364 research outputs found
Using the J1-J2 Quantum Spin Chain as an Adiabatic Quantum Data Bus
This paper investigates numerically a phenomenon which can be used to
transport a single q-bit down a J1-J2 Heisenberg spin chain using a quantum
adiabatic process. The motivation for investigating such processes comes from
the idea that this method of transport could potentially be used as a means of
sending data to various parts of a quantum computer made of artificial spins,
and that this method could take advantage of the easily prepared ground state
at the so called Majumdar-Ghosh point. We examine several annealing protocols
for this process and find similar result for all of them. The annealing process
works well up to a critical frustration threshold.Comment: 14 pages, 13 figures (2 added), revisions made to add citations and
additional discussion at request of referee
Limitations in Predicting Radiation-Induced Pharmaceutical Instability during Long-Duration Spaceflight
As human spaceflight seeks to expand beyond low-Earth orbit, NASA and its
international partners face numerous challenges related to ensuring the safety
of their astronauts, including the need to provide a safe and effective
pharmacy for long-duration spaceflight. Historical missions have relied upon
frequent resupply of onboard pharmaceuticals; as a result, there has been
little study into the effects of long-term exposure of pharmaceuticals to the
space environment. Of particular concern are the long-term effects of space
radiation on drug stability, especially as missions venture away from the
protective proximity of the Earth. Here we highlight the risk of space
radiation to pharmaceuticals during exploration spaceflight, identifying the
limitations of current understanding. We further seek to identify ways in which
these limitations could be addressed through dedicated research efforts aimed
towards the rapid development of an effective pharmacy for future spaceflight
endeavors.Comment: in press, Nature Microgravit
Murine ethanol ingestion promotes hepatic platelet accumulation mimicking acute Ccl₄ exposure
Background: Dysregulated coagulation contributes to inflammation and fibrosis from chemical injury. Platelets are key contributors to inflammation and are primary sources of TGF-b, PDGF, and EGF that promote fibrosis, and so may contribute to hepatic fibrosis. We questioned whether platelets accumulate during chronic ethanol- or chemical-induced hepatic injury, whether platelet accumulation would occur prior to induction of hepatic fibrotic responses, and whether platelet accumulation reflects deposition of intravascular microthrombi or individual platelets intercalated into liver parenchyma.Methods: We modeled acute hepatic injury with a single injection of CCl₄, a chronic model of moderate ethanol ingestion, or a combination of the two insults. C57Bl6 mice ingested a control liquid diet or provided free access to 1% ethanol (2d), then 2% ethanol (2d, 11% calories). At day 4, mice received, or not, a single i.p. injection of CCl₄ (1 μl/g, 1:3 in olive oil), with sacrifice 72h later. Formalin-fixed livers were transversely sectioned, paraffin-embedded prior to immunohistochemistry with anti platelet integrin gpIIb (CD41), endothelial CD31, or a-smooth muscle actin (aSMA) antibodies with DAPI nuclear staining. Adherent platelets spread to micron thickness, so detection was by serial tyramide amplification (Biotium). This catalyzed reporter deposition system uses a single tyramide dye activated by HRP-derived H₂O₂ to a reactive specie that multiply ligates adjacent molecules before the antibody complex is thermally stripped prior to a subsequent tyramide labeling.Results: Our preliminary data show basal parenchymal platelet deposition with inflammation 24h after CCl₄ injection massively increasing platelet accumulation, with enhanced expression of aSMA, just below the outer Glisson’s sheath encasement, correlating to the area of highest arterial flow (DOI 10.1139/y93- 018). Platelet accumulation, but not aSMA, within liver parenchyma was modestly increased at this time. 72h after CCl₄ injection, subsurface platelet accumulation in association with endothelial cell PECAM1 remained apparent, with aSMA now extended in disordered filaments surrounding portal tracts. Ethanol ingestion alone, similar to CCl₄ exposure, revealed massive platelet accumulation just below the Glisson’s sheath liver encasement in association with endothelial cell PECAM1 without aSMA deposition. The combination of ethanol and CCl₄ presented similarly.Conclusions: We conclude ethanol ingestion promotes hepatic platelet accumulation, providing a nontranscriptional source of fibrotic growth factors, that parallels hepatic injury invoked by CCl₄ exposure
MsFLASH Participants’ Priorities for Alleviating Menopausal Symptoms
Objective To describe self-reported menopausal symptom priorities and their association with demographics and other symptoms among participants in an intervention trial for vasomotor symptoms (VMS).
Methods Cross-sectional study embedded in the MsFLASH 02 trial, a three-by-two factorial design of yoga vs. exercise vs. usual activity and omega-3-fatty acid vs. placebo. At baseline, women (n = 354) completed hot flush diaries, a card sort task to prioritize symptoms they would most like to alleviate, and standardized questionnaires.
