Mind the gap: testing the Rayleigh hypothesis in T-matrix calculations with adjacent spheroids.

The T-matrix framework offers accurate and efficient modelling of electromagnetic scattering by nonspherical particles in a wide variety of applications ranging from nano-optics to atmospheric science. Its analytical setting, in contrast to purely numerical methods, also provides a fertile ground for further theoretical developments. Perhaps the main purported limitation of the method, when extended to systems of multiple particles, is the often-stated requirement that the smallest circumscribed spheres of neighbouring scatterers not overlap. We consider here such a scenario with two adjacent spheroids whose aspect ratio we vary to control the overlap of the smallest circumscribed spheres, and compute far-field cross-sections and near-field intensities using the superposition T-matrix method. The results correctly converge far beyond the no-overlap condition, and although numerical instabilities appear for the most extreme cases of overlap, requiring high multipole orders, convergence can still be obtained by switching to quadruple precision. Local fields converge wherever the Rayleigh hypothesis is valid for each single scatterer and, remarkably, even in parts of the overlap region. Our results are validated against finite-element calculations, and the agreement demonstrates that the superposition T-matrix method is more robust and broadly applicable than generally assumed.

High prevalence of psychiatric disorders in patients with skin-restricted lupus: a case-control study.

BACKGROUND: Psychiatric disorders have been extensively documented in patients with systemic lupus erythematosus (SLE). However, the prevalence of psychiatric disorders in patients with skin-restricted lupus (SRL) remains unknown, although SRL is more common than SLE. OBJECTIVES: To assess current and lifetime prevalence of Axis I psychiatric disorders among outpatients with SRL and to examine the factors associated with psychiatric disorders among such patients. METHODS: A multicentre case-control study involving outpatients with SRL and controls matched for sex, age and education level. The Mini International Neuropsychiatric Interview was used for psychiatric evaluation. RESULTS: We evaluated 75 patients and 150 controls. Of these, 49% of patients vs. 13% of controls fulfilled the criteria for at least one current psychiatric disorder (P < 0·001). The following disorders were significantly more frequent among patients than controls: current and lifetime major depressive disorder (9% vs. 0%, P < 0·001 and 44% vs. 26%, P = 0·01), generalized anxiety disorder (23% vs. 3%, P < 0·001 and 35% vs. 19%, P = 0·03), panic disorder (7% vs. 0%, P = 0·004 and 21% vs. 3%, P < 0·001), current suicide risk (24% vs. 7%, P = 0·003), alcohol dependence (7% vs. 0%, P = 0·004) and lifetime agoraphobia (20% vs. 9%, P = 0·01). Lupus duration and lupus past treatment by thalidomide were significantly higher among patients with current psychiatric disorders. CONCLUSIONS: This study demonstrates a high prevalence of several psychiatric disorders (anxiety, depression, suicide risk, alcohol dependence) in patients with SRL.

MCL-1 is a stress sensor that regulates autophagy in a developmentally regulated manner.

Apoptosis has an important role during development to regulate cell number. In differentiated cells, however, activation of autophagy has a critical role by enabling cells to remain functional following stress. In this study, we show that the antiapoptotic BCL-2 homologue MCL-1 has a key role in controlling both processes in a developmentally regulated manner. Specifically, MCL-1 degradation is an early event not only following induction of apoptosis, but also under nutrient deprivation conditions where MCL-1 levels regulate activation of autophagy. Furthermore, deletion of MCL-1 in cortical neurons of transgenic mice activates a robust autophagic response. This autophagic response can, however, be converted to apoptosis by either reducing the levels of the autophagy regulator Beclin-1, or by a concomitant activation of BAX. Our results define a pathway whereby MCL-1 has a key role in determining cell fate, by coordinately regulating apoptosis and autophagy.

Inverted V-shaped extracapsular stabilisation technique and arthroscopic findings in six dogs with medial shoulder instability.

