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Measuring and Managing Healthcare Supply and Demand in Real-Time. Stud Health Technol Inform 2024; 312:9-15. [PMID: 38372304 DOI: 10.3233/shti231302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
Measuring the supply and demand for access to and wait-times for healthcare is key to managing healthcare services and allocating resources appropriately. Yet, few jurisdictions in distributed, socialized medicine settings have any way to do so. In this paper, we propose the requirements for a jurisdictional patient scheduling system that can measure key metrics, such as supply of and demand for regulated health care professional care, access to and wait times for care, real-time health system utilization and provide the data to compute patient journeys. The system is also capable of tracking new supply of providers and who does not have access to a primary care provider. Benefits, limitations and risks of the model are discussed.
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Towards a Regulatory Framework for Electronic Medical Record Interoperability in Canada. Stud Health Technol Inform 2024; 312:59-63. [PMID: 38372312 DOI: 10.3233/shti231312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
All complex systems are potentially predisposed to failure. Healthcare systems are complex systems that are prone to many errors that can result in dire consequences for patients and healthcare providers. The healthcare system in Canada is under unprecedented strain due to shortages of healthcare providers, provider burnout, inefficient workflows, and a lack of appropriate digital infrastructure. We used failure mode and effects analysis (FMEA) to identify the failure modes for care provided in primary care settings. We identified failure modes in appointment scheduling, patient-provider communications, referrals, laboratory and diagnostic procedures, and medication prescriptions as the main failure modes. To mitigate the detected risks, we recommend solutions to 'close the loop' on failure modes to prevent patients from falling through the cracks, as vulnerable patients who cannot advocate for themselves are most likely to do so. We provide preliminary requirements for a regulatory regime for electronic health records that can reduce provider burnout, improve regulatory compliance, and improve system efficiency, all while improving patient safety, experience, and outcomes.
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Towards a Regulatory Framework for Workflow Improvement in Electronic Medical Records. Stud Health Technol Inform 2024; 312:54-58. [PMID: 38372311 DOI: 10.3233/shti231311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
Physicians have to complete several time-consuming and burnout-inducing tasks in their EMRs for everyday care of patients. Poor workflow design generates increased effort for physicians. In this study, we measure time doctors take to retrieve and review information in the patient chart at the beginning of a visit; one of approximately 12 tasks a doctor must do in the EMR during the visit. Information retrieval takes approximately 40 minutes per day. Automation could save 75% of that time. We estimate that if every family doctor in Canada could save 30 minutes through automation of just this one process, we could free up time equivalent to >3000 physicians and >5 million patients; enough to absorb the vast majority of patients who currently do not have a doctor. We know of no more powerful intervention than workflow automation in Canadian EMRs to increase the supply of doctors while simultaneously reducing a major cause of burnout. We recommend an accelerated research program to identify additional opportunities for workflow automation and a regulatory program to ensure that every physician has access to workflow automation in their EMR.
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0356 Does Unconscious Socioeconomic Bias Influence Tele-evaluation of Obstructive Sleep Apnea? A Tele-Equity Exploratory Analysis. Sleep 2022. [DOI: 10.1093/sleep/zsac079.353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Introduction
Telemedicine, once of limited scope, has become common and widespread due to the present and ongoing SARS-CoV-2 pandemic. Center to home delivery, the most common model, allows for convenient and efficient care. Concurrent with this groundshift, there is increasing attention to disparities in medical services, and how these disparities may impact patient outcomes. Telemedicine could be used to help bridge barriers to timely quality care, however, patient access and longstanding institutional biases may limit the potential. Healthcare providers must actively develop systems to ensure that telemedicine is optimized for people across the income spectrum. This exploratory analysis examined how economic disparities in patients being evaluated for obstructive sleep apnea may be associated with providers’ clinical impressions. The objective was to study the inter-method reliability of pre-test probability of obstructive sleep apnea assessed via telemedicine and in-person evaluations, and to compare that reliability between income classes.
