3,979 research outputs found
Efficient Irrigation of Trees and Shrubs
In Utah, urban landscape irrigation accounts for 50-75% of the annual municipal water use, and much of it is applied in excess of the plant’s needs. This excess is a tremendous resource waste and the overspray causes substantial damage to hardscape (i.e., decks, patios, fountains, decorative concrete, etc.). Scheduling irrigation according to landscape plant water needs can reduce excess water use. In addition to conserving water, proper irrigation can encourage deeper root growth and healthier, more drought tolerant landscapes
Dipeptidylpeptidase IV (CD26) defines leukemic stem cells (LSC) in chronic myeloid leukemia
Chronic myeloid leukemia (CML) is a stem cell (SC) neoplasm characterized by the BCR/ABL1 oncogene. Although mechanisms of BCR/ABL1-induced transformation are well-defined, little is known about effector-molecules contributing to malignant expansion and the extramedullary spread of leukemic SC (LSC) in CML. We have identified the cytokine-targeting surface enzyme dipeptidylpeptidase-IV (DPPIV/CD26) as a novel, specific and pathogenetically relevant biomarker of CD34+/CD38─ CML LSC. In functional assays, CD26 was identified as target enzyme disrupting the SDF-1-CXCR4-axis by cleaving SDF-1, a chemotaxin recruiting CXCR4+ SC. CD26 was not detected on normal SC or LSC in other hematopoietic malignancies. Correspondingly, CD26+ LSC decreased to low or undetectable levels during successful treatment with imatinib. CD26+ CML LSC engrafted NOD-SCID-IL-2Rγ−/− (NSG) mice with BCR/ABL1+ cells, whereas CD26─ SC from the same patients produced multilineage BCR/ABL1– engraftment. Finally, targeting of CD26 by gliptins suppressed the expansion of BCR/ABL1+ cells. Together, CD26 is a new biomarker and target of CML LSC. CD26 expression may explain the abnormal extramedullary spread of CML LSC, and inhibition of CD26 may revert abnormal LSC function and support curative treatment approaches in this malignancy
Van der Waals density functional: Self-consistent potential and the nature of the van der Waals bond
We derive the exchange-correlation potential corresponding to the nonlocal
van der Waals density functional [M. Dion, H. Rydberg, E. Schroder, D. C.
Langreth, and B. I. Lundqvist, Phys. Rev. Lett. 92, 246401 (2004)]. We use this
potential for a self-consistent calculation of the ground state properties of a
number of van der Waals complexes as well as crystalline silicon. For the
latter, where little or no van der Waals interaction is expected, we find that
the results are mostly determined by semilocal exchange and correlation as in
standard generalized gradient approximations (GGA), with the fully nonlocal
term giving little effect. On the other hand, our results for the van der Waals
complexes show that the self-consistency has little effect at equilibrium
separations. This finding validates previous calculations with the same
functional that treated the fully nonlocal term as a post GGA perturbation. A
comparison of our results with wave-function calculations demonstrates the
usefulness of our approach. The exchange-correlation potential also allows us
to calculate Hellmann-Feynman forces, hence providing the means for efficient
geometry relaxations as well as unleashing the potential use of other standard
techniques that depend on the self-consistent charge distribution. The nature
of the van der Waals bond is discussed in terms of the self-consistent bonding
charge.Comment: submitted to Phys. Rev.
