215 research outputs found
Lingual Raynaud\u27s Phenomenon after Surgical and Radiotherapeutic Intervention for Oral Squamous Cell Carcinoma
Raynaud\u27s phenomenon of the tongue after radiation therapy with or without chemotherapy is an exceedingly rare complication. Symptoms are similar to Raynaud\u27s disease of other sites and involve pallor and discomfort on exposure to cold temperatures that resolve with rewarming. Presentation occurs approximately 18-24 months after radiotherapy on average and can usually be managed effectively with lifestyle modification and pharmacotherapy. Here, we present a case of lingual Raynaud\u27s following surgery and adjuvant radiation therapy in a patient with squamous cell carcinoma of the oral cavity
Theory of Moment Propagation for Quantum Dynamics in Single-Particle Description
We present a novel theoretical formulation for performing quantum dynamics in
terms of moments within the single-particle description. By expressing the
quantum dynamics in terms of increasing orders of moments, instead of
single-particle wave functions as generally done in time-dependent density
functional theory, we describe an approach for reducing the high computational
cost of simulating the quantum dynamics. The equation of motion is given for
the moments by deriving analytical expressions for the first-order and
second-order time derivatives of the moments, and a numerical scheme is
developed for performing quantum dynamics by expanding the moments in the
Taylor series as done in classical molecular dynamics simulation. We propose a
few numerical approaches using this theoretical formalism on a simple
one-dimensional model system, for which an analytically exact solution can be
derived. Application of the approaches to an anharmonic system is also
discussed to illustrate their generality. We also discuss the use of an
artificial neural network model to circumvent the numerical evaluation of the
second-order time derivatives of the moments, as analogously done in the
context of classical molecular dynamics simulations
The Past, Present and Future of Title VI of the Civil Rights Act as a Tool of Environmental Justice
Mr. Michael Gerrard: I am going to try to do something a little unconventional. After hearing some remarks from Professor Johnson, I will try to start a dialogue. I have been requested to ask very tough questions of our panelists, so I will do that in the hope of drawing all of you in the audience into the dialogue. First, we will hear some remarks from Professor Nicholas Johnson of Fordham University School of Law
The cellular eff ect of lead poisoning and its clinical picture
Abstract Lead intoxication affects many systems of the body including the cardiovascular, renal, and reproductive systems. Its most detrimental effects occur in the nervous system, where lead blocks the receptor know as N-methyl-D-aspartate, an effective receptor involved in the maturation of brain plasticity. The toxicity of lead plays a major role in the communication between astrocytes and endothelial cells. By disrupting the blood-brain barrier, it causes encephalopathy and edema that primarily affects the cerebellum. Fetus' astrocytes in utero are at an especially high risk of lead intoxication because the immature endothelial cells that form the capillaries of the brain offer a decreased resistance to lead, and thereby easily allow Pb2+ to enter the brain. Intracellularly, lead replaces calcium as a second messenger, binding with calmodulin more readily than calcium, resulting in an alteration in protein conformation. This altered conformation leads protein kinases to phosphoylate and activate substrate molecules, which alter various cellular processes leading to the clinical picture of lead poisoning. In order to prevent the deleterious effects that Pb2+ has on the human system, it is important to understand the various means by which it is introduced into the body. Environmental and domestic sources of Pb2+ are the most often seen causes for the disease, but with proper precautionary measures, it is easily possible to adequately reduce the level of risk associated with lead poisoning
Rapidly Changing Range Limits in a Warming World: Critical Data Limitations and Knowledge Gaps for Advancing Understanding of Mangrove Range Dynamics in the Southeastern USA
Climate change is altering species’ range limits and transforming ecosystems. For example, warming temperatures are leading to the range expansion of tropical, cold-sensitive species at the expense of their cold-tolerant counterparts. In some temperate and subtropical coastal wetlands, warming winters are enabling mangrove forest encroachment into salt marsh, which is a major regime shift that has significant ecological and societal ramifications. Here, we synthesized existing data and expert knowledge to assess the distribution of mangroves near rapidly changing range limits in the southeastern USA. We used expert elicitation to identify data limitations and highlight knowledge gaps for advancing understanding of past, current, and future range dynamics. Mangroves near poleward range limits are often shorter, wider, and more shrublike compared to their tropical counterparts that grow as tall forests in freeze-free, resource-rich environments. The northern range limits of mangroves in the southeastern USA are particularly dynamic and climate sensitive due to abundance of suitable coastal wetland habitat and the exposure of mangroves to winter temperature extremes that are much colder than comparable range limits on other continents. Thus, there is need for methodological refinements and improved spatiotemporal data regarding changes in mangrove structure and abundance near northern range limits in the southeastern USA. Advancing understanding of rapidly changing range limits is critical for foundation plant species such as mangroves, as it provides a basis for anticipating and preparing for the cascading effects of climate-induced species redistribution on ecosystems and the human communities that depend on their ecosystem services
Quantum railroads and directed localization at the juncture of quantum Hall systems
The integer quantum Hall effect (QHE) and one-dimensional Anderson
localization (AL) are limiting special cases of a more general phenomenon,
directed localization (DL), predicted to occur in disordered one-dimensional
wave guides called "quantum railroads" (QRR). Here we explain the surprising
results of recent measurements by Kang et al. [Nature 403, 59 (2000)] of
electron transfer between edges of two-dimensional electron systems and
identify experimental evidence of QRR's in the general, but until now entirely
theoretical, DL regime that unifies the QHE and AL. We propose direct
experimental tests of our theory.Comment: 11 pages revtex + 3 jpeg figures, to appear in Phys. Rev.
