Interaction Effects on Number Fluctuations in a Bose-Einstein Condensate of Light

We investigate the effect of interactions on condensate-number fluctuations in Bose-Einstein condensates. For a contact interaction we variationally obtain the equilibrium probability distribution for the number of particles in the condensate. To facilitate comparison with experiment, we also calculate the zero-time delay autocorrelation function $g^{(2)}(0)$ for different strengths of the interaction. Finally, we focus on the case of a condensate of photons and discuss possible mechanisms for the interaction.Comment: 13 pages, version 3, 4 figure

Phase diffusion in a Bose-Einstein condensate of light

We study phase diffusion in a Bose-Einstein condensate of light in a dye-filled optical microcavity, i.e., the spreading of the probability distribution for the condensate phase. To observe this phenomenon, we propose an interference experiment between the condensed photons and an external laser. We determine the average interference patterns, considering quantum and thermal fluctuations as well as dissipative effects due to the dye. Moreover, we show that a representative outcome of individual measurements can be obtained from a stochastic equation for the global phase of the condensate

Theory for Bose-Einstein condensation of light in nano-fabricated semiconductor microcavities

We construct a theory for Bose-Einstein condensation of light in nano-fabricated semiconductor microcavities. We model the semiconductor by one conduction and one valence band which consist of electrons and holes that interact via a Coulomb interaction. Moreover, we incorporate screening effects by using a contact interaction with the scattering length for a Yukawa potential and describe in this manner the crossover from exciton gas to electron-hole plasma as we increase the excitation level of the semiconductor. We then show that the dynamics of the light in the microcavities is damped due to the coupling to the semiconductor. Furthermore, we demonstrate that on the electron-hole plasma side of the crossover, which is relevant for the Bose-Einstein condensation of light, this damping can be described by a single dimensionless damping parameter that depends on the external pumping. Hereafter, we propose to probe the superfluidity of light in these nano-fabricated semiconductor microcavities by making use of the differences in the response in the normal or superfluid phase to a sudden rotation of the trap. In particular, we determine frequencies and damping of the scissors modes that are excited in this manner. Moreover, we show that a distinct signature of the dynamical Casimir effect can be observed in the density-density correlations of the excited light fluid

Vitamin D concentration and psychotic disorder:associations with disease status, clinical variables and urbanicity

Background The association between schizophrenia and decreased vitamin D levels is well documented. Low maternal and postnatal vitamin D levels suggest a possible etiological mechanism. Alternatively, vitamin D deficiency in patients with schizophrenia is presumably (also) the result of disease-related factors or demographic risk factors such as urbanicity. Methods In a study population of 347 patients with psychotic disorder and 282 controls, group differences in vitamin D concentration were examined. Within the patient group, associations between vitamin D, symptom levels and clinical variables were analyzed. Group x urbanicity interactions in the model of vitamin D concentration were examined. Both current urbanicity and urbanicity at birth were assessed. Results Vitamin D concentrations were significantly lower in patients (B= -8.05; 95% confidence interval (CI) -13.68 to -2.42;p= 0.005). In patients, higher vitamin D concentration was associated with lower positive (B= -0.02; 95% CI -0.04 to 0.00;p= 0.049) and negative symptom levels (B= -0.03; 95% CI -0.05 to -0.01;p= 0.008). Group differences were moderated by urbanicity at birth (chi(2)= 6.76 andp= 0.001), but not by current urbanicity (chi(2)= 1.50 andp= 0.224). Urbanicity at birth was negatively associated with vitamin D concentration in patients (B= -5.11; 95% CI -9.41 to -0.81;p= 0.020), but not in controls (B= 0.72; 95% CI -4.02 to 5.46;p= 0.765). Conclusions Lower vitamin D levels in patients with psychotic disorder may in part reflect the effect of psychosis risk mediated by early environmental adversity. The data also suggest that lower vitamin D and psychopathology may be related through direct or indirect mechanisms.</p

Factors for changes in self-care and mobility capabilities in young children with cerebral palsy involved in regular outpatient rehabilitation care