Methods
This is a secondary analysis of a pre-pandemic interrater reliability study, conducted between March 2017 and January 2019. Our researchers completed a randomized, blinded study comparing the pre-test probability of obstructive sleep apnea between an in-person physician and a separate physician seeing the same patient via televideo conferencing. Patients referred to the University of Rochester (UR) Sleep Center were eligible for the study. Women and men 30-70 years old were invited to participate. The patients were not necessarily referred to the center for evaluation of sleep disordered breathing. Patients with dementia, hearing or visual loss, severe psychiatric or developmental illness, or not fluent in English were excluded. Patients had adequate computer literacy, access to high speed internet, and a computing device with appropriate video camera and microphone.The primary objective of the original study was to assess the interrater reliability between the in-person and telemedicine raters for pre-test probability of sleep apnea (high, moderate, or low). Providers used clinical judgement from the history and examination to determine pre-test probabilityFor this present analysis, we assessed the inter-method reliability separately for strata defined by reported annual income level: low income (< $50,000), middle income ($50,000-$100,000), and high income (> $100,000). Reliability was quantified for each stratum using weighted kappa statistics given the ordinal nature of the outcome variable, pre-test probability of obstructive sleep apnea (high, moderate, or low). Weighted kappa statistics were compared between the income strata (high vs. middle, high vs. low, middle vs. low). The operant statistic assumed an approximate standard normal distribution under the null hypothesis of equal kappa values in the two income strata. The Bonferroni method was used to adjust the p-values for the three pairwise comparisons performed among the three income strata.
Results
Data from 53 patients were avaiable for this analysis. 11 of these patients were in the low income group, 22 in the middle income, and 16 were in the high income group. 9 patients did not include their income bracket, and were not included in the analysis. Inter-method reliabilities, assessed using weighted kappa, were 0.83 (low income), 0.24 (middle income), and 0.66 (high income). When comparing between the strata, the kappa statistics were significantly different (p=0.005) between the low and moderate income groups. There was a trend between the high and moderate income groups that did not meet statistical significance (p=0.07).
Conclusion
The intermethod reliability was substantial in the low income stratum, moderate in the high income stratum, and slight in the middle income group based on the kappa statistic. There was a significant difference in the reliability values of telemedicine versus in-person assessments between the low and middle income brackets, and there was a trend between the high and moderate groups. Since the raters were unaware of the patients’ income levels, this association might suggest possible unconscious bias in evaluating for OSA. It may also suggest that beyond access to telemedicine technology, the quality of the care may also be influenced by socioeconomic factors. With telemedicine in its early stages, it is important to develop this technology that will minimize biases that could result from patients’ economic fortunes.
Support (If Any)
The study was funded by a grant from the American Academy of Sleep Foundation (AASM Foundation grant #163-FP-17).
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Clinical significance of tumor location for ureteroscopic tumor grading in upper tract urothelial carcinoma. Eur Urol 2022. [DOI: 10.1016/s0302-2838(22)00383-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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805 Towards a more perfect union: interrater reliability between telemedicine and in-person evaluators in sleep disordered breathing. Sleep 2021. [DOI: 10.1093/sleep/zsab072.802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Introduction
Telemedicine has rapidly changed the landscape of all of clinical practice, and is now widely employed in sleep medicine. To date, the accuracy of telemedicine in identifying patients at risk for obstructive sleep apnea (OSA) is still unknown. Given differences in technique and fidelity, a perfect correlation between these two types of encounters cannot be assumed. We studied how providers using a telemedicine platform compared to providers using traditional in-person encounters in identifying risk for sleep disordered breathing.
Methods
90 participants referred to a comprehensive university sleep program were randomized to this interrater reliability study. Subjects were representative of the gender and ethnic breakdown of the outlying community. The subjects were evaluated by an in-person clinician investigator, then randomized to a second clinician investigator who performed an evaluation online using a common teleconferencing platform. Both types of evaluations included a history and physical exam. The primary outcome was pretest probability for obstructive sleep apnea. Secondary comparators included level of daytime sleepiness, snoring volume, apneas witnessed by a third party, modified Mallampati score, presence/absence of tonsils, degree of overjet bite, and severity of apnea based on home sleep testing.
Results
Interrater reliability for pretest probability of OSA was reflected in a weighted kappa value of 0.414 (SE 0.090, p=0.002). This suggests moderate agreement between the an in-person and telemedicine evaluator. Kappa values of our secondary outcomes ranged from -0.044 (degree of maxillary overjet) to 0.702 (apneas witnessed by a third party), and were generally higher for historical elements and lower for physical exam findings.
Conclusion
Evaluation for pretest probability for sleep apnea via telemedicine has a moderate interrater correlation with in-person assessment. A relatively high degree of interrater reliability for historical elements suggests that the accuracy of telemedicine for OSA is tempered by a suboptimal physical exam. Telemedicine evaluations might become more accurate through standardization. For instance, using validated scales for OSA or templated encounter scripts may help with risk-stratification, and ultimately lead to more uniform management.
