3,042 research outputs found
Influence of diesel surrogates on the behavior of simplified spray models
Numerous experimental investigations make use of diesel surrogates to make the computational time reasonable. In the few studies where measured (surrogate and real diesel) and computed (surrogate only) results have been compared, the selection methodology for the surrogate constituent compounds and the measures taken to validate the chemical kinetic models are not discussed, and the range of operating conditions used is often small. Additionally, most simplified models use tuning variables to fit model results to measurements. This work makes the comparison between some frequently used diesel surrogates using a simple 1D vaporizing spray model, with the spray cone angle as the tuning parameter. Results show that liquid length and fuel fraction strongly depend on the physical properties of the used fuel for a fixed spray angle. These parameters are important for modeling auto-ignition and pollutant formation. The spray angle is varied till the spray length is the same for each surrogate. Results show important differences between other spray parameters such as local mixture fraction and axial velocity
Reply to: Atom gravimeters and the gravitational redshift
We stand by our result [H. Mueller et al., Nature 463, 926-929 (2010)]. The
comment [P. Wolf et al., Nature 467, E1 (2010)] revisits an interesting issue
that has been known for decades, the relationship between test of the
universality of free fall and redshift experiments. However, it arrives at its
conclusions by applying the laws of physics that are questioned by redshift
experiments; this precludes the existence of measurable signals. Since this
issue applies to all classical redshift tests as well as atom interferometry
redshift tests, these experiments are equivalent in all aspects in question.Comment: Reply to P. Wolf et al., arXiv:1009.060
Initial fixation placement in face images is driven by top-down guidance
The eyes are often inspected first and for longer period during face exploration. To examine whether this saliency of the eye region at the early stage of face inspection is attributed to its local structure properties or to the knowledge of its essence in facial communication, in this study we investigated the pattern of eye movements produced by rhesus monkeys (Macaca mulatta) as they free viewed images of monkey faces. Eye positions were recorded accurately using implanted eye coils, while images of original faces, faces with scrambled eyes, and scrambled faces except for the eyes were presented on a computer screen. The eye region in the scrambled faces attracted the same proportion of viewing time and fixations as it did in the original faces, even the scrambled eyes attracted substantial proportion of viewing time and fixations. Furthermore, the monkeys often made the first saccade towards to the location of the eyes regardless of image content. Our results suggest that the initial fixation placement in faces is driven predominantly by ‘top-down’ or internal factors, such as the prior knowledge of the location of “eyes” within the context of a face
New mutations at the imprinted Gnas cluster show gene dosage effects of Gsα in postnatal growth and implicate XLαs in bone and fat metabolism, but not in suckling
The imprinted Gnas cluster is involved in obesity, energy metabolism, feeding behavior, and viability. Relative contribution of paternally expressed proteins XLαs, XLN1, and ALEX or a double dose of maternally expressed Gsα to phenotype has not been established. In this study, we have generated two new mutants (Ex1A-T-CON and Ex1A-T) at the Gnas cluster. Paternal inheritance of Ex1A-T-CON leads to loss of imprinting of Gsα, resulting in preweaning growth retardation followed by catch-up growth. Paternal inheritance of Ex1A-T leads to loss of imprinting of Gsα and loss of expression of XLαs and XLN1. These mice have severe preweaning growth retardation and incomplete catch-up growth. They are fully viable probably because suckling is unimpaired, unlike mutants in which the expression of all the known paternally expressed Gnasxl proteins (XLαs, XLN1 and ALEX) is compromised. We suggest that loss of ALEX is most likely responsible for the suckling defects previously observed. In adults, paternal inheritance of Ex1A-T results in an increased metabolic rate and reductions in fat mass, leptin, and bone mineral density attributable to loss of XLαs. This is, to our knowledge, the first report describing a role for XLαs in bone metabolism. We propose that XLαs is involved in the regulation of bone and adipocyte metabolism
Cross modal perception of body size in domestic dogs (Canis familiaris)
While the perception of size-related acoustic variation in animal vocalisations is well documented, little attention has been given to how this information might be integrated with corresponding visual information. Using a cross-modal design, we tested the ability of domestic dogs to match growls resynthesised to be typical of either a large or a small dog to size- matched models. Subjects looked at the size-matched model significantly more often and for a significantly longer duration than at the incorrect model, showing that they have the ability to relate information about body size from the acoustic domain to the appropriate visual category. Our study suggests that the perceptual and cognitive mechanisms at the basis of size assessment in mammals have a multisensory nature, and calls for further investigations of the multimodal processing of size information across animal species
A primary care, multi-disciplinary disease management program for opioid-treated patients with chronic non-cancer pain and a high burden of psychiatric comorbidity
