20,584 research outputs found
FINANCIAL PROSPECTS, BUSINESS ORGANIZATION, AND MANAGEMENT: FARM BUSINESS CHALLENGES
Farm Management,
Spontaneous Tetraploid Melons
Since 1968, three spontaneous 4x melons (Cucumis melo L.) plants were discovered in our field or greenhouse plantings. Two were found in the cultivar Planters Jumbo and one in the virescent marker C879-52. Each of these 4x plants had rounded cotyledons, shorter internodes, thicker stems and leaves, more hairs, and smaller fruits, with larger stem and blossom scars, than their 2x counterparts. Also, their flowers, pollen grains, stomates, and seeds were larger. The discovery of a 4x virescent plant in 1987 allows easier germplasm transfer between ploidy levels. Morphological characteristics of 2x and 4x melons will allow identification without need for chromosome counts
Magnetoelectric polarizability: A microscopic perspective
We extend a field theoretic approach for the investigation of the electronic
charge-current density response of crystalline systems to arbitrary applied
electromagnetic fields. The approach leads to the introduction of microscopic
polarization and magnetization fields, as well as free charge and current
densities, the dynamics of which are described by a lattice gauge theory. The
spatial averages of such quantities constitute the fields of macroscopic
electrodynamics. We implement this formalism to study the orbital electronic
response of a class of insulators to applied uniform dc electric and magnetic
fields at zero temperature. To first-order in the applied fields, the free
charge and current densities vanish; thus the response of the system is
characterized by the first-order modifications to the microscopic polarization
and magnetization fields. Associated with the dipole moment of the microscopic
polarization (magnetization) field is a macroscopic polarization
(magnetization), for which we extract various response tensors. We focus on the
orbital magnetoelectric polarizability (OMP) tensor, and find the accepted
expression as derived from the "modern theory of polarization and
magnetization." Since our results are based on the spatial averages of
microscopic fields, we can identify the distinct contributions to the OMP
tensor from the perspective of this microscopic theory, and we establish the
general framework in which extensions to finite frequency can be made.Comment: 24 page
From magnetoelectric response to optical activity
We apply a microscopic theory of polarization and magnetization to
crystalline insulators at zero temperature and consider the orbital electronic
contribution of the linear response to spatially varying, time-dependent
electromagnetic fields. The charge and current density expectation values
generally depend on both the microscopic polarization and magnetization fields,
and on the microscopic free charge and current densities. But contributions
from the latter vanish in linear response for the class of insulators we
consider. Thus we need only consider the former, which can be decomposed into
"site" polarization and magnetization fields, from which "site multipole
moments" can be constructed. Macroscopic polarization and magnetization fields
follow, and we identify the relevant contributions to them; for electromagnetic
fields varying little over a lattice constant these are the electric and
magnetic dipole moments per unit volume, and the electric quadrupole moment per
unit volume. A description of optical activity and related magneto-optical
phenomena follows from the response of these macroscopic quantities to the
electromagnetic field and, while in this paper we work within the independent
particle and frozen-ion approximations, both optical rotary dispersion and
circular dichroism can be described with this strategy. Earlier expressions
describing the magnetoelectric effect are recovered as the zero frequency limit
of our more general equations. Since our site quantities are introduced with
the use of Wannier functions, the site multipole moments and their macroscopic
analogs are generally gauge dependent. However, the resulting macroscopic
charge and current densities, together with the optical effects to which they
lead, are gauge invariant, as would be physically expected.Comment: 24 pages. Minor typographical errors in Eq. 5, 14, 15 of the earlier
version are correcte
PAT proteins, an ancient family of lipid droplet proteins that regulate cellular lipid stores.
The PAT family of lipid droplet proteins includes 5 members in mammals: perilipin, adipose differentiation-related protein (ADRP), tail-interacting protein of 47 kDa (TIP47), S3-12, and OXPAT. Members of this family are also present in evolutionarily distant organisms, including insects, slime molds and fungi. All PAT proteins share sequence similarity and the ability to bind intracellular lipid droplets, either constitutively or in response to metabolic stimuli, such as increased lipid flux into or out of lipid droplets. Positioned at the lipid droplet surface, PAT proteins manage access of other proteins (lipases) to the lipid esters within the lipid droplet core and can interact with cellular machinery important for lipid droplet biogenesis. Genetic variations in the gene for the best-characterized of the mammalian PAT proteins, perilipin, have been associated with metabolic phenotypes, including type 2 diabetes mellitus and obesity. In this review, we discuss how the PAT proteins regulate cellular lipid metabolism both in mammals and in model organisms
Emerging Roles of Health Care Providers to Mitigate Climate Change Impacts: A Perspective from East Harlem, New York
Professional associations of health care workers are issuing policy statements on climate change and health with greater frequency, calling on their members to act in their duty to protect and fulfill the right to health. These health care providers’ perceptions of their roles in the intersection of climate and health, however, have not been well-studied. This article presents results from a qualitative study using focus groups conducted with health care providers serving the low-income, ethnic minority population in East Harlem, New York. The focus groups sought to identify and explore providers’ perceived health threats of climate change, as well as their perceived role as frontline disseminators of information and detectors of disease for their patients. Extreme heat events were used to frame the discussion in each group. Three major themes emerged: 1) environmental awareness, 2) an “ecohealth” lens, and 3) heat and health vulnerability. The participants demonstrated their interest in playing a role in climate change adaptation by identifying at-risk patients and helping to tailor clinical care to better serve these individuals
Kaluza-Klein electrically charged black branes in M-theory
We present a class of Kaluza-Klein electrically charged black p-brane
solutions of ten-dimensional, type IIA superstring theory. Uplifting to eleven
dimensions these solutions are studied in the context of M-theory. They can be
interpreted either as a p+1 extended object trapped around the eleventh
dimension along which momentum is flowing or as a boost of the following
backgrounds: the Schwarzschild black (p+1)-brane or the product of the
(10-p)-dimensional Euclidean Schwarzschild manifold with the (p+1)-dimensional
Minkowski spacetime.Comment: 16 pages, uses latex and epsf macro, figures include
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