Reduced brain serotonin transporter availability in major depression as measured by [123I]-2 beta-carbomethoxy-3 beta-(4-iodophenyl)tropane and single photon emission computed tomography

BACKGROUND: Prior research has suggested reductions in the density of serotonin transporter (SERT) binding sites in blood platelets and post-mortem brain tissue of depressed patients. We sought to determine whether patients with unipolar major depression have diminished SERT availability as assessed by both brainstem [123I] beta-CIT SPECT and platelet [3H]paroxetine binding. METHODS: Drug-free depressed and healthy subjects were injected with 211 +/- 22 MBq [123I] beta-CIT and imaged 24 +/- 2 h later under equilibrium conditions. A ratio of specific to nonspecific brain uptake (V3" = (brainstem-occipital)/occipital), a measure proportional to the binding potential (Bmax/Kd), was used for all comparisons. RESULTS: Results showed a statistically significant reduction in brainstem V3" values in depressed as compared to healthy subjects (3.1 +/- .9 vs. 3.8 +/- .8, p = .02). Platelet [3H]paroxetine binding was not altered (Bmax = 2389 +/- 484 vs. 2415 +/- 538 fmol/mg protein, p = .91) and was not significantly correlated with brainstem [123I] beta-CIT binding (r = -0.14, p = .48). CONCLUSIONS: These data are the first to suggest reductions in the density of brain SERT binding sites in living depressed patients. These findings provide further support for a preeminent role for alterations in serotonergic neurons in the pathophysiology of depression.     

Pain threshold values during periodontal probing: assessment of maxillary incisor and molar sites

Probing pain threshold (PPT) assessments were conducted in the facial and oral sulci of maxillary central incisors and first molars of 10 periodontally healthy adults. All subjects were systemically healthy, free of pain, and reported no current medication usage. A computer-linked electronic probe, modified to deliver steadily increasing forces up to 200 grams, was used to collect the data. The system contained a subject operated "off-switch" which, upon activation, signaled the computer to record the subject's PPT. Assessments of each subject's PPTs were conducted on 3 separate occasions at 7-day intervals. Results indicated that the facial sulci of the incisors were the most pain sensitive. They displayed a mean PPT of 50.9 +/- 26.6 grams. The oral sulci of the incisors exhibited a mean PPT of 76.5 +/- 45.2 grams. Facial and oral sulci of the molars evidenced mean PPT values of 102.6 +/- 52.1 grams and 113.5 +/- 51.3 grams, respectively. These data suggest that sulci associated with incisor teeth are nearly twice as pain sensitive as sulci associated with molar teeth. In addition, facial sulci are significantly more pain sensitive than oral sulci. Data did not indicate a visit effect nor a side-of-mouth effect on PPT values.     

Elliptical trough reflector for the collection of light from linear sources

A trough reflector with a reflective, truncated elliptical surface was designed to efficiently collect freely propagating light from a linear source. The source was placed at one focus of the reflector, and light was collected through a rectangular aperture near the second focus. Collection efficiency was much greater than that of a spherical integrator and approximately 6.5x greater than that of an objective lens; as much as approximately 55% of the light could be captured from the full aperture. This reflector could be used to efficiently collect surface fluorescence excited by use of evanescent waves in fluorescence-based fiber optic or capillary waveguide sensors.     

Polarization-Dependent Periodic Pulse Oscillation in a Diode-Laser-Pumped and Intracavity Frequency-Doubled Nd:YVO 4 Laser

We demonstrate that two cross-polarized longitudinal modes can have 50% higher conversion efficiency than two parallel-polarized longitudinal modes in a diode-laser-pumped and intracavity frequency-doubled Nd:YVO(4) laser when operated under periodic pulse oscillation. Through simulations of the rate equations for primary frequency intensities and gains, we also verify that this effect can be attributed to gain competition and complementary conversion coefficient between second-harmonic and sum-frequency generations.     

Mixed films of TiO(2)-SiO(2) deposited by double electron-beam coevaporation

We used double electron-beam coevaporation to fabricate TiO(2)-SiO(2) mixed films. The deposition process included oxygen partial pressure, substrate temperature, and deposition rate, all of which were real-time computer controlled. The optical properties of the mixed films varied from pure SiO(2) to pure TiO(2) as the composition of the films varied accordingly. X-ray diffraction showed that the mixed films all have amorphous structure with a SiO(2) content of as low as 11%. Atomic force microscopy showed that the mixed film has a smoother surface than pure TiO(2) film because of its amorphous structure.

Linear and Bruggeman's effective medium approximation models fit the experimental data better than other models.

     

Anatomical structures determining blood flow in the heart left ventricle

The presence of twisted helical flow patterns in the cardiac cavities during ventricular filling and ejection was supposed. This work was intended in order to show that the intra-ventricular trabeculation plays the determining role in such a flow formation and to find some analytical approaches for its analysis. The morphometric study of human left-ventricular and aortic corrosion casts and dynamic measurement of the aorta by MRI-technique were performed. The data were analysed by means of the Mathematica program. Two groups of trabecules were identified that refer to the inlet and outlet of the ventricular blood flow. The first group consists of trabecules of the free left-ventricular wall. The second group consists of long trabecules going along the anterior left-ventricular wall and intracavital lines of the papillary muscles. Both are twisted clockwise and converge in the flow direction. Each group of trabecules is oriented towards the mitral or aortic valve orifices, correspondingly. It was concluded that the helical trabecular organization acts as flow directing paddles that change their mutual orientation during the cardiac cycle evolution. The reorientation of the flow takes place due to sequential contraction of the ventricular structures. The formalization of trabecular orientation will allow one to calculate improved models of implantable substitutes and auxiliary devices for cardio-vascular surgery.Sadly deceased.     

