title stringlengths 0 1.13k | abstract stringlengths 1 15.7k | PMID int64 22 36.5M |
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Chiral ligand-exchange chromatography of amino acids using porous graphitic carbon coated with a dinaphthyl derivative of neamine. | In this paper, we describe the preparation and the evaluation of a porous graphitic carbon (PGC) column coated with a new dinaphthyl derivative of neamine for chiral ligand-exchange (LE) chromatography. It was shown that the graphitic surface/dinaphthyl anchor system efficiently (1.15 micromol/m(2)) and stably (three months of intensive use) adsorbs the neamine template onto the chromatographic support. The resulting coated PGC stationary phase showed appreciable LE-based enantioselective properties towards several native amino acids. | 18,998,115 |
Energetics and dynamics of global integrals modeling interaction between stiff filaments. | The attractive and spacing interaction between pairs of filaments via cross-linkers, e.g. myosin oligomers connecting actin filaments, is modeled by global integral kernels for negative binding energies between two intersecting stiff and long rods in a (projected) two-dimensional situation, for simplicity. Whereas maxima of the global energy functional represent intersection angles of 'minimal contact' between the filaments, minima are approached for energy values tending to -infinity, representing the two degenerate states of parallel and anti-parallel filament alignment. Standard differential equations of negative gradient flow for such energy functionals show convergence of solutions to one of these degenerate equilibria in finite time, thus called 'super-stable' states. By considering energy variations under virtual rotation or translation of one filament with respect to the other, integral kernels for the resulting local forces parallel and orthogonal to the filament are obtained. For the special modeling situation that these variations only activate 'spring forces' in direction of the cross-links, explicit formulas for total torque and translational forces are given and calculated for typical examples. Again, the two degenerate alignment states are locally 'super-stable' equilibria of the assumed over-damped dynamics, but also other stable states of orthogonal arrangement and different asymptotic behavior can occur. These phenomena become apparent if stochastic perturbations of the local force kernels are implemented as additive Gaussian noise induced by the cross-link binding process with appropriate scaling. Then global filament dynamics is described by a certain type of degenerate stochastic differential equations yielding asymptotic stationary processes around the alignment states, which have generalized, namely bimodal Gaussian distributions. Moreover, stochastic simulations reveal characteristic sliding behavior as it is observed for myosin-mediated interaction between actin filaments. Finally, the forgoing explicit and asymptotic analysis as well as numerical simulations are extended to the more realistic modeling situation with filaments of finite length. | 18,998,136 |
[Complications after refractive lens exchange]. | This overview discusses specific complications after refractive lens exchange (RLE). The complication spectrum is similar to that following cataract surgery, with some differences: RLE is implemented in very short or very long eyes, and the average patient age is significantly lower. Regarding specific situations, this article particularly considers the risks of retinal pathologies after myopic RLE and reviews the typical intraoperative difficulties induced by a short anterior segment in hyperopic RLE. Modern microincisional surgery and the use of foldable intraocular lenses with a sharp edge design reduce posterior capsule opacification and, together with optimal postoperative management, may reduce RLE-specific complications. In summary, despite the minor complication rate, RLE for the correction of high ametropias in the presbyopic age group is a safe and effective refractive treatment option. | 18,998,144 |
Frequent deletion of ING2 locus at 4q35.1 associates with advanced tumor stage in head and neck squamous cell carcinoma. | Loss of heterozygosity (LOH) in the ING family members has been shown in head and neck squamous cell carcinoma (HNSCC) except for ING2. Like all the other members of ING family, ING2, which is located at chromosome 4q35.1, is a promising tumor suppressor gene (TSG). In this study, we performed LOH analysis of ING2 in HNSCC and compared it with clinicopathological variables. We performed LOH analysis in DNAs from 80 paired of normal and HNSCC tissues, using a specifically designed microsatellite marker on chromosome 4q35.1, which detects allelic loss of ING2. TP53 mutation analysis and its relationship with ING2 chromosomal deletion were also performed in available 68 of the samples. The correlation between LOH status and clinicopathological characteristics was evaluated by using statistical methods. The overall survival (OS) and disease free survival (DFS) were also determined. LOH was detected in 54.6% (30/55) of the informative samples. Statistical significance was obtained between LOH and tumor (T) stage (P = 0.02), application of radiotherapy and chemotherapy. Positive node status (N) appeared to be the only independent prognostic factor for both OS (P = 0.031) and DFS (P = 0.044). Our study showed allelic loss of 4q35.1 in HNSCC. The high percentage of LOH suggests ING2 as a candidate TSG in HNSCC. High LOH frequency was statistically associated with advanced T stage, suggesting that ING2 LOH might occur in late stages during HNSCC progression. | 18,998,165 |
Effects of grass and browse consumption on the winter mass dynamics of elk. | Much of the research into herbivore ecology and evolution has focused on patterns and mechanisms of niche partitioning in the diets of specialized grazers and browsers, but the significance of the balance of grazing and browsing within intermediate feeders present unique questions that have received less attention. We explored the nutritional effects of varying the balance of grass and browse in the winter diets of elk (Cervus elaphus). We compiled published data from three similar studies that monitored the mass dynamics of captive elk fed diets of pure grass, pure browse or 1 of 14 mixed diets in winter feeding trials. Elk lost mass (up to 22% of initial body weight) in 29 of 33 feeding trials, similar to wild elk in winter. We used regression models of mass dynamics, considering the linear, quadratic or logarithmic effects of the proportion of the diet that was grass ( approximately 1 - proportion of the diet that was browse) and the additive and interactive effects of nitrogen intake. Diet composition had strong effects on mass dynamics, and all models explained > or =73% of the variation (adjusted r (2)) in mass dynamics. Nitrogen intake had uniformly positive effects on mass balance, and increasing grass intake caused improved maintenance of body mass up to a point, but further increases in the proportion of grass in the diet had neutral or negative effects on body mass. Overall, the data suggest that elk are adapted to consuming mixed diets. Nonetheless, data on the foraging behavior and diet selection of wild elk in many populations show that elk often consume grass-dominated diets and sometimes consume browse-dominated diets, but rarely consume mixed diets. Physiological adaptations to mixed diets may place unique spatio-temporal constraints on diet selection in intermediate feeders and impose large penalties for a sub-optimal balance of grazing and browsing. | 18,998,170 |
Physicians' attitudes towards copy and pasting in electronic note writing. | The ability to copy and paste text within computerized physician documentation facilitates electronic note writing, but may affect the quality of physician notes and patient care. Little is known about physicians' collective experience with the copy and paste function (CPF). To determine physicians' CPF use, perceptions of its impact on notes and patient care, and opinions regarding its future use. Cross-sectional survey. Resident and faculty physicians within two affiliated academic medical centers currently using a computerized documentation system. Responses on a self-administered survey. A total of 315 (70%) of 451 eligible physicians responded to the survey. Of the 253 (80%) physicians who wrote inpatient notes electronically, 226 (90%) used CPF, and 177 (70%) used it almost always or most of the time when writing daily progress notes. While noting that inconsistencies (71%) and outdated information (71%) were more common in notes containing copy and pasted text, few physicians felt that CPF had a negative impact on patient documentation (19%) or led to mistakes in patient care (24%). The majority of physicians (80%) wanted to continue to use CPF. Although recognizing deficits in notes written using CPF, the majority of physicians used CPF to write notes and did not perceive an overall negative impact on physician documentation or patient care. Further studies of the effects of electronic note writing on the quality and safety of patient care are required. | 18,998,191 |
A novel hirudin derivative characterized with anti-platelet aggregations and thrombin inhibition. | Hirudin is an anti-coagulative product of the salivary glands of the medicinal leech Hirudo medicinalis. It is a powerful and specific thrombin inhibitor. Peptides containing the RGD motif competitively inhibit the binding of fibrinogen to GP IIb/IIIa on the platelets, thus inhibiting platelet aggregation. We have constructed a recombinant RGD-hirudin (r-RGD-hirudin) by fusing the tripeptide RGD sequence to the native hirudin (wt-hirudin). The r-RGD-hirudin was expressed at high levels in Pichia pastoris, and was purified to approximately 97% homogeneity. The specific anti-thrombin activity of purified r-RGD-hirudin is 12,000 ATU/mg, which is equivalent to wt-hirudin, but only r-RGD-hirudin can inhibit platelet aggregation. The biological effects of r-RGD-hirudin on Thrombin Time (TT), Prothrombin Time (PT), Activated Partial Thromboplastin Time (APTT), Bleeding Time (BT), maximum platelet aggregation (PAGm) induced by ADP were studied in rabbit model and compared with that of wt-hirudin. The rabbits were infused r-RGD-hirudin had prolonged TT, PT, and aPTT which were similar to that of wt-hirudin; but only r-RGD-hirudin was capable of inhibiting PAGm. Histopathological analyses showed that r-RGD-hirudin was two to three times more effective than wt-hirudin in preventing thrombosis. r-RGD-hirudin can potentially be used as a novel anti-coagulant for the prevention of thrombosis after carotid artery anastomosis or in other thrombotic events. | 18,998,199 |
Role of insulin-like growth factor binding proteins in mammary gland development. | Insulin-like growth factors (IGFs) play an important role in mammary gland development and their effects are, in turn, influenced by a family of 6 IGF-binding proteins (IGFBPs). The IGFBPs are expressed in time- and tissue-specific fashion during the periods of rapid growth and involution of the mammary gland. The precise roles of these proteins in vivo have, however, been difficult to determine. This review examines the indirect evidence (evolution, chromosomal location and roles in lower life-forms) the evidence from in vitro studies and the attempts to examine their roles in vivo, using IGFBP-deficient and over-expression models. Evidence exists for a role of the IGFBPs in inhibition of the survival effects of IGFs as well as in IGF-enhancing effects from in vitro studies. The location of the IGFBPs, often associated with the extracellular matrix, suggests roles as a reservoir of IGFs or as a potential barrier, restricting access of IGFs to distinct cellular compartments. We also discuss the relative importance of IGF-dependent versus IGF-independent effects. IGF-independent effects include nuclear localization, activation of proteases and interaction with a variety of extracellular matrix and cell surface proteins. Finally, we examine the increasing evidence for the IGFBPs to be considered as part of a larger family of extracellular matrix proteins involved in morphogenesis and tissue re-modeling. | 18,998,203 |