OBJECTIVES: The aim of this case series was to report arthroscopic findings and to evaluate clinical outcomes of dogs treated with an inverted V-shaped extracapsular stabilisation technique without additional external coaptation for medial shoulder instability. MATERIAL AND METHODS: Medical records of dogs with medial shoulder instability that underwent arthroscopy and an inverted V-shaped extracapsular stabilisation technique were retrospectively reviewed. Extracapsular stabilisation was performed in all dogs using screws and spiked washers as anchor points for the coated polyester prosthetic ligament. No additional external coaptation was used in any dog. A minimum 18-month follow-up period was required for study inclusion. Complications and long-term outcomes were recorded. RESULTS: The subscapularis tendon and medial glenohumeral ligament were the structures most commonly affected. All dogs had pathological cartilage fibrillations. Implants were successfully placed in all dogs. Implant loosening was recorded in two out of six dogs on recheck but no revision surgery was performed. Function at the time of last clinical follow-up (median, 28 months, range 18 to 33 months) was full in four out of six and acceptable in two out of six dogs. CLINICAL SIGNIFICANCE: Surgical treatment of medial shoulder instability using the novel inverted V-shaped extracapsular stabilisation technique was successful. Potential complications such as implant loosening may occur. Despite the limited number of cases, the present study suggests that additional postoperative external coaptation may not be necessary for successful management of dogs with medial shoulder instability.

Mcl-1 is a key regulator of apoptosis during CNS development and after DNA damage.

Despite the importance of Mcl-1, an anti-apoptotic Bcl-2 family member, in the regulation of apoptosis, little is known regarding its role in nervous system development and injury-induced neuronal cell death. Because germline deletion of Mcl-1 results in peri-implantation lethality, we address the function of Mcl-1 in the nervous system using two different conditional Mcl-1 mouse mutants in the developing nervous system. Here, we show for the first time that Mcl-1 is required for neuronal development. Neural precursors within the ventricular zone and newly committed neurons in the cortical plate express high levels of Mcl-1 throughout cortical neurogenesis. Loss of Mcl-1 in neuronal progenitors results in widespread apoptosis. Double labeling with active caspase 3 and Tuj1 reveals that newly committed Mcl1 deficient neurons undergo apoptosis as they commence migration away from the ventricular zone. Examination of neural progenitor differentiation in vitro demonstrated that cell death in the absence of Mcl1 is cell autonomous. Although conditional deletion of Mcl-1 in cultured neurons does not trigger apoptosis, loss of Mcl-1 sensitizes neurons to an acute DNA damaging insult. Indeed, the rapid reduction of Mcl-1 mRNA and protein levels are early events after DNA damage in neurons, and maintaining high Mcl-1 levels can protect neurons against death. Together, our results are the first to demonstrate the requirement of Mcl-1, an anti-apoptotic Bcl-2 family protein, for cortical neurogenesis and the survival of neurons after DNA damage.

Effects of autologous platelet rich plasma gel and calcium phosphate biomaterials on bone healing in an ulnar ostectomy model in dogs.

The aim of the study was to evaluate the bone healing properties of an osteopromotive platelet rich plasma (PRP) gel in combination with osteoconductive calcium phosphate (CaP) ceramic granules in a long-bone critical size defect in dogs. A standardised 2 cm long ulnar ostectomy was performed bilaterally in four dogs to compare new-bone formation by CaP matrix with and without association with PRP. Radiographic and histological evaluations were performed blindly. Radiographic evaluation was performed at three, six, nine, 12 and 16 weeks postoperatively. Quantitative measurements of new-bone formation were compared using statistical analysis. At explantation 16 weeks after surgery, no significant ossification was present, neither with CaP granules alone nor in association with PRP gel, and there was no difference of radiodensity between the groups. Qualitative histological evaluation demonstrated for both types of implants the presence of non-mineralised fibrous connective tissue around the CaP granules. New-bone formation was only present to a very small extent within the macropores of the CaP granules at the distal bone-implant interface. In our model which exhibited very limited osteoconduction, neither the CaP granules alone nor in association with PRP were sufficient to stimulate bone healing. In this canine model employing a critical size ulnar gap, the combination of CaP granules and PRP did not effectively promote bone regeneration.

Modelling of the near-field of metallic nanoparticle gratings: localized surface plasmon resonance and SERS applications.

We numerically study the influence of the shape of gold nanostructures on the spectral position of their localized surface plasmon resonance and on Surface Enhanced Raman Scattering efficiency. Calculations are performed using a Finite-Difference Time-Domain (FDTD) method, whose accuracy for dispersive media is enhanced through the use of a Drude-Lorentz model. The relevance of this method is then pointed out by comparing the calculations with experimental data for both the plasmon resonance and the Raman signal enhancement. The influence of a thin layer of water is also investigated.