Support (if any)
This study was supported by an AASM Foundation Focused Project Award
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Evaluation of minimal important difference (MID) for the European organisation for research and treatment of cancer (EORTC) pancreatic cancer module (PAN26) in patients with surgically resected pancreatic adenocarcinoma. Ann Oncol 2019. [DOI: 10.1093/annonc/mdz247.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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1066 Interrater Reliability in Telemedicine vs. In-person Evaluations for Obstructive Sleep Apnea. Sleep 2018. [DOI: 10.1093/sleep/zsy061.1065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Single photon emitters in exfoliated WSe2 structures. NATURE NANOTECHNOLOGY 2015; 10:503-6. [PMID: 25938573 DOI: 10.1038/nnano.2015.67] [Citation(s) in RCA: 304] [Impact Index Per Article: 33.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 03/12/2015] [Indexed: 05/20/2023]
Abstract
Crystal structure imperfections in solids often act as efficient carrier trapping centres, which, when suitably isolated, act as sources of single photon emission. The best known examples of such attractive imperfections are well-width or composition fluctuations in semiconductor heterostructures (resulting in the formation of quantum dots) and coloured centres in wide-bandgap materials such as diamond. In the recently investigated thin films of layered compounds, the crystal imperfections may logically be expected to appear at the edges of commonly investigated few-layer flakes of these materials exfoliated on alien substrates. Here, we report comprehensive optical micro-spectroscopy studies of thin layers of tungsten diselenide (WSe2), a representative semiconducting dichalcogenide with a bandgap in the visible spectral range. At the edges of WSe2 flakes (transferred onto Si/SiO2 substrates) we discover centres that, at low temperatures, give rise to sharp emission lines (100 μeV linewidth). These narrow emission lines reveal the effect of photon antibunching, the unambiguous attribute of single photon emitters. The optical response of these emitters is inherently linked to the two-dimensional properties of the WSe2 monolayer, as they both give rise to luminescence in the same energy range, have nearly identical excitation spectra and have very similar, characteristically large Zeeman effects. With advances in the structural control of edge imperfections, thin films of WSe2 may provide added functionalities that are relevant for the domain of quantum optoelectronics.
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Influence of additives on the structure of surfactant-free microemulsions. Phys Chem Chem Phys 2015; 17:32528-38. [DOI: 10.1039/c5cp06364g] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In surfactant-free microemulsions, the combination ethanol/antagonistic salt behaves like a surfactant.
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11
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Early Americans: respecting ancestors. Science 2014; 345:390. [PMID: 25061197 DOI: 10.1126/science.345.6195.390-b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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Valsalva maneuver shows prolonged sympathetic outflow in patients with a history of mild traumatic brain injury. J Neurol Sci 2013. [DOI: 10.1016/j.jns.2013.07.2378] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Dependence of the structural, transport and magnetic properties of Tl(1-y)Fe(2-z)(Se(1-x)S(x))2 with isovalent substitution of Se by S. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:075703. [PMID: 23343616 DOI: 10.1088/0953-8984/25/7/075703] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The effect of selenium substitution by sulfur in the Tl(1-y)Fe(2-z)Se(2) antiferromagnet was studied by x-ray and electron diffraction, magnetization and transport measurements. Tl(0.8)Fe(1.5)(Se(1-x)S(x))(2) (nominal composition) solid solution was synthesized in the full x range (0 ≤ x(S) ≤ 1) using the sealed tube technique. No superconductivity was found down to 4.2 K in the series despite the fact that the optimal crystallographic parameters, determined by Rietveld refinements, are reached in the series (i.e. the Fe-(Se, S) interplane height and (Se, S)-Fe-(Se, S) angle for which the critical superconducting transition T(c) is usually maximal in pnictides). A quasi-full Tl site (y ~ 0.05) compared to significant alkaline deficiency (y = 0.2-0.3) in analogous A(1-y)Fe(2-z)Se(2) (A = K, Rb, Cs), and the resulting differences in iron valency, density of states and doping, are suggested as an explanation for this absence of superconductivity. Transmission electron microscopy confirmed the existence of an ordered iron vacancies network in the samples of the Tl(0.8)Fe(1.5)(Se(1-x)S(x))(2) series in the form of the tetragonal √5a × √5a × c superstructure (I4/m). The Néel temperature (T(N)) indicating the onset of antiferromagnetism order in this √5a × √5a × c supercell is found to decrease from 450 K in the selenide (x = 0) to 330 K in the sulfide (x = 1). Finally, we demonstrate a direct linear relationship between T(N) and the Fe-(Se, S) bond length (or Fe-(Se, S) height).
