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Second Instance (second + instance)

Distribution by Scientific Domains

Medical Sciences	40%

Selected Abstracts

Simulations to Verify Horizontal Flow Measurements from a Borehole Flowmeter

GROUND WATER, Issue 3 2006
Scott C James
This paper reports on experiments and simulations of subsurface flow from a slotted acrylic tube deployed in a sand-tank flow chamber for two different purposes. In the first instance, the slotted tube is used to represent a single fracture intersected by an uncased well. In the second instance, the slotted tube is used to represent a multislot well screen within a porous medium. In both cases, the scanning colloidal borescope flowmeter (SCBFM) measures ground water velocity within the well by imaging colloids traveling through a well to measure their speed and direction. Measurements are compared against model simulations. For the case of a slotted tube representing a single fracture, SCBFM and model results agree with respect to the flow direction and to within a factor of 1.5 for the speed near the well's center. Model and experimental agreement lend confidence that for an uncased well drilled in a fractured-rock medium, a calibrated SCBFM could be used to identify and quantify flowing features. Next, the SCBFM was deployed in a four-column multislotted casing with slots aligned with the flow direction. Another numerical model was developed to estimate the flow field within this well screen to evaluate the potential usefulness of employing the SCBFM in a screened well to estimate flow speed and direction in the surrounding porous medium. Results indicate that if the slots are not aligned with the flow, the SCBFM may only provide order-of-magnitude speed measurements and direction measurements with an uncertainty of approximately ±25°. [source]

Counterpoints of care: two moments of struggle

JOURNAL OF INTELLECTUAL DISABILITY RESEARCH, Issue 2010
B. Gleeson
Abstract This paper examines the history of care in modern society and seeks to expose how deep transformations in care arise from wider social relations. From historical survey we may discern a series of transitional points, where the practice and the experience of care was greatly, sometimes suddenly, redefined. Each betrayed deeper political and ethical struggles that went to the core of social relations, and which weren't merely therapeutic in nature. This paper explores two such ,moments'. I first examine the emergence of a new institutional landscape during the middle industrial era, in the wake of a series of legal and political reforms that sought to settle a social order uprooted and distressed by raw modernisation. I provide a composite, yet incomplete view, of how this transformation proceeded in one urban setting, colonial Melbourne. In the second instance, I review the ambitions and process of deinstitutionalisation in the late 20th century. Ostensibly, this reform sought, inter alia, to collapse the great division between ,fit' and ,unfit' established in 1834. Again, empirical reference is made to the reconstitution of care in Melbourne, Australia, this time during its late 20th experience of institutional reform. The focus in this case is the process of downscaling and closure for a major congregate facility, Kew Cottages. The major conclusion is that periods of intense transition in the ideology and mode of care are reflective of wider social transformations not merely of therapeutic or institutional shifts. [source]

Spontaneous Redox Reactions of Dopaquinone and the Balance between the Eumelanic and Phaeomelanic Pathways

PIGMENT CELL & MELANOMA RESEARCH, Issue 4 2000
E.J. LAND
Eumelanogenesis and phaeomelanogenesis diverge at an early stage in pigment formation, namely at the point where dopaquinone, the initial product of tyrosine oxidation by tyrosinase, undergoes one of two types of reaction: either (1) a reductive endocyclisation in which a Michael addition of the side-chain amino group takes place; or (2) a reductive addition of cysteine to give cysteinyldopa. In the former case, the product cyclodopa, is known rapidly to undergo a redox exchange reaction with dopaquinone to yield dopachrome, the precursor of the eumelanogenic pathway. In the second instance, cysteinyldopa is regarded as leading to the formation of benzothiazoles, which are characteristic of phaeomelanin. The precursor molecule of the phaeomelanic pathway is cysteinyldopaquinone. We have examined quantitatively the role of dopaquinone in the non-enzymatic oxidation of 5-S-cysteinyldopa using pulse radiolysis and have demonstrated that the redox exchange reaction between dopaquinone and 5-S-cysteinyldopa occurs spontaneously with a rate constant of 8.8×105 M,1 sec,1. This study has also enabled an improved estimate of ,4×107 M,1sec,1 to be obtained for the rate constant of the reaction of dopaquinone with cyclodopa. Calculations utilising these figures and estimates of the rate constants for the other reactions in early melanogenesis, demonstrate that, whilst similar pathways are invoked, the phaeomelanic pathway predominates in the presence of cysteine, irrespective of the availability of dopaquinone and thus independently of the rate of tyrosinase-catalysed oxidation. This suggests that the balance between the formation of eumelanin and phaeomelanin is regulated principally by the availability of cysteine at the site of melanogenesis. [source]

