3,750 research outputs found
When Is Employee Blogging Protected by Section 7 of the NLRA?
The National Labor Relations Act forbids employers from retaliating against certain types of employee speech or intimidating those who engage in it. This iBrief examines how blogging fits into the current statutory framework and recommends how the National Labor Relations Board and the courts should address the unique features of employee blogs
Do agonistic behaviours bias baited remote underwater video surveys of fish?
Marine environments require monitoring to determine the effects of impacts such as climate change, coastal development and pollution and also to assess the effectiveness of conservation measures. Marine protected areas (MPAs) are being established globally and require periodic monitoring to determine whether their objectives are being met. Baited underwater video systems are becoming a popular method for monitoring change within protected fish populations, because they are less damaging to habitats than bottom trawling and allow for more statistical powerful comparisons to determine spatial and temporal patterns in the relative abundances, lengths and biomass of demersal and pelagic fishes. However, much remains uncertain about how interactions between the fish and bait and between the fish themselves affect the results obtained. Agonistic behaviours are frequently observed around the bait of the camera and potentially bias fish density estimates by altering the number and size classes seen at cameras. Here we counted the number of agonistic behaviours between pink snappers (Pagrus auratus), the size of fish involved and whether the fish left the field of view following such behaviours. The study consisted of 20 baited underwater video deployments inside a New Zealand marine reserve and 20 in adjacent open areas. We observed a significant relationship between the peak number of fish observed at the camera and the total number of agonistic behaviours, as well as the number of both aggressor and subordinate fish leaving the camera field of view following interactions. The slope of the latter relationship and thus the absolute numbers of fish leaving were higher for subordinate fish. As subordinates were significantly smaller than aggressors, the apparent size frequency distribution is likely skewed away from smaller size classes. The staying time of the fish and thus the maximum number of fish present at the camera will be reduced by agonistic behaviours and the absolute magnitude of this effect appears to be greater at high fish densities. Our results suggest that an overall effect of these phenomena is to underestimate the differences in abundance between MPAs and open areas, but also to overestimate differences in average size
Possible male infanticide in wild orangutans and a re-evaluation of infanticide risk
Infanticide as a male reproductive tactic is widespread across mammals, and is particularly prevalent in catarrhine primates. While it has never been observed in wild orangutans, infanticide by non-sire males has been predicted to occur due to their extremely long inter-birth intervals, semi-solitary social structure, and the presence of female counter-tactics to infanticide. Here, we report on the disappearance of a healthy four-month-old infant, along with a serious foot injury suffered by the primiparous mother. No other cases of infant mortality have been observed at this site in 30 years of study. Using photographic measurements of the injury, and information on the behavior and bite size of potential predators, we evaluate the possible causes of this injury. The context, including the behavior of the female and the presence of a new male at the time of the injury, lead us to conclude that the most likely cause of the infant loss and maternal injury was male infanticide. We suggest that in orangutans, and other species where nulliparous females are not preferred mates, these females may be less successful at using paternity confusion as an infanticide avoidance tactic, thus increasing the likelihood of infanticide of their first-born infants.Published versio
Optical spectroscopy of radio galaxies in the 7C Redshift Survey
We present optical spectroscopy of all 49 radio galaxies in the 7C-I and
7C-II regions of the 7C Redshift Survey (7CRS). The low-frequency (151 MHz)
selected 7CRS sample contains all sources with flux-densities S_151 > 0.5 Jy in
three regions of the sky; 7C-I and 7C-II were chosen to overlap with the 5C6
and 5C7 surveys respectively, and cover a total sky area of 0.013 sr. The
sample has been completely identified and spectroscopy of the quasars and
broad-lined radio galaxies has been presented in Willott et al. (1998). Only
seven of the radio galaxies do not have redshift determinations from the
spectroscopy, giving a redshift completeness for the sample of >90%. The median
redshift of the 7CRS is 1.1. We present a composite 0.2<z<0.8 7CRS radio galaxy
spectrum and investigate the strengths of the 4000 Angstrom breaks in these
radio galaxies. We find an anti-correlation between the 4000 Angstrom break
strength and emission line luminosity, indicating that departures from old
elliptical galaxy continuum shapes are most likely due to non-stellar emission
associated with the active nucleus.Comment: 14 pages, 6 figures, MNRAS in pres
Galerkin spectral estimation of vortex-dominated wake flows
