211 research outputs found
Short-Term Feedback Regulation of cAMP by Accelerated Degradation in Rat Tissues
A recent study showed that cAMP analogs lowered cAMP levels in rat hepatocytes. The present work demonstrates that cAMP analogs also lowered cAMP in a rapid, concentration-dependent manner in heart and fat cells. In order to determine if the cAMP-dependent protein kinase mediated this effect, techniques were developed to assay the protein kinase activity ratio in hepatocytes treated with cAMP analogs. The activation of protein kinase and phosphorylase in hepatocytes by 8-pClΦS-cAMP (where 8-pClΦS- indicates 8-parachlorothiophenyl-) was concentration-dependent and occurred in parallel to proportionate decreases in cAMP. More than 20% of the cAMP binding sites on the protein kinase were unoccupied at concentrations of 8-pClΦS-cAMP that produced maximal cAMP lowering. Thus, the possibility that 8-pClΦS-cAMP lowered cAMP by displacing it from protein kinase binding sites, making it available for hydrolysis, seemed unlikely. In adipocytes, the lowering of cAMP by 8-pClΦS-cAMP occurred in parallel with increases in lipolysis and activation of low K(m) phosphodiesterase, suggesting that the phosphodiesterase was responsible for the cAMP lowering. Further evidence for this assertion was the finding that in hepatocytes preloaded with low concentrations of 8-pClΦS-cAMP, glucagon lowered 8-pClΦS-cAMP by about 50%, an amount similar to the cAMP lowering observed with 8-pClΦS-cAMP treatment. The results were consistent with a cAMP-dependent protein kinase-catalyzed activation of a phosphodiesterase and suggested that 8-pClΦS-cAMP-mediated hydrolysis of cAMP mimicked a physiologically significant response. The observation of this phenomenon in several tissues further suggested that it may a general mechanism for dampening and terminating the hormonal signal through accelerated degradation of cAMP
Images in Christmas Balls
We describe light-reflection properties of spherically curved mirrors, like
balls in the Christmas tree. In particular, we study the position of the image
which is formed somewhere beyond the surface of a spherical mirror, when an eye
observes the image of a pointlike light source. The considered problem,
originally posed by Abu Ali Hasan Ibn al-Haitham -- alias Alhazen -- more than
a millennium ago, turned out to have the now well known analytic solution of a
biquadratic equation, being still of great relevance, e.g. for the
aberration-free construction of telescopes. We do not attempt to perform an
exhaustive survey of the rich historical and engineering literature on the
subject, but develop a simple pedagogical approach to the issue, which we
believe to be of continuing interest in view of its maltreating in many
high-school textbooks.Comment: 13 pages, 7 figures plain LaTeX; Also see
http://cft.fis.uc.pt/eef/mirrors.htm, revised version has simplified
formulas, more transparent for a wider audience, one reference adde
The Ursinus Weekly, February 17, 1964
Preparations in final stage for Four Freshmen concert • Asian students: APO will begin to collect books for foundation • Evolution and world federalism to be topic of Dr. Charles Price • Art exhibit set for weekend • Summer job opportunities • Three sororities begin Spring rush • Traditional Lorelei turnabout held; Dance king crowned, Whitians presented • Freshman pre-med views Christian concept of unity • Women to receive colors Thursday • English Club to hear Harvard poet • Editorial: A bit of discretion, please; Ursinus big time; Apology • Sub-species new theory of race evolution • Review of books • Letters to the editor • After one week the acting Dean: Dr. Vorrath speaks • Lincoln University students featured at Kaffee Klatsch: A well-attended affair • Greek gleanings • Impending crisis in our American railroads: Part two • Grapplers decision Hopkins after bowing at E-town • UC cagers success at PMC, bunglers at Swarthmore • WC drops Ursinus cagettes, 50-31 • Women trounce opponents in season openerhttps://digitalcommons.ursinus.edu/weekly/1264/thumbnail.jp
Student’s Perceptions of Spiritual Preparedness and Contribution to their Community Following An Emergency Preparedness Interprofessional Collaborative Practice Simulation
