2,082 research outputs found
Retinal nerve fiber layer photography as an indicator of nerve fiber integrity in ocular hypertensive subjects
To evaluate the usefulness of retinal nerve fiber layer (RNFL) photography in the estimation of nerve fiber layer integrity in ocular hypertensive subjects; we examined 89 eyes of normal (59 eyes, 48 subjects), ocular hypertensive (26 eyes, 14 subjects), and glaucomatous (4 eyes, 2 subjects) patients. Preliminary studies included verification of the Statpac program for the Humphrey field analyzer, and establishing the method of nerve fiber layer photography sensitive enough to detect nerve fiber layer loss. The main study matched 14 ocular hypertensive subjects with 14 normal subjects. The subjects were matched by age(+/- 5 years), sex, and race. It was found that 2 of the 59 total normal eyes (3.4%) [ 2 of the 48 normal subjects (4.2%)]; 2 of the 15 matched normal eyes (13.3%) [2 of 14 matched normal subjects (14.3%)]; and 2 of 24 assessable ocular hypertensive eyes (8.3%) [2 of 13 subjects (15.4%)] showed suspected focal nerve fiber layer defects. None of our normal or ocular hypertensive subjects showed diffuse nerve fiber layer loss. We feel that retinal nerve fiber layer photography is a valuable indicator of nerve fiber layer integrity
Autonomous planning and control of soft untethered grippers in unstructured environments
The use of small, maneuverable, untethered and reconfigurable robots could provide numerous advantages in various micromanipulation tasks. Examples include microassembly, pick-and-place of fragile microobjects for lab-on-a-chip applications, assisted hatching for in-vitro fertilization and minimally invasive surgery. This study assesses the potential of soft untethered magnetic grippers as alternatives or complements to conventional tethered or rigid micromanipulators. We demonstrate closed-loop control of untethered grippers and automated pick-and-place of biological material on porcine tissue in an unstructured environment. We also demonstrate the ability of the soft grippers to recognize and sort non-biological micro-scale objects. The fully autonomous nature of the experiments is made possible by the integration of planning and decision-making algorithms, as well as by closed-loop temperature and electromagnetic motion control. The grippers are capable of completing pick-and-place tasks of biological material at an average velocity of 1.8±0.71 mm/s and a drop-off error of 0.62±0.22 mm. Color-sensitive sorting of three micro-scale objects is completed at a velocity of 1.21±0.68 mm/s and a drop-off error of 0.85±0.41 mm. Our findings suggest that improved autonomous un-tethered grippers could augment the capabilities of current soft-robotic instruments especially in advanced tasks involving manipulation
Disorder, pseudospins, and backscattering in carbon nanotubes
We address the effects of disorder on the conducting properties of metal and
semiconducting carbon nanotubes. Experimentally, the mean free path is found to
be much larger in metallic tubes than in doped semiconducting tubes. We show
that this result can be understood theoretically if the disorder potential is
long-ranged. The effects of a pseudospin index that describes the internal
sublattice structure of the states lead to a suppression of scattering in
metallic tubes, but not in semiconducting tubes. This conclusion is supported
by tight-binding calculations.Comment: four page
Cumulant Expansions and the Spin-Boson Problem
The dynamics of the dissipative two-level system at zero temperature is
studied using three different cumulant expansion techniques. The relative
merits and drawbacks of each technique are discussed. It is found that a new
technique, the non-crossing cumulant expansion, appears to embody the virtues
of the more standard cumulant methods.Comment: 26 pages, LaTe
Negative Thermal Expansion Coefficient of Graphene Measured by Raman Spectroscopy
The thermal expansion coefficient (TEC) of single-layer graphene is estimated
with temperature-dependent Raman spectroscopy in the temperature range between
200 and 400 K. It is found to be strongly dependent on temperature but remains
negative in the whole temperature range, with a room temperature value of
-8.0x10^{-6} K^{-1}. The strain caused by the TEC mismatch between graphene and
the substrate plays a crucial role in determining the physical properties of
graphene, and hence its effect must be accounted for in the interpretation of
experimental data taken at cryogenic or elevated temperatures.Comment: 17 pagese, 3 figures, and supporting information (4 pages, 3
figures); Nano Letters, 201
Changes in serum biomarker profiles after percutaneous mitral valve repair with the MitraClip system
BACKGROUND
Mitral regurgitation (MR) is one of the most common valvular diseases. Percu-taneous mitral valve repair with the MitraClipTM system is a novel percutaneous mitral valve repair (PMVR) technique for high-surgical-risk patients. However, the effect of PMVR on cir-culating cardiac or inflammatory biomarkers and their association with individual functional, echocardiographic and clinical outcomes is poorly investigated.
METHODS
A group of 144 patients with functional or degenerative MR (age, 75 ± 11 years; 41% females) underwent PMVR with the MitraClip system at the University Heart Center Zu-rich. Serum biomarkers as N-terminal pro-B-type natriuretic peptide (NT-proBNP), C-reactive protein (CRP) and creatinine were obtained from venous sampling at baseline and follow-up of 3-6 months.