Probing surface plasmon fields by far-field Raman imaging.

This article reports on the imaging of the surface plasmon fields of lithographically designed micrometre-sized gold structures. We investigate rings made of disk-shaped particles and individual crescent-shaped particles. These structures are imaged with two techniques, dark field imaging of elastically scattered light and imaging the surface-enhanced Raman scattering signal of methylene blue dye adsorbed onto the structures. Although elastically scattered light images result from the coherently summed contributions from all elementary scattering volumes, surface-enhanced Raman scattering images reflect the optical near-field intensity incoherently averaged over a surface area corresponding to the spatial resolution of the microscope objective. The combination of both imaging methods enables us to emphasize the role of plasmon coupling and antenna effect in the surface-enhanced Raman scattering enhancement.

Mapping local field enhancements at nanostructured metal surfaces by second-harmonic generation induced in the near field.

We report on an aperture scanning near-field optical microscope in which femtosecond pulses are coupled to a hollow-pyramid aperture sensor. Such probe displays high throughput and preserves pulse duration and polarization, enabling the achievement of sufficiently high peak power in the near field to perform nonlinear optics on the nanoscale. We use the system to observe the nonlinear optical response of nanostructured metal surfaces with sub-100-nm spatial resolution. We study second-harmonic generation from gold nanoparticles both isolated and in high-density patterns, highlighting a strong dependence of the generation efficiency on the shape and on the fine structure of the nanoemitter. In particular, we present results on closely packed gold triangles as well as on nanoellipsoids with different local surface plasmon resonances.

An axial pattern flap based on the dorsal perineal artery in a cat.

CASE REPORT: A 3-year-old male neutered Domestic Shorthair cat was evaluated for a skin mass of approximately 2 × 3 cm arising from the right dorsolateral aspect of the tail at the junction between the proximal and middle one-thirds of the tail length. Incisional biopsy sample was consistent with granulomatous inflammation. The granuloma was surgically excised with 5 mm margins of normal skin. The resulting defect was closed using an axial pattern flap based on a cutaneous branch of the dorsal perineal artery and augmented by a local subdermal plexus transposition flap. There was 100% survival of the flaps at postoperative days 7, 15 and 21. CLINICAL SIGNIFICANCE: We describe an axial pattern flap based on a cutaneous branch of the dorsal perineal artery in a cat. This flap offers surgeons a viable option for closing skin defects situated on the proximal one-third of the tail and a practical alternative to tail amputation.

[Development of an intravesial oxybutynin chloride solution: from formulation to quality control]. / Développement d'une solution de chlorhydrate d'oxybutynine pour instillation vésicale: de la formulation au contrôle qualité.

Intravesical oxybutynin chloride has demonstrated its efficacy in children with neurogenic bladder and urinary incontinence refractory to oral anticholinergic agents. We developed a 205 microg/ml oxybutynin chloride solution in accordance with the specifications of the European Pharmacopeae. To guarantee quality, we assessed and validated formulation, the preparation process, and packaging. The solution was obtained by disolving oxybutynin chloride in 0.9% saline and sterile filtration. The solution was then packaged in syringes. Physical properies for intravesical instillation were met: pH 5.76 +/- 0.03, osmolality 281 mosmol/kg. The unit dose package guarantees sterility of the solution until use. The medication is given by adapting the syringe on the Luer Lock exteremity of the urinary catheter. The solution remains stable up to one month at 4 degrees C.

A new simple method to perform pressure-volume curves obtained under quasi-static conditions during mechanical ventilation.

OBJECTIVE: To describe a fast, simple method to acquire pressure-volume curves of the respiratory system and to compare this with a classic method in terms of reliability of the data and speed. DESIGN: Acquisition of pressure-volume curves by low flow inflation technique (P-Vlf) versus the occlusion technique (P-Vst) using the standard equipment of a Cesar ventilator. SETTING: General ICU - Aix en Provence Hospital. PATIENTS: Ten sedated, curarized patients undergoing mechanical ventilation. INTERVENTIONS: P-Vlf curves were acquired by setting the ventilator parameters at f = 5 c./min, duty time Ti/Ttot = 80 %, VT = 1100 ml, pause time = 0. The pressure and volume data were collected directly on the ventilator screen. P-Vst curves were acquired using an airway occlusion technique. The pressures obtained for the same inflation volumes and times necessary for performance of the two techniques were compared. RESULTS: The time needed to acquire a P-Vlf curve was 3 min versus 38 min for P-Vst curve. Concordance analysis between the two methods showed a 95 % confidence interval of (-0.5 cm H2O, + 1.8 cm H2O) for pressure. CONCLUSIONS: P-Vlf curves are close to P-Vst curves, are much less time-consuming, easy to acquire with Cesar ventilator equipment, and may be used in clinical routine to assess the elastic properties of the respiratory system.

