense groves. Other differences may relate to the procedures used to determine evapotranspiration
The prolonged diagnostic pathway of young adults (Aged 25–39) with cancer in the United Kingdom:Results from the young adult cancer patient journey study
Purpose: Teenagers and young adults (TYAs; aged 13–24) experience prolonged intervals to cancer diagnosis. Insight into diagnostic intervals in young adults (YAs; aged 25–39) and sub-groups at risk for long intervals is lacking. We investigated the diagnostic pathway of YA cancer patients, examined patient and tumor characteristics associated with its length, and compared the patient interval length of our sample with a TYA cohort. Methods: In this cross-sectional survey YAs diagnosed with cancer in the UK in the past five years completed a questionnaire describing their patient (time from first symptom to first doctor consultation) and healthcare interval (from first consultation until consultation with a cancer specialist), sociodemographic, and clinical characteristics. Associations between characteristics and interval length were examined and compared with previously published data in TYAs. Results: Among 341 YAs the patient interval lasted ≥2 weeks, ≥1 month, and ≥3 months in 60%, 42%, and 21%, respectively, compared to 48%, 27%, and 12% in the TYA group. The healthcare interval lasted ≥2 weeks, ≥1 month, and ≥3 months in 62%, 40%, and 17% of YA patients, respectively. YAs with melanoma or cervical cancer were most likely to experience long intervals, whereas YAs with breast cancer and leukemia were most likely to experience short intervals. Conclusions: Most YAs were not seen by a cancer specialist within 2 weeks of GP consultation. Interval lengths in YAs were associated with cancer diagnosis. Patient intervals were longer among YAs than among TYAs. Our study highlights long diagnostic pathways among YAs and calls for more awareness among healthcare professionals about malignancies in this age group.</p
The Offline Software Framework of the Pierre Auger Observatory
To be published in the ProceedingsInternational audienceThe Pierre Auger Observatory is designed to unveil the nature and the origins of the highest energy cosmic rays. The large and geographically dispersed collaboration of physicists and the wide-ranging collection of simulation and reconstruction tasks pose some special challenges for the offline analysis software. We have designed and implemented a general purpose framework which allows collaborators to contribute algorithms and sequencing instructions to build up the variety of applications they require. The framework includes machinery to manage these user codes, to organize the abundance of user-contributed configuration files, to facilitate multi-format file handling, and to provide access to event and time-dependent detector information which can reside in various data sources. A number of utilities are also provided, including a novel geometry package which allows manipulation of abstract geometrical objects independent of coordinate system choice. The framework is implemented in C++, and takes advantage of object oriented design and common open source tools, while keeping the user side simple enough for C++ novices to learn in a reasonable time. The distribution system incorporates unit and acceptance testing in order to support rapid development of both the core framework and contributed user code
Geomagnetic storm dependence on the solar flare class
Content. Solar flares are often used as precursors of geomagnetic storms. In
particular, Howard and Tappin (2005) recently published in A&A a dependence
between X-ray class of solar flares and Ap and Dst indexes of geomagnetic
storms which contradicts to early published results.
Aims. We compare published results on flare-storm dependences and discuss
possible sources of the discrepancy.
Methods. We analyze following sources of difference: (1) different intervals
of observations, (2) different statistics and (3) different methods of event
identification and comparison.
Results. Our analysis shows that magnitude of geomagnetic storms is likely to
be independent on X-ray class of solar flares.Comment: 3 pages, 1 tabl
Interplay of quantum magnetic and potential scattering around Zn or Ni impurity ions in superconducting cuprates
To describe the scattering of superconducting quasiparticles from
non-magnetic (Zn) or magnetic (Ni) impurities in optimally doped high T
cuprates, we propose an effective Anderson model Hamiltonian of a localized
electron hybridizing with -wave BCS type superconducting
quasiparticles with an attractive scalar potential at the impurity site. Due to
the strong local antiferromagnetic couplings between the original Cu ions and
their nearest neighbors, the localized electron in the Ni-doped materials is
assumed to be on the impurity sites, while in the Zn-doped materials the
localized electron is distributed over the four nearest neighbor sites of the
impurities with a dominant symmetric form of the wave function.
