Options for Processing Shrimp Landed in South Carolina

Resource /Energy Economics and Policy,

Patterns in transitional shear flows. Part 1. Energy transfers and mean-flow interaction

Low Reynolds number turbulence in wall-bounded shear flows en route to laminar flow takes the form of localised turbulent structures. In plane shear flows, these appear as a regular alternation of turbulent and quasi-laminar flow. Both the physical and the spectral energy balance of a turbulent-laminar pattern are computed and compared to those of uniform turbulence at low $Re$. In the patterned state, the mean flow is strongly modulated and is fuelled by two mechanisms: primarily, the nonlinear self-interaction of the mean flow (via mean advection), and, secondly, the extraction of energy from turbulent fluctuations (via negative production, associated to a strong energy transfer from small to large scales). These processes are surveyed as uniform turbulence loses its stability. Inverse energy transfers and negative production are also found in the uniformly turbulent state.Comment: 29 pages, 15 figure

Patterns in transitional shear flows. Part 2: Nucleation and optimal spacing

Low Reynolds number turbulence in wall-bounded shear flows \emph{en route} to laminar flow takes the form of oblique, spatially-intermittent turbulent structures. In plane Couette flow, these emerge from uniform turbulence via a spatiotemporal intermittent process in which localised quasi-laminar gaps randomly nucleate and disappear. For slightly lower Reynolds numbers, spatially periodic and approximately stationary turbulent-laminar patterns predominate. The statistics of quasi-laminar regions, including the distributions of space and time scales and their Reynolds number dependence, are analysed. A smooth, but marked transition is observed between uniform turbulence and flow with intermittent quasi-laminar gaps, whereas the transition from gaps to regular patterns is more gradual. Wavelength selection in these patterns is analysed via numerical simulations in oblique domains of various sizes. Via lifetime measurements in minimal domains, and a wavelet-based analysis of wavelength predominance in a large domain, we quantify the existence and non-linear stability of a pattern as a function of wavelength and Reynolds number. We report that the preferred wavelength maximises the energy and dissipation of the large-scale flow along laminar-turbulent interfaces. This optimal behaviour is primarily due to the advective nature of the large-scale flow, with turbulent fluctuations playing only a secondary role.Comment: 27 pages, 14 figure

Distribution and Population Characteristics of Lower Walleye in the Eleven Point River, Arkansas

Walleye Sander vitreus (Mitchill) distributions and ecology have been poorly studied in southern river basins. We studied the longitudinal distribution and population characteristics of walleye in an unregulated river within the Ozark region of the U.S., the lower Eleven Point River, Arkansas, which has high species diversity. Walleye were collected in a 60 km segment of the river by daytime boat electrofishing over a three year period (2002-2004). Catch rates, growth rates and size structure were high relative to other streams studied in North America. Catch per effort ( = 5.2/h) was similar seasonally, spatially and among years. Proportional stock structures were quite high ( = 80), with numerous fish collected over 600 mm total length, 4 kg in mass and greater than 10 years of age. Relative weights of all length groups (stock size, proportional size structure, relative size structure) were at or greater than 90. Stomach contents of walleye were more suggestive of a generalist strategy in a stream of high species diversity, as compared to the targeting of a single numerically dominant prey, which is common in lentic systems

Characterization of aerosol associated with enhanced small particle number concentrations in a suburban forested environment

Two elevated particle number/mass growth events associated with Aitken‐mode particles were observed during a sampling campaign (13–29 September 2004) at the Duke University Free‐Air CO2 Enrichment facility, a forested field site located in suburban central North Carolina. Aerosol growth rates between 1.2 and 4.9 nm hr−1 were observed, resulting in net increases in geometric mean diameter of 21 and 37 nm during events. Growth was dominated by addition of oxidized organic compounds. Campaign‐average aerosol mass concentrations measured by an Aerodyne quadrupole aerosol mass spectrometer (Q‐AMS) were 1.9 ± 1.6 (σ), 1.6 ± 1.9, 0.1 ± 0.1, and 0.4 ± 0.4 μg m−3 for organic mass (OM), sulfate, nitrate, and ammonium, respectively. These values represent 47%, 40%, 3%, and 10%, respectively, of the measured submicron aerosol mass. Based on Q‐AMS spectra, OM was apportioned to hydrocarbon‐like organic aerosol (HOA, likely representing primary organic aerosol) and two types of oxidized organic aerosol (OOA‐1 and OOA‐2), which constituted on average 6%, 58%, and 36%, respectively, of the apportioned OM. OOA‐1 probably represents aged, regional secondary organic aerosol (SOA), while OOA‐2 likely reflects less aged SOA. Organic aerosol characteristics associated with the events are compared to the campaign averages. Particularly in one event, the contribution of OOA‐2 to overall OM levels was enhanced, indicating the likelihood of less aged SOA formation. Statistical analyses investigate the relationships between HOA, OOA‐1, OOA‐2, other aerosol components, gas‐phase species, and meteorological data during the campaign and individual events. No single variable clearly controls the occurrence of a particle growth event