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P1-S2.41 Sentinel survillance for pharyngeal chlamydia and gonorrhoea among men who have sex with men - San Francisco, 2010. Br J Vener Dis 2011. [DOI: 10.1136/sextrans-2011-050108.98] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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16
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P1-S5.08 Attendance at local and national sex-events associated with STD diagnosis, San Francisco, 2010. Br J Vener Dis 2011. [DOI: 10.1136/sextrans-2011-050108.186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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O2-S3.06 Area-based socioeconomic measures associated with female chlamydia and gonorrhoea, San Francisco, 2009. Br J Vener Dis 2011. [DOI: 10.1136/sextrans-2011-050109.84] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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18
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P2-S6.11 The cost-effectiveness of screening men who have sex with men for rectal chlamydial and gonococcal infection to prevent HIV infection. Br J Vener Dis 2011. [DOI: 10.1136/sextrans-2011-050108.363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Disorder effects in pnictides: a tunneling spectroscopy study. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:465701. [PMID: 21403373 DOI: 10.1088/0953-8984/22/46/465701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We present the synthesis and the tunneling spectroscopy study of superconducting FeSe(0.5)Te(0.5) (T(c) = 14 K), SmFeAsO(0.85) (T(c) = 54 K) and SmFeAsO(0.9)F(0.1) (T(c) = 45 K). The samples were characterized by Rietveld refinement of x-ray diffraction patterns and transport as well as temperature-dependent magnetic measurements. Tunneling experiments on FeSe(0.5)Te(0.5) revealed a single superconducting gap ∼ 1 meV in BCS-like tunneling conductance spectra. In SmFeAsO(0.85) and SmFeAsO(0.9)F(0.1), however, more complex spectra were observed, characterized by two gap-like structures at ∼ 4 and ∼ 10 meV. These spectra are qualitatively understood assuming a two-band superconductor with a 's ±' order parameter. We show that, depending on the sign relation between the pairing amplitudes in the two bands, the interband quasiparticle scattering has a crucial effect on the shape of the tunneling spectra. On the other hand, single-gap spectra found in FeSe(0.5)Te(0.5) are more compatible with a disorder-induced 's '-wave gap, due to the Se-Te substitution.
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FemVue Sono Tubal Evaluation System for Selective Sonohysterosalpingography in the Office Setting. J Minim Invasive Gynecol 2010. [DOI: 10.1016/j.jmig.2010.08.286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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FemVue™ Sono Tubal Evalution System for selective sonohysterosalpingography in the office setting. Fertil Steril 2010. [DOI: 10.1016/j.fertnstert.2010.07.303] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Abstract
Thus far I have discussed ancient Maya sociopolitical structure from the upper levels of the hierarchy downward. Let me now summarize their territorial organization from the bottom upward, starting at the hamlet level (Fig. 8). The smallest unit of settlement-one usually overlooked by archeological surveys in the lowland rain forest-was probably a cluster of thatched huts occupied by a group of related families; larger clusters may have been divided into four quadrants along the lines suggested by Coe (26). Because of the long fallow period (6 to 8 years) characteristic of slash-and-burn agriculture in the Petén, these small hamlets are presumed to have changed location over the years, although they probably shifted in a somewhat circular fashion around a tertiary ceremonial-civic center for whose maintenance they were partly responsible. These tertiary centers were spaced at fairly regular intervals around secondary ceremonial-civic centers with pyramids, carved monuments, and palace-like residences. In turn, the secondary centers occurred at such regular intervals as to form hexagonal patterns around primary centers, which were still larger, with acropolises, multiple ceremonial plazas, and greater numbers of monuments. In some cases, the distance between secondary centers was roughly twice the distance between secondary and tertiary centers, creating a lattice of nested hexagonal cells. This pattern, which conforms to a Western theoretical construct, was presumably caused by factors of service function, travel, and transport. The pattern was not recognized by the Maya at all. They simply recognized that a whole series of smaller centers were dependent on a primary center and therefore mentioned its emblem glyph. Linking the centers of the various hexagons were marriage alliances between members of royal dynasties, who had no kinship ties with the farmers in the hamlets. Out of the large number of primary centers available to them, the Maya selected four as regional capitals. True to their cosmology, the Maya regarded these capitals as associated with the four quadrants of their realm, regardless of their actual location. Each was the home city for a very important dynasty whose junior members probably ruled secondary centers. Since the hexagonal lattices were probably adjusted to variations in population density, each of the four quadrants of the Maya realm probably controlled a comparable number of persons. So strong was the cognized model that, despite the rise and fall of individual centers, there seem always to have been four capitals, each associated with a direction and, presumably, with a color. There is still a great deal to learn about the social, political, and territorial organization of the lowland Maya, and parts of the picture presented here need far more data for their confirmation. What seems likely is that the Maya had an overall quadripartite organization (rather than a core and buffer zone) and that within each quadrant there was at least a five-tiered administrative hierarchy of capital, secondary center, tertiary center, village, and hamlet. Perhaps most significant, there was no real conflict between the lattice-like network predicted by locational analysis and the cosmological four-part structure predicted by epigraphy and ethnology.