BACKGROUND: Assessing prognosis of self-care and mobility capabilities in children with cerebral palsy (CP) is important for goal setting, treatment guidance and meaningful professional-caregiver conversations. AIMS: Identifying factors associated with changes in self-care and mobility capabilities in regular outpatient multidisciplinary paediatric CP rehabilitation care. METHODS AND PROCEDURES: Routinely monitored longitudinal data, assessed with the Paediatric Evaluation of Disability Inventory (PEDI-Functional-Skills-Scale, FSS 0–100) was retrospectively analysed. We determined contributions of age, gross-motor function, bimanual-arm function, intellectual function, education type, epilepsy, visual function, and psychiatric comorbidity to self-care and mobility capability changes (linear-mixed-models). OUTCOMES AND RESULTS: For 90 children (53 boys), in all Gross-Motor-Function-Classification-System (GMFCS) levels, 272 PEDI's were completed. Mean PEDI–FSS–scores at first measurement (median age: 3,2 years) for self-care and mobility were 46.3 and 42.4, and mean final FSS-scores respectively were 55.1 and 53.1 (median age: 6,5 years). Self-care capability change was significantly associated with age (2.81, p < 0.001), GMFCS levels III-V (-9.12 to -46.66, p < 0.01), and intellectual impairment (-6.39, p < 0.01). Mobility capability change was significantly associated with age (3.25, p < 0.001) and GMFCS levels II-V (-6.58 to -47.12, p < 0.01). CONCLUSIONS AND IMPLICATIONS: Most important prognostic factor for self-care and mobility capabilities is GMFCS level, plus intellectual impairment for self-care. Maximum capability levels are reached at different ages, which is important for individual goal setting and managing expectations

Paraneoplastic cerebellar degeneration associated with antineuronal antibodies: analysis of 50 patients

Paraneoplastic cerebellar degeneration (PCD) is a heterogeneous group of disorders characterized by subacute cerebellar ataxia, specific tumour types and (often) associated antineuronal antibodies. Nine specific antineuronal antibodies are associated with PCD. We examined the relative frequency of the antineuronal antibodies associated with PCD and compared the neurological symptoms and signs, associated tumours, disability and survival between groups of PCD with different antibodies. Also, we attempted to identify patient-, tumour- and treatment-related characteristics associated with functional outcome and survival. In a 12-year period, we examined >5000 samples for the presence of antineuronal antibodies. A total of 137 patients were identified with a paraneoplastic neurological syndrome and high titre (> or =400) antineuronal antibodies. Fifty (36%) of these patients had antibody-associated PCD, including 19 anti-Yo, 16 anti-Hu, seven anti-Tr, six anti-Ri and two anti-mGluR1. Because of the low number, the anti-mGluR1 patients were excluded from the statistical analysis. While 100% of patients with anti-Yo, anti-Tr and anti-mGluR1 antibodies suffered PCD, 86% of anti-Ri and only 18% of anti-Hu patients had PCD. All patients presented with subacute cerebellar ataxia progressive over weeks to months and stabilized within 6 months. The majority of patients in all antibody groups had both truncal and appendicular ataxia. The frequency of nystagmus and dysarthria was lower in anti-Ri patients (33 and 0%). Later in the course of the disease, involvement of non-cerebellar structures occurred most frequently in anti-Hu patients (94%). In 42 patients (84%), a tumour was detected. The most commonly associated tumours were gynaecological and breast cancer (anti-Yo and anti-Ri), lung cancer (anti-Hu) and Hodgkin's lymphoma (anti-Tr and anti-mGluR1). In one anti-Hu patient, a suspect lung lesion on CT scan disappeared while the PCD evolved. Seven patients improved by at least 1 point on the Rankin scale, while 16 remained stable and 27 deteriorated. All seven patients that improved received antitumour treatment for their underlying cancer, resulting in complete remission. The functional outcome was best in the anti-Ri patients, with three out of six improving neurologically and five were able to walk at the time of last follow-up or death. Only four out of 19 anti-Yo and four out of 16 anti-Hu patients remained ambulatory. Also, survival from time of diagnosis was significantly worse in the anti-Yo (median 13 months) and anti-Hu (median 7 months) patients compared with anti-Tr (median >113 months) and anti-Ri (median >69 months). Patients receiving antitumour treatment (with or without immunosuppressive therapy) lived significantly longer [hazard ratio (HR) 0.3; 95% confidence interval (CI) 0.1-0.6; P = 0.004]. Patients > or =60 years old lived somewhat shorter from time of diagnosis, although statistically not significant (HR 2.9; CI 1.0-8.5; P = 0.06)