Competition, cooperation, or control? Tales from the British National Health Service.

The British National Health Service (NHS) recently underwent a massive social experiment, inspired in large part by the ideas of U.S. experts. This involved the creation of an internal or quasi-market, separating purchaser from provider and encouraging competition among providers. After reviewing the evidence concerning the impact of this experiment, I conclude that the impact in fact was minimal, partly because of the retention of central government control and partly because the experiment was based on an inadequate understanding of professional and managerial motivations. The paper draws out general lessons of the experiment for other market-oriented health care systems and examines whether the lessons are reflected in the new batch of NHS reforms initiated by the recently elected Labour Government.

Regional inequalities in mortality.

STUDY OBJECTIVE: To examine the hypothesis of sustained and persistent inequalities in health between British regions and to ask how far they are a consequence of using standardised mortality ratios as the tool of measurement. DESIGN, SETTING AND PARTICIPANTS: Data are regional, age specific death rates at seven points in time from 1931 to 1987-89 for the British regions, reconstructed to make them comparable with the 1981 regional definitions. Log variance is used to measure inequality; regional rankings are also used. MEASUREMENTS AND MAIN RESULTS: There has been a substantial convergence in age specific death rates between regions in younger but not in older age groups. In younger age groups the historic north/south gradient has disappeared; it persists in older groups. CONCLUSIONS: Use of standardised mortality ratios obscures differences in the convergence rates of age specific death rates between regions. Simple conclusions about the persistence of a north/south divide are not justified. Different processes of change seem to be at work in different age groups.

The economic analysis of inequalities in health.

The paper explains the economist's concept of human capital, and uses it to analyse some of the problems raised in the Black Report on inequalities in health. Individuals are assumed to have an optimal 'stock' of health, defined as the level of stock for which the marginal benefits of further investment in the stock falls below its marginal cost. Differences in marginal benefits and costs between individuals will thus lead to differences in their health stocks. Use of this simple model and its associated concepts can be used to help explain, for instance, why social class differences in mortality are steepest in early adulthood and shallowest in the decade before retirement or why manual workers who 'need' more health than non-manual workers are nonetheless in general less healthy. The model can also contribute to the discussion of normative issues, for instance, to refine the concept of equality of access. However, while it has great potential in organising and analysing hypotheses concerning health behaviour, the model is in no way a substitute for other approaches; indeed it only becomes meaningful when interpreted in sociological, epidemiological and medical terms.

KIE: The economist's concept of human capital is explained and applied to some of the problems raised in the "Black Report," Inequalities in Health (London: Department of Health and Social Security; 1980). Individuals are assumed to have an optimal "stock" of health, defined as the level of stock for which the marginal benefit of further investment falls below its marginal cost for that individual. This "health stock" model can be used to help explain, for example, why social class differences in mortality are steepest in early adulthood and shallowest in the decade before retirement or why manual laborers who "need" more health than nonmanual workers are generally less healthy. It can also contribute to a discussion of normative issues, such as equality of access to health care.

The motivation and behaviour of hospital Trusts.

This paper explores the motivation and behaviour of hospitals, using data from UK hospital Trusts. Managers and consultants (hospital specialists) are identified as the main alternative sources of power within Trusts. It is hypothesised that consultants are interested in production or service (volume and quality) while managers are interested primarily in financial break-even, and that in the long run consultants will dominate. A survey of 1500 consultants and managers and a statistical analysis of the behaviour of 100 Trusts over 3 years yielded the empirical results that were largely but not entirely consistent with these hypotheses. Consultants did indeed consider production goals to be more important than financial breakeven, but within those goals, considered quality to be more important than service volume. While the break-even target was found to be the primary goal of managers on average, they proved to be a heterogeneous group with quality ranking as the main priority among those managers who are closest to service delivery. This is at odds with the apparent objective of Trusts, which both groups perceive as being the single-minded pursuit of financial targets, consistent with the formal, government-set requirements. We find that this strong and unequivocal financial driver is not owned or acted upon by either consultants or managers and it is inferred that, in accordance with the dominant motivation of consultants, the Trust's primary objective is to maintain service quality.

