Thrust augmentation and vortex ring evolution in a fully pulsed jet

The time-averaged thrust of an incompressible fully pulsed jet containing a period of no flow between pulses is studied experimentally as a function of pulsing duty cycle Sr_L and the ratio of the ejected slug length (per pulse) to the jet diameter L/D. The parameter ranges investigated were 2≤L/D≤6 and 0.1≤Sr_L≤0.98. Significant thrust augmentation by pulsing was observed over the entire parameter range tested, both in terms of thrust compared to an equivalent steady jet with identical mass flux, denoted F_(SJ) >1, and in terms of thrust compared to an equivalent intermittent jet where vortex ring formation by pulsation was ignored, denoted F_(IJ) >1. F_(SJ) as high as 1.90 (90% thrust augmentation) was observed for the smaller L/D as Sr_L approached 1.0 (with larger F_(SJ) at lower Sr_L). The F_(IJ) results, which directly measured overpressure at the nozzle exit plane developed during vortex ring formation as the mechanism responsible for thrust augmentation, showed reduced augmentation at large L/D and Sr_L. The L/D dependence of F_(IJ) parallels single-pulse (Sr_L =0) results previously studied by the authors. The Sr_L dependence of F_(IJ) was linked to the interaction of forming vortex rings with vorticity from preceding pulses using digital particle image velocimetry (DPIV) measurements of the vorticity field. DPIV also revealed that the vortex rings tended to wander off axis and disintegrate as Sr_L became sufficiently large

The core structure of presolar graphite onions

Of the ``presolar particles'' extracted from carbonaceous chondrite dissolution residues, i.e. of those particles which show isotopic evidence of solidification in the neighborhood of other stars prior to the origin of our solar system, one subset has an interesting concentric graphite-rim/graphene-core structure. We show here that single graphene sheet defects in the onion cores (e.g. cyclopentane loops) may be observable edge-on by HREM. This could allow a closer look at models for their formation, and in particular strengthen the possibility that growth of these assemblages proceeds atom-by-atom with the aid of such in-plane defects, under conditions of growth (e.g. radiation fluxes or grain temperature) which discourage the graphite layering that dominates subsequent formation of the rim.Comment: 4 pages, 7 figures, 11 refs, see also http://www.umsl.edu/~fraundor/isocore.htm

Correlations in Bipartite Collaboration Networks

Collaboration networks are studied as an example of growing bipartite networks. These have been previously observed to have structure such as positive correlations between nearest-neighbour degrees. However, a detailed understanding of the origin of this phenomenon and the growth dynamics is lacking. Both of these are analyzed empirically and simulated using various models. A new one is presented, incorporating empirically necessary ingredients such as bipartiteness and sublinear preferential attachment. This, and a recently proposed model of team assembly both agree roughly with some empirical observations and fail in several others.Comment: 13 pages, 17 figures, 2 table, submitted to JSTAT; manuscript reorganized, figures and a table adde

Sensation Seeking and Perceived Need for Structure Moderate Soldiers’ Well-Being Before and After Operational Deployment

This study examined associations between sensation seeking and perceived need for structure, and changes in reported well-being among deployed soldiers. Participants (n = 167) were assessed before and after a six-month deployment to south Afghanistan. Results indicated that although well-being declined in the soldier sample as a whole following deployment, the degree of decrease was significantly different among soldiers with different personality profiles. Differences were moderated by soldiers’ level of sensation seeking and perceived need for structure. Results are discussed in terms of a person-environment fit theory in the context of preparation and rehabilitation of deployed military personnel

Influence of Predation Mortality on Survival of Chinook Salmon Parr in a Lake Michigan Tributary

Predation mortality among Chinook salmon Oncorhynchus tshawytscha parr can act at small spatiotemporal scales and cause variability in parr survival and potential recruitment. We analyzed predator diets and multiplied per capita consumption rates by predator population estimates to evaluate the relative effect of predation by stocked sport fishes on the variability in survival of Chinook salmon parr in the Muskegon River, Michigan, from 2004 to 2007. Brown trout Salmo trutta were a major predator of Chinook salmon parr, consuming from 15% to 34% of the total number available, while walleyes Sander vitreus consumed from 0.2% to 15%. Walleyes also consumed large quantities of brown trout and rainbow trout O. mykiss. Brown trout predation on Chinook salmon parr was largely dependent on parr size, while walleye predation was buffered by the availability of rainbow trout and brown trout. Predation mortality appeared to be responsible for a more than three‐fold difference in the survival of Chinook salmon parr in the Muskegon River. The vulnerability of Chinook salmon parr to predation appeared to be controlled by parr growth rates, brown trout stocking dates, and the number of brown trout stocked. Fishery regulations to manipulate piscivore abundance may lead to higher survival and lower variability in the survival of Chinook salmon parr.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141027/1/tafs0147.pd