This presentation highlights findings from a study exploring student perceptions of spirituality and contributing to their community after participating in an emergency preparedness interprofessional simulation. Mixed methods were utilized and an online survey was emailed to a convenience sample (N=338). The majority self-reported they can better contribute to their community
Leptin-induced lipolysis opposes the tonic inhibition of endogenous adenosine in white adipocytes
The aim of the present study was to gain insight into the signaling pathway used
by leptin to stimulate lipolysis. The lipolytic rate of white adipocytes from
sex- and age-matched lean (+/+) and fa/fa rats was determined in the absence or
presence of leptin together with a number of agents acting at different levels of
the signaling cascade. Leptin did not modify FSK-, dbcAMP-, and IBMX-stimulated
lipolysis. Lipolysis can also be maximally stimulated by lowering media adenosine
levels with adenosine deaminase (ADA), i.e., in the ligand-free state. Although
ADA produced near maximal lipolysis in adipocytes of lean animals, only half of
the maximal lipolytic rate (50.9+/-3.2%) was achieved in fat cells from fa/fa
rats (P=0.0034). In adipocytes from lean animals preincubated with ADA, leptin
caused a concentration-related stimulation of lipolysis (P=0.0001). However,
leptin had no effect on the lipolytic activity of adipocytes in the ligand-free
state from fa/fa rats. The adenosine A1 receptor agonist CPA effectively
inhibited basal lipolysis in both lean and obese adipocytes (P=0.0001 and
P=0.0090, respectively). Leptin had no effect on the lipolytic rate of adipocytes
isolated from fa/fa rats and preincubated with CPA. When adipocytes were
incubated with the A1 receptor antagonist DPCPX, a significant increase in
glycerol release was observed in fa/fa fat cells (P=0.009), whereas cells
isolated from lean rats showed no differences to ADA-stimulated lipolysis. After
pretreatment with PTX, which inactivates receptor-mediated Gi function,
adipocytes of obese rats became as responsive to the stimulatory actions of ISO
as cells from lean rats (P=0.0090 vs. ISO in fa/fa rats; P=0.2416 vs. lean rats,
respectively). PTX treatment of lean cells, however, did not alter their response
to this lipolytic agent. It can be concluded that the lipolytic effect of leptin
is located at the adenylate cyclase/Gi proteins level and that leptin-induced
lipolysis opposes the tonic inhibition of endogenous adenosine in white
adipocytes
Characterizing Bufferbloat and its Impact at End-hosts
Part 2: Performance at the EdgeInternational audienceWhile buffers on forwarding devices are required to handle bursty Internet traffic, overly large or badly sized buffers can interact with TCP in undesirable ways. This phenomenon is well understood and is often called “bufferbloat”. Although a number of previous studies have shown that buffering (particularly, in home) can delay packets by as much as a few seconds in the worst case, there is less empirical evidence of tangible impacts on end-users. In this paper, we develop a modified algorithm that can detect bufferbloat at individual end-hosts based on passive observations of traffic. We then apply this algorithm on packet traces collected at 55 end-hosts, and across different network environments. Our results show that 45 out of the 55 users we study experience bufferbloat at least once, 40% of these users experience bufferbloat more than once per hour. In 90% of cases, buffering more than doubles RTTs, but RTTs during bufferbloat are rarely over one second. We also show that web and interactive applications, which are particularly sensitive to delay, are the applications most often affected by bufferbloat
Studies on the antiobesity effect of zinc-α2-glycoprotein in the ob/ob mouse