With Ni impurities, two resonant states are formed above the Fermi level in the
local density of states at the impurity site, while for Zn impurities a sharp
resonant peak below the Fermi level dominates in the local density of states at
the Zn site, accompanied by a small and broad resonant state above the Fermi
level mainly induced by the potential scattering. In both cases, there are no
Kondo screening effects. The local density of states and their spatial
distribution at the dominant resonant energy around the substituted impurities
are calculated for both cases, and they are in good agreement with the
experimental results of scanning tunneling microscopy in
BiSrCaCuO with Zn or Ni impurities, respectively.Comment: 24 pages, Revtex, 8 figures, submitted to Physical Review B for
publication. Sub-ject Class: Superconductivity; Strongly Correlated Electron
Homestake result, sterile neutrinos and low energy solar neutrino experiments
The Homestake result is about ~ 2 \sigma lower than the Ar-production rate,
Q_{Ar}, predicted by the LMA MSW solution of the solar neutrino problem. Also
there is no apparent upturn of the energy spectrum (R \equiv N_{obs}/N_{SSM})
at low energies in SNO and Super-Kamiokande. Both these facts can be explained
if a light, \Delta m^2_{01} ~ (0.2 - 2) \cdot 10^{-5} eV^2, sterile neutrino
exists which mixes very weakly with active neutrinos: \sin^2 2\alpha ~ (10^{-5}
- 10^{-3}). We perform both the analytical and numerical study of the
conversion effects in the system of two active neutrinos with the LMA
parameters and one weakly mixed sterile neutrino. The presence of sterile
neutrino leads to a dip in the survival probability in the intermediate energy
range E = (0.5 - 5) MeV thus suppressing the Be, or/and pep, CNO as well as B
electron neutrino fluxes. Apart from diminishing Q_{Ar} it leads to decrease of
the Ge-production rate and may lead to decrease of the BOREXINO signal and
CC/NC ratio at SNO. Future studies of the solar neutrinos by SNO, SK, BOREXINO
and KamLAND as well as by the new low energy experiments will allow us to check
this possibility. We present a general analysis of modifications of the LMA
energy profile due to mixing with new neutrino states.Comment: Figures 5 and 6 modified, shorter version will be published in PR
The Pierre Auger Observatory offline software
The Pierre Auger Observatory aims to discover the nature and origins of the highest energy cosmic rays. The large number of physicists involved in the project and the diversity of simulation and reconstruction tasks pose a challenge for the offline analysis software, not unlike the challenges confronting software for very large high energy physics experiments. Previously we have reported on the design and implementation of a general purpose but relatively lightweight framework which allows collaborators to contribute algorithms and sequencing instructions to build up the variety of applications they require. In this report, we update the status of this work and describe some of the successes and difficulties encountered over the last few years of use. We explain the machinery used to manage user contributions, to organize the abundance of configuration files, to facilitate multi-format file handling, and to provide access to event and time-dependent detector information residing in various data sources. We also describe the testing procedures used to help maintain stability of the code in the face of a large number of contributions. Foundation classes will also be discussed, including a novel geometry package which allows manipulation of abstract geometrical objects independent of coordinate system choice
Observation of Burst Intensification by Singularity Emitting Radiation generated from relativistic plasma with a high-intensity laser
Coherent x-rays via the Burst Intensification by Singularity Emitting Radiation (BISER) mechanism are generated from relativistic plasma in helium gas target. A broad modulation of the BISER spectrum, which is significantly wider than the harmonic order, is observed and characterized. In particular, we found that the modulation period can be as large as 41 eV
Critical properties of the Fermi-Bose Kondo and pseudogap Kondo models: Renormalized perturbation theory
Magnetic impurities coupled to both fermionic and bosonic baths or to a
fermionic bath with pseudogap density of states, described by the Fermi-Bose
Kondo and pseudogap Kondo models, display non-trivial intermediate coupling
fixed points associated with critical local-moment fluctuations and local
non-Fermi liquid behavior. Based on renormalization group together with a
renormalized perturbation expansion around the free-impurity limit, we
calculate various impurity properties in the vicinity of those
intermediate-coupling fixed points. In particular, we compute the conduction
electron T matrix, the impurity susceptibility, and the residual impurity
entropy, and relate our findings to certain scenarios of local quantum
criticality in strongly correlated lattice models.Comment: 16 pages, 5 figs; (v2) large-N results for entropy of Bose-Kondo
model added; (v3) final version as publishe
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