Results The most common symptom priorities were: VMS (n = 322), sleep (n = 191), concentration (n = 140), and fatigue (n = 116). In multivariate models, women who chose VMS as their top priority symptom (n = 210) reported significantly greater VMS severity (p = 0.004) and never smoking (p = 0.012), and women who chose sleep as their top priority symptom (n = 100) were more educated (p ≤ 0.001) and had worse sleep quality (p < 0.001). ROC curves identified sleep scale scores that were highly predictive of ranking sleep as a top priority symptom.
Conclusions Among women entering an intervention trial for VMS and with relatively low prevalence of depression and anxiety, VMS was the priority symptom for treatment. A card sort may be a valid tool for quickly assessing symptom priorities in clinical practice and research
The Reputational Consequences of Failed Replications and Wrongness Admission among Scientists
Scientists are dedicating more attention to replication efforts. While the scientific utility of replications is unquestionable, the impact of failed replication efforts and the discussions surrounding them deserve more attention. Specifically, the debates about failed replications on social media have led to worry, in some scientists, regarding reputation. In order to gain data-informed insights into these issues, we collected data from 281 published scientists. We assessed whether scientists overestimate the negative reputational effects of a failed replication in a scenario-based study. Second, we assessed the reputational consequences of admitting wrongness (versus not) as an original scientist of an effect that has failed to replicate. Our data suggests that scientists overestimate the negative reputational impact of a hypothetical failed replication effort. We also show that admitting wrongness about a non-replicated finding is less harmful to one’s reputation than not admitting. Finally, we discovered a hint of evidence that feelings about the replication movement can be affected by whether replication efforts are aimed one’s own work versus the work of another. Given these findings, we then present potential ways forward in these discussions
Long-term Site Fidelity and Individual Home Range Shifts in Lophocebus albigena
We investigated long-term site fidelity of gray-cheeked mangabey (Lophocebus albigena) groups in Kibale National Park, Uganda. Concurrently, we monitored shifts in home range by individual females and subadult and adult males. We documented home range stability by calculating the area of overlap in successive years, and by recording the drift of each group’s monthly centroid from its initial location. Home ranges remained stable for 3 of our 4 groups (overlap over 10 yr >60%). Core areas were more labile, but group centroids drifted an average of only 530 m over the entire decade. Deviations from site fidelity were associated with dispersal or group fission. During natal dispersal, subadult males expanded their home ranges over many months, settling ≤4 home ranges away. Adult males, in contrast, typically dispersed within a few days to an adjacent group in an area of home range overlap. Adult males made solitary forays, but nearly always into areas used by their current group or by a group to which they had previously belonged. After secondary dispersal, they expanded their ranging in the company of their new group, apparently without prior solitary exploration of the new area. Some females also participated in home range shifts. Females shifted home ranges only within social groups, in association with temporary or permanent group splits. Our observations raise the possibility that male mangabeys use a finder-joiner mechanism when moving into new home ranges during secondary dispersal. Similarly, females might learn new resource locations from male immigrants before or during group fission
Demography and Life Histories of Sympatric Patas Monkeys, Erythrocebus patas, and Vervets, Cercopithecus aethiops, in Laikipia, Kenya
Mortality patterns are thought to be strong selective forces on life history traits, with high adult mortality and low immature mortality favoring early and rapid reproduction. Patas monkeys (Erythrocebus patas) have the highest potential rates of population increase for their body size of any haplorhine primate because they reproduce both earlier and more often. We report here 10 yr of comparative demographic data on a population of patas monkeys and a sympatric population of vervet monkeys (Cercopithecus aethiops), a closely related species differing in aspects of social system, ecology, and life history. The data reveal that 1) adult female patas monkeys have significantly higher mortality than adult female vervets; 2) infant mortality in patas monkeys is relatively low compared to the norm for mammals because it is not significantly different from that of adult female patas monkeys; and 3) infant mortality is significantly higher than adult female mortality in vervets. For both species, much of the mortality could be attributed to predation. An epidemic illness was also a major contributor to the mortality of adult female patas monkeys whereas chronic exposure to pathogens in a cold and damp microenvironment may have contributed to the mortality of infant vervets. Both populations experienced large fluctuations during the study period. Our results support the prediction from demographic models of life history evolution that high adult mortality relative to immature mortality selects for early maturation
The Curse of Online Friends: The Detrimental Effects of Online Social Network Usage on Well-Being
In the pursuit of happiness, it has been conventionally accepted that more friends would bring us a better quality of life. However, with the advent of social networking sites, unprecedented social influence has pervaded our daily lives. Across two studies we show that even though people feel more satisfied with their lives when they view the friends added on Facebook, reading friends’ posts reduces their well-being. This is because the more friends people have on Facebook, the more ostentatious information they see. The resultant drop in life satisfaction occurs because people fail to draw a connection between the number of friends and the amount of ostentatious information. Moreover, this decrease in life satisfaction is mediated by envy. We contribute to the literature on consumer well-being by identifying a novel and ubiquitous phenomenon of making social comparisons with hundreds of people, a phenomenon that arose with the advent of social networking and was previously outside the scope of social comparison literature
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