[First favourable results of the group education programme Go4it for overweight and obese adolescents]. | To evaluate the effect of Go4it, a multidisciplinary group education programme for adolescents with overweight or obesity. Uncontrolled intervention study. At the obesity outpatient clinic of the Transmural Research and Treatment Centre for Overweight and Obese Children of the VU University Medical Center, Amsterdam, The Netherlands, a group education programme was developed for adolescents (age 12-18 year) who are overweight or obese. Obese adolescents who were referred to the obesity outpatient clinic were asked to participate. During 7 sessions (one session every two weeks) the adolescents were educated on the health consequences of obesity, diet, physical activity, energy balance, improving self-esteem and how to handle bullying and other difficult situations. All sessions were held in groups of 8-10 adolescents. In addition, two sessions were organised for the parents concerning the health consequences of obesity, diet, and physical activity. Body weight and height, glucose tolerance (by an oral glucose tolerance test; OGTT), and insulin resistance were measured at enrolment into the Go4it programme and 6 months later. In total, 93 adolescents (39 boys, 54 girls) were included with a mean age of 3.9 (SD: 1.7) years. Of those, 69 adolescents (74%) attended at least 6 out of 7 sessions of the education programme. Stabilisation or reduction in obesity levels following completion of Go4it was achieved in 51 (74%) of these participants. 50 adolescents had a second OGTT. The BMI standard deviation score (BMI-sds) decreased by 4.3% for boys (p = 0.020) and 3.3% for girls (p = 0.017). Among girls, fasting blood glucose levels decreased by an average of 0.37 mmol/l (95% CI: 0.14-0.60) and insulin concentrations decreased by an average of 299 pmol/l (95% CI: 71-528). Participation in the Go4it education programme is accompanied by a stabilisation or reduction in the level of obesity and has favourable effects on glucose and insulin metabolism. | 18,998,271 |
Perforated sigmoid diverticulum mimicking acute appendicitis in a young patient: a case report. | Acute colonic diverticula are uncommon in patients <40 years of age, with an incidence between 2% and 10%. In such patients, the condition may be misdiagnosed in the acute setting, because it is often not considered and may be mistaken for acute appendicitis, particularly if there are predominantly right-sided signs. As a result, it may result in diagnostic delay and complications. We report a case of a young patient who presented with a perforated sigmoid diverticulum mimicking acute appendicitis, which was not diagnosed initially, and the resulting course of events. | 18,998,285 |
[A possible case of superior mesenteric artery syndrome of congenital origin]. | We describe a case of a 10 yr old boy, who suffered from gastroesophageal reflux in the neonatal period and from recurrent abdominal pain, epigastric distension and vomiting since birth, but with an increase in this clinic in the last two years, especially in the last five months, without suffering weight loss, having operations or other illnesses. After the diagnosis of superior mesenteric artery syndrome was confirmed by a superior barium series and a CT-scan, a laparotomy was performed, carrying out the Koecher manoeuvre, cutting the Treitz ligament near of the 4th part of the duodenum until descend that and freeing the aorto-mesenteric space. The follow up after 5 years showed an excellent clinical evolution. In our opinion, this case should be considered to be of congenital origin, but without other associated abdominal anomalies. The possible different interventions are also discussed. | 18,998,374 |
5-n-Alkylresorcinols from the nitrogen-fixing soil bacterium Azotobacter chroococcum Az12. | A mixture of five saturated 5-n-alkylresorcinol homologues was isolated from vegetative cells of the nitrogen-fixing soil bacterium Azotobacter chroococcum Az12. Their structures were established by spectrometry (1H NMR, EI-MS, FAB-MS, FAB-MS/MS) and chromatography (GC, TLC) means. | 18,998,393 |
Free radical scavengers and antioxidants from Tagetes mendocina. | Tagetes mendocina (Asteraceae) is a medicinal plant widely used in the Andean provinces of Argentina. Preliminary assays showed free radical scavenging activity in the methanol extract of the aerial parts, measured by the decoloration of a methanolic solution of the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) and scavenging of the superoxide anion. Assay-guided isolation led to 4'-hydroxyacetophenone (1), protocatechuic acid (2), syringic acid (3), patuletin (4), quercetagetin 7-O-beta-D-glucoside (5), patuletin 7-O-beta-D-glucoside (6) and axillarin 7-O-beta-D-glucoside (7) as the free radical scavengers and antioxidant compounds from Tagetes mendocina. On the basis of dry starting material, the total phenolic content of the crude drug was 3.00% with 0.372% of flavonoids. The content of compounds 1-7 in the crude drug was 0.008, 0.015, 0.010, 0.029, 0.238, 0.058 and 0.017%, respectively. Quercetagetin 7-O-beta-D-glucoside proved to be the main free radical scavenger of the extracts measured by the DPPH decoloration test as well as for quenching the superoxide anion and inhibition of lipoperoxidation in erythrocytes. In the lipid peroxidation assay the percentual inhibition was related with the number of methoxy groups in the molecule, ranging from 86% for the quercetagetin glucoside to 67% for the monomethoxylated and 31% for the dimethoxylated derivative. The compounds showed low cytotoxicity towards human lung fibroblasts with IC50 > 1 mM for compounds 1-3 and 0.24 to 0.52 mM for the flavonoids 4-7. | 18,998,399 |
Antiradical activity of hydrolyzed and non-hydrolyzed extracts from Helichrysi inflorescentia and its phenolic contents. | A methanol extract was obtained from defatted (petroleum ether) inflorescence of Helichrysum arenarium (L.) Moench (perennial herb native to Middle and Southeast Europe). The extract was evaporated under reduced pressure and the dry residue was dissolved in hot water. The aqueous solution was stored for 6 d at 4 degrees C and the precipitate discarded. The remaining solution was divided into three aliquots a, b and c. Part a was extracted with ethyl acetate to obtain extract (A), part b was extracted with diethyl ether to obtain extract (B) and part c was subjected to alkaline hydrolysis and then extracted with diethyl ether to obtain extract (C). Extracts (A), (B) and (C) were evaporated under reduced pressure to obtain the dry residues A, B and C which were further investigated for phenolic compound content by TLC and HPLC and for antiradical activity with 2,2-diphenyl-1-picrylhydrazyl radical (DPPH*) as a substrate. Residue C exhibited stronger antiradical properties than non-hydrolysed residues A and B. HPLC analysis showed a great increase of caffeic acid in residue C. We concluded that the hydrolysis process led to a significant increase of free caffeic acid (strong antioxidant) concentration resulting in increased antiradical activity of residue C. | 18,998,402 |
Tulasnein and podospirone from the coprophilous xylariaceous fungus Podosordaria tulasnei. | Tulasnein (1), a new metabolite with strong antimicrobial and weaker cytotoxic and phytotoxic activity, was isolated from culture filtrates of three strains of the xylariaceous coprophilous fungus Podosordaria tulasnei. The producing strains were identified by their rhizomorphs and by ITS rDNA sequence analysis. A second new metabolite, podospirone (2), was also produced by all three strains whereas the weakly cytotoxic (+)-3,4-anhydroshikimic acid methyl ester (3) was detected in only one strain. | 18,998,405 |
Salt-stress induced alterations in protein profile and protease activity in the mangrove Bruguiera parviflora. | Two-month-old seedlings of Bruguiera parvifora were treated with varying levels of NaCl (100, 200 and 400 mM) under hydroponic culture. Total proteins were extracted from leaves of control and NaCl treated plants after 7, 14, 30 and 45 d of treatment and analysed by SDS-PAGE. As visualized from SDS-PAGE, the intensity of several protein bands of molecular weight 17, 23, 32, 33 and 34 kDa decreased as a result of NaCl treatment. The degree of decrease of these protein bands seemed to be roughly proportional to the external NaCl concentration. The most obvious change concerned a 23 kDa-polypeptide (SSP-23), which disappeared after 45 d treatment in 400 mM NaCl. Moreover, the SSP-23 protein, which disappeared in B. parviflora under salinity stress, reappeared when these salinized seedlings were desalinized. These observations suggest the possible involvement of these polypeptides for osmotic adjustment under salt stress. NaCl stress also caused an increase in the activity of both acid and alkaline protease. The increasing activity of proteases functions as a signal of salt stress in B. parviflora, which induces the reduction of protein level. | 18,998,411 |
[Correlation of the content and expression of urokinase plasminogen activator with asthenospermia in rat models]. | To investigate the content and expression of the urokinase plasminogen activator (uPA) in the ornidazole-induced asthenospermia animal model, and to probe the mechanism of ornidazole inducing asthenospermia and the possibility of using uPA for the prevention and treatment of asthenospermia. Forty-eight male rats were equally randomized into 5 medication groups (1 d, 5 d, 10 d, 15 d and 20 d) and a blank control group, and ornidazole (200 mg/kg) was given intragastrically every day to the former five while 0.5% carboxymethylcellulose Na (CMC-Na) to the latter for 20 successive days. Then the rats were sacrificed by intraperitoneal injection of pentobarbital at 1, 5, 10, 15 and 20 days respectively and the epididymides and testes harvested. The integrity of the sperm cell membrane was detected by hypoosmotic swelling experiments, the uPA expression in the testicular and epididymal tissues dynamically observed by immunohistochemistry and the level of uPA mRNA in the testis determined by RT-PCR. The integrity of the sperm cell membrane was reduced at 10 days and remained low till the end of the medication, but with no statistic significance. Compared with the blank controls, the uPA expression and mRNA content in the testicular and epididymal tissues showed no conspicuous difference in the 1 d and 5 d groups, decreased insignificantly in the 10 d group, but significantly in the 15 d and 20 d groups (P < 0.05). The defect of sperm cell membrane and decrease of sperm motility go in parallel with the reduced expression and content of uPA, which may be one of the factors for the development of asthenospermia. | 18,998,460 |
Hearing deficit in a birth cohort of U.S. male commuter air carrier and air taxi pilots. | Long-term exposure to multiple risk factors in aviation may place pilots at excess risk of developing hearing deficits. We examined the incidence and risk factors for hearing deficit in a birth cohort of male commuter and air taxi pilots. The subjects (N = 3019), who were 45-54 yr of age and held Class I medical certificates in 1987, were followed up from 1987 to 1997 through the medical certification system of the Federal Aviation Administration (FAA). In this study, hearing deficit refers to the FAA pathology code 220 (defective hearing, deafness, not elsewhere classified). Poisson regression modeling based on generalized estimation equations was used to assess the associations between pilot characteristics and the risk of developing hearing deficit. The 10-yr follow-up accumulated a total of 20,671 person-years and 574 incident cases of hearing deficit, yielding an incidence rate of 27.8 per 1000 person-years. Compared with age 45-49 yr, the risk of developing hearing deficit at age 50-54 yr, 55-59 yr, and 60-64 yr increased by 12% [adjusted relative risk (RR) 1.12, 95% confidence interval (CI) 0.98-1.30], 34% (RR 1.34, 95% CI 1.13-1.59), and 79% (RR 1.79, 95% CI 1.20-2.67), respectively. Hearing deficit is prevalent among commuter air carrier and air taxi pilots and the risk of hearing deficit increases progressively with pilot age. Effective programs for preventing excess hearing loss in the pilot population are warranted. | 18,998,487 |
Vertebral fracture in a pilot during centrifuge training: finding of osteopenia. | We report on a case of an F-16 pilot who suffered a compression fracture of the L5 vertebral body during centrifuge training. The pilot sustained the injury during a rapid onset to 6 G run. He was subsequently diagnosed to have osteopenia with a bone mineral density T-score of -1.95. This report discusses the medical and operational management of the pilot with this rare condition. The pilot has since returned to flying duties, albeit in a transportplatform. | 18,998,491 |
