5,225 research outputs found
Weak sex-specific evolution of locomotor activity of Sepsis punctum (Diptera: Sepsidae) thermal experimental evolution lines
Elevated temperatures are expected to rise beyond what the physiology of many organisms can tolerate. Behavioural responses facilitating microhabitat shifts may mitigate some of this increased thermal selection on physiology, but behaviours are themselves mediated by physiology, and any behavioural response may trade-off against other fitness-related activities. We investigated whether experimental evolution in different thermal regimes (Cold: 15 °C; Hot: 31 °C; Intergenerational fluctuation 15/31 °C; Control: 23 °C) resulted in genetic differentiation of standard locomotor activity in the dung fly Sepsis punctum. We assessed individual locomotor performance, an integral part of most behavioral repertoires, across eight warm temperatures from 24 °C to 45 °C using an automated device. We found no evidence for generalist-specialist trade-offs (i.e. changes in the breadth of the performance curve) for this trait. Instead, at the warmest assay temperatures hot-selected flies showed somewhat higher maximal performance than all other, especially cold-selected flies, overall more so in males than females. Yet, the flies' temperature optimum was not higher than that of the cold-selected flies, as expected under the 'hotter-is-better' hypothesis. Maximal locomotor performance merely weakly increased with body size. These results suggest that thermal performance curves are unlikely to evolve as an entity according to theory, and that locomotor activity is a trait of limited use in revealing thermal adaptation
Crisis Management Software: Aspects that affect the usefulness of CIM
Bacheloroppgave i beredskap og krisehĂ„ndtering 2017Kommunenes krisestĂžtteverktĂžy, CIM, er i kommuneundersĂžkelsen til DSB oppgitt Ă„ vĂŠre det blant fem alternativer som styrker samfunnssikkhetsarbeidet minst. UndersĂžkelsen vĂ„r har hatt som formĂ„l Ă„ belyse Ă„rsaker til hvorfor CIM fortsatt ikke nĂždvendigvis oppleves som nyttig. Dette for Ă„ kunne gi indikasjoner pĂ„ hva som kan gjĂžres for Ă„ bedre nytten av verktĂžyet. Ved hjelp av dybdeintervjuer og grounded theory som metodisk tilnĂŠrming har vi funnet at menneskelige faktorer begrenser nytten av et verktĂžy som er normativt sett er virker bedre enn det er i praksis. Vi finner imidlertid ogsĂ„ at flere har opplevelsen av at verktĂžyet ikke er sĂ„ nyttig som det normativt skal vĂŠre, og at det ikke nĂždvendigvis styrker kommunens proaktive tilnĂŠrming til beredskap. Etter Ă„ ha drĂžftet disse funnene, foreslĂ„r vi Ă„ forske mer pĂ„ effekten av bruk av krisestĂžtteverktĂžy, ettersom det er grunn til Ă„ tro at bruken av CIM i kommunene ikke svarer til direktoratets forventing.The Norwegian municipalitiesâ crisis management software, CIM, is in the annual survey from the Norwegian Directorate for Civil Protection reported to be the one among five alternatives that strengthens the work on preparedness the least. The purpose of this thesis is to enlighten why CIM still not necessarily is perceived as very useful and to indicate actions to be taken to improve the usefulness. By in-depth interviews and grounded theory as methodical approach, this thesis finds that human factors can affect the usefulness of a tool that theoretically can be very pertinent. The research also shows that CIM not necessarily contributes to the municipalities proactive approach to preparedness. After discussing these findings, this thesis suggests more research on the effectiveness of tools like CIM, since there is reason to believe that the municipalities use of CIM is not what is expected from the Norwegian Directorate for Civil Protection
A search for stable strange quark matter nuggets in helium
A search for stable strange quark nuggets has been conducted in helium and
argon using a high sensitivity mass spectrometer. The search was guided by a
mass formula for strange quark nuggets which suggested that stable strange
helium might exist at a mass around 65 u. The chemical similarity of such
``strangelets'' to noble gas atoms and the gravitational unboundedness of
normal helium result in a large enhancement in the sensitivity of such a
search. An abundance limit of no more than strangelets per
normal nucleus is imposed by our search over a mass region from 42 to 82 u,
with much more stringent limits at most (non-integer) masses.Comment: 11 pages RevTeX, Accepted for publication in Physics Letters B. 2
updated references added. Air abundance to cosmic abundance ratios now
reflect updated references. No change in results or figures. Also see
ftp://www-physics.mps.ohio-state.edu/pub/nucex/sq
Perfluoroalkyl acids (PFAAs) in childrenâs serum and contribution from PFAA-contaminated drinking water
We investigated associations between serum perfluoroalkyl acid (PFAA) concentrations in children aged 4, 8, and 12 years (sampled in 2008â2015; n = 57, 55, and 119, respectively) and exposure via placental transfer, breastfeeding, and ingestion of PFAA-contaminated drinking water. Sampling took place in Uppsala County, Sweden, where the drinking water has been historically contaminated with perfluorobutanesulfonate (PFBS), perfluorohexanesulfonate (PFHxS), perfluorooctanesulfonate (PFOS), perfluoroheptanoate (PFHpA), and perfluorooctanoate (PFOA). PFOS showed the highest median concentrations in serum (3.8â5.3 ng gâ1 serum), followed by PFHxS (1.6â5.0 ng gâ1 serum), PFOA (2.0â2.5 ng gâ1 serum), and perfluorononanoate (PFNA) (0.59â0.69 ng gâ1 serum) in children. Including all children, serum PFOA, PFHxS, and PFOS concentrations in children increased 10, 10, and 1.3% (adjusted mean), respectively, per unit (ng gâ1 serum) of increase in the maternal serum level (at delivery), the associations being strongest for 4 year-old children. PFHxS and PFOS significantly increased 3.9 and 3.8%, respectively, per month of nursing, with the highest increase for 4 year-olds. PFOA, PFBS, PFHxS, and PFOS increased 1.2, 207, 7.4, and 0.93%, respectively, per month of cumulative drinking water exposure. Early life exposure to PFOA, PFHxS, and PFOS is an important determinant of serum concentrations in children, with the strongest influence on younger ages. Drinking water with low to moderate PFBS, PFHxS, PFOS, and PFOA contamination is an important source of exposure for children with background exposure from other sources
Analysis of a time-lens based optical frame synchronizer and retimer for 10G Ethernet aiming at a Tb/s optical router/switch design
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