Nesting biology of the bee Caupolicana yarrowi.
20 pages : illustrations (some color), color maps ; 26 cm.
Appendix: Use of nectar by the desert bee Caupolicana yarrowi (Colletidae) in cell construction / James H. Cane and Jerome G. Rozen, Jr.The first part of this publication, written by a group of participants in Bee Course 2018, results from the discovery of three nests of Caupolicana yarrowi (Cresson, 1875) at the base of the Chiricahua Mountains in southeastern Arizona. The nests are deep with branching laterals that usually connect to large vertical brood cells by an upward turn before curving downward and attaching to the top of the chambers. This loop of the lateral thus seems to serve as a "sink trap," excluding rainwater from reaching open cells during provisioning. Although mature larvae had not yet developed, an egg of C. yarrowi was discovered floating on the provisions allowing an SEM examination of its chorion, the first such study for any egg of the Diphaglossinae. Larval food for this species at this site came from Solanum elaeagnifolium Cav. (Solanaceae). Nests were parasitized by Triepeolus grandis (Friese, 1917) (Epeolini), which previously was known to attack only Ptiloglossa (Diphaglossinae: Caupolicanini). The subterranean nest cells of the desert bee Caupolicana yarrowi (Colletidae), which are enveloped by a casing of hardened soil that easily separates from the surrounding matrix, are discussed in a separate appendix. Chemical analysis revealed the casing to be rich in reducing sugars, indicating that the mother bee had regurgitated floral nectar onto the rough interior walls of the cell cavity before smoothing and waterproofing them. This novel use of nectar in nest construction is compared with that of other bee species that bring water to a nest site to soften soil for excavation
Spin and valley quantum Hall ferromagnetism in graphene
In a graphene Landau level (LL), strong Coulomb interactions and the fourfold
spin/valley degeneracy lead to an approximate SU(4) isospin symmetry. At
partial filling, exchange interactions can spontaneously break this symmetry,
manifesting as additional integer quantum Hall plateaus outside the normal
sequence. Here we report the observation of a large number of these quantum
Hall isospin ferromagnetic (QHIFM) states, which we classify according to their
real spin structure using temperature-dependent tilted field magnetotransport.
The large measured activation gaps confirm the Coulomb origin of the broken
symmetry states, but the order is strongly dependent on LL index. In the high
energy LLs, the Zeeman effect is the dominant aligning field, leading to real
spin ferromagnets with Skyrmionic excitations at half filling, whereas in the
`relativistic' zero energy LL, lattice scale anisotropies drive the system to a
spin unpolarized state, likely a charge- or spin-density wave.Comment: Supplementary information available at http://pico.phys.columbia.ed
Rapidly Changing Range Limits in a Warming World: Critical Data Limitations and Knowledge Gaps for Advancing Understanding of Mangrove Range Dynamics in the Southeastern USA
Climate change is altering species’ range limits and transforming ecosystems. For example, warming temperatures are leading to the range expansion of tropical, cold-sensitive species at the expense of their cold-tolerant counterparts. In some temperate and subtropical coastal wetlands, warming winters are enabling mangrove forest encroachment into salt marsh, which is a major regime shift that has significant ecological and societal ramifications. Here, we synthesized existing data and expert knowledge to assess the distribution of mangroves near rapidly changing range limits in the southeastern USA. We used expert elicitation to identify data limitations and highlight knowledge gaps for advancing understanding of past, current, and future range dynamics. Mangroves near poleward range limits are often shorter, wider, and more shrublike compared to their tropical counterparts that grow as tall forests in freeze-free, resource-rich environments. The northern range limits of mangroves in the southeastern USA are particularly dynamic and climate sensitive due to abundance of suitable coastal wetland habitat and the exposure of mangroves to winter temperature extremes that are much colder than comparable range limits on other continents. Thus, there is need for methodological refinements and improved spatiotemporal data regarding changes in mangrove structure and abundance near northern range limits in the southeastern USA. Advancing understanding of rapidly changing range limits is critical for foundation plant species such as mangroves, as it provides a basis for anticipating and preparing for the cascading effects of climate-induced species redistribution on ecosystems and the human communities that depend on their ecosystem services
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