Auditory skills development among children with developmental delays and cochlear implants. | We sought to understand auditory skills outcomes in young children with cochlear implants and developmental delay. Children who received cochlear implants at less than 36 months of age were identified via chart review. Their postimplant auditory skills outcomes were measured with the Auditory Skills Checklist. Of 35 children who received cochlear implants before the age of 36 months, 14 children (40%) had additional disabilities or some form of developmental delay. The 12-month postimplant data indicated progress in all groups of children. Children with additional disabilities had the same rate of auditory skills progress as children with no additional disabilities (beta = 9.3 versus 9.3; p = 0.5). However, the children with additional disabilities tended to start at a lower baseline skills set (approximately 6 points lower) on the Auditory Skills Checklist. For children with average developmental quotients (at least 80), the rate of progress was twice that of children with a developmental quotient of less than 80, irrespective of a developmental disability (beta = 9.9 versus 4.8; p = 0.03). Children with a developmental quotient of less than 80 were less likely to gain skills in discrimination and identification after the first postimplant year. Children with additional disabilities make progress in auditory skills, but may not develop higher auditory skills of identification and comprehension within the first 6 months after implantation. Categorizing children according to a cognitive developmental quotient may provide more predictive ability than does categorizing them by disability type. | 18,998,496 |
[Selection of a novel single-chain variable fragment antibody specifically against a linear epitope of white spot syndrome virus]. | White spot syndrome virus (WSSV) is one of the most important pathogens in shrimp farm throughout the world. Many researches on WSSV have been done, but no efficient approach has been gained to protect and cure the disease. In this study, we constructed a single-chain fragment variable (scFv) antibody library displayed on phage using spleen cells from mice immunized with denatured WSSV. After several rounds of panning respectively against purified intact WSSV virions and purified VP28 expressed in Escherichia coli, five novel scFv antibodies specifically against WSSV were selected, one of which, clone P75E8, recognized a linear epitope. The location in virions of the epitopes recognized by the five scFv clones was determined by immunoelectron microscopy. This study provides a new way to obtain more different antibodies specifically binding to WSSV, and especially provides a new strategy to obtain scFvs against linear epitopes. | 18,998,540 |
[Zirconia and removable partial dentures]. | The present paper deals with the double crown technique in removable prosthodontics. New ceramic materials like zirconia are increasingly used in combination with CAD/CAM technologies for framework fabrication of fixed prosthesis, tooth- or implant-supported. However, zirconia is also a newly accepted material in removable prosthodontics. It replaces gold alloys for the fabrication of primary telescopic crowns. The Galvanoforming technology is preferably used to fabricate the secondary crowns. The combination of both techniques and materials results in a prosthetic reconstruction of high quality, optimum fit and good biocompatibility. | 18,998,581 |
Ab initio studies of properties of small potassium clusters. | We have studied the properties of various isomers of potassium clusters containing even number of atoms ranging from 2 to 20 at the ab initio level. The geometry optimization calculations of the isomers of each cluster are performed by using all-electron density functional theory with gradient corrected exchange-correlation functional. Using the optimized geometries of different isomers we investigate the evolution of binding energy, ionization potential, and static polarizability with the increasing size of the clusters. The polarizabilities are calculated by employing Möller-Plesset perturbation theory and time-dependent density functional theory. The polarizabilities of dimer and tetramer are also calculated by employing large basis set coupled cluster theory with single and double excitations and perturbative triple excitations. The time-dependent density functional theory calculations of polarizabilities are carried out with two different exchange-correlation potentials: (i) an asymptotically correct model potential and (ii) within the local density approximation. A systematic comparison with the other available theoretical and experimental data for various properties of small potassium clusters mentioned above has been performed. These comparisons reveal that both the binding energy and the ionization potential obtained with gradient-corrected potential match quite well with the already published data. Similarly, the polarizabilities obtained with Möller-Plesset perturbation theory and with model potential are quite close to each other and also close to experimental data. | 18,998,655 |
Reactivity of superoxide radical anion and hydroperoxyl radical with alpha-phenyl-N-tert-butylnitrone (PBN) derivatives. | Nitrones have exhibited pharmacological activity against radical-mediated pathophysiological conditions and as analytical reagents for the identification of transient radical species by electron paramagnetic resonance (EPR) spectroscopy. In this work, competitive spin trapping, stopped-flow kinetics, and density functional theory (DFT) were employed to assess and predict the reactivity of O(2)(*-) and HO(2)(*) with various para-substituted alpha-phenyl-N-tert-butylnitrone (PBN) spin traps. Rate constants of O(2)(*-) trapping by nitrones were determined using competitive UV-vis stopped-flow method with phenol red (PR) as probe, while HO(2)(*) trapping rate constants were calculated using competition kinetics with 5,5-dimethylpyrroline N-oxide (DMPO) by employing EPR spectroscopy. The effects of the para substitution on the charge density of the nitronyl-carbon and on the free energies of nitrone reactivity with O(2)(*-) and HO(2)(*) were computationally rationalized at the PCM/B3LYP/6-31+G(d,p)//B3LYP/6-31G(d) level of theory. Theoretical and experimental data show that the rate of O(2)(*-) addition to PBN derivatives is not affected by the polar effect of the substituents. However, the reactivity of HO(2)(*) follows the Hammett equation and is increased as the substituent becomes more electron withdrawing. This supports the conclusion that the nature of HO(2)(*) addition to PBN derivatives is electrophilic, while the addition of O(2)(*-) to PBN-type compounds is only weakly electrophilic. | 18,998,656 |
Highly enantioselective radical addition to N-benzoyl hydrazones using chiral ammonium salts. | In the presence of a protonated cinchonine derivative, radical addition reactions proceeded efficiently, affording addition adducts in high yields with an extremely high enantioselectivity. The chiral ammonium salt was recyclable after a simple aqueous workup. The reaction provides environmentally benign reaction conditions. | 18,998,683 |
Synthesis of condensed pyrroloindoles via Pd-catalyzed intramolecular C-H bond functionalization of pyrroles. | A new strategy for the synthesis of condensed hetero- or carbocycles such as pyrroloindoles or fluorenes has been developed that involves the Pd-catalyzed cyclization of readily available N-(2-halobenzyl)pyrroles or their phenyl derivatives. The reaction is proposed to proceed via oxidative addition of benzylic halides to Pd(0) followed by base-assisted C-H bond activation. A broad range of condensed cyclic products could be obtained in good to excellent yields under mild conditions. | 18,998,684 |
Pramlintide in the treatment of diabetes mellitus. | Pramlintide, the first member of a new class of drugs for the treatment of insulin-using patients with type 2 or type 1 diabetes mellitus, is an analog of the peptide hormone amylin. Amylin is co-secreted with insulin from pancreatic beta cells and acts centrally to slow gastric emptying, suppress postprandial glucagon secretion, and decrease food intake. These actions complement those of insulin to regulate blood glucose concentrations. Amylin is relatively deficient in patients with type 2 diabetes, depending on the severity of beta-cell secretory failure, and is essentially absent in patients with type 1 diabetes. Through mechanisms similar to those of amylin, pramlintide improves overall glycemic control, reduces postprandial glucose levels, and reduces bodyweight in patients with diabetes using mealtime insulin. Reductions in postprandial glucose and bodyweight are important, since postprandial hyperglycemia is associated with an increased risk of microvascular and macrovascular complications, and increased weight is an independent risk factor for cardiovascular disease. Pramlintide is generally well tolerated, with the most frequent treatment-emergent adverse event being mild to moderate nausea, which decreases over time. Pramlintide treatment is also associated with improvements in markers of oxidative stress and cardiovascular risk and improved patient-reported treatment satisfaction. These factors make pramlintide an attractive option for the treatment of postprandial hyperglycemia in patients with diabetes using mealtime insulin. | 18,998,755 |
Multi-professional communication during a patient handoff. | Little is known about the communication principles necessary for successful design and implementation of information technology that supports the needs of healthcare providers from multiple professions. New methods are needed to understand the influence of technology on existing workflow and communication patterns in the complex patient care environment. Social Network Analysis is an approach that examines how the interactions between individual providers and environmental constraints, such as health information technology, influence individual communication behavior. | 18,998,774 |
Infobuttons: anticipatory passive decision support. | "Infobuttons" are context-specific links from one system (typically a clinical information system) to a second system (typically an on-line knowledge resource) that attempt to use contextual information to anticipate users' information needs. Infobuttons have been around for over 15 years but are only recently finding wide-spread adoption, with various "infobutton managers", and infobutton-like projects being developed at several academic medical centers. Vendors of electronic health records systems have begun working with vendors of knowledge resources to create "infobutton access" methods for communicating from the former to the latter. In response to this increased interest, and the attendant need to standardize communication between clinical systems and infobutton managers and between infobutton managers and knowledge resources, Health Level 7 (HL7) is developing a standard message structure for exchange contextual information and information-needs requests. At least one project is underway to develop a tailoring environment that can be used by health librarians to customize infobutton managers for use at their own institutions, with their own users, and their preferred knowledge resources. | 18,998,777 |
NLP-based identification of pneumonia cases from free-text radiological reports. | Radiological reports are a rich source of clinical data which can be mined to assist with biosurveillance of emerging infectious diseases. In addition to biosurveillance, radiological reports are an important source of clinical data for health service research.Pneumonias and other radiological findings on chest x ray or chest computed tomography (CT) are one type of relevant finding to both biosurveillance and health services research. In this study we examined the ability of a Natural Language Processing system to accurately identify pneumonias and other lesions from within free text radiological reports. The system encoded the reports in the SNOMED CT Ontology and then a set of SNOMED CT based rules were created in our Health Archetype Language aimed at the identification of these radiological findings and diagnoses. The encoded rule was executed against the SNOMED CT encodings of the radiological reports. The accuracy of the reports was compared with a Clinician review of the Radiological Reports. The accuracy of the system in the identification of pneumonias was high with a Sensitivity (recall) of 100%, a specificity of 98%, and a positive predictive value (precision) of 97%. We conclude that SNOMED CT based computable rules are accurate enough for the automated biosurveillance of pneumonias from radiological reports. | 18,998,791 |
