1,323 research outputs found
Electronic properties of H on vicinal Pt surfaces: A first-principles study
In this work, we use the first-principle density-functional approach to study
the electronic structure of a H atom adsorbed on the ideal Pt(111) and vicinal
Pt(211) and Pt(331) surfaces. Full three-dimensional potential-energy surfaces
(3D PES's) as well as local electronic density of states on various adsorption
sites are obtained. The results show that the steps modify the PES
considerably. The effect is nonlocal and extends into the region of the (111)
terraces. We also find that different type of steps have different kind of
influence on the PES when compared to the one of the ideal Pt(111) surface. The
full 3D PES's calculated in this work provide a starting point for the
theoretical study of vibrational and diffusive dynamics of H adatoms adsorbed
on these vicinal surfaces.Comment: 8 pages with 5 figures and 3 tables. In version 2, there have been
made some minor changes and a bigger one in Section III.A.1 where the results
of the test calculations dealt with the accuracy of the present results have
been adde
Value Efficiency Analysis for Incorporating Preference Information in Data Envelopment Analysis
We develop a procedure and the requisite theory for incorporating preference information in a novel way in the efficiency analysis of Decision Making Units. The efficiency of Decision Making Units is defined in the spirit of Data Envelopment Analysis (DEA), complemented with Decision Maker's preference information concerning the desirable structure of inputs and outputs. Our procedure begins by aiding the Decision Maker in searching for the most preferred combination of inputs and outputs of Decision Making Units (for short, Most Preferred Solution) which are efficient in DEA. Then, assuming that the Decision Maker's Most Preferred Solution maximizes his/her underlying (unknown) value function at the moment when the search is terminated, we approximate the indifference contour of the value function at this point with its possible tangent hyperplanes. Value Efficiency scores are then calculated for each Decision Making Unit comparing the inefficient units to units having the same value as the Most Preferred Solution. The resulting Value Efficiency scores are optimistic approximations of the true scores. The procedure and the resulting efficiency scores are immediately applicable to solving practical problems
Sequential double cross-validation for assessment of added predictive ability in high-dimensional omic applications
Enriching existing predictive models with new biomolecular markers is an important task in the new multi-omic era. Clinical studies increasingly include new sets of omic measurements which may prove their added value in terms of predictive performance. We introduce a two-step approach for the assessment of the added predictive ability of omic predictors, based on sequential double cross-validation and regularized regression models. We propose several performance indices to summarize the two-stage prediction procedure and a permutation test to formally assess the added predictive value of a second omic set of predictors over a primary omic source. The performance of the test is investigated through simulations. We illustrate the new method through the systematic assessment and comparison of the performance of transcriptomics and metabolomics sources in the prediction of body mass index (BMI) using longitudinal data from the Dietary, Lifestyle, and Genetic determinants of Obesity and Metabolic syndrome (DILGOM) study, a population-based cohort from Finland
Long lasting pain hypersensitivity following ligation of the tendon of the masseter muscle in rats: A model of myogenic orofacial pain
<p>Abstract</p> <p>Background</p> <p>A major subgroup of patients with temporomandibular joint (TMJ) disorders have masticatory muscle hypersensitivity. To study myofacial temporomandibular pain, a number of preclinical models have been developed to induce myogenic pain of the masseter muscle, one of the four muscles involved in mastication. The currently used models, however, generate pain that decreases over time and only lasts from hours to weeks and hence are not suitable for studying chronicity of the myogenic pain in TMJ disorders. Here we report a model of constant myogenic orofacial pain that lasts for months.</p> <p>Results</p> <p>The model involves unilateral ligation of the tendon of the anterior superficial part of the rat masseter muscle (TASM). The ligation of the TASM was achieved with two chromic gut (4.0) ligatures via an intraoral approach. Nocifensive behavior of the rat was assessed by probing the skin site above the TASM with a series of von Frey filaments. The response frequencies were determined and an EF<sub>50 </sub>value, defined as the von Frey filament force that produces a 50% response frequency, was derived and used as a measure of mechanical sensitivity. Following TASM ligation, the EF<sub>50 </sub>of the injured side was significantly reduced and maintained throughout the 8-week observation period, suggesting the presence of mechanical hyperalgesia/allodynia. In sham-operated rats, the EF<sub>50 </sub>of the injured side was transiently reduced for about a week, likely due to injury produced by the surgery. Somatotopically relevant Fos protein expression was indentified in the subnucleus caudalis of the spinal trigeminal sensory complex. In the same region, persistent upregulation of NMDA receptor NR1 phosphorylation and protein expression and increased expression of glial markers glial fibrillary acidic protein (astroglia) and CD11b (microglia) were found. Morphine (0.4-8 mg/kg, s.c.) and duloxetine (0.4-20 mg/kg, i.p.), a selective serotonin-norepinephrine reuptake inhibitor, produced dose-dependent attenuation of hyperalgesia.</p> <p>Conclusions</p> <p>Ligation injury of the TASM in rats led to long-lasting and constant mechanical hypersensitivity of myogenic origin. The model will be particularly useful in studying the chronicity of myogenic pain TMJ disorders. The model can also be adapted to other regions of the body for studying pathology of painful tendinopathy seen in sports injury, muscle overuse, and rheumatoid arthritis.</p
EEG Artifact Removal in TMS Studies of Cortical Speech Areas
The combination of transcranial magnetic stimulation (TMS) and electroencephalography (EEG) is commonly applied for studying the effective connectivity of neuronal circuits. The stimulation excites neurons, and the resulting TMS-evoked potentials (TEPs) are recorded with EEG. A serious obstacle in this method is the generation of large muscle artifacts from scalp muscles, especially when frontolateral and temporoparietal, such as speech, areas are stimulated. Here, TMS–EEG data were processed with the signal-space projection and source-informed reconstruction (SSP–SIR) artifact-removal methods to suppress these artifacts. SSP–SIR suppressed muscle artifacts according to the difference in frequency contents of neuronal signals and muscle activity. The effectiveness of SSP–SIR in rejecting muscle artifacts and the degree of excessive attenuation of brain EEG signals were investigated by comparing the processed versions of the recorded TMS–EEG data with simulated data. The calculated individual lead-field matrix describing how the brain signals spread on the cortex were used as simulated data. We conclude that SSP–SIR was effective in suppressing artifacts also when frontolateral and temporoparietal cortical sites were stimulated, but it may have suppressed also the brain signals near the stimulation site. Effective connectivity originating from the speech-related areas may be studied even when speech areas are stimulated at least on the contralateral hemisphere where the signals were not suppressed that much.Peer reviewe
Onset of Impaired Sleep and Cardiovascular Disease Risk Factors: A Longitudinal Study
STUDY OBJECTIVES:
Impaired sleep has been linked to increased risk of cardiovascular disease (CVD), but the underlying mechanisms are still unsettled. We sought to determine how onset of impaired sleep affects the risk of established physiological CVD risk factors (i.e., hypertension, diabetes, and dyslipidemia).