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Ultrasonic properties near 50 K of the quasi-one-dimensional conductors A(0.30)MoO(3) (A = K, Rb) and Rb(0.30)(Mo(1-x)V(x))O(3). JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:215603. [PMID: 21825552 DOI: 10.1088/0953-8984/21/21/215603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The charge density wave (CDW) nonlinear conductivity of the blue bronzes A(0.30)MoO(3) (A = K, Rb) shows two different regimes depending on the temperature: a strongly damped CDW motion above ∼50 K and a CDW motion with almost no damping below ∼50 K. In a search for an elastic signature of this CDW behaviour, we performed ultrasonic measurements on A(0.30)MoO(3) single crystals in the temperature range 4-300 K. In Rb(0.30)MoO(3), at T∼50 K, upon cooling, a large increase of the sound velocity for the longitudinal mode measured along the [Formula: see text], [102] and b directions is observed. The ultrasonic attenuation coefficient shows an increase down to 50 K followed by a plateau. Similar results are found in K(0.30)MoO(3). In V-doped samples, Rb(0.30)(Mo(1-x)V(x))O(3) (x = 0.4%) the anomaly broadens and is shifted towards higher temperatures. The results are discussed in relation to the changes in the CDW rigidity, disorder and dielectric response. A scenario based on a glass transition for the CDW superstructure is proposed.
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Observation of micrometric correlations in sliding incommensurate charge-density waves. Acta Crystallogr A 2008. [DOI: 10.1107/s0108767308084833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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A phase II study of erlotinib (E) and bevacizumab (B) in chemo naive patients (pts) with locally advanced or metastatic non small cell lung cancer (NSCLC): Predictive value of molecular imaging. J Clin Oncol 2008. [DOI: 10.1200/jco.2008.26.15_suppl.8055] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Observation of correlations up to the micrometer scale in sliding charge-density waves. PHYSICAL REVIEW LETTERS 2008; 100:096403. [PMID: 18352733 DOI: 10.1103/physrevlett.100.096403] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Indexed: 05/26/2023]
Abstract
A high resolution coherent x-ray diffraction experiment has been performed on the charge-density wave (CDW) system K0.3MoO3. The 2kF satellite reflection associated with the CDW has been measured with respect to external dc currents. In the sliding regime, the 2kF satellite reflection displays secondary satellites along the chain axis which corresponds to correlations up to the micrometer scale. This super long-range order is 1500 times larger than the CDW period itself. This new type of electronic correlation seems inherent to the collective dynamics of electrons in charge-density wave systems. Several scenarios are discussed.
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Anisotropy of the Sommerfeld coefficient in magnesium diboride single crystals. PHYSICAL REVIEW LETTERS 2007; 98:137001. [PMID: 17501231 DOI: 10.1103/physrevlett.98.137001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2006] [Indexed: 05/15/2023]
Abstract
The anisotropic field dependence of the Sommerfeld coefficient gamma has been measured down to B-->0 by combining specific heat and Hall probe magnetization measurements in MgB2 single crystals. We find that gamma(B,theta) is the sum of two contributions arising from the sigma and pi band, respectively. We show that gammasigma(B,theta)=B/Bc2(theta) where Bc2(theta)=Bc2ab/sqrt[sin2theta+Gamma2cos2theta] with Gamma approximately 5.4 (theta being the angle between the applied field and the c axis) and gammapi(B,theta)=gammapi(B)=B/Bpi(B). The "critical field" of the pi band Bpi is fully isotropic but field dependent increasing from approximately 0.25 T for B< or =0.1 T up to 3 T approximately Bc2c for B-->3 T. Because of the coupling of the two bands, superconductivity survives in the pi band up to 3 T but is totally destroyed above for any orientation of the field.