Optimizing feature representation for automated systematic review work prioritization. | Automated document classification can be a valuable tool for enhancing the efficiency of creating and updating systematic reviews (SRs) for evidence-based medicine. One way document classification can help is in performing work prioritization: given a set of documents, order them such that the most likely useful documents appear first. We evaluated several alternate classification feature systems including unigram, n-gram, MeSH, and natural language processing (NLP) feature sets for their usefulness on 15 SR tasks, using the area under the receiver operating curve as a measure of goodness. We also examined the impact of topic-specific training data compared to general SR inclusion data. The best feature set used a combination of n-gram and MeSH features. NLP-based features were not found to improve performance. Furthermore, topic-specific training data usually provides a significant performance gain over more general SR training. | 18,998,798 |
Web service access to semantic web ontologies for data annotation. | Recent advances in semantic web technologies now provide the methodology for efficient and adaptable deployment of ontology support to biomedical applications for data annotation and integration. | 18,998,840 |
Effectiveness of automatic acute stroke alert system based on UMLS mapped local terminology codes at emergency department. | Acute stroke team activation process is needed to improve acute stroke management at emergency department. Recently automatic acute stroke alert system was developed at Asan Medical Center by using local terminology codes mapped to UMLS codes. The effectiveness of this system was evaluated with the aspect of alert time, contribution to activation, and stroke predictability. | 18,998,845 |
A web-based biosignal data management system for U-health data integration. | In the ubiquitous healthcare environment, the biosignal data should be easily accessed and properly maintained. This paper describes a web-based data management system. It consists of a device interface, a data upload control, a central repository, and a web server. For the user-specific web services, a MFER Upload ActiveX Control was developed. | 18,998,847 |
An experience of "learning by doing": the hand surface images archive. | For a common user, bioimages seem to be very easy to treat, to read, to understand and, therefore, to archive. Conversely, bioimage archiving requires a complex design and implementation process. We proposed to a class of bioengineering students the implementation of a hand image repository specifically designed for highlighting the main features that should be taken into account when treating bioimage archives. | 18,998,854 |
Effect of nurse reminder on depression screening rates in racial/ethnic minorities. | We analyzed a set of clinical encounters (n=4,160) in which nurses received a reminder to screen for depression. Patients who were African-American or Hispanic were less likely to be screened as were those with Medicaid or Medicare insurance. | 18,998,860 |
Role of Health Information Technology (HIT) in disability determinations: when medical records become medical evidence. | This exploratory study investigated the impact of incomplete medical evidence on the SSA disability determination process and the role of HIT as a solution. We collected qualitative data from nineteen expert-interviews. Findings indicate that HIT can lead to innovative solutions that can significantly improve the determination process. | 18,998,861 |
Web screening of US nursing homes by location and quality. | To assist American families who will one day need to find a nursing home for a loved one, NLM is developing a Web 2.0 interface to important evaluative information about nursing homes in the US. Currently in prototype form, our Nursing Home Screener locates homes on a Google Map. It allows nursing home quality, indicated by map icons, to be surveyed in any of four major categories: staffing, fire safety deficiencies, healthcare deficiencies, and quality of care inferred from residents health. Within each category, options can be tailored to user preferences. Furthermore, home attributes can be used to selectively hide home markers of less interest. The goal is to offer the public a timely, easy to use site for the rapid location and comparison of nursing homes, thus identifying those worth further review or a personal visit. | 18,998,890 |
Statewide real-time in-flight trauma patient vital signs collection system. | Continuous recorded in-flight vital signs monitoring and life-saving interventions linked to outcomes may provide better understanding of pre-hospital triage, care management and patient responses during the 'golden hour' of trauma care. Evaluation of 157 patients' vital signs data collected from our statewide network has identified episodes of physiological decompensation which holds promise for creation of new triage algorithms and enhanced trauma center preparedness. | 18,998,900 |
Automating the maintenance of problem list documentation using a clinical decision support system. | We designed and tested a clinical decision support system (CDSS) prototype to investigate whether a CDSS that assists matching ordered drugs to problems on the problem list can enhance the maintenance of medications and problem lists in the electronic medical record. We evaluated the capability of this CDSS in medication-problem matching using clinical expert chart audits. The analysis revealed that this CDSS could determine the completeness of medication and problem lists if a mismatch occurs. | 18,998,927 |
Minnesota framework for identification, endorsement and adoption of standards for interoperable electronic health records statewide. | The Minnesota e-Health Initiative developed a framework for identification, endorsement and adoption of standards as part of a state mandate for providers to implement interoperable electronic health records by 2015. The framework builds on national work and assesses opportunities and readiness for collaborative action to support implementation. Opportunities for sharing resources and benefits for a collaborative focus are discussed. | 18,998,947 |
An operational citywide electronic infection control network: results from the first year. | The prevalence of drug resistant bacteria such as Methicillin-resistant Staphylococcus aureus (MRSA) continues to increase nationwide. Infection control is a regional problem, particularly in urban settings, requiring a coordinated effort. To enable coordinated infection control efforts, we created a citywide electronic notification system to prospectively track and share information regarding all known patients with MRSA. We currently track almost 17,000 patients with a history of MRSA infection or colonization across the Indianapolis region. Since May 2007, we have delivered 2698 admission alerts on patients with a history of MRSA, one-fifth of which (19%) were based on data from another institution. Our system delivers alerts to 20 infection control providers (ICPs) spanning 16 hospital in five different systems across Indianapolis. Electronic coordination of regional infection control information appears to be a critical step to reduce infection rates across an urban population. | 18,999,011 |
Automatic pre-hospital vital signs waveform and trend data capture fills quality management, triage and outcome prediction gaps. | Trauma Triage errors are frequent and costly. What happens in pre-hospital care remains anecdotal because of the dual responsibility of treatment (resuscitation and stabilization) and documentation in a time-critical environment. Continuous pre-hospital vital signs waveforms and numerical trends were automatically collected in our study. Abnormalities of pulse oximeter oxygen saturation (< 95%) and validated heart rate (> 100/min) showed better prediction of injury severity, need for immediate blood transfusion, intra-abdominal surgery, tracheal intubation and chest tube insertion than Trauma Registry data or Pre-hospital provider estimations. Automated means of data collection introduced the potential for more accurate and objective reporting of patient vital signs helping in evaluating quality of care and establishing performance indicators and benchmarks. Addition of novel and existing non-invasive monitors and waveform analyses could make the pulse oximeter the decision aid of choice to improve trauma patient triage. | 18,999,022 |
Selecting data elements to build a patient-centric electronic health record that will support adherence to therapeutic lifestyle change. | Cardiovascular disease (CVD) remains the leading cause of death in the US. Therapeutic lifestyle change (TLC) is an effective intervention to reduce the risk of CVD. In developing a patient-centric electronic health record (PC-EHR), our project aims to build an evidence-based support system to facilitate patient-provider interaction, foster cooperative chronic disease management, and promote adherence to TLC guidelines by both providers and patients. In this paper we report on the findings of a modified Delphi method (MDM) study to determine the behavioral and psychosocial elements needed to extend the clinical data model and support the TLC decision support algorithm. An eight-member expert advisory committee reviewed a list of 83 proposed data elements including those from the National Cholesterol Education Program Adult Treatment Panel III guidelines and finalized a set of 30 data elements for inclusion. The MDM proved to be an effective approach for prioritizing data elements. | 18,999,031 |
Visualizing multivariate time series data to detect specific medical conditions. | Efficient unsupervised algorithms for the detection of patterns in time series data, often called motifs, have been used in many applications, such as identifying words in different languages, detecting anomalies in ECG readings, and finding similarities between images. We present a process that creates a personalized multivariate time series representation a Multivariate Time Series Amalgam (MTSA) of physiological data and laboratory results that physicians can visually interpret. We then apply a technique that has demonstrated success with the interpretation of univariate data, named Symbolic Aggregate Approximation (SAX), to visualize patterns in the MTSAs that may differentiate between medical conditions such as renal and respiratory failure. | 18,999,033 |
A novel system for rapidly identifying toxic chemicals. | First-responders have a critical need to rapidly identify toxic chemicals during emergencies. However, current systems such as WISER require a large number of inputs before a chemical can be identified. Here we present a novel system which significantly reduces the number of inputs required to identify a toxic chemical. | 18,999,084 |
Construction of a dictionary of laboratory tests mapped to LOINC at AP-HP. | We report on the ongoing process implemented at Assistance Publique-Hôpitaux de Paris (AP-HP), the largest hospital system in Europe, to build a common reference for laboratory tests in French with LOINC mappings. At the time of writing, it contained 24,000 tests, covering all fields of biology, in use in 19 AP-HP hospitals, 30% of which had a mapping to LOINC with a peak of over 60% in biochemistry. | 18,999,107 |
Real-time process "defect" collection within the anatomic pathology laboratory to facilitate informatics driven workflow optimization. | Our anatomic pathology laboratory workflow optimization project developed a 2-pronged approach to real-time rapid process "defect" collection using a customized Post-it (3M) note for non-computerized workstations and a data collection module within our workflow integration software system, each of which takes less than 5 minutes to complete. We present results from our baseline, pre-implementation data collection event and discuss the applicability for other areas of healthcare. | 18,999,113 |
An engineering work analysis applied to patient falls in the nursing domain. | Patient falls in hospitals result in negative outcomes such as prolonged lengths of stay, various injuries, and even death. Nurses are responsible for identifying patients at risk for falls and implementing preventative measures. The focus of this research is to apply a systems engineering approach, Cognitive Work Analysis (CWA) to the nursing domain. Our interdisciplinary effort has begun to identify areas of risk and preventative measures. | 18,999,114 |