Effect of Cyclosporin A and Zidovudine on Immune Abnormalities Observed in the Murine Acquired Immunodeficiency Syndrome
Two therapeutic modalities, zidovudine (targeting retroviral replication) and cyclosporin A (targeting immunopathologic consequences of retroviral expression) were evaluated in a murine model of AIDS. In previous studies, cyclosporin A treatment (40 or 60 mg/kg/day) before and after infection with LP-BM5 murine leukemia viruses protected against the development of immunodeficiency disease. The present study extends these findings. First, a low dose of cyclosporin A (20 mg/kg/day) was ineffective, and treatment initiated 5 days after infection did not protect against virus-induced lymphoproliferation and hypergammaglobulinemia. Second, zidovudine added to drinking water (0.1 mg initiated 5 days after infection and continued for 8 weeks) was more effective than 0.2 mg/ml, given day 5–12 after infection. This treatment reduced lymph node size, disease severity as determined histologically, retrovirus-induced gp70 expression, and IgE (but not IgM and IgG) levels. Third, combined treatment had an additive, protective effect on lymphocyte proliferative capacity. This successful dual therapeutic strategy in a mouse model has potential applicability for similar approaches in treating human immunodeficiency virus infection
Quantum heuristic algorithm for traveling salesman problem
We propose a quantum heuristic algorithm to solve a traveling salesman
problem by generalizing Grover search. Sufficient conditions are derived to
greatly enhance the probability of finding the tours with extremal costs,
reaching almost to unity and they are shown characterized by statistical
properties of tour costs. In particular for a Gaussian distribution of the
tours along the cost we show that the quantum algorithm exhibits the quadratic
speedup of its classical counterpart, similarly to Grover search.Comment: Published versio
RELICS: The Reionization Lensing Cluster Survey and the Brightest High-z Galaxies
Massive foreground galaxy clusters magnify and distort the light of objects behind them, permitting a view into both the extremely distant and intrinsically faint galaxy populations. We present here the z ~ 6-8 candidate high-redshift galaxies from the Reionization Lensing Cluster Survey (RELICS), a Hubble and Spitzer Space Telescope survey of 41 massive galaxy clusters spanning an area of ≈200 arcmin². These clusters were selected to be excellent lenses, and we find similar high-redshift sample sizes and magnitude distributions as the Cluster Lensing And Supernova survey with Hubble (CLASH). We discover 257, 57, and eight candidate galaxies at z ~ 6, 7, and 8 respectively, (322 in total). The observed (lensed) magnitudes of the z ~ 6 candidates are as bright as AB mag ~23, making them among the brightest known at these redshifts, comparable with discoveries from much wider, blank-field surveys. RELICS demonstrates the efficiency of using strong gravitational lenses to produce high-redshift samples in the epoch of reionization. These brightly observed galaxies are excellent targets for follow-up study with current and future observatories, including the James Webb Space Telescope
Transport and superconducting properties of Fe-based superconductors: SmFeAs(O1-x Fx) versus Fe1+y (Te1-x, Sex)
We present transport and superconducting properties - namely resistivity,
magnetoresistivity, Hall effect, Seebeck effect, thermal conductivity, upper
critical field - of two different families of Fe-based superconductors, which
can be viewed in many respects as end members: SmFeAs(O1-xFx) with the largest
Tc and the largest anisotropy and Fe1+y(Te1-x,Sex), with the largest Hc2, the
lowest Tc and the lowest anisotropy. In the case of the SmFeAs(O1-xFx) series,
we find that a single band description allows to extract an approximated
estimation of band parameters such as carrier density and mobility from
experimental data, although the behaviour of Seebeck effect as a function of
doping demonstrates that a multiband description would be more appropriate. On
the contrary, experimental data of the Fe1+y(Te1-x,Sex) series exhibit a
strongly compensated behaviour, which can be described only within a multiband
model. In the Fe1+y(Te1-x,Sex) series, the role of the excess Fe, tuned by Se
stoichiometry, is found to be twofold: it dopes electrons in the system and it
introduces localized magnetic moments, responsible for Kondo like scattering
and likely pair-breaking of Cooper pairs. Hence, excess Fe plays a crucial role
also in determining superconducting properties such as the Tc and the upper
critical field Bc2. The huge Bc2 values of the Fe1+y(Te1-x,Sex) samples are
described by a dirty limit law, opposed to the clean limit behaviour of the
SmFeAs(O1-xFx) samples. Hence, magnetic scattering by excess Fe seems to drive
the system in the dirty regime, but its detrimental pairbreaking role seems not
to be as severe as predicted by theory. This issue has yet to be clarified,
addressing the more fundamental issue of the interplay between magnetism and
superconductivity
Dual Superconductor Scenario of Confinement: A Systematic Study of Gribov Copy Effects
We perform a study of the effects from maximal abelian gauge Gribov copies in
the context of the dual superconductor scenario of confinement, on the basis of
a novel approach for estimation of systematic uncertainties from incomplete
gauge fixing. We present numerical results, in SU(2) lattice gauge theory,
using the overrelaxed simulated annealing gauge fixing algorithm. We find
abelian and non-abelian string tensions to differ significantly, their ratio
being 0.92(4) at BETA = 2.5115. An approximate factorization of the abelian
potential into monopole and photon contributions has been confirmed, the former
giving rise to the abelian string tension.Comment: 35 pages uucompressed LaTeX with 10 encapsuled postscript figure
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