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Charge-density-wave instabilities in the low-dimensional molybdenum bronzes and oxides. ACTA ACUST UNITED AC 2006. [DOI: 10.1080/13642818508240627] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Abstract
Galactocerebroside (GalC) and sulfatide are abundant myelin lipids. In mice incapable of synthesizing these lipids, myelin is thin and regionally unstable and exhibits several subtle structural abnormalities. Although galactolipid-null mice have been beneficial in the analysis of galactolipid function, it has not been possible to differentiate between the functions of GalC and sulfatide with these mice alone. In the present work, we have analyzed a murine model that forms normal levels of GalC but is incapable of synthesizing sulfatide. By comparing a plethora of morphological features between the galactolipid-null and the sulfatide-null mice, we have begun to differentiate between the specific functions of these closely related lipids. The most striking difference between these two mutants is the reduction of myelin developmental abnormalities (e.g., redundant and uncompacted myelin sheaths) in young adult sulfatide-null mice as compared with the galactolipid-null animals. Although sulfatide appears to play a limited role in myelin development, this lipid is essential for myelin maintenance, as the prevalence of redundant, uncompacted, and degenerating myelin sheaths as well as deteriorating nodal/paranodal structure is increased significantly in aged sulfatide-null mice as compared with littermate wildtype mice. Finally, we show that the role played by sulfatide in CNS maintenance is not limited to the myelin sheath, as axonal caliber and circularity are normal in young adult mutant mice but are significantly altered in aged sulfatide-null animals.
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High magnetic field magnetoresistance anomalies in the charge density wave state of the quasi-two dimensional bronze KMo6O17. ACTA ACUST UNITED AC 2005. [DOI: 10.1051/jp4:2005131066] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Charge density wave dislocation as revealed by coherent x-ray diffraction. PHYSICAL REVIEW LETTERS 2005; 95:116401. [PMID: 16197025 DOI: 10.1103/physrevlett.95.116401] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2005] [Indexed: 05/04/2023]
Abstract
Coherent x-ray diffraction experiments have been performed on high quality crystals of the charge density wave (CDW) system K0.3MoO3. The satellite reflections associated with the CDW have been measured as a function of the 20-microm-diameter beam position. For some positions, regular fringes have been observed. We show that this observation is consistent with the presence of a single CDW dislocation. Beyond charge density wave systems, this experiment shows that coherent x-ray diffraction is a suitable tool to probe topological defects embedded in the bulk.
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Abstract 6. Arch Phys Med Rehabil 2005. [DOI: 10.1016/j.apmr.2005.07.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Dependence of the superconducting transition temperature on the doping level in single-crystalline diamond films. PHYSICAL REVIEW LETTERS 2004; 93:237005. [PMID: 15601192 DOI: 10.1103/physrevlett.93.237005] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2004] [Indexed: 05/24/2023]
Abstract
Homoepitaxial diamond layers doped with boron in the 10(20)-10(21) cm(-3) range are shown to be type II superconductors with sharp transitions (approximately 0.2 K) at temperatures increasing from 0 to 2.1 K with boron contents. The critical concentration for the onset of superconductivity in those 001-oriented single-crystalline films is about 5-7 10(20) cm(-3). The H-T phase diagram has been obtained from transport and ac-susceptibility measurements down to 300 mK.
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Anisotropies of the lower and upper critical fields in MgB2 single crystals. PHYSICAL REVIEW LETTERS 2004; 92:057001. [PMID: 14995332 DOI: 10.1103/physrevlett.92.057001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2003] [Indexed: 05/24/2023]
Abstract
The temperature dependence of the upper (H(c2)) and lower (H(c1)) critical fields has been deduced from Hall probe magnetization measurements of high quality MgB2 single crystals along the two main crystallographic directions. We show that Gamma(H(c2))=H(c2 axially ab)/H(c2 axially c) and Gamma(H(c1))=H(c1 axially c)/H(c1 axially ab) differ significantly at low temperature (being approximately 5 and approximately 1, respectively) and have opposite temperature dependencies. We suggest that MgB2 can be described by a single field dependent anisotropy parameter gamma(H) (=lambda(c)/lambda(ab)=xi(ab)/xi(c)) that increases from Gamma(H(c1)) at low field to Gamma(H(c2)) at high field.
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Direct transition from Bose glass to normal state in the (K,Ba)BiO3 superconductor. PHYSICAL REVIEW LETTERS 2004; 92:037005. [PMID: 14753899 DOI: 10.1103/physrevlett.92.037005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2003] [Indexed: 05/24/2023]
Abstract
The introduction of columnar defects in (K,Ba )Bi O3 single crystals shifts both the irreversibility and thermodynamic transition lines, respectively, deduced from ac susceptibility (and/or transport) and specific heat measurements, upwards. This shift can be attributed to the defect-induced decrease of the difference (Delta F) between the free energies in the superconducting and the normal states, assuming that the position of the superconducting transition is given by the condition absolute value Delta F approximately k(B )T/xi(3 ). This criterion also perfectly reproduces the influence of the angle between the tracks and the external field. This result suggests that no vortex liquid phase exists in this system.
