747 research outputs found
The Fish Fauna of Lake Maurepas, an Oligohaline Part of the Lake Pontchartrain Estuary
Lake Maurepas is a slightly saline body of water located at the upper end of the Lake Pontchartrain estuary. Of 67 fish species collected during 1983-84, 33 species (49%) are primarily freshwater, 6 (9%) are primarily marine, and 28 (42%) are estuarine or diadromous, commonly occurring in both freshwater and marine habitats. Major freshwater species (e.g. lctalurus furcatus, I. punctatus, and Aplodinotus grunniens) were present throughout the year, whereas most marine and estuarine species were seasonally present (e.g. Anchoa mitchilli, Brevoortia patronus, and Micropogonias undulatus), or were present during periods of higher (up to 2.5 o/oo) salinity (e.g. Cynoscion arenarius, Leiostomus xanthurus, and Pogonias cromis). Literature records indicate that larger percentages of marine species are present during years when salinities are higher (up to 8 o/oo)
Slowest local operators in quantum spin chains
We numerically construct slowly relaxing local operators in a nonintegrable
spin-1/2 chain. Restricting the support of the operator to consecutive
spins along the chain, we exhaustively search for the operator that minimizes
the Frobenius norm of the commutator with the Hamiltonian. We first show that
the Frobenius norm bounds the time scale of relaxation of the operator at high
temperatures. We find operators with significantly slower relaxation than the
slowest simple "hydrodynamic" mode due to energy diffusion. Then, we examine
some properties of the nontrivial slow operators. Using both exhaustive search
and tensor network techniques, we find similar slowly relaxing operators for a
Floquet spin chain; this system is hydrodynamically "trivial", with no
conservation laws restricting their dynamics. We argue that such slow
relaxation may be a generic feature following from locality and unitarity.Comment: 14 pages, 12 figures, published versio
Markov entropy decomposition: a variational dual for quantum belief propagation
We present a lower bound for the free energy of a quantum many-body system at
finite temperature. This lower bound is expressed as a convex optimization
problem with linear constraints, and is derived using strong subadditivity of
von Neumann entropy and a relaxation of the consistency condition of local
density operators. The dual to this minimization problem leads to a set of
quantum belief propagation equations, thus providing a firm theoretical
foundation to that approach. The minimization problem is numerically tractable,
and we find good agreement with quantum Monte Carlo for the spin-half
Heisenberg anti-ferromagnet in two dimensions. This lower bound complements
other variational upper bounds. We discuss applications to Hamiltonian
complexity theory and give a generalization of the structure theorem of Hayden,
Jozsa, Petz and Winter to trees in an appendix
Moving towards effective therapeutic strategies for Neuronal Ceroid Lipofuscinosis.
The Neuronal Ceroid Lipofuscinoses (NCLs) are a family of autosomal recessive neurodegenerative disorders that annually affect 1:100,000 live births worldwide. This family of diseases results from mutations in one of 14 different genes that share common clinical and pathological etiologies. Clinically, the diseases are subcategorized into infantile, late-infantile, juvenile and adult forms based on their age of onset. Though the disease phenotypes may vary in their age and order of presentation, all typically include progressive visual deterioration and blindness, cognitive impairment, motor deficits and seizures. Pathological hallmarks of NCLs include the accumulation of storage material or ceroid in the lysosome, progressive neuronal degeneration and massive glial activation. Advances have been made in genetic diagnosis and counseling for families. However, comprehensive treatment programs that delay or halt disease progression have been elusive. Current disease management is primarily targeted at controlling the symptoms rather than curing the disease. Recognizing the growing need for transparency and synergistic efforts to move the field forward, this review will provide an overview of the therapeutic approaches currently being pursued in preclinical and clinical trials to treat different forms of NCL as well as provide insight to novel therapeutic approaches in development for the NCLs
Social marketing and healthy eating : Findings from young people in Greece
This document is the Accepted Manuscript version. The final publication is available at Springer via http://dx.doi.org/10.1007/s12208-013-0112-xGreece has high rates of obesity and non-communicable diseases owing to poor dietary choices. This research provides lessons for social marketing to tackle the severe nutrition-related problems in this country by obtaining insight into the eating behaviour of young adults aged 18–23. Also, the main behavioural theories used to inform the research are critically discussed. The research was conducted in Athens. Nine focus groups with young adults from eight educational institutions were conducted and fifty-nine participants’ views towards eating habits, healthy eating and the factors that affect their food choices were explored. The study found that the participants adopted unhealthier nutritional habits after enrolment. Motivations for healthy eating were good health, appearance and psychological consequences, while barriers included lack of time, fast-food availability and taste, peer pressure, lack of knowledge and lack of family support. Participants reported lack of supportive environments when deciding on food choices. Based on the findings, recommendations about the development of the basic 4Ps of the marketing mix, as well as of a fifth P, for Policy are proposedPeer reviewe
Polynomial-time algorithm for simulation of weakly interacting quantum spin systems
We describe an algorithm that computes the ground state energy and
correlation functions for 2-local Hamiltonians in which interactions between
qubits are weak compared to single-qubit terms. The running time of the
algorithm is polynomial in the number of qubits and the required precision.