RESULTS
Median NT-proBNP decreased insignificantly from 2,942 (IQR 1,596-5,722) to 2,739 (IQR 1,440-4,296) ng/L, p = 0.21. NT-proBNP changes did not correlate with baseline left ventricular (LV) ejection fraction or LV dimensions, with New York Heart Association class on follow-up, or with clinical events on follow-up. CRP levels reached a peak on the third postoperative day at 34.0 mg/L with a subsequent slow decrease over the ensuing days.
CONCLUSIONS
Despite successful PMVR, NT-proBNP remain fairly unchanged on follow-up and changes in NT-proBNP levels are poor predictors of functional improvement or clinical outcome after MitraClip treatment
Changes in serum biomarker profiles after percutaneous mitral valve repair with the MitraClip system
Background: Mitral regurgitation (MR) is one of the most common valvular diseases. Percutaneous mitral valve repair with the MitraClipTM system is a novel percutaneous mitral valve repair (PMVR) technique for high-surgical-risk patients. However, the effect of PMVR on circulating cardiac or inflammatory biomarkers and their association with individual functional, echocardiographic and clinical outcomes is poorly investigated.
Methods: A group of 144 patients with functional or degenerative MR (age, 75 ± 11 years; 41% females) underwent PMVR with the MitraClip system at the University Heart Center Zurich. Serum biomarkers as N-terminal pro-B-type natriuretic peptide (NT-proBNP), C-reactive protein (CRP) and creatinine were obtained from venous sampling at baseline and follow-up of 3–6 months.
Results: Median NT-proBNP decreased insignificantly from 2,942 (IQR 1,596–5,722) to 2,739 (IQR 1,440–4,296) ng/L, p = 0.21. NT-proBNP changes did not correlate with baseline left ventricular (LV) ejection fraction or LV dimensions, with New York Heart Association class on follow-up, or with clinical events on follow-up. CRP levels reached a peak on the third postoperative day at 34.0 mg/L with a subsequent slow decrease over the ensuing days.
Conclusions: Despite successful PMVR, NT-proBNP remain fairly unchanged on follow-up and changes in NT-proBNP levels are poor predictors of functional improvement or clinical outcome after MitraClip treatment
Electronic states and quantum transport in double-wall carbon nanotubes
Electronic states and transport properties of double-wall carbon nanotubes
without impurities are studied in a systematic manner. It is revealed that
scattering in the bulk is negligible and the number of channels determines the
average conductance. In the case of general incommensurate tubes, separation of
degenerated energy levels due to intertube transfer is suppressed in the energy
region higher than the Fermi energy but not in the energy region lower than
that. Accordingly, in the former case, there are few effects of intertube
transfer on the conductance, while in the latter case, separation of
degenerated energy levels leads to large reduction of the conductance. It is
also found that in some cases antiresonance with edge states in inner tubes
causes an anomalous conductance quantization, , near the Fermi
energy.Comment: 24 pages, 13 figures, to be published in Physical Review
Use of a Prescribed Ephedrine/Caffeine Combination and the Risk of Serious Cardiovascular Events: A Registry-based Case-Crossover Study
Ephedrine and herbal ephedra preparations have been shown to induce a small-to-moderate weight loss. Owing to reports on serious cardiovascular events, they were banned from the US market in 2004. There have been no large controlled studies on the possible association between prescribed ephedrine/caffeine and cardiovascular events in general. The authors linked data from four different sources within Statistics Denmark, using data on 257,364 users of prescribed ephedrine/caffeine for the period 1995–2002. The data were analyzed using a case-crossover technique with a composite endpoint: death outside of a hospital, myocardial infarction, or stroke. To account for effects of chronic exposure and effects in naïve users, the authors performed a secondary case-control study nested within the cohort of ephedrine/caffeine ever users. Among 2,316 case subjects, 282 (12.2%) were current users of ephedrine/caffeine. The case-crossover analysis yielded an odds ratio of 0.84 (95% confidence interval: 0.71, 1.00); after adjustment for trends in ephedrine/caffeine use, it was 0.95 (95% confidence interval: 0.79, 1.16). Subgroup analyses revealed no strata with significantly elevated risk. In the case-control substudy, there was no increased risk among naïve users or users with large cumulative doses. Prescribed ephedrine/caffeine was not associated with a substantially increased risk of adverse cardiovascular outcomes in this study
Aromaticity in a Surface Deposited Cluster: Pd on TiO (110)
We report the presence of \sigma-aromaticity in a surface deposited cluster,
Pd on TiO (110). In the gas phase, Pd adopts a tetrahedral
structure. However, surface binding promotes a flat, \sigma-aromatic cluster.
This is the first time aromaticity is found in surface deposited clusters.
Systems of this type emerge as a promising class of catalyst, and so
realization of aromaticity in them may help to rationalize their reactivity and
catalytic properties, as a function of cluster size and composition.Comment: 4 pages, 3 figure
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