BACKGROUND: Chronic non-cancer pain is a common problem that is often accompanied by psychiatric comorbidity and disability. The effectiveness of a multi-disciplinary pain management program was tested in a 3 month before and after trial. METHODS: Providers in an academic general medicine clinic referred patients with chronic non-cancer pain for participation in a program that combined the skills of internists, clinical pharmacists, and a psychiatrist. Patients were either receiving opioids or being considered for opioid therapy. The intervention consisted of structured clinical assessments, monthly follow-up, pain contracts, medication titration, and psychiatric consultation. Pain, mood, and function were assessed at baseline and 3 months using the Brief Pain Inventory (BPI), the Center for Epidemiological Studies-Depression Scale scale (CESD) and the Pain Disability Index (PDI). Patients were monitored for substance misuse. RESULTS: Eighty-five patients were enrolled. Mean age was 51 years, 60% were male, 78% were Caucasian, and 93% were receiving opioids. Baseline average pain was 6.5 on an 11 point scale. The average CESD score was 24.0, and the mean PDI score was 47.0. Sixty-three patients (73%) completed 3 month follow-up. Fifteen withdrew from the program after identification of substance misuse. Among those completing 3 month follow-up, the average pain score improved to 5.5 (p = 0.003). The mean PDI score improved to 39.3 (p < 0.001). Mean CESD score was reduced to 18.0 (p < 0.001), and the proportion of depressed patients fell from 79% to 54% (p = 0.003). Substance misuse was identified in 27 patients (32%). CONCLUSIONS: A primary care disease management program improved pain, depression, and disability scores over three months in a cohort of opioid-treated patients with chronic non-cancer pain. Substance misuse and depression were common, and many patients who had substance misuse identified left the program when they were no longer prescribed opioids. Effective care of patients with chronic pain should include rigorous assessment and treatment of these comorbid disorders and intensive efforts to insure follow up
A meta-analytic review of stand-alone interventions to improve body image
Objective
Numerous stand-alone interventions to improve body image have been developed. The
present review used meta-analysis to estimate the effectiveness of such interventions, and
to identify the specific change techniques that lead to improvement in body image.
Methods
The inclusion criteria were that (a) the intervention was stand-alone (i.e., solely focused on
improving body image), (b) a control group was used, (c) participants were randomly
assigned to conditions, and (d) at least one pretest and one posttest measure of body
image was taken. Effect sizes were meta-analysed and moderator analyses were conducted.
A taxonomy of 48 change techniques used in interventions targeted at body image
was developed; all interventions were coded using this taxonomy.
Results
The literature search identified 62 tests of interventions (N = 3,846). Interventions produced
a small-to-medium improvement in body image (d+ = 0.38), a small-to-medium reduction in
beauty ideal internalisation (d+ = -0.37), and a large reduction in social comparison tendencies
(d+ = -0.72). However, the effect size for body image was inflated by bias both within
and across studies, and was reliable but of small magnitude once corrections for bias were
applied. Effect sizes for the other outcomes were no longer reliable once corrections for
bias were applied. Several features of the sample, intervention, and methodology moderated
intervention effects. Twelve change techniques were associated with improvements in
body image, and three techniques were contra-indicated.
Conclusions
The findings show that interventions engender only small improvements in body image, and
underline the need for large-scale, high-quality trials in this area. The review identifies effective
techniques that could be deployed in future interventions
Some size relationships in phytoflagellate motility
Data from the literature are used to assess some hypothesised adaptive advantages of the flagellate life form among phytoplankton. Possible advantages include increased nutrient uptake by movement through a homogeneous medium as opposed to exploitation of spatial hetrogeneity of the environment. Maximal migrational amplitudes and maximal swimming velocities of phytoflagellates were compared to body size. Both were found to increase with size. Relative amplitudes and relative velocities, however, were found to decrease with size. Hydrophysical considerations show that additional gain of nutrients by swimming through a homogeneous medium is only minimal for small flagellates at their attainable swimming velocities. It is suggested that exploitation of environmental heterogeneity in nutrient distribution may be one of the most important advantages for flagellates over coccoid algae
Age-Related Attenuation of Dominant Hand Superiority
The decline of motor performance of the human hand-arm system with age is well-documented. While dominant hand performance is superior to that of the non-dominant hand in young individuals, little is known of possible age-related changes in hand dominance. We investigated age-related alterations of hand dominance in 20 to 90 year old subjects. All subjects were unambiguously right-handed according to the Edinburgh Handedness Inventory. In Experiment 1, motor performance for aiming, postural tremor, precision of arm-hand movement, speed of arm-hand movement, and wrist-finger speed tasks were tested. In Experiment 2, accelerometer-sensors were used to obtain objective records of hand use in everyday activities
The Hubbard model within the equations of motion approach
The Hubbard model has a special role in Condensed Matter Theory as it is
considered as the simplest Hamiltonian model one can write in order to describe
anomalous physical properties of some class of real materials. Unfortunately,
this model is not exactly solved except for some limits and therefore one
should resort to analytical methods, like the Equations of Motion Approach, or
to numerical techniques in order to attain a description of its relevant
features in the whole range of physical parameters (interaction, filling and
temperature). In this manuscript, the Composite Operator Method, which exploits
the above mentioned analytical technique, is presented and systematically
applied in order to get information about the behavior of all relevant
properties of the model (local, thermodynamic, single- and two- particle ones)
in comparison with many other analytical techniques, the above cited known
limits and numerical simulations. Within this approach, the Hubbard model is
shown to be also capable to describe some anomalous behaviors of the cuprate
superconductors.Comment: 232 pages, more than 300 figures, more than 500 reference
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