OBJECTIVE: To investigate the mechanism of the lipid depletion by zinc-a(2)-glycoprotein (ZAG). DESIGN: Studies were conducted in the ob/ob mouse, or on isolated adipocytes from these animals or their lean counterparts. RESULTS: Treatment of these animals for 15 days with ZAG (100? µg, intravenously, daily) resulted in a reduction of body weight of 6.55? g compared with phosphate-buffered saline-treated controls, without a change in food or water intake, but with a 0.4?°C rise in rectal temperature. ZAG-treated mice had a 30% reduction in carcass fat mass and a twofold increase in weight of brown adipose tissue. Epididymal adipocytes from ZAG-treated mice showed an increased expression of ZAG and hormone-sensitive lipase (HSL), and this was maintained for a further 3 days in the absence of ZAG. There was an increased lipolytic response to isoproterenol, which was retained for 3 days in vitro in the absence of ZAG. Expression of HSL was also increased in subcutaneous and visceral adipose tissue, as was also adipose triglyceride lipase (ATGL). There was a rapid loss of labelled lipid from epididymal adipose tissue of ZAG-treated mice, but not from the other depots, reflecting the difference in sensitivity to lipolytic stimuli. The increased expression of HSL and ATGL may involve the extracellular signal-regulated kinase (ERK) pathway, as the active (phospho) form was upregulated in all adipose depots after ZAG administration, whereas in vitro studies showed induction of HSL and ATGL by ZAG to be attenuated by PD98059, an inhibitor of the ERK pathway. CONCLUSION: These results suggest that ZAG not only induces direct lipolysis, but also sensitizes adipose tissue to other lipolytic stimuli
Identifying invasive species threats, pathways, and impacts to improve biosecurity
Managing invasive species with prevention and early-detection strategies can avert severe ecological and economic impacts. Horizon scanning, an evidence-based process combining risk screening and consensus building to identify threats, has become a valuable tool for prioritizing invasive species management and prevention. We assembled a working group of experts from academic, government, and nonprofit agencies and organizations, and conducted a multi-taxa horizon scan for Florida, USA, the first of its kind in North America. Our primary objectives were to identify high-risk species and their introduction pathways, to detail the magnitude and mechanism of potential impacts, and, more broadly, to demonstrate the utility of horizon scanning. As a means to facilitate future horizon scans, we document the process used to generate the list of taxa for screening. We evaluated 460 taxa for their potential to arrive, establish, and cause negative ecological and socioeconomic impacts, and identified 40 potential invaders, including alewife, zebra mussel, crab-eating macaque, and red swamp crayfish. Vertebrates and aquatic invertebrates posed the greatest invasion threat, over half of the high-risk taxa were omnivores, and there was high confidence in the scoring of high-risk taxa. Common arrival pathways were ballast water, biofouling of vessels, and escape from the pet/aquarium/horticulture trade. Competition, predation, and damage to agriculture/forestry/aquaculture were common impact mechanisms. We recommend full risk analysis for the high-risk taxa; increased surveillance at Florida's ports, state borders, and high-risk pathways; and periodic review and revision of the list. Few horizon scans detail the comprehensive methodology (including list-building), certainty estimates for all scoring categories and the final score, detailed pathways, and the magnitude and mechanism of impact. Providing this information can further inform prevention efforts and can be efficiently replicated in other regions. Moreover, harmonizing methodology can facilitate data sharing and enhance interpretation of results for stakeholders and the general public.</p
Effect of invader removal: pollinators stay but some native plants miss their new friend
Removal of invasive species often benefits
biological diversity allowing ecosystems’ recovery.
However, it is important to assess the functional roles
that invaders may have established in their new areas
to avoid unexpected results from species elimination.
Invasive animal-pollinated plants may affect the
plant–pollination interactions by changing pollinator
availability and/or behaviour in the community. Thus,
removal of an invasive plant may have important
effects on pollinator community that may then be
reflected positive or negatively on the reproductive
success of native plants. The objective of this study
was to assess the effect of removing Oxalis pescaprae,
an invasive weed widely spread in the
Mediterranean basin, on plant–pollinator interactions
and on the reproductive success of co-flowering native
plants. For this, a disturbed area in central Portugal,
where this species is highly abundant, was selected.