The Long-Term Evolution of Social Organization

This chapter outlines how the ‘innovation innovation’ transformed the world of our distant ancestors into that in which we live today. It focuses on the relationship between people and the material world, as it is the material world that has been most drastically, and measurably, transformed over the last several tens of thousands of years. In view of what we know about such distant periods, and in view of the space allot-ted to us here, it will not surprise the reader that we do so in the form of a narrative that is only partly underpinned by substantive data. We emphasize this because we do not want to hide from the reader the speculative nature of the story that follows. Yet we firmly believe that, in very general terms, this scenario is correct, and that further research will vindicate us.We first give examples of the kinds of abstractions, and the hierarchy of conceptual dimensions necessary for prehistoric human beings and their ancestors, to conquer matter, i.e. to conceptually understand, transmit and apply the operations needed to master the making of a range of objects made out of stone, bone, wood, clay and other materials. Some of the abstractions that had to be conceived in this domain re-semble those that Read et al. (http://www.escholarship.org/uc/item/2798j162) refer to, while others apply to this domain alone, and had to be truly ‘invented’. It is then argued that such ‘identification of conceptual dimensions’ is a process that underlies all human activity, and we look a little closer at how that process relates to invention and innovation.Lastly, we shift our attention to the role of innovation, information processing and communication in the emergence of social institutions, and in the structural transformation of human societies as they grow in size and complexity. In particular, we look at the role that problem solving and invention play in creating more and more complex societies, encompassing increasing numbers of people, more and more diverse institutions, and an – ultimately seemingly all-encompassing – appropriation of the natural environment. To illustrate this development we will focus on the origins and growth of urban systems

Lifestyle changes and kidney function: A 10-year follow-up study in patients with manifest cardiovascular disease

BACKGROUND: Patients with cardiovascular disease (CVD) are at higher risk of kidney function decline. The current study aimed to examine the association of lifestyle changes with kidney function decline in patients with manifest CVD. METHODS: A total of 2260 patients from the Utrecht Cardiovascular Cohort-Second Manifestations of ARTerial disease cohort with manifest CVD who returned for a follow-up visit after a median of 9.9 years were included. The relation between change in lifestyle factors (smoking, alcohol consumption, physical activity and obesity) and change in kidney function (eGFR and uACR) was assessed using linear regression models. RESULTS: An increase in body mass index (β -2.81; 95% CI -3.98; -1.63 per 5 kg/m2 ) and for men also an increase in waist circumference (β -0.87; 95% CI -1.28; -0.47 per 5 cm) were significantly associated with a steeper decline in eGFR over 10 years. Continuing smoking (β -2.44, 95% CI -4.43; -0.45) and recent smoking cessation during follow-up (β -3.27; 95% CI -5.20; -1.34) were both associated with a steeper eGFR decline compared to patients who remained as non- or previous smokers from baseline. No significant association was observed between physical exercise or alcohol consumption and kidney function decline. No significant relation between any lifestyle factor and change in uACR was observed. CONCLUSIONS: In patients with CVD, continuing smoking, recent smoking cessation and an increase in obesity markers were related to a steeper kidney function decline. Although no definite conclusions from this study can be drawn, the results support the importance of encouraging weight loss and smoking cessation in high-risk patients as a means of slowing down kidney function decline

HIFI spectroscopy of low-level water transitions in M82

We present observations of the rotational ortho-water ground transition, the two lowest para-water transitions, and the ground transition of ionised ortho-water in the archetypal starburst galaxy M82, performed with the HIFI instrument on the Herschel Space Observatory. These observations are the first detections of the para-H2O(111-000) (1113\,GHz) and ortho-H2O+(111-000) (1115\,GHz) lines in an extragalactic source. All three water lines show different spectral line profiles, underlining the need for high spectral resolution in interpreting line formation processes. Using the line shape of the para-H2O(111-000) and ortho-H2O+(111-000) absorption profile in conjunction with high spatial resolution CO observations, we show that the (ionised) water absorption arises from a ~2000 pc^2 region within the HIFI beam located about ~50 pc east of the dynamical centre of the galaxy. This region does not coincide with any of the known line emission peaks that have been identified in other molecular tracers, with the exception of HCO. Our data suggest that water and ionised water within this region have high (up to 75%) area-covering factors of the underlying continuum. This indicates that water is not associated with small, dense cores within the ISM of M82 but arises from a more widespread diffuse gas component.Comment: 5 pages, 4 figures. Accepted for publication in A&

Increased accuracy in computed tomography coronary angiography; a new body surface area adapted protocol

Vascular Biology and Interventio