Specifically, we consider Hamiltonians of the form , where
H_0 describes non-interacting qubits, V is a perturbation that involves
arbitrary two-qubit interactions on a graph of bounded degree, and
is a small parameter. The algorithm works if is below a certain
threshold value that depends only upon the spectral gap of H_0, the maximal
degree of the graph, and the maximal norm of the two-qubit interactions. The
main technical ingredient of the algorithm is a generalized Kirkwood-Thomas
ansatz for the ground state. The parameters of the ansatz are computed using
perturbative expansions in powers of . Our algorithm is closely
related to the coupled cluster method used in quantum chemistry.Comment: 27 page
Searching for Novel Biomarkers Using a Mouse Model of CLN3-Batten Disease
CLN3-Batten disease is a rare, autosomal recessive disorder involving seizures, visual, motor and cognitive decline, and premature death. The Cln3Δex7/8 mouse model recapitulates several phenotypic characteristics of the most common 1.02kb disease-associated deletion. Identification of reproducible biomarker(s) to facilitate longitudinal monitoring of disease progression and provide readouts for therapeutic response has remained elusive. One factor that has complicated the identification of suitable biomarkers in this mouse model has been that variations in animal husbandry appear to significantly influence readouts. In the current study, we cross-compared a number of biological parameters in blood from Cln3Δex7/8 mice and control, non-disease mice on the same genetic background from multiple animal facilities in an attempt to better define a surrogate marker of CLN3-Batten disease. Interestingly, we found that significant differences between Batten and non-disease mice found at one site were generally not maintained across different facilities. Our results suggest that colony variation in the Cln3Δex7/8 mouse model of CLN3-Batten disease can influence potential biomarkers of the disease
Bayesian Methods for Exoplanet Science
Exoplanet research is carried out at the limits of the capabilities of
current telescopes and instruments. The studied signals are weak, and often
embedded in complex systematics from instrumental, telluric, and astrophysical
sources. Combining repeated observations of periodic events, simultaneous
observations with multiple telescopes, different observation techniques, and
existing information from theory and prior research can help to disentangle the
systematics from the planetary signals, and offers synergistic advantages over
analysing observations separately. Bayesian inference provides a
self-consistent statistical framework that addresses both the necessity for
complex systematics models, and the need to combine prior information and
heterogeneous observations. This chapter offers a brief introduction to
Bayesian inference in the context of exoplanet research, with focus on time
series analysis, and finishes with an overview of a set of freely available
programming libraries.Comment: Invited revie
BMQ
BMQ: Boston Medical Quarterly was published from 1950-1966 by the Boston University School of Medicine and the Massachusetts Memorial Hospitals
Toward a New Technology and Policy Program (TPP) Curriculum
The mission of the MIT Technology and Policy Program (TPP) is:
“Provide an integrative education to scientists and engineers who wish to lead in the development and implementation of responsible strategies and policies for exploitation of technology for the benefit of their communities” (Hastings, 2000).
Embedded in the TPP mission statement are several educational requirements: (1) a comprehensive and diverse set of solid analytical skills needed to develop and assess strategies and policies, (2) the flexibility to manage the conflicting interests and values that are present at all stages of the policy process, and (3) the ability to provide leadership at each stage in the policy process. With these concepts in mind, the TPP Curriculum Development Committee will work to place TPP at the forefront of educating the “leaders (researchers and practitioners) of the fields of technology and policy studies” (Hastings, 2000)
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