Visitation rates, natural pollen loads, pollen tube
growth and natural fruit set of native plants were
compared in the presence of O. pes-caprae and after
manual removal of their flowers. Our results showed a
highly resilient pollination network but also revealed
some facilitative effects of O. pes-caprae on the
reproductive success of co-flowering native plants.
Reproductive success of the native plants seems to
depend not only on the number and diversity of floral
visitors, but also on their efficiency as pollinators. The
information provided on the effects of invasive species
on the sexual reproductive success of natives is
essential for adequate management of invaded areas.This work is financed by FEDER funds through the
COMPETE Program and by Portuguese Foundation for Science
and Technology (FCT) funds in the ambit of the project PTDC/
BIA-BIC/110824/2009, by CRUP Acc¸o˜es Integradas Luso-
Espanholas 2010 with the project E10/10, by MCI-Programa de
Internacionalizacio´n de la I ? D (PT2009-0068) and by the
Spanish DGICYT (CGL2009-10466), FEDER funds from the
European Union, and the Xunta de Galicia (INCITE09-
3103009PR). FCT also supported the work of S. Castro (FCT/
BPD/41200/2007) and J. Costa (CB/C05/2009/209; PTDC/
BIA-BIC/110824/2009). The work of V. Ferrero was supported
by the Fundacio´n Ramo´n Areces
The quality of options in strategic decision making: a study about creativity and completeness in business decision making
A qualidade das decisões estratégicas dos empresários está diretamente relacionada
à capacidade que eles demonstram para encontrar alternativas criativas
quando enfrentam os problemas de suas empresas. Essas alternativas podem
ser geradas intuitivamente, utilizando heurísticas. As pesquisas sobre geração
de alternativas têm indicado consistentemente que as pessoas não são eficientes
nessa atividade. As explicações para esse fato, contidas na literatura sobre
decisão, não são conclusivas e permitem especulações a respeito. Para explorar
essa questão e relacioná-la ao administrador brasileiro, foi idealizado um experimento
com 174 alunos de quatro cursos de MBA para avaliar a originalidade
e a completude das alternativas. O experimento e a respectiva análise basearam-se
na confluência da pesquisa experimental, oriunda da psicologia cognitiva
da decisão, com as visões da ciência da decisão organizacional tradicional e o
novo campo de estudo das decisões intuitivas ou naturalísticas. Para mensurar a
criatividade das alternativas apresentadas durante o experimento, empregou-se
o conceito de árvore hierárquica, que demonstrou ser uma poderosa ferramenta
para a tipologia de alternativas. O resultado desse experimento confirmou o
baixo desempenho em geração de alternativas dos gerentes e, ao mesmo tempo,
indicou que, provavelmente, a etapa de geração de alternativas isolada da etapa
de escolha pode melhorar a qualidade das alternativas. A heurística, por sua vez,
não demonstrou influenciar o conjunto de alternativas geradas. _________________________________________________________________________________________ ABSTRACT: The quality of strategic decisions of executives is directly related to the ability they
have to find creative alternatives when facing business problems. These alternatives could be generated intuitively, using heuristics. On the other hand, the
researches on alternatives generation have consistently indicated that people are
not efficient on this duty. The argument for that, contained in the decision’s literature,
is not conclusive and it allows speculation about it. To explore this issue
and relate it to the Brazilian Administration, an experiment was designed for 174
students of four courses of MBA. The experiment and the analysis were resulted
from the confluence between the experimental research from decision cognitive
psychology with science’s vision of the traditional organizational decision and the
new field of study on naturalistic or intuitive decisions. To measure the creativity
of the alternatives presented during the experiment, the concept of hierarchical
tree was utilized and it has proved a powerful tool to the typology of alternatives.
The result of this experiment confirmed the poor performance in alternatives
generation by managers and at the same time, indicated that probably, the generation
of options isolated of analysis can produce better quality of alternatives.
The heuristic, do not demonstrated any influence on options generated
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