Analysis of right ventricular function during bypass of the left side of the heart by afterload alterations in both normal and failing hearts

This study investigated the mechanism of right ventricular failure during bypass of the left side of the heart by precisely assessing right ventricular function with use of a conductance catheter. Bypass of the left side of the heart was established with a centrifugal pump in 10 mongrel dogs weighing 11 to 19 kg. Right ventricular function during left heart bypass was evaluated by two parameters that were both derived from measurement of relative change in right ventricular volume by the conductance catheter technique. One parameter was the right ventricular end-systolic pressure-volume relationship as a load-independent index, and the other was the peak right ventricular pressure-right ventricular stroke volume relationship as a "force-velocity relationship." These parameters were measured in both normal and failing hearts while afterload was increased by bilateral intrapulmonary balloon inflation. Moreover, changes in these relationships were observed by varying assist ratios of left heart bypass from 0% to 100%. Failing heart models were induced by normothermic aortic clamping for 20 minutes. The right ventricular end-systolic pressure-volume relationship in normal hearts did not change, irrespective of the assist ratio of left heart bypass, whereas that in failing hearts decreased from 4.25 +/- 1.41 mm Hg/ml without bypass of the left side of the heart to 3.53 +/- 1.30 mm Hg/ml after 100% assist of left heart bypass (p < 0.05). In the peak right ventricular pressure-right ventricular stroke volume relationship, right ventricular stroke volume was almost constant in normal hearts when afterload was increased regardless of the assist ratio of left heart bypass. Moreover, right ventricular stroke volume was maintained at a higher level during bypass of the left side of the heart compared with that without left heart bypass. However, that slope of the relationship in failing hearts was inversely linear and became significantly steeper after 100% assist of bypass of the left side of the heart compared with that without left heart bypass (-0.131 +/- 0.042 versus -0.051 +/- 0.038, p < 0.005). Therefore ++these two slopes of the relationship intersected at a point that was considered the critical point of afterload during bypass of the left side of the heart. In other words, right ventricular stroke volume was decreased by 100% left heart bypass above the critical point of afterload. In conclusion, this study demonstrates not only that bypass of the left side of the heart results in an increase in right ventricular stroke volume in both normal and failing hearts at the physiologic range of afterload, but also that right ventricular function against higher afterload is impaired by 100% assist of bypass of the left side of the heart in failing hearts.     

Global exponential robust stability of reaction–diffusion interval neural networks with continuously distributed delays

This paper considers the existence of the equilibrium point and its global exponential robust stability for reaction-diffusion interval neural networks with variable coefficients and distributed delays by means of the topological degree theory and Lyapunov-functional method. The sufficient conditions on global exponential robust stability established in this paper are easily verifiable. An example is presented to demonstrate the effectiveness and efficiency of our results.     

Filtering Data Streams for Entity-Based Continuous Queries

The idea of allowing query users to relax their correctness requirements in order to improve performance of a data stream management system (e.g., location-based services and sensor networks) has been recently studied. By exploiting the maximum error (or tolerance) allowed in query answers, algorithms for reducing the use of system resources have been developed. In most of these works, however, query tolerance is expressed as a numerical value, which may be difficult to specify. We observe that in many situations, users may not be concerned with the actual value of an answer, but rather which object satisfies a query (e.g., "who is my nearest neighbor?”). In particular, an entity-based query returns only the names of objects that satisfy the query. For these queries, it is possible to specify a tolerance that is "nonvalue-based.” In this paper, we study fraction-based tolerance, a type of nonvalue-based tolerance, where a user specifies the maximum fractions of a query answer that can be false positives and false negatives. We develop fraction-based tolerance for two major classes of entity-based queries: 1) nonrank-based query (e.g., range queries) and 2) rank-based query (e.g., k-nearest-neighbor queries). These definitions provide users with an alternative to specify the maximum tolerance allowed in their answers. We further investigate how these definitions can be exploited in a distributed stream environment. We design adaptive filter algorithms that allow updates be dropped conditionally at the data stream sources without affecting the overall query correctness. Extensive experimental results show that our protocols reduce the use of network and energy resources significantly.     

同行导师体验报告(英文)

Students at the University of Derby are required to complete a year in industry as part of their Bachelor of Science degrees.This is a daunting prospect for some of them,and they can be reluctant to engage in the process of finding a placement position.As part of a second year module,students seeking placement are paired with students already on placement in a mentee/mentor relationship to support the second year students in their search for an internship.This arrangement helps the mentees by introducing them to potential role models close to their experience,receiving encouragement from peers and the inculcation of belief that it is possible to find a placement.The mentors also benefit from a recognition of how much they have learnt.However,there are difficulties in establishing and managing the scheme which should be recognised.This paper reports our experience over the last three years.