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Superconductivity in doped sp3 semiconductors: the case of the clathrates. PHYSICAL REVIEW LETTERS 2003; 91:247001. [PMID: 14683147 DOI: 10.1103/physrevlett.91.247001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2003] [Indexed: 05/24/2023]
Abstract
We present a joint experimental and theoretical study of the superconductivity in doped silicon clathrates. The critical temperature in Ba(8)@Si-46 is shown to strongly decrease with applied pressure. These results are corroborated by ab initio calculations using MacMillan's formulation of the BCS theory with the electron-phonon coupling constant lambda calculated from perturbative density functional theory. Further, the study of I(8)@Si-46 and of gedanken pure silicon diamond and clathrate phases doped within a rigid-band approach show that the superconductivity is an intrinsic property of the sp(3) silicon network. As a consequence, carbon clathrates are predicted to yield large critical temperatures with an effective electron-phonon interaction much larger than in C60.
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Investigation of the Rb–W–O system in connexion with the superconducting properties of the hexagonal tungsten bronzes. J SOLID STATE CHEM 2003. [DOI: 10.1016/s0022-4596(03)00006-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Anisotropic enhancement of superconductivity in heavy-ion irradiated (K, Ba)BiO3. PHYSICAL REVIEW LETTERS 2003; 90:037004. [PMID: 12570520 DOI: 10.1103/physrevlett.90.037004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2002] [Indexed: 05/24/2023]
Abstract
We have measured the specific heat, resistivity, and ac susceptibility of (K,Ba)BiO3 single crystals before and after introduction of either point or columnar defects by electron (EI) or heavy-ion irradiation (HII). While the magnetic field dependence of these properties remains mainly unaffected by EI, the irreversibility line and the location of the specific heat anomaly are both shifted up in temperature after HII. The shift is apparent only if the magnetic field is applied parallel to the ion tracks. For perpendicularly applied fields, both lines lie at the same field as in the pristine sample. These experiments call the nature of the vortex liquid state into question.
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Anomalous magnetic field dependence of the thermodynamic transition line in the isotropic superconductor (K,Ba)BiO3. PHYSICAL REVIEW LETTERS 2002; 88:177201. [PMID: 12005780 DOI: 10.1103/physrevlett.88.177201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2001] [Indexed: 05/23/2023]
Abstract
Thermodynamic (specific heat, reversible magnetization, tunneling spectroscopy) and transport measurements have been performed on high quality (K,Ba)BiO3 single crystals. The temperature dependence of the magnetic field H(C(p)) corresponding to the onset of the specific heat anomaly presents a clear positive curvature. H(C(p)) is significantly smaller than the field H(Delta) for which the superconducting gap vanishes but is closely related to the irreversibility line deduced from transport data. Moreover, the temperature dependence of the reversible magnetization presents a strong deviation from the Ginzburg-Landau theory emphasizing the peculiar nature of the superconducting transition in this material.
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Two-gap state density in MgB(2): a true bulk property or a proximity effect? PHYSICAL REVIEW LETTERS 2001; 87:177008. [PMID: 11690301 DOI: 10.1103/physrevlett.87.177008] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2001] [Indexed: 05/23/2023]
Abstract
We report on the temperature dependence of the quasiparticle density of states in the simple binary compound MgB(2) directly measured using scanning tunneling microscope (STM). To achieve high quality tunneling conditions, a small crystal of MgB(2) is used as a tip in the STM experiment. The "sample" is chosen to be a 2H- NbSe(2) single crystal presenting an atomically flat surface. At low temperature the tunneling conductance spectra show a gap at the Fermi energy followed by two well-pronounced conductance peaks on each side. They appear at voltages V(S) approximately +/-3.8 mV and V(L) approximately +/-7.8 mV. With rising temperature both peaks disappear at the T(C) of the bulk MgB(2), a behavior consistent with the model of two-gap superconductivity. The possibility of a particular proximity effect is also discussed.
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Evidence for diverging barriers in the disordered vortex solid in the (K,Ba)BiO(3) superconducting oxide. PHYSICAL REVIEW LETTERS 2001; 87:167002. [PMID: 11690226 DOI: 10.1103/physrevlett.87.167002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2001] [Indexed: 05/23/2023]
Abstract
Vortex dynamics has been investigated in the cubic (K,Ba)BiO (3) superconductor using ac susceptibility measurements on a large frequency range (0.03 Hz<omega<60 kHz). Power law diverging barriers have been obtained on both sides of the order-disorder transition line. The mu exponent remains close to 5/2 (elastic creep value) in some part of the disordered phase and finally decreases at high temperature and/or high field, in good agreement with the recent plastic collective creep theory [J. Kierfeld, H. Nordborg, and V. M. Vinokur, Phys. Rev. Lett., 85, 4948 (2000)].