Coarse-grained model of entropic allostery

Many signaling functions in molecular biology require proteins to bind to substrates such as DNA in response to environmental signals such as the simultaneous binding to a small molecule. Examples are repressor proteins which may transmit information via a conformational change in response to the ligand binding. An alternative entropic mechanism of "allostery" suggests that the inducer ligand changes the intramolecular vibrational entropy, not just the mean static structure. We present a quantitative, coarse-grained model of entropic allostery, which suggests design rules for internal cohesive potentials in proteins employing this effect. It also addresses the issue of how the signal information to bind or unbind is transmitted through the protein. The model may be applicable to a wide range of repressors and also to signaling in trans-membrane proteins

Assessing speech, language and communication difficulties in children referred for ADHD: a qualitative evaluation of a UK child and adolescent mental health service

Background: Attention-deficit hyperactivity disorder (ADHD) is one of the most common childhood neuropsychiatric disorders and is highly comorbid with speech, language and communication difficulties (SLCDs). However, it is unclear how often SLCDs are identified in ADHD referrals in routine practice and whether there are unidentified SLCDs within this population. Method: A thematic analysis was conducted on a random sample of case notes from 18 referrals for ADHD made to a child and adolescent mental health service (CAMHS) in London, United Kingdom. Analyses aimed to identify (a) the types of SLCDs detected during assessment, (b) at which point of the episode of care these SLCDs were suspected and (c) whether a referral or consultation was made to a speech and language therapist (SLT) for further evaluation. Results: Out of 18 cases investigated, 15 were found to have possible SLCDs based on case notes and reports provided by external agencies. However, only four were referred by CAMHS for further assessment. It is unclear what, if any, steps other external agencies took. Themes describing types of SLCDs, comorbidities and the process of identification are discussed. Conclusion: The analysis of this service’s case notes revealed a range of different routes to the identification of SLCDs, and it was unclear what steps were taken as a result of assessment. A limitation is that this is just one service and the results may not generalise. However, given the similarity in practitioner training received across the country and that practitioners move from service to service, there are grounds for repeating the study in other services. We recommend a more structured approach to identifying SLCDs and recording assessment and treatment decisions made

The social anatomy of 'collusion'

This paper offers a conceptual analysis of collusion, the often overlooked relative of plagiarism in debates on academic integrity. Considered as an inherently social phenomenon, we present the results of a systematic effort to understand the anatomy of collusion. The term’s meanings and associated governance practices are compared for contexts outside Higher Education (HE). These are considered alongside a thematic analysis of publicly available UK university academic integrity documentation that specifies for students what counts as collusion. We indicate how current guideline practice can (1) appear incomplete by concentrating on classroom peers, (2) create blurred boundaries around useful collaboration, peer review and dishonest practice and (3) may be so unrealistic as to have unwelcome, unintended consequences for students and staff. Taking an ecological perspective on the conditions of collusion emphasises how these guidelines - by seeking to constrain social interactions around assignment work - may create an uncomfortable incoherence between their prescriptions and well-established patterns of study

Coupled Maps on Trees

We study coupled maps on a Cayley tree, with local (nearest-neighbor) interactions, and with a variety of boundary conditions. The homogeneous state (where every lattice site has the same value) and the node-synchronized state (where sites of a given generation have the same value) are both shown to occur for particular values of the parameters and coupling constants. We study the stability of these states and their domains of attraction. As the number of sites that become synchronized is much higher compared to that on a regular lattice, control is easier to effect. A general procedure is given to deduce the eigenvalue spectrum for these states. Perturbations of the synchronized state lead to different spatio-temporal structures. We find that a mean-field like treatment is valid on this (effectively infinite dimensional) lattice.Comment: latex file (25 pages), 4 figures included. To be published in Phys. Rev.

Which executive functioning deficits are associated with AD/HD, ODD/CD and comorbid AD/HD+ODD/CD?

Item does not contain fulltextThis study investigated (1) whether attention deficit/hyperactivity disorder (AD/HD) is associated with executive functioning (EF) deficits while controlling for oppositional defiant disorder/conduct disorder (ODD/CD), (2) whether ODD/CD is associated with EF deficits while controlling for AD/HD, and (3)~whether a combination of AD/HD and ODD/CD is associated with EF deficits (and the possibility that there is no association between EF deficits and AD/HD or ODD/CD in isolation). Subjects were 99~children ages 6–12 years. Three putative domains of EF were investigated using well-validated tests: verbal fluency, working memory, and planning. Independent of ODD/CD, AD/HD was associated with deficits in planning and working memory, but not in verbal fluency. Only teacher rated AD/HD, but not parent rated AD/HD, significantly contributed to the prediction of EF task performance. No EF deficits were associated with ODD/CD. The presence of comorbid AD/HD accounts for the EF deficits in children with comorbid AD/HD+ODD/CD. These results suggest that EF deficits are unique to AD/HD and support the model proposed by R. A. Barkley (1997).17 p