Ethnicity, equity and the use of health services in the British NHS.

This paper addresses the extent to which equity of treatment is received by people of different ethnic groups from the British National Health Service. Using data from the General Household Surveys of 1984-91 it examines the use of general practitioner, outpatient services using three different methods to adjust for need and for other possible confounding variables. The results do not suggest there is any gross pattern of inequity between ethnic groups, except perhaps with respect to the Chinese population which displays consistently low levels of utilisation. However, while use of GP services by minority ethnic groups is in general as high or higher than the white population, use of outpatient service is low. Some of the results also suggest that there may be important ethnic differences underlying the broader finding of equity. For example, females of Pakistani origin report low levels of GP use. More generally, excess use of GP services among several minority ethnic groups appears to be associated with need, while people from most minority ethnic groups who do not report illness display especially low use of outpatient services relative to the corresponding group in the white population. The paper examines the implications of these findings.

Incentives and health policy: primary and secondary care in the British National Health Service.

This paper argues that issues concerning incentives and motivation are crucial to recent reforms to the British National Health Service. It examines how the incentive structure of General Practitioners with respect to the interface between primary and secondary care changed with the introduction of GP fundholding, and how it might change further with the new Primary Care Groups. It concludes that the effectiveness of the internal incentive structure of the new groups will depend on the location of power within the PCGs, and that the external incentives involving the possibility of heavy central monitoring may affect the behaviour and motivation of GPs in potentially harmful ways.

Contaminants in molting long-tailed ducks and nesting common eiders in the Beaufort Sea.

In 2000, we collected blood from long-tailed ducks (Clangula hyemalis) and blood and eggs from common eiders (Somateria mollissima) at near-shore islands in the vicinity of Prudhoe Bay, Alaska, and at a reference area east of Prudhoe Bay. Blood was analyzed for trace elements and egg contents were analyzed for trace elements, organochlorine pesticides, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons. Except for Se (mean=36.1 microg/g dry weight (dw) in common eiders and 48.8 microg/g dw in long-tailed ducks), concentrations of trace elements in blood were low and, although several trace elements differed between areas, they were not consistently higher at one location. In long-tailed ducks, Se in blood was positively correlated with activities of two serum enzymes, suggestive of an adverse effect of increasing Se levels on the liver. Although common eiders had high Se concentrations in their blood, Se residues in eggs were low (mean=2.28 microg/g dw). Strontium and Ni were higher in eggs near Prudhoe Bay than at the reference area, but none of the other trace elements or organic contaminants in eggs differed between locations. Concentrations of Ca, Sr, Mg, and Ni differed among eggs having no visible development, early-stage embryos, or late-stage embryos. Residues of 4,4'-DDE, cis-nonachlor, dieldrin, hexachlorobenzene, oxychlordane, and trans-nonachlor were found in 100% of the common eider eggs, but at low concentrations (means of 2.35-7.45 microg/kg wet weight (ww)). The mean total PCB concentration in eggs was 15.12 microg/kg ww. Of PAHs tested for, residues of 1- and 2-methylnaphthalene and naphthalene were found in 100% of the eggs, at mean concentrations of 0.36-0.89 microg/kg ww.

A cognitive model of dangerous delusional misidentification syndromes.

The hallmark of the delusional misidentification syndromes is the presence of a misidentification delusion of the self or others. Delusional misidentification may present with an increased risk for dangerous behaviors. Individuals suffering from delusional misidentification syndromes may express hostility in ways ranging from serious verbal threats to homicidal acts. The causes of dangerous misidentification delusions remain for the most part undetermined. In this article, we report a series of six cases of individuals who harbored dangerous misidentification delusions. These individuals were studied phenomenologically and forensically. They were also studied biologically, including neuropsychological testing. A cognitive hypothesis aimed at explaining dangerousness and delusional misidentification is proposed. Implications of the hypothesis for further research are briefly outlined.