Predicting hemodialysis mortality utilizing blood pressure trends. | Mean Systolic Blood Pressure (SBP) is a predictor of mortality in hemodialysis (HD) patients. The hypothesis is that transforming SBP measurements to reflect trends would improve the quality of predictions. Data consisted of 4,500 patients from a dialysis provider in the US with at least six months follow-up. Relative Difference in Percentage yielded six transformed variables, representing SBP trends. Models were constructed using Support Vector Machine (SVM). RESULTS were compared to a baseline model utilizing six-month mean SBP. All models included age, gender, race, diabetes, vintage, and BMI. Pooling of repeated observations incorporated all repeated observations in a generalized person-month approach. The AUC for the model using transformed variables on unseen data was 0.70, compared to 0.63 for the baseline model (p<0.00001). The AUC was 0.69 when modeling a pooled data set. The use of SBP trends significantly improved mortality prediction in HD patients. | 18,999,118 |
A trend map for e-health information. | Health information of varying levels of quality is available and accessed on the web by patients and medical personnel, who base their decisions on the knowledge they find on the sites they visit. Providing a network map showing different types of sources for medical information is a powerful way to visualize the complex, overlapping web of information available to providers and consumers. We present a prototype map representing consumer e-health information web sites. | 18,999,131 |
Evaluation and comparison of IV insulin-treatment protocols using data from critically ill patients in the ICU. | In critically ill patients control of blood sugar levels with IV insulin has been shown to improve clinical outcomes in the intensive care units. We have developed an analytical framework with which to evaluate and compare IV insulin-treatment models and protocols. Performance of the analytical framework is demonstrated using protocols published by others and new protocols under development by our group. | 18,999,145 |
Extracting structured medication event information from discharge summaries. | We present a method that extracts medication information from discharge summaries. The program relies on parsing rules written as a set of regular expressions and on a user-configurable drug lexicon. Our evaluation shows a precision of 94% and recall of 83% in the extraction of medication information. We use a broader definition of medication information than previous studies, including drug names appearing with and without dosage information, misspelled drug names, and contextual information. | 18,999,147 |
Representing nursing assessment documentation with ICNP. | The purpose of this study was to identify key concepts and semantic relations necessary to represent standardized and local patient assessment items in an electronic documentation system and to evaluate the degree to which coverage of both are represented by ICNP. A total of 805 unique assessment concepts were identified. Forty-three percent had exact matches in ICNP, and an additional 20% had matches in the ICNP classified as narrower, broader or other. | 18,999,149 |
Stay tuned. Comparison of journal updates tracking using RSS and e-mail technologies. | Electronic subscription alerts provide new possibilities for health care providers to stay abreast with current literature and practice evidence-based medicine. During a 5 month prospective observation we compared the performance of the three common subscription methods: email and Really Simple Syndication (RSS) from the publisher and RSS from PubMed. The 3 methods were reliably updated without interruption in service but demonstrated significant variability in the contents and timing. | 18,999,160 |
Analysis of Maryland poisoning deaths using classification and regression tree (CART) analysis. | Our study is a cross-sectional analysis of Maryland poisoning deaths for years 2003 and 2004. We used Classification and Regression Tree (CART) methodology to classify undetermined intent Maryland poisoning deaths as either unintentional or suicidal poisonings. The predictive ability of the selected set of variables (i.e., poisoned in the home or workplace, location type, where poisoned, place of death, poison type, victim race and age, year of death) was extremely good. Of the 301 test cases, only eight were misclassified by the CART regression tree. Of 1,204 undetermined intent poisoning deaths, CART classified 903 as suicides and 301 as unintentional deaths. The major strength of our study is the use of CART to differentiate with a high degree of accuracy between unintentional and suicidal poisoning deaths among Maryland undetermined intent poisoning deaths. | 18,999,168 |
Use of decision support to prevent errors when documenting height and weight in the hospital electronic medical record. | This study evaluates the impact of decision support to improve documentation of height and weight as a means to prevent medication errors. We developed a real-time expert system rule that calculates age-specific limits and provides an alert if the value entered is outside these limits. We compare data before and after the implementation of the rule, demonstrating a significant reduction of errors. | 18,999,178 |
The MidSouth eHealth Alliance: use and impact in the first year. | The MidSouth e-Health Alliance is a health information exchange that has been in use in the Memphis, Tennessee region since May, 2006. This health information exchange took two years to develop from the time it was initially conceived. Following on the work done by the Indianapolis project, the MidSouth e-Health Alliance focused initially on implementations in emergency departments throughout this region. A total of 321 clinicians have used the system in the 5 emergency departments since s initial deployment. This paper reports on the processes users are engaged in to use the system as well as the demographics and patient characteristics associated with system use to date. | 18,999,184 |
Semiotic web for translational medicine. | The semiotic web for translational medicine generalizes the concept of the semantic web. We present the functions of the semiotic web as a simple ontology with three dimensions, namely: (a) the four steps of semiotics, (b) the two processes in semiotics, and (c) the four types of research. The resulting 32 combinations represent all its functions. | 18,999,185 |
Defining medication complexity and its effect on outcomes in community dwelling elders receiving home care. | Complexity of medication regimens in community dwelling elders is examined in relationship to emergent care use, hospitalization and self management of medications in this secondary data analysis of OASIS data and medication data from all 2004 open admissions to 15 home health care agencies. Preliminary findings and the use of innovative techniques are discussed highlighting the predictive potential for medication complexity in other settings, risk stratification, and design implications for both clinical tools and databases. | 18,999,187 |
The impact of web-based diabetes risk calculators on information processing and risk perceptions. | As consumer demand for online health information grows, many organizations are providing personalized and interactive health risk communication tools. In response, there is a need to better understand how effective these features are in influencing user attention, information processing and risk perceptions. This study randomly assigned 100 middle-aged and elderly adult users to one of three versions of an experimental type 2 diabetes "risk calculator" in order to determine if personalized risk estimates and interactive risk feedback impact usage behavior and beliefs about future diabetes onset. Results suggest that personalization and interactive features did not lead to increases in user attention or systematic information processing. The experiment provided only modest evidence that personalization was related to increased accuracy in absolute diabetes risk perceptions. Future studies are warranted to more precisely explain the descriptive and normative implications when laypersons use web-based risk communication tools. | 18,999,192 |
Linking test ordering with order tracking: closing the loop in ambulatory care. | Test non-completion decreases quality of care and accounts for many diagnosis-related malpractice claims. Currently, clinicians using Partners' electronic Longitudinal Medical Record (LMR) can track results but lack a mechanism for tracking non-completed tests. This pilot intervention will study an "order tracking" functionality that flags newly-ordered tests and will lead to generation of written patient reminders if tests are not completed within pre-specified timeframes. If test completion rates improve, we will pursue development of a dedicated LMR application. | 18,999,233 |
A tag based recommendation engine to suggest information resources in an online community for health promotion. | WEB 2.0 or the "social web" has created a new paradigm of collaborative information creation, organization and consumption. Among these, the social process of "tagging" has emerged as a bottom-up user-driven method to index content. We describe the use of tags as a way to connect users to resources in an online community that we are developing which utilizes social content creation and collaboration to promote health. Such connections are the basis of a recommendation engine that will suggest users a) other users who have similar health profiles, b) relevant information resources such as articles or blogs on health promotion and c) community resources such as local health facilities. | 18,999,253 |
Somatic mutation signatures of cancer. | The advancement of cancer diagnosis, prognosis, and treatment would be hastened via a robust method to identify patterns that indicate a tumor's state. Prior research has established that sporadic, colorectal-cancer pathogenesis involves a series of genetic mutations that allow benign polyps to develop and eventually progress to malignant tumors in distinguishable patterns. Using a publicly available database of somatic mutations for many cancer types, we identified somatic-mutation signatures. Our results for colorectal cancer are consistent with what extant biological models as described in the literature. This approach is potentially useful for identifying previously undiscovered patterns and generating hypotheses related to biological pathways. Such signatures could prove valuable for eventual translation into clinical practice. | 18,999,255 |
Three years experience with the implementation of a networked electronic medical record in Haiti. | Since 2005 we have been developing and implementing an electronic medical record (EMR) that supports both individual and population health care of HIV-infected patients in Haiti. Unreliable electrical power and network infrastructure, cultural differences, variable levels of experience and computer literacy, and the geographic dispersion of the team remain challenges, but the system is now implemented in about 40 sites nationwide providing antiretroviral therapy, and includes records for about 18,600 patients. The need to support country-wide monitoring and evaluation drove early architectural decisions to support linking systems under conditions of network uncertainty. We have found surprising end user acceptance of the system, with the adoption of interactive EMR usage exceeding our expectations and timeline. | 18,999,283 |
Evaluating the technical adequacy of electronic prescribing standards: Results of an expert panel process. | To support more informed prescribing decisions, e-prescribing systems need data on patients' medication histories and their drug-specific insurance coverage. We used an expert panel process to evaluate the technical adequacy of two standards for delivering this information, the Medication History function of the NCPDP SCRIPT Standard and the NCPDP Formulary and Benefit Standard. We convened a panel representing 14 organizations that had experience with these standards. Experts within each organization submitted narrative responses and ratings assessing the standards in 6 domains, including data quality,completeness, usability, and interoperability. Areas of disagreement were discussed in recorded teleconferences. Narrative was analyzed using a grounded-theory approach. Panelists agreed that the structure of the Medication History Standard was adequate for delivering accurate and complete information but implementation problems made the data difficult to use for decision support.The panel also agreed that the Formulary and Benefit Standard was adequate to deliver formulary status lists, but other parts of the standard were not used consistently and group-level variations in coverage were not represented. A common problem for both standards was the lack of unambiguous drug identifiers; panelists agreed that RxNorm deserves further evaluation as a solution to this problem. A panel of industry experts found the basic structure of these two standards to be technically adequate, but to enable benefits for patient care, improvements are needed in the standards' implementation. | 18,999,287 |
