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

Hydrogen bonding of nitroxide spin labels in membrane proteins

On the basis of experiments at 275 GHz, we reconsider the dependence of the continuous-wave EPR spectra of nitroxide spin-labeled protein sites in sensory- and bacteriorhodopsin on the micro-environment. The high magnetic field provides the resolution necessary to disentangle the effects of hydrogen bonding and polarity. In the gxx region of the 275 GHz EPR spectrum, bands are resolved that derive from spin-label populations carrying no, one or two hydrogen bonds. The gxx value of each population varies hardly from site to site, significantly less than deduced previously from studies at lower microwave frequencies. The fractions of the populations vary strongly, which provides a consistent description of the variation of the average gxx and the average nitrogen-hyperfine interaction Azz from site to site. These variations reflect the difference in the proticity of the micro-environment, and differences in polarity contribute marginally. Concomitant W-band ELDOR- detected NMR experiments on the corresponding nitroxide in perdeuterated water resolve population-specific nitrogen-hyperfine bands, which underlies the interpretation for the proteins

Spatial resolution and refractive index contrast of resonant photonic crystal surfaces for biosensing

By depositing a resolution test pattern on top of a Si3N4 photonic crystal resonant surface, we have measured the dependence of spatial resolution on refractive index contrast \Delta n. Our experimental results and finite-difference time-domain (FDTD) simulations at different refractive index contrasts show that the spatial resolution of our device reduces with reduced contrast, which is an important consideration in biosensing, where the contrast may be of order 10{-2} . We also compare 1-D and 2-D gratings, taking into account different incidence polarizations, leading to a better understanding of the excitation and propagation of the resonant modes in these structures, as well as how this contributes to the spatial resolution. At \Delta n = 0.077, we observe resolutions of 2 and 6 \mu\hbox{m} parallel to and perpendicular to the grooves of a 1-D grating, respectively, and show that for polarized illumination of a 2-D grating, resolution remains asymmetrical. Illumination of a 2-D grating at 45 ^{\circ} results in symmetric resolution. At very low index contrast, the resolution worsens dramatically, particularly for \Delta n\ <\ 0.01, where we observe a resolution exceeding 10 \mu\hbox{m} for our device. In addition, we measure a reduction in the resonance linewidth as the index contrast becomes lower, corresponding to a longer resonant mode propagation length in the structure and contributing to the change in spatial resolution

An Organic Vortex Laser

Optical vortex beams are at the heart of a number of novel research directions, both as carriers of information and for the investigation of optical activity and chiral molecules. Optical vortex beams are beams of light with a helical wavefront and associated orbital angular momentum. They are typically generated using bulk optics methods or by a passive element such as a forked grating or a metasurface to imprint the required phase distribution onto an incident beam. Since many applications benefit from further miniaturization, a more integrated yet scalable method is highly desirable. Here, we demonstrate the generation of an azimuthally polarized vortex beam directly by an organic semiconductor laser that meets these requirements. The organic vortex laser uses a spiral grating as a feedback element that gives control over phase, handedness, and degree of helicity of the emitted beam. We demonstrate vortex beams up to an azimuthal index <i>l</i> = 3 that can be readily multiplexed into an array configuration

Focusing with planar microlenses made of two-dimensionally varying high contrast gratings

The authors thank the European Union for the financial support through Marie Curie Action FP7-PEOPLE-2010-ITN Project No. 264687 “PROPHET”.We report on the focusing performance of reflective two-dimensionally varying high contrast grating lenses based on silicon. The combination of their subwavelength nature and their high refractive index contrast makes it possible to create highly tolerant and planar microlenses. We used a rigorous mathematical code to design the lenses and verified their performance with finite element simulations. We also investigated the effects of grating thickness, angle, and wavelength of incidence in these simulations. Experimentally, we show the evolution of the beam profile along the optical axis for a lens with a high (0.37) numerical aperture. We have explored a wide range of numerical apertures (0.1-0.93) and show that the lenses behave as expected across the full range. Our analyses demonstrate the large design flexibility with which these lenses can be made along with ease of fabrication and potential for a number of applications in micro-optics.Publisher PDFPeer reviewe

The regulator's conundrum. How market reflexivity limits fundamental financial reform

Financial firms’ valuation approaches are key to financial market functioning. The financial crisis exposed fundamental faults in pre-crisis practices and the regulations that bolstered them. Critics pointed to reflexivity: financial markets have no solid anchor outside of market participants’ assessments, which makes them inherently unstable. Reflexivity implies valuation techniques are performative: they shape rather than reflect risks. Critics thus called for root and branch reform: regulators needed to regain control over these valuation practices. In spite of a flurry of changes, progress on the reforms has been limited in precisely those domains where it seemed most necessary. We argue that this lack of progress does not persist in spite of market reflexivity, but because of it. Public prescriptiveness might mandate widespread use of deficient valuation routines, exacerbating their deleterious performative effects and implicating public authorities in future financial crises. In the regulator's conundrum, neither a hands-off approach to valuation approaches, nor an interventionist stance promises to be effective. Empirically, we show how reflexivity has obstructed fundamental reforms in the European Union in three key domains: credit ratings, liquidity regulation, and accounting standards. Market reflexivity itself is, therefore, crucial to understanding the limited regulatory reforms we have witnessed since the crisis

The unstable core of global finance: contingent valuation and governance of international accounting standards

Accounting standards are the foundations of the financial regulatory edifice, and global financial governance is no more stable than the asset valuations that feed it. Yet for two decades and up to this day, no international accounting rule for financial instruments - the bulk of banks' balance sheets - has emerged that was more than a temporary fix, to be succeeded by further reforms. We show how banking regulators have been central to this dynamic and how their support for applying fair value accounting to financial instruments, the cornerstone of regulatory debate, has oscillated throughout the whole period. The two common IPE approaches to global financial governance, which analyze it either as interest-based bargaining or as ideas-driven expert governance, fail to account for this pattern. In contrast, we show how the contingency of financial valuations itself has made it impossible for regulators to embrace or reject a stable set of accounting rules

Ontbrekende alternatieven en gevestigde belangen: een studie naar de posities van overheden in hervormingsdebatten tijdens de financiële crisis

The credit crisis that began in the summer of 2007 has fundamentally challenged much financial regulation and the political institutions that produced it. Measured against the criticisms that have been brought forth against previous financial governance, the extent of governments’ overall reform ambitions has been disappointing. Starting from this observation, this article asks: what explains governments’ reform choices, and thus also their limited ambitions? To explore this question, this article focuses on the positions that four governments central to global financial regulation (the USA, the UK, Germany and France) have taken in advance of the G20 meetings in 2009 across four key issue areas: accounting standards, derivatives trading, credit ratings agencies and banking rules. It evaluates both the overlap between positions across domains and governments as well as the differences between them. Such variation, we argue, provides key clues to the overall drivers behind reforms - as well as their limits. The overall picture that emerges can be summarized as follows: governments have been staunch defenders of their national firms’ competitive interests in regulatory reforms. That has not necessarily meant that they followed industry preferences across the board. It has been the relative impact, compared to foreign competitors, that counted in reform positions, not the absolute impact. These differences of opinion have played out within the context and the limits of the overall debates about thinkable policy alternatives. In spite of fundamental criticisms of pre-crisis regulatory orthodoxy, convincing and coherent alternatives have been forthcoming slowly at best. This has made reform proposals less radical than criticisms, seen on their own, might suggest