METHODS:
In a longitudinal cohort study with 3 survey waves (2000, 2004, 2008) from the Finnish Public Sector study we used repeated information on sleep duration and disturbances to determine onset of impaired sleep. Information on development of CVD risk factors, as indicated by initiation of medication for hypertension, diabetes, and dyslipidemia was derived from electronic medical records within 8 years of follow-up. Data on 45,647 participants was structured as two data-cycles to examine the effect of change in sleep (between two waves) on incident CVD events. We applied strict inclusion and exclusion criteria to determine temporality between changes in sleep and the outcomes.
RESULTS:
While we did not find consistent effects of onset of short or long sleep, we found onset of disturbed sleep to predict subsequent risk of hypertension (hazard ratio = 1.22, 95% CI: 1.04–1.44) and dyslipidemia (HR = 1.17, 95% CI: 1.07–1.29) in fully adjusted analyses.
CONCLUSIONS:
Results suggest that onset of sleep disturbances rather than short or long sleep mark an increase in physiological risk factors, which may partly explain the higher risk of CVD observed among impaired sleepers
Role of concerted atomic movements on the diffusion of small islands on fcc(100) metal surfaces
The master equation formalism is used to analytically calculate the center-of-mass diffusion coefficient for small two-dimensional islands on fcc(100) metal surfaces. We consider the case of Cu on Cu(100) containing up to nine atoms, with energetics obtained from semiempirical interaction potentials. In the case where only single-particle processes are taken into account, the analytic results agree well with previous Monte Carlo simulation data. However, when recently proposed many-particle processes are included, in some cases the diffusion coefficients increase by an order of magnitude at room temperatures. Qualitatively, the oscillatory behavior of diffusion as a function of the island size is not affected by the many-particle processes.Peer reviewe
Disintegrin and metalloproteinases (ADAMs) expression in gastroesophageal reflux disease and in esophageal adenocarcinoma
Clinically useful marker molecules for the progression of gastroesophageal reflux disease and Barrett's esophagus (BE) to esophageal adenocarcinoma (EAC) are lacking. Many adenocarcinomas and inflammatory conditions exhibit increased expression of ADAMs, 'a disintegrin and metalloproteinases'. We assessed the expression of five ADAMs (9, 10, 12, 17, 19) in three esophageal cell lines (Het-1A, OE19, OE33) by RT-PCR and Western blotting, and in human samples of normal esophagus, esophagitis, BE, Barrett's dysplasia, and EAC by RT-PCR, and in selected samples by immunohistochemistry. EAC patients showed increased mRNA expression of ADAMs 9, 12, 17 and 19, as compared to controls. At immunohistochemistry, ADAM9 and ADAM10 proteins were increased in EAC. Patient samples also showed increased mRNA expression of ADAM12 in esophagitis, of ADAM9 in BE, and of ADAMs 9, 12 and 19 in Barrett's dysplasia, as compared to controls. Two EAC cell lines showed increased ADAM9 mRNA. ADAM9 expression is increased in EAC. Its predecessors show increased ADAM9 mRNA expression. The importance of the alterations in ADAM expression for the development of EAC, and their use as marker molecules, warrant further studies.Peer reviewe
Early retirement from work among employees with a diagnosis of personality disorder compared to anxiety and depressive disorders
Objective:Â Risk of retirement from work before statutory retirement age among employees with personality disorders is unknown.Method:Â We used diagnoses of awarded medical rehabilitations and hospitalisations to select two clinical cohorts from a population of 151,618 employees: participants in rehabilitation (total N=1942, 233 personality disorder, 419 anxiety disorder and 1290 depression cases) and hospitalised patients (N=1333, 354, 126 and 853, respectively). Early retirement from work was tracked through national registers during a period of 5 years. Cox proportional hazard models were used to examine the association of diagnostic groups with risk of early retirement.Results:Â In models adjusted for age, sex and socioeconomic position, the relative risk of early retirement for patients with personality disorders was 3.5-fold (95% CI 2.1 to 5.8) in the rehabilitation cohort and 2.3-fold (95% CI 1.6 to 3.5) in the hospital cohort compared with anxiety disorders. The corresponding hazard ratios of early retirement for personality disorders compared with depressive disorders were 1.1 (95% CI 0.8-1.5) and 1.7 (95% CI 1.4-2.1), respectively.Conclusions:Â Personality disorders increase the risk of early retirement at least to an equal extent as depression and more than twice that of anxiety disorders.</p
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