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Abstract
Although crystals are usually quite stable, they are sensitive to a disordered environment: even an infinitesimal amount of impurities can lead to the destruction of crystalline order. The resulting state of matter has been a long-standing puzzle. Until recently it was believed to be an amorphous state in which the crystal would break into 'crystallites'. But a different theory predicts the existence of a novel phase of matter: the so-called Bragg glass, which is a glass and yet nearly as ordered as a perfect crystal. The 'lattice' of vortices that contain magnetic flux in type II superconductors provide a good system to investigate these ideas. Here we show that neutron-diffraction data of the vortex lattice provides unambiguous evidence for a weak, power-law decay of the crystalline order characteristic of a Bragg glass. The theory also predicts accurately the electrical transport properties of superconductors; it naturally explains the observed phase transitions and the dramatic jumps in the critical current associated with the melting of the Bragg glass. Moreover, the model explains experiments as diverse as X-ray scattering in disordered liquid crystals and the conductivity of electronic crystals.
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Evidence for two superconducting energy gaps in MgB(2) by point-contact spectroscopy. PHYSICAL REVIEW LETTERS 2001; 87:137005. [PMID: 11580620 DOI: 10.1103/physrevlett.87.137005] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2001] [Indexed: 05/23/2023]
Abstract
Experimental support is found for the multiband model of the superconductivity in the recently discovered system MgB(2) with the transition temperature T(c) = 39 K. By means of Andreev reflection, evidence is obtained for two distinct superconducting energy gaps. The sizes of the two gaps ( Delta(S) = 2.8 meV and Delta(L) = 7 meV) are, respectively, smaller and larger than the expected weak coupling value. Because of the temperature smearing of the spectra the two gaps are hardly distinguishable at elevated temperatures, but when a magnetic field is applied the presence of two gaps can be demonstrated close to the bulk T(c) in the raw data.
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Abstract
OBJECTIVE To better understand whether poor social adjustment, a core characteristic of schizophrenic illness, may also be an indicator of vulnerability in young people who are at genetic risk for schizophrenia, but who do not have schizophrenia. METHOD Between 1992 and 1996, 27 Israeli adolescents with a schizophrenic parent, 29 adolescents with no mentally ill parent, and 30 adolescents with a parent having a nonschizophrenic mental disorder were assessed on multiple domains of social adjustment measured using the Social Adjustment Inventory for Children and Adolescents and the Youth Self-Report. RESULTS Young people with a schizophrenic parent showed poor peer engagement, particularly heterosexual engagement, and social problems characterized by immaturity and unpopularity with peers. These social adjustment difficulties in youths at risk for schizophrenia could not be attributed solely to the presence of early-onset mental disorders, although problems were greater in those with disorders in the schizophrenia spectrum. Young people whose parents had other disorders showed different patterns of social maladjustment characterized by difficult, conflictual relationships with peers and family. CONCLUSION Adolescents at risk for schizophrenia have social deficits that extend beyond early-onset psychopathology and that may reflect vulnerability to schizophrenic disorder.
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Non-fermi liquid angle resolved photoemission line shapes of li0. 9Mo6O17. PHYSICAL REVIEW LETTERS 2000; 85:3985. [PMID: 11041982 DOI: 10.1103/physrevlett.85.3985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/1999] [Indexed: 05/23/2023]
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Abstract
The galactolipids galactocerebroside and sulfatide, which require the enzyme UDP-galactose:ceramide galactosyltransferase (CGT) for their synthesis, are among the most prevalent molecules in the myelin sheath. Numerous studies, mainly using antibody perturbation methods in vitro, have suggested that these molecules are crucial mediators of oligodendrocyte differentiation and myelin formation. Although we have previously demonstrated that myelin formation occurs in CGT null mutant mice, which are incapable of synthesizing the myelin galactolipids, here we show that there are developmental alterations in the CNS of these animals. There is a significant decrease in the number of myelinated axon segments in the mutant spinal cord despite normal levels of myelin gene-specific mRNAs and proteins. Also, there is an increased cellularity in the mature mutant spinal cord and the distinctive morphology of the additional cells suggests that they are actively myelinating oligodendrocytes. Using in situ hybridization techniques, we show that there is a 50% increase in the number of oligodendrocytes in the mutant spinal cord. The data suggest that galactolipids play an important developmental role in regulating the maturation program and final number of oligodendrocytes.
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