A multi-level spatial clustering algorithm for detection of disease outbreaks. | In this paper, we proposed a Multi-level Spatial Clustering (MSC) algorithm for rapid detection of emerging disease outbreaks prospectively. We used the semi-synthetic data for algorithm evaluation. We applied BARD algorithm [1] to generate outbreak counts for simulation of aerosol release of Anthrax. We compared MSC with two spatial clustering algorithms: Kulldorff's spatial scan statistic [2] and Bayesian spatial scan statistic [3]. The evaluation results showed that the areas under ROC had no significant difference among the three algorithms, so did the areas under AMOC. MSC demonstrated significant computational efficiency (100 + times faster) and higher PPV. However, MSC showed 2-6 hours delay on average for outbreak detection when the false alarm rate was lower than 1 false alarm per 4 weeks. We concluded that the MSC algorithm is computationally efficient and it is able to provide more precise and compact clusters in a timely manner while keeping high detection accuracy (cluster sensitivity) and low false alarm rates. | 18,999,304 |
Identifying functional discrepancies in self monitoring intake applications. | Self Monitoring Intake (SMI) has been shown to be an effective method to motivate adherence to a healthy diet. The key function in SMI applications is to document daily dietary intake, which requires users to select intake from a long pick list of items. Current approaches for food item selection are poor in usability because of insufficient representation of knowledge behind the work domain. This poster presents a new approach to discover and model the underlying knowledge. | 18,999,313 |
Racial identity, social context, and race-related social cognition in African Americans during middle childhood. | This study examined the effect of changes in racial identity, cross-race friendships, same-race friendships, and classroom racial composition on changes in race-related social cognition from 3rd to 5th grade for 73 African American children. The goal of the study was to determine the extent to which preadolescent racial identity and social context predict expectations of racial discrimination in cross-race social interactions (social expectations). Expectations of racial discrimination were assessed using vignettes of cross-race social situations involving an African American child in a social interaction with European Americans. There were 3 major findings. First, expectations for discrimination declined slightly from 3rd to 5th grade. Second, although racial composition of children's classrooms, number of European American friends, gender, and family poverty status were largely unrelated to social expectations, having more African American friends was associated with expecting more discrimination in cross-racial interactions from 3rd to 5th grade. Third, increases in racial centrality were related to increases in discrimination expectations, and increases in public regard were associated with decreases in discrimination expectations. These data suggest that as early as 3rd grade, children are forming attitudes about their racial group that have implications for their cross-race social interactions. | 18,999,320 |
Age differences in sensation seeking and impulsivity as indexed by behavior and self-report: evidence for a dual systems model. | It has been hypothesized that sensation seeking and impulsivity, which are often conflated, in fact develop along different timetables and have different neural underpinnings, and that the difference in their timetables helps account for heightened risk taking during adolescence. In order to test these propositions, the authors examined age differences in sensation seeking and impulsivity in a socioeconomically and ethnically diverse sample of 935 individuals between the ages of 10 and 30, using self-report and behavioral measures of each construct. Consistent with the authors' predictions, age differences in sensation seeking, which are linked to pubertal maturation, follow a curvilinear pattern, with sensation seeking increasing between 10 and 15 and declining or remaining stable thereafter. In contrast, age differences in impulsivity, which are unrelated to puberty, follow a linear pattern, with impulsivity declining steadily from age 10 on. Heightened vulnerability to risk taking in middle adolescence may be due to the combination of relatively higher inclinations to seek excitement and relatively immature capacities for self-control that are typical of this period of development. | 18,999,337 |
Less efficient elementary visuomotor processes in 7- to 10-year-old preterm-born children without cerebral palsy: an indication of impaired dorsal stream processes. | Follow-up studies of preterm children without serious neurological complications have consistently found deficits in visuomotor skills. To determine whether these deficits may be related to impaired elementary visuomotor processes, we investigated movement programming and execution of simple pointing movements in 7- to 10-year-old preterm (<34 weeks g.a. and/or b.w. <1800 g) and full-term children. Such detailed analysis of simple pointing movements provides information on the extent to which processes associated with dorsal and/or cerebellar functions are impaired. Multi-level analysis showed that movement programming and execution were slowed in the 7-, 9-, and 10-year-old preterm groups. This indicates impaired dorsal visual stream functioning in preterm children, but do not rule out impaired cerebellar functioning. At 8 years of age, there were no differences between the two groups in movement execution time. This could have reflected a transition in the development of movement control in the control group, which has been associated in typically developing children with a decrease in motor speed. Interestingly, a similar decrease was not found in the preterm group at 8 years of age. | 18,999,349 |
Selective attention in human associative learning and recognition memory. | Four experiments examined the role of selective attention in a new causal judgment task that allowed measurement of both causal strength and cue recognition. In Experiments 1 and 2, blocking was observed; pretraining with 1 cue (A) resulted in reduced learning about a 2nd cue (B) when those 2 cues were trained in compound (AB+). Participants also demonstrated decreased recognition performance for the causally redundant Cue B, suggesting that less attention had been paid to it in training. This is consistent with the idea that attention is preferentially allocated toward the more predictive Cue A, and away from the less predictive Cue B (e.g., N. J. Mackintosh, 1975). Contrary to this hypothesis, in Experiments 3 and 4, participants demonstrated poorer recognition for the most predictive cues, relative to control cues. A new model, which is based on N. J. Mackintosh's (1975) model, is proposed to account for the observed relationship between the extent to which each cue is attended to, learned about, and later recognized | 18,999,357 |
Will a category cue attract you? Motor output reveals dynamic competition across person construal. | People use social categories to perceive others, extracting category cues to glean membership. Growing evidence for continuous dynamics in real-time cognition suggests, contrary to prevailing social psychological accounts, that person construal may involve dynamic competition between simultaneously active representations. To test this, the authors examined social categorization in real-time by streaming the x, y coordinates of hand movements as participants categorized typical and atypical faces by sex. Though judgments of atypical targets were largely accurate, online motor output exhibited a continuous spatial attraction toward the opposite sex category, indicating dynamic competition between multiple social category alternatives. The authors offer a dynamic continuity account of social categorization and provide converging evidence across categorizations of real male and female faces (containing a typical or an atypical sex-specifying cue) and categorizations of computer-generated male and female faces (with subtly morphed sex-typical or sex-atypical features). In 3 studies, online motor output revealed continuous dynamics underlying person construal, in which multiple simultaneously and partially active category representations gradually cascade into social categorical judgments. Such evidence is challenging for discrete stage-based accounts. | 18,999,360 |
Stereotype threat and executive resource depletion: examining the influence of emotion regulation. | Research shows that stereotype threat reduces performance by diminishing executive resources, but less is known about the psychological processes responsible for these impairments. The authors tested the idea that targets of stereotype threat try to regulate their emotions and that this regulation depletes executive resources, resulting in underperformance. Across 4 experiments, they provide converging evidence that targets of stereotype threat spontaneously attempt to control their expression of anxiety and that such emotion regulation depletes executive resources needed to perform well on tests of cognitive ability. They also demonstrate that providing threatened individuals with a means to effectively cope with negative emotions--by reappraising the situation or the meaning of their anxiety--can restore executive resources and improve test performance. They discuss these results within the framework of an integrated process model of stereotype threat, in which affective and cognitive processes interact to undermine performance. | 18,999,361 |
Connection between matrix-product states and superposition of Bernoulli shock measures. | We consider a generalized coagulation-decoagulation system on a one-dimensional discrete lattice with reflecting boundaries. It is known that a Bernoulli shock measure with two shock fronts might have a simple random-walk dynamics, provided that some constraints on the microscopic reaction rates of this system are fulfilled. Under these constraints the steady state of the system can be written as a linear superposition of such shock measures. We show that the coefficients of this expansion can be calculated using the finite-dimensional representation of the quadratic algebra of the system obtained from a matrix-product approach. | 18,999,380 |
Zero-temperature dynamics in the two-dimensional axial next-nearest-neighbor Ising model. | We investigate the dynamics of a two-dimensional axial next-nearest-neighbor Ising model following a quench to zero temperature. The Hamiltonian is given by H= -J_(0) summation operator(L)_(i,j=1)S_(i,j)S_(i+1,j)-J_(1)summation operator_(i,j=1)(S_{i,j}S_{i,j+1}-kappaS_{i,j}S_{i,j+2}) . For kappa<1 , the system does not reach the equilibrium ground state but slowly evolves to a metastable state. For kappa>1 , the system shows a behavior similar to that of the two-dimensional ferromagnetic Ising model in the sense that it freezes to a striped state with a finite probability. The persistence probability shows algebraic decay here with an exponent theta=0.235+/-0.001 while the dynamical exponent of growth z=2.08+/-0.01 . For kappa=1 , the system belongs to a completely different dynamical class; it always evolves to the true ground state with the persistence and dynamical exponent having unique values. Much of the dynamical phenomena can be understood by studying the dynamics and distribution of the number of domain walls. We also compare the dynamical behavior to that of a Ising model in which both the nearest and next-nearest-neighbor interactions are ferromagnetic. | 18,999,391 |