We propose a technique for performing spectral (in time) analysis of
spatially-resolved flowfield data, without needing any temporal resolution or
information. This is achieved by combining projection-based reduced-order
modeling with spectral proper orthogonal decomposition. In this method,
space-only proper orthogonal decomposition is first performed on velocity data
to identify a subspace onto which the known equations of motion are projected,
following standard Galerkin projection techniques. The resulting reduced-order
model is then utilized to generate time-resolved trajectories of data. Spectral
proper orthogonal decomposition (SPOD) is then applied to this model-generated
data to obtain a prediction of the spectral content of the system, while
predicted SPOD modes can be obtained by lifting back to the original velocity
field domain. This method is first demonstrated on a forced, randomly generated
linear system, before being applied to study and reconstruct the spectral
content of two-dimensional flow over two collinear flat plates perpendicular to
an oncoming flow. At the range of Reynolds numbers considered, this
configuration features an unsteady wake characterized by the formation and
interaction of vortical structures in the wake. Depending on the Reynolds
number, the wake can be periodic or feature broadband behavior, making it an
insightful test case to assess the performance of the proposed method. In
particular, we show that this method can accurately recover the spectral
content of periodic, quasi-periodic, and broadband flows without utilizing any
temporal information in the original data. To emphasize that temporal
resolution is not required, we show that the predictive accuracy of the
proposed method is robust to using temporally-subsampled data.Comment: 35 pages, 12 figure
Google EarthÂź Models with COLLADA and WxAzygyÂź Transparent Interface: An example from Grotto Creek, Front Ranges, Canadian Cordillera
Virtual globes represent a paradigm shift for geoscience education. It is now possible to explore real world experiences across the entire Earth, the Moon, and Mars, and also to combine multiple 2-D images into one 3-D image with topography. Models viewed in Google EarthÂź are more intuitive for visualizing 3-D geological structures than traditional paper maps and cross-sections. Here a student-constructed geological map and cross-sections from an introductory field school are used to illustrate the creation of a draped geological map over topography. A custom vertical slider elevates the cross-sections above topography and a horizontal slider restores thrust faulting. Models located in situ in topography are made queryable via a âcut-awayâ using the WxAzygyÂź transparent interface.SOMMAIRE La notion de « globes virtuels » constitue un changement de paradigme dans le domaine de lâĂ©ducation en gĂ©oscience. Il est maintenant possible de traiter de la rĂ©alitĂ© de tous les recoins de la Terre, de la lune et de Mars, et aussi de combiner de multiples images 2-D en une image 3-D affichant la topographie. Les modĂšles de Google EarthÂź permettent une visualisation 3-D plus intuitive des structures gĂ©ologiques que ne le permettent les cartes papiers usuelles et les coupes. Dans la prĂ©sente, une carte gĂ©ologique et une coupe rĂ©alisĂ©es par un Ă©tudiant dâun cours dâintroduction au travail de terrain sont utilisĂ©es pour illustrer la confection dâune carte gĂ©ologique appliquĂ©e sur la topographie correspondante. Un curseur vertical personnalisĂ© dessine les coupes au-dessus de la topographie, et un curseur horizontal permet de restaurer les failles de chevauchement. Ces modĂšles ancrĂ©s au droit de la topographie peuvent ĂȘtre exploiter au moyen dâun Ă©corchĂ© produit par lâinterface transparent WxAzygyÂź
EMG-Driven inverse dynamic analysis of knee contact forces during gait and cycling using OpenSim
Joint contact forces determine the loading experienced by cartilage tissue and, thus, may be used to predict risk of cartilage tissue damage and osteoarthritis (OA). Participating in low impact and/or non-weight bearing activities such as cycling may help reduce knee OA risk by limiting forces exerted during exercise [1]. Cycling is a common recommendation for rehabilitative or fitness sustainment exercise for select patients [1]. Although knee joint contact forces have been directly measured in gait and cycling using instrumented knee implants [2,3] and calculated in gait using EMG-driven analysis [4]; they have not been calculated in cycling using EMG-driven analysis.
The long-term goal of this study is to identify weight control exercises for overweight (OW) and obese (OB) subjects that minimize OA risk. This current study tests the hypothesis that knee joint contact forces are significantly lower during cycling than gait. The objectives are to: (1) conduct motion analysis experiments and EMG-driven OpenSim analyses for gait and cycling, (2) compare predicted tibiofemoral (TF) contact forces to published values, and (3) test for significant differences in maximum TF compressive forces in gait and cycling
Plasma PLP Concentration and Depressive Symptomatology, over time, in older Latino Adults
Background: Low vitamin B-6 status has been linked to depressive symptomatology. However, most studies have been cross-sectional and may not have controlled for relevant confounders. Few studies have examined this association in Latino populations at high risk for major depression.