The Genetic and Environmental Sources of Resemblance Between Normative Personality and Personality Disorder Traits

Recent work has suggested a high level of congruence between normative personality, most typically represented by the big five factors, and abnormal personality traits. In 2,293 Norwegian adult twins ascertained from a population-based registry, the authors evaluated the degree of sharing of genetic and environmental influences on normative personality, assessed by the Big Five Inventory (BFI), and personality disorder traits (PDTs), assessed by the Personality Inventory for DSM-S-Norwegian Brief Form (PID-5NBF). For four of the five BFI dimensions, the strongest genetic correlation was observed with the expected PID-5-NBF dimension (e.g., neuroticism with negative affectivity [+], conscientiousness with disinhibition [-]). However, neuroticism, conscientiousness, and agreeableness had substantial genetic correlations with other PID-S-NBF dimensions (e.g., neuroticism with compulsivity [+], agreeableness with detachment [-]). Openness had no substantial genetic correlations with any PID-5-NBF dimension. The proportion of genetic risk factors shared in aggregate between the BFI traits and the PID-5-NBF dimensions was quite high for conscientiousness and neuroticism, relatively robust for extraversion and agreeableness, but quite low for openness. Of the six PID-S-NBF dimensions, three (negative affectivity, detachment, and disinhibition) shared, in aggregate, most of their genetic risk factors with normative personality traits. Genetic factors underlying psychoticism, antagonism, and compulsivity were shared to a lesser extent, suggesting that they are influenced by etiological factors not well indexed by the BFI

Squeezing the limit: Quantum benchmarks for the teleportation and storage of squeezed states

We derive fidelity benchmarks for the quantum storage and teleportation of squeezed states of continuous variable systems, for input ensembles where the degree of squeezing $s$ is fixed, no information about its orientation in phase space is given, and the distribution of phase space displacements is a Gaussian. In the limit where the latter becomes flat, we prove analytically that the maximal classical achievable fidelity (which is 1/2 without squeezing, for $s=1$) is given by $\sqrt{s}/(1+s)$, vanishing when the degree of squeezing diverges. For mixed states, as well as for general distributions of displacements, we reduce the determination of the benchmarks to the solution of a finite-dimensional semidefinite program, which yields accurate, certifiable bounds thanks to a rigorous analysis of the truncation error. This approach may be easily adapted to more general ensembles of input states.Comment: 19 pages, 4figure

Assessment and diagnosis of Developmental Language Disorder: The experiences of speech and language therapists

© The Author(s) 2019. This article is distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 License (http://www.creativecommons.org/licenses/by-nc/4.0/) which permits non-commercial use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access pages (https://us.sagepub.com/en-us/nam/open-access-at-sage).Background: For many years research and practice have noted the impact of the heterogeneous nature of Developmental Language Disorder (also known as language impairment or specific language impairment) on diagnosis and assessment. Recent research suggests the disorder is not restricted to the language domain and against this background, the challenge for the practitioner is to provide accurate assessment and effective therapy. The language practitioner aims to support the child and their carers to achieve the best outcomes. However, little is known about the experiences of the language practitioner in the assessment process, in contrast to other childhood disorders, yet their expertise is central in the assessment and diagnosis of children with language disorder. Aims: This study aimed to provide a detailed qualitative description of the experiences of speech and language therapists involved in the assessment and diagnosis of children with Developmental Language Disorder. Methods & Procedures: The qualitative study included three focus groups to provide a credible and rich description of the experiences of speech and language therapists involved in the assessment of Developmental Language Disorder. The speech and language therapists who participated in the study were recruited from three NHS Trusts across the UK and all were directly involved in the assessment and diagnosis procedures. The lengths of practitioner experience ranged from 2 years to 38 years. The data was analysed using a thematic analysis in accordance with the principles set out by Braun & Clarke (2006). Outcomes & Results: The data showed a number of key themes concerning the experiences of speech and language therapists in assessing children with Developmental Language Disorder (DLD). These themes ranged from the participants’ experiences of the barriers to early referral, challenges for assessment and the concerns over continued future support. Conclusions & Implications: This study provides first-hand evidence from speech and language therapists in the assessment of children with Developmental Language Disorder, drawing together experiences from language practitioners from different regions. The findings provide insight to the barriers to referral, the potential variations in the assessment process, the role of practitioner expertise and the challenges faced them. The importance of early intervention, useful assessment tools and future support were expressed. Taken together, the results relate to some issues to be addressed on a practical level and a continuing need for initiatives to raise awareness of DLD in the public domain.Peer reviewe