Structure and stability of isotropic states of hard platelet fluids. | We study the thermodynamics and the pair structure of hard, infinitely thin, circular platelets in the isotropic phase. Monte Carlo simulation results indicate a rich spatial structure of the spherical expansion components of the direct correlation function, including nonmonotonical variation of some of the components with density. Integral equation theory is shown to reproduce the main features observed in simulations. The hypernetted chain closure, as well as its extended versions that include the bridge function up to second and third order in density, perform better than both the Percus-Yevick closure and Verlet bridge function approximation. Using a recent fundamental measure density functional theory, an analytic expression for the direct correlation function is obtained as the sum of the Mayer bond and a term proportional to the density and the intersection length of two platelets. This is shown to give a reasonable estimate of the structure found in simulations, but to fail to capture the nonmonotonic variation with density. We also carry out a density functional stability analysis of the isotropic phase with respect to nematic ordering and show that the limiting density is consistent with that where the Kerr coefficient vanishes. As a reference system, we compare to simulation results for hard oblate spheroids with small, but nonzero elongations, demonstrating that the case of vanishingly thin platelets is approached smoothly. | 18,999,406 |
Experimental measurements of the collapse of a two-dimensional granular gas under gravity. | We experimentally measure the decay of a quasi-two-dimensional granular gas under gravity. A granular gas is created by vibrofluidization, after which the energy input is halted, and the time-dependent statistical properties of the decaying gas are measured with video particle tracking. There are two distinct cooling stages separated by a high temperature settling shock. In the final stage, the temperature of a fluid packet decreases as a power law T proportional, variant(t{c}-t);{alpha} just before the system collapses to a static state. The measured value of alpha ranges from 3.3 to 6.1 depending on the height, significantly higher than the exponent of 2 found in theoretical work on this problem [D. Volfson, B. Meerson, and L. S. Tsimring, Phys Rev. E 73, 61305 (2006)]. We also address the question of whether the collapse occurs simultaneously at different heights in the system. | 18,999,413 |
Experimental study of granular flows in a rough annular shear cell. | The study of granular flows in physics has always been important because of their recurring presence in nature and industry. However, the nonlinear and multiphase behavior exhibited by these particulate systems makes them hard to model and predict. Several experiments were conducted in the past to gain insight into granular flows. The current experimental work furthers this insight and specifically attempts to understand the effect of rough surfaces on granular flows, namely, their local flow behavior. Understanding this interaction can have implications on industrial-scale granular problems. In this work, a granular shear cell, a two-dimensional annular shear cell, was developed to conduct shear experiments where roughness is imposed on the driving surface and experimentally quantified. A digital particle tracking velocimetry data retrieval scheme was developed to extract solid fraction, velocity, and granular temperature data from the experiments as a function of the roughness factor and wheel rotation rate. In general, the steady-state results show the two distinct regions as expected-a high-velocity and dilute-gas-like kinetic region near the moving wall and a high-solid-fraction liquid-like frictional flow regime away from the moving wall. Parametric studies conducted show that the normalized slip near the moving wall decreases with increasing wall roughness and decreasing wall rotation rate. Slip is an important parameter which can be easily interpreted as momentum transfer or traction performance in granular systems related to wheel-terrain interaction, agricultural processing, and most notably granular lubrication. | 18,999,417 |
Visualization of collisional substructure in granular shock waves. | We study shock wave formation and propagation in an experimental vertically driven quasi-two-dimensional granular gas. We measure the moments of the single particle velocity distribution as a function of space and time. The space-time fields of the velocity moments show acoustic waves with a serrated substructure on the scale of a particle diameter. We show that this substructure is the result of collisional transport in which sequential collisions each transport momentum and energy by one particle diameter. | 18,999,420 |
Dynamical heterogeneity in a model for permanent gels: different behavior of dynamical susceptibilities. | We present a systematic study of dynamical heterogeneity in a model for permanent gels upon approaching the gelation threshold. We find that the fluctuations of the self-intermediate scattering function are increasing functions of time, reaching a plateau whose value, at large length scales, coincides with the mean cluster size and diverges at the percolation threshold. Another measure of dynamical heterogeneities-i.e., the fluctuations of the self-overlap-displays instead a peak and decays to zero at long times. The peak, however, also scales as the mean cluster size. Arguments are given for this difference in the long-time behavior. We also find that the non-Gaussian parameter reaches a plateau in the long-time limit. The value of the plateau of the non-Gaussian parameter, which is connected to the fluctuations of diffusivity of clusters, increases with the volume fraction and remains finite at the percolation threshold. | 18,999,424 |
Connections of activated hopping processes with the breakdown of the Stokes-Einstein relation and with aspects of dynamical heterogeneities. | We develop an extended version of the mode-coupling theory (MCT) for glass transition, which incorporates activated hopping processes via the dynamical theory originally formulated to describe diffusion-jump processes in crystals. The dynamical-theory approach adapted here to glass-forming liquids treats hopping as arising from vibrational fluctuations in the quasiarrested state where particles are trapped inside their cages, and the hopping rate is formulated in terms of the Debye-Waller factors characterizing the structure of the quasiarrested state. The resulting expression for the hopping rate takes an activated form, and the barrier height for the hopping is "self-generated" in the sense that it is present only in those states where the dynamics exhibits a well defined plateau. It is discussed how such a hopping rate can be incorporated into MCT so that the sharp nonergodic transition predicted by the idealized version of the theory is replaced by a rapid but smooth crossover. We then show that the developed theory accounts for the breakdown of the Stokes-Einstein relation observed in a variety of fragile glass formers. It is also demonstrated that characteristic features of dynamical heterogeneities revealed by recent computer simulations are reproduced by the theory. More specifically, a substantial increase of the non-Gaussian parameter, double-peak structure in the probability distribution of particle displacements, and the presence of a growing dynamic length scale are predicted by the extended MCT developed here, which the idealized version of the theory failed to reproduce. These results of the theory are demonstrated for a model of the Lennard-Jones system, and are compared with related computer-simulation results and experimental data. | 18,999,429 |
Interplay of subthreshold activity, time-delayed feedback, and noise on neuronal firing patterns. | Feedback connections and noise are ubiquitous features of neuronal networks and affect in a determinant way the patterns of neural activity. Here we study how the subthreshold dynamics of a neuron interacts with time-delayed feedback and noise. We use a Hodgkin-Huxley-type model of a thermoreceptor neuron and assume the feedback to be linear, corresponding effectively to a recurrent electrical connection via gap junctions. This type of feedback can model electrical autapses, which connect the terminal fibers of a neuron's axon with dendrites from the same neuron. Thus the delay in the feedback loop is due basically to the axonal propagation time. We chose model parameters for which the neuron displays, in the absence of feedback and noise, only subthreshold oscillations. These oscillations, however, take the neuron close to the firing threshold, such that small perturbations can drive it above the level for generation of action potentials. The resulting interplay between weak delayed feedback, noise, and the subthreshold intrinsic activity is nontrivial. For negative feedback, depending on the delay, the firing rate can be lower than in the noise-free situation. This is due to the fact that noise inhibits feedback-induced spikes by driving the neuronal oscillations away from the firing threshold. For positive feedback, there are regions of delay values where the noise-induced spikes are inhibited by the feedback; in this case, it is the feedback that drives the neuronal oscillations away from the threshold. Our study contributes to a better understanding of the role of electrical self-connections in the presence of noise and subthreshold activity. | 18,999,455 |
Effects of the chemomechanical stepping cycle on the traffic of molecular motors. | We discuss effects of the stepping kinetics of molecular motors on their traffic behavior on crowded filaments using a simple two-state chemomechanical cycle. While the general traffic behavior is quite robust with respect to the detailed kinetics of the step, a few observable parameters exhibit a strong dependence on these parameters. Most strikingly, the effective unbinding rate of the motors may both increase and decrease with increasing traffic density, depending on the details of the motor step. Likewise the run length either exhibits a strong decrease or almost no dependence on the traffic density. We compare our theoretical results with recent experimental observations on motor traffic. | 18,999,457 |
Simplified model of cytosolic Ca2+ dynamics in the presence of one or several clusters of Ca2+ -release channels. | Calcium release from intracellular stores plays a key role in the regulation of a variety of cellular activities. In various cell types this release occurs through inositol-triphosphate (IP3) receptors which are Ca2+ channels whose open probability is modulated by the cytosolic Ca2+ concentration itself. Thus, the combination of Ca2+ release and Ca2+ diffusion evokes a variety of Ca2+ signals depending on the number and relative location of the channels that participate of them. In fact, a hierarchy of Ca2+ signals has been observed in Xenopus laevis oocytes, ranging from very localized events (puffs and blips) to waves that propagate throughout the cell. In this cell type channels are organized in clusters. The behavior of individual channels within a cluster cannot be resolved with current optical techniques. Therefore, a combination of experiments and mathematical modeling is unavoidable to understand these signals. However, the numerical simulation of a detailed mathematical model of the problem is very hard given the large range of spatial and temporal scales that must be covered. In this paper we present an alternative model in which the cluster region is modeled using a relatively fine grid but where several approximations are made to compute the cytosolic Ca2+ concentration ([Ca;{2+}]) distribution. The inner-cluster [Ca;{2+}] distribution is used to determine the openings and closings of the channels of the cluster. The spatiotemporal [Ca;{2+}] distribution outside the cluster is determined using a coarser grid in which each (active) cluster is represented by a point source whose current is proportional to the number of open channels determined before. A full reaction-diffusion system is solved on this coarser grid. | 18,999,463 |
Benchmark graphs for testing community detection algorithms. | Community structure is one of the most important features of real networks and reveals the internal organization of the nodes. Many algorithms have been proposed but the crucial issue of testing, i.e., the question of how good an algorithm is, with respect to others, is still open. Standard tests include the analysis of simple artificial graphs with a built-in community structure, that the algorithm has to recover. However, the special graphs adopted in actual tests have a structure that does not reflect the real properties of nodes and communities found in real networks. Here we introduce a class of benchmark graphs, that account for the heterogeneity in the distributions of node degrees and of community sizes. We use this benchmark to test two popular methods of community detection, modularity optimization, and Potts model clustering. The results show that the benchmark poses a much more severe test to algorithms than standard benchmarks, revealing limits that may not be apparent at a first analysis. | 18,999,496 |