Design: We used two-level hierarchical linear regression models (HLM) for continuous outcomes. Level-1 data included three measures of participantâs depressive symptomatology collected at baseline, 2y follow-up and 5y follow-up. Participants constituted level-2 data. Vitamin B-6 was associated with depressive symptomatology across these time points.
Objective: We examined the longitudinal association of vitamin B-6 status with depressive symptomatology across 3 time points over ~ 5-7 y in a cohort of older Puerto Rican adults, a population previously identified to be at high risk for depressive symptomatology and clinical depression.
Results: Plasma pyridoxyl-5â-phosphate (PLP) concentration, a time-varying predictor, was significantly associated with depressive symptomatology. Study participants with PLP deficiency, vs. optimal PLP, had higher baseline depressive symptoms (22±14, vs. 20±13); this differential remained constant over time and persisted after controlling for age, sex, education, BMI, smoking and alcohol use, other relevant nutritional factors, perceived stress, stressful life events and allostatic load; and use of antidepressant medication. However, PLP concentration was not associated with the rate of change in depressive symptomatology over time.
Conclusions: Suboptimal plasma PLP is associated with higher depressive symptomatology in older Puerto Rican adults and this appears to persist over time. Our data suggest that identification and treatment of vitamin B-6 deficiency may be a useful preventive and intervention approach in this population
Dynamic association between perfusion and white matter integrity across time since injury in Veterans with history of TBI.
ObjectiveCerebral blood flow (CBF) plays a critical role in the maintenance of neuronal integrity, and CBF alterations have been linked to deleterious white matter changes. Although both CBF and white matter microstructural alterations have been observed within the context of traumatic brain injury (TBI), the degree to which these pathological changes relate to one another and whether this association is altered by time since injury have not been examined. The current study therefore sought to clarify associations between resting CBF and white matter microstructure post-TBI.Methods37 veterans with history of mild or moderate TBI (mmTBI) underwent neuroimaging and completed health and psychiatric symptom questionnaires. Resting CBF was measured with multiphase pseudocontinuous arterial spin labeling (MPPCASL), and white matter microstructural integrity was measured with diffusion tensor imaging (DTI). The cingulate cortex and cingulum bundle were selected as a priori regions of interest for the ASL and DTI data, respectively, given the known vulnerability of these regions to TBI.ResultsRegression analyses controlling for age, sex, and posttraumatic stress disorder (PTSD) symptoms revealed a significant time since injury Ă resting CBF interaction for the left cingulum (p < 0.005). Decreased CBF was significantly associated with reduced cingulum fractional anisotropy (FA) in the chronic phase; however, no such association was observed for participants with less remote TBI.ConclusionsOur results showed that reduced CBF was associated with poorer white matter integrity in those who were further removed from their brain injury. Findings provide preliminary evidence of a possible dynamic association between CBF and white matter microstructure that warrants additional consideration within the context of the negative long-term clinical outcomes frequently observed in those with history of TBI. Additional cross-disciplinary studies integrating multiple imaging modalities (e.g., DTI, ASL) and refined neuropsychiatric assessment are needed to better understand the nature, temporal course, and dynamic association between brain changes and clinical outcomes post-injury
Examining the learning effects of live streaming video game instruction over Twitch
Technology facilitates advances in learning and drives learning paradigms. One recent innovation is Twitchâą, an online streaming platform often used for video game tutorials but also enables amateur online instruction (Hamilton, Garretson, & Kerne, 2014)). Twitch represents a unique learning paradigm that is not perfectly represented in previous technologies because of its âground-upâ evolution and the opportunity for novice instructors to educate mass audiences in real-time over the Internet while enabling interaction between teachers and learners and among learners. The purpose of this research is to empirically examine the efficacy of Twitch as a learning platform by manipulating each of the key characteristics of Twitch and to understand the conditions in which novice instructors may be beneficial. Drawing from Cognitive Load Theory, we demonstrate the worked-example effect in the Twitch environment by manipulating teacher-learner-learner interactions, live versus recorded streaming, and expert-versus novice-based instruction. Based on a laboratory experiment involving 350 participants, we found that learning performance under novice instructors was at least as good as that of experts. However, an exploratory analysis of learner personalities revealed that extroverts benefit only when learner-learner interaction is enabled. Surprisingly, those who are highly agreeable and less neurotic benefited more from novice instructors
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