Tuning curve of type-0 spontaneous parametric down-conversion

We study the tuning curve of entangled photons generated by type-0 spontaneous parametric down-conversion in a periodically poled potassium titanyl phosphate crystal. We demonstrate the X-shaped spatiotemporal structure of the spectrum by means of measurements and numerical simulations. Experiments for different pump waists, crystal temperatures, and crystal lengths are in good agreement with numerical simulations.

Down-Regulation of Annexin A1 in the Urothelium Decreases Cell Survival After Bacterial Toxin Exposure

PURPOSE: We examined the role of annexins in bladder urothelium. We characterized expression and distribution in normal bladders, biopsies from patients with bladder pain syndrome, cultured human urothelium and urothelial TEU-2 cells. MATERIALS AND METHODS: Annexin expression in bladder layers was analyzed by quantitative reverse transcriptase-polymerase chain reaction and immunofluorescence. We assessed cell survival after exposure to the pore forming bacterial toxin streptolysin O by microscopy and alamarBlue® assay. Bladder dome biopsies were obtained from 8 asymptomatic controls and 28 patients with symptoms of bladder pain syndrome. RESULTS: Annexin A1, A2, A5 and A6 were differentially distributed in bladder layers. Annexin A6 was abundant in detrusor smooth muscle and low in urothelium, while annexin A1 was the highest in urothelium. Annexin A2 was localized to the lateral membrane of umbrella cells but excluded from tight junctions. TEU-2 cell differentiation caused up-regulation of annexin A1 and A2 and down-regulation of annexin A6 mRNA. Mature urothelium dedifferentiation during culture caused the opposite effect, decreasing annexin A1 and increasing annexin A6. Annexin A2 influenced TEU-2 cell epithelial permeability. siRNA mediated knockdown of annexin A1 in TEU-2 cells caused significantly decreased cell survival after streptolysin O exposure. Annexin A1 was significantly reduced in biopsies from patients with bladder pain syndrome. CONCLUSIONS: Several annexins are expressed in human bladder and TEU-2 cells, in which levels are regulated during urothelial differentiation. Annexin A1 down-regulation in patients with bladder pain syndrome might decrease cell survival and contribute to compromised urothelial function.

New insights into the pathobiology of Down syndrome--hyaluronan synthase-2 overexpression is regulated by collagen VI α2 chain.

Down syndrome (DS) is a common birth defect characterized by the trisomy of chromosome 21. DS-affected umbilical cords (UCs) of fetuses show altered architecture of the extracellular matrix. Overexpression of the chromosome 21 genes encoding the collagen type VI (COLVI) chains α1(VI) and α2(VI), COL6A1 and COL6A2, respectively, has also reported to occur in the nuchal skin of DS fetuses. The aim of this study was therefore to evaluate the COLVI content in euploid and DS-affected UCs and human skin fibroblasts, and to investigate the relationships between COLVI and hyaluronan (HA) and HA synthase-2 (HAS2). We found that the UCs of DS fetuses showed denser staining of COLVI and increased COL6A2 expression at both early and term gestational ages. In vitro expression studies in DS-derived fibroblasts showed similarly increased amounts of α1(VI) and α2(VI) chains at the protein and transcriptional level, supporting the hypothesis of the gene dosage effect. Furthermore, increased levels of HA and HAS2 were also found in DS-derived skin fibroblast cultures. Notably, silencing of COL6A2 in DS-derived cells resulted in downregulation of HAS2, with a simultaneous decrease in secreted HA. Exogenous addition of COLVI to normal fibroblasts did not have any effect on HAS2 expression. In conclusion, UCs and skin fibroblasts in DS show significant increases in COLVI and HA; the overexpression of COL6A2 in DS tissue and cells is closely related to the increased expression of HAS2. These data may explain the DS phenotypes and their effects in organ tissue maturation.

Response of liquid xenon to Compton electrons down to 1.5 keV

The response of liquid xenon to low-energy electronic recoils is relevant in the search for dark-matter candidates which interact predominantly with atomic electrons in the medium, such as axions or axionlike particles, as opposed to weakly interacting massive particles which are predicted to scatter with atomic nuclei. Recently, liquid-xenon scintillation light has been observed from electronic recoils down to 2.1 keV, but without applied electric fields that are used in most xenon dark-matter searches. Applied electric fields can reduce the scintillation yield by hindering the electron-ion recombination process that produces most of the scintillation photons. We present new results of liquid xenon's scintillation emission in response to electronic recoils as low as 1.5 keV, with and without an applied electric field. At zero field, a reduced scintillation output per unit deposited energy is observed below 10 keV, dropping to nearly 40% of its value at higher energies. With an applied electric field of 450 V/cm, we observe a reduction of the scintillation output to about 75% relative to the value at zero field. We see no significant energy dependence of this value between 1.5 and 7.8 keV. With these results, we estimate the electronic-recoil energy thresholds of ZEPLIN-III, XENON10, XENON100, and XMASS to be 2.8, 2.5, 2.3, and 1.1 keV, respectively, validating their excellent sensitivity to low-energy electronic recoils.