Scale-free topology-induced double resonance in networked two-state systems. | We study numerically the effect of a scale-free topology on the signal-to-noise ratio of networked two-state systems and find a double resonance phenomenon, i.e., a resonance on coupling strength and a stochastic resonance on noise strength. This finding suggests an alternative approach of self-tuning, i.e., tuning from the scale-free topology, instead of the self-tuning of potential. A heuristic theory through a starlike network is presented to explain the double resonance. | 18,999,497 |
Rhythmic oscillation and dynamic instability of micrometer-size phase separation under continuous photon flux by a focused laser. | We report the dynamical behavior of microm-sized phase separation for a homogeneous mixture of D2O and 3-methylpyridine (3MP) induced under continuous photon-flux by a focused YAG laser. At a water-rich composition, stable rhythmic oscillation of the emergence-growth escape of a 3MP-rich droplet is generated. In contrast, at a near-critical composition, an emergent droplet exhibits significant nonequilibrium fluctuation. Such dynamic phenomena are interpreted in terms of the effect of a local dielectric field and a dissipative system generated by a focused laser on the binary mixture. | 18,999,515 |
Electromagnetic transparency by coated spheres with radial anisotropy. | We establish an account of electromagnetic scattering by coated spheres with radial dielectric and magnetic anisotropy. Within full-wave scattering theory, we show that the total scattering cross section Qs is strongly dependent on both the dielectric anisotropy and magnetic anisotropy. As a consequence, by a suitable adjustment of the radius ratio, one may make the anisotropic coated particle nearly transparent or invisible. In the quasistatic case, we take one step forward to derive the effective permittivity and permeability for the coated particle, and the near-zero scattering radius ratio can be well described within effective medium theory. To one's interest, the introduction of radial anisotropy is helpful to achieve better transparency quality such as a much smaller Qs and wider range of near-zero scattering ratio. Moreover, when the coated particle is anisotropic, the position of the near-zero scattering radius ratio can be tunable, resulting in a tunable electromagnetic cloaking. | 18,999,553 |
Random input problem for the nonlinear Schrödinger equation. | We consider the random input problem for a nonlinear system modeled by the integrable one-dimensional self-focusing nonlinear Schrödinger equation (NLSE). We concentrate on the properties obtained from the direct scattering problem associated with the NLSE. We discuss some general issues regarding soliton creation from random input. We also study the averaged spectral density of random quasilinear waves generated in the NLSE channel for two models of the disordered input field profile. The first model is symmetric complex Gaussian white noise and the second one is a real dichotomous (telegraph) process. For the former model, the closed-form expression for the averaged spectral density is obtained, while for the dichotomous real input we present the small noise perturbative expansion for the same quantity. In the case of the dichotomous input, we also obtain the distribution of minimal pulse width required for a soliton generation. The obtained results can be applied to a multitude of problems including random nonlinear Fraunhoffer diffraction, transmission properties of randomly apodized long period Fiber Bragg gratings, and the propagation of incoherent pulses in optical fibers. | 18,999,554 |
Perturbational formulation of principal component analysis in molecular dynamics simulation. | Conformational fluctuations of a molecule are important to its function since such intrinsic fluctuations enable the molecule to respond to the external environmental perturbations. For extracting large conformational fluctuations, which predict the primary conformational change by the perturbation, principal component analysis (PCA) has been used in molecular dynamics simulations. However, several versions of PCA, such as Cartesian coordinate PCA and dihedral angle PCA (dPCA), are limited to use with molecules with a single dominant state or proteins where the dihedral angle represents an important internal coordinate. Other PCAs with general applicability, such as the PCA using pairwise atomic distances, do not represent the physical meaning clearly. Therefore, a formulation that provides general applicability and clearly represents the physical meaning is yet to be developed. For developing such a formulation, we consider the conformational distribution change by the perturbation with arbitrary linearly independent perturbation functions. Within the second order approximation of the Kullback-Leibler divergence by the perturbation, the PCA can be naturally interpreted as a method for (1) decomposing a given perturbation into perturbations that independently contribute to the conformational distribution change or (2) successively finding the perturbation that induces the largest conformational distribution change. In this perturbational formulation of PCA, (i) the eigenvalue measures the Kullback-Leibler divergence from the unperturbed to perturbed distributions, (ii) the eigenvector identifies the combination of the perturbation functions, and (iii) the principal component determines the probability change induced by the perturbation. Based on this formulation, we propose a PCA using potential energy terms, and we designate it as potential energy PCA (PEPCA). The PEPCA provides both general applicability and clear physical meaning. For demonstrating its power, we apply the PEPCA to an alanine dipeptide molecule in vacuum as a minimal model of a nonsingle dominant conformational biomolecule. The first and second principal components clearly characterize two stable states and the transition state between them. Positive and negative components with larger absolute values of the first and second eigenvectors identify the electrostatic interactions, which stabilize or destabilize each stable state and the transition state. Our result therefore indicates that PCA can be applied, by carefully selecting the perturbation functions, not only to identify the molecular conformational fluctuation but also to predict the conformational distribution change by the perturbation beyond the limitation of the previous methods. | 18,999,556 |
Observation of nonadditive mixed-state phases with polarized neutrons. | In a neutron polarimetry experiment the mixed-state relative phases between spin eigenstates are determined from the maxima and minima of measured intensity oscillations. We consider evolutions leading to purely geometric, purely dynamical, and combined phases. It is experimentally demonstrated that the sum of the individually determined geometric and dynamical phases is not equal to the associated total phase which is obtained from a single measurement, unless the system is in a pure state. | 18,999,577 |
Role of the Majorana fermion and the edge mode in chiral superfluidity near a p-wave Feshbach resonance. | The visualization of chiral p-wave superfluidity in Fermi gases near p-wave Feshbach resonances is theoretically examined. It is proposed that the superfluidity becomes detectable in the entire BCS-BEC regimes through (i) vortex visualization by the density depletion inside the vortex core and (ii) intrinsic angular momentum in vortex-free states. It is revealed that both (i) and (ii) are closely connected with the Majorana zero energy mode of the vortex core and the edge mode, which survive until the strong coupling BCS regime is approached from the weak coupling limit and vanish in the Bose-Einstein condensation regime. | 18,999,582 |
Development of electron-proton density functionals for multicomponent density functional theory. | We present a strategy for the development of electron-proton density functionals in multicomponent density functional theory, treating electrons and selected nuclei quantum mechanically without the Born-Oppenheimer approximation. An electron-proton functional is derived using an explicitly correlated electron-proton pair density. This functional provides accurate hydrogen nuclear densities, thereby enabling reliable calculations of molecular properties. This approach is potentially applicable to relatively large molecular systems with key hydrogen nuclei treated quantum mechanically. | 18,999,594 |
Quantum interferences in cooperative Dicke emission from spatial variation of the laser phase. | We report the generation of a new quantum interference effect in spontaneous emission from a resonantly driven system of two identical two-level atoms due to the spatial variation of the laser phase at the positions of the atoms. This interference affects significantly the spectral features of the emitted radiation and the quantum entanglement in the system. The interference leads to dynamic coupling of the populations and coherences in a basis, determined by the laser phase and represents a kind of vacuum mediated superexchange between the symmetric and antisymmetric states. | 18,999,596 |
Phase reduction of stochastic limit cycle oscillators. | We point out that for an oscillator subjected to noise the conventional phase equation is not a proper approximation even for weak noise. We present a phase reduction method valid for an oscillator subjected to weak white Gaussian noise. Numerical evidence demonstrates that the phase equation properly approximates dynamics of the original oscillator. Moreover, we show that, in general, noise causes a shift of the oscillator frequency and discuss its effects on entrainment. | 18,999,602 |
Binding of a 3He impurity to a screw dislocation in solid 4He. | Using first-principles simulations for the probability density of finding a 3He atom in the vicinity of the screw dislocation in solid 4He, we determine the binding energy to the dislocation nucleus E(B)=0.8+/-0.1 K and the density of localized states at larger distances. The specific heat due to 3He features a peak similar to the one observed in recent experiments, and our model can also account for the observed increase in shear modulus at low temperature. We further discuss the role of 3He in the picture of superfluid defects. | 18,999,608 |
First-principles theory of competing order types, phase separation, and phonon spectra in thermoelectric AgPbmSbTe(m+2) alloys. | Using a first-principles cluster expansion, we shed light on the solid-state phase diagram and structure of the recently discovered high-performance Pb-Ag-Sb-Te thermoelectrics. The calculated bulk thermodynamics favors the formation of coherent precipitates of ordered Ag(m)Sb(n)Te(m+n) phases immiscible with rocksalt PbTe, such as AgSbTe2. The solubility is high for Pb in AgSbTe2 and low for (Ag,Sb) in PbTe (8% vs 0.6% at 850 K). The differences in the phonon spectra of PbTe and AgSbTe2 suggest that these precipitates enhance the thermoelectric performance by lowering thermal conductivity. | 18,999,614 |
Anisotropy of antiferromagnetic 180 degrees domains in LiCoPO4 and LiNiPO4. | Unexpected three-dimensional distributions of antiferromagnetic 180 degrees domains are observed in LiCoPO4 and LiNiPO4 by optical second harmonic generation. Domains in LiCoPO4 are isotropic in spite of the quasi-two-dimensional magnetic structure whereas domains in LiNiPO4 are distinctly anisotropic, but in contrast to the anisotropy of the magnetic structure. The diversity reveals a potential for fine-tuning magnetic properties determined by the distribution of domains or domain walls and the urgent need for an improved understanding of spatial correlations in antiferromagnets. | 18,999,633 |
Magnetic circular dichroism from the impurity band in III-V diluted magnetic semiconductors. | The magnetic circular dichroism of III-V diluted magnetic semiconductors, calculated within a theoretical framework suitable for highly disordered materials, is shown to be dominated by optical transitions between the bulk bands and an impurity band formed from magnetic dopant states. The real-space Green's functions incorporate spatial correlations in the disordered conduction band and valence-band electronic structure, and include extended and localized states on an equal basis. Our findings reconcile unusual trends in the experimental magnetic circular dichroism in III-V diluted magnetic semiconductors with the antiferromagnetic p-d exchange interaction between a magnetic dopant spin and its host. | 18,999,634 |
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