Emotional issues after kidney transplantation: a prospective psychotherapeutic study

CLINICAL TRANSPLANTATION, Issue 6 2002
Lyndsay S Baines
Abstract:,Background:, Negative emotional states are the single most influential factor in determining quality of life after a successful kidney transplant. We designed a prospective study using psychotherapeutic principles to understand and intervene in emotional issues in adult recipients of first cadaver kidney transplants. Methods:, Forty-nine recipients of first cadaver kidney transplants were subjected to 12 sessions (at weekly intervals) of psychotherapy within 3 months of receiving their transplant. The Beck Depression Inventory (BDI) was utilized as a measure of change in emotional state, pretherapy, at 3, 6, 9 and 12 months. A higher score on BDI was suggestive of psychological dysfunction. In the first instance, data was analysed within a quantitative framework, by virtue of the BDI. In the second instance, data was considered in terms of recurring themes described by patients during psychotherapy and was analysed qualitatively. In the third instance, both qualitative and quantitative data was considered in terms of individual patient's ability to achieve some feeling of having implemented some social, relational and vocational equilibrium into their everyday life. Recipients of live kidneys, paediatric transplants and patients who received more than one transplant were excluded, as emotional issues are different in this cohort of patients. All patients have completed 1 yr of follow up. None of the patients were on antidepressant medication before or after therapy. Results:, This is an ongoing study in which we are comparing individual vs. group therapy vs. controls (who receive no therapy). The total number of patients recruited will be 120 and the final report will be available in 2003,04. The results reported in this paper form the 49 patients in the individual arm of the study. All the patients in our study happened to be white people. There was significant improvement in the BDI scores following therapy. The mean score was 26.3 ± 7.9 before and 20.5 ± 8.8 after therapy (p = 0.001); the lowering of the scores remained sustained at 12 months. Multivariate analysis of age, gender, employment status, duration of dialysis (if in dialysis for more than 3 yrs) and psychotherapy given before transplantation did not affect the results of our study. For the qualitative aspect of the study, we grouped the emotional problems as expressed by the patients into three recurring themes (i) fear of rejection, (ii) feelings of paradoxical loss post-transplant despite having received a successful transplant and (iii) the psychological integration of the newly acquired kidney. Conclusions:, Psychotherapeutic intervention was an effective means of addressing emotional problems in recipients of kidney transplants. The recurring themes as identified above provided a baseline for psychotherapeutic exploration and resolution of these issues. Successful resolution of these issues was associated with lower BDI scores and the redefinition of normality in daily living post-transplant. [source]

Stable signal recovery from incomplete and inaccurate measurements

COMMUNICATIONS ON PURE & APPLIED MATHEMATICS, Issue 8 2006
Emmanuel J. Candès
Suppose we wish to recover a vector x0 , ,,, (e.g., a digital signal or image) from incomplete and contaminated observations y = A x0 + e; A is an ,, × ,, matrix with far fewer rows than columns (,, , ,,) and e is an error term. Is it possible to recover x0 accurately based on the data y? To recover x0, we consider the solution x# to the ,,1 -regularization problem where , is the size of the error term e. We show that if A obeys a uniform uncertainty principle (with unit-normed columns) and if the vector x0 is sufficiently sparse, then the solution is within the noise level As a first example, suppose that A is a Gaussian random matrix; then stable recovery occurs for almost all such A's provided that the number of nonzeros of x0 is of about the same order as the number of observations. As a second instance, suppose one observes few Fourier samples of x0; then stable recovery occurs for almost any set of ,, coefficients provided that the number of nonzeros is of the order of ,,/(log ,,)6. In the case where the error term vanishes, the recovery is of course exact, and this work actually provides novel insights into the exact recovery phenomenon discussed in earlier papers. The methodology also explains why one can also very nearly recover approximately sparse signals. © 2006 Wiley Periodicals, Inc. [source]