Combining Bottom-up and Top-down Generation of Interactive Knowledge Maps for Enterprise Search

Our research project develops an intranet search engine with concept- browsing functionality, where the user is able to navigate the conceptual level in an interactive, automatically generated knowledge map. This knowledge map visualizes tacit, implicit knowledge, extracted from the intranet, as a network of semantic concepts. Inductive and deductive methods are combined; a text ana- lytics engine extracts knowledge structures from data inductively, and the en- terprise ontology provides a backbone structure to the process deductively. In addition to performing conventional keyword search, the user can browse the semantic network of concepts and associations to find documents and data rec- ords. Also, the user can expand and edit the knowledge network directly. As a vision, we propose a knowledge-management system that provides concept- browsing, based on a knowledge warehouse layer on top of a heterogeneous knowledge base with various systems interfaces. Such a concept browser will empower knowledge workers to interact with knowledge structures.

Up, down, strange and charm quark masses with Nf = 2+1+1 twisted mass lattice QCD

We present a lattice QCD calculation of the up, down, strange and charm quark masses performed using the gauge configurations produced by the European Twisted Mass Collaboration with Nf=2+1+1 dynamical quarks, which include in the sea, besides two light mass degenerate quarks, also the strange and charm quarks with masses close to their physical values. The simulations are based on a unitary setup for the two light quarks and on a mixed action approach for the strange and charm quarks. The analysis uses data at three values of the lattice spacing and pion masses in the range 210–450 MeV, allowing for accurate continuum limit and controlled chiral extrapolation. The quark mass renormalization is carried out non-perturbatively using the RI′-MOM method. The results for the quark masses converted to the scheme are: mud(2 GeV)=3.70(17) MeV, ms(2 GeV)=99.6(4.3) MeV and mc(mc)=1.348(46) GeV. We obtain also the quark mass ratios ms/mud=26.66(32) and mc/ms=11.62(16). By studying the mass splitting between the neutral and charged kaons and using available lattice results for the electromagnetic contributions, we evaluate mu/md=0.470(56), leading to mu=2.36(24) MeV and md=5.03(26) MeV.

Impaired top-down modulation of saccadic latencies in patients with schizophrenia but not in first-degree relatives

Impaired eye movements have a long history in schizophrenia research and meet the criteria of a reliable biomarker. However, the effects of cognitive load and task difficulty on saccadic latencies (SL) are less understood. Recent studies showed that SL are strongly task dependent: SL are decreased in tasks with higher cognitive demand, and increased in tasks with lower cognitive demand. The present study investigates SL modulation in patients with schizophrenia and their first-degree relatives. A group of 13 patients suffering from ICD-10 schizophrenia, 10 first-degree relatives, and 24 control subjects performed two different types of visual tasks: a color task and a Landolt ring orientation task. We used video-based oculography to measure SL. We found that patients exhibited a similar unspecific SL pattern in the two different tasks, whereas controls and relatives exhibited 20–26% shorter average latencies in the orientation task (higher cognitive demand) compared to the color task (lower cognitive demand). Also, classification performance using support vector machines suggests that relatives should be assigned to the healthy controls and not to the patient group. Therefore, visual processing of different content does not modulate SL in patients with schizophrenia, but modulates SL in the relatives and healthy controls. The results reflect a specific oculomotor attentional dysfunction in patients with schizophrenia that is a potential state marker, possibly caused by impaired top-down disinhibition of the superior colliculus by frontal/prefrontal areas such as the frontal eye fields.

Imaging the Heliosphere using neutral Atoms from Solar Wind Energy down to 15 eV

We study the spatial and temporal distribution of hydrogen energetic neutral atoms (ENAs) from the heliosheath observed with the IBEX-Lo sensor of the Interstellar Boundary EXplorer (IBEX) from solar wind energies down to the lowest available energy (15 eV). All available IBEX-Lo data from 2009 January until 2013 June were included. The sky regions imaged when the spacecraft was outside of Earth's magnetosphere and when the Earth was moving toward the direction of observation offer a sufficient signal-to-noise ratio even at very low energies. We find that the ENA ribbon—a 20° wide region of high ENA intensities—is most prominent at solar wind energies whereas it fades at lower energies. The maximum emission in the ribbon is located near the poles for 2 keV and closer to the ecliptic plane for energies below 1 keV. This shift is an evidence that the ENA ribbon originates from the solar wind. Below 0.1 keV, the ribbon can no longer be identified against the globally distributed ENA signal. The ENA measurements in the downwind direction are affected by magnetospheric contamination below 0.5 keV, but a region of very low ENA intensities can be identified from 0.1 keV to 2 keV. The energy spectra of heliospheric ENAs follow a uniform power law down to 0.1 keV. Below this energy, they seem to become flatter, which is consistent with predictions. Due to the subtraction of local background, the ENA intensities measured with IBEX agree with the upper limit derived from Lyα observations.

Top-Down Parsing with Parsing Contexts

The domain of context-free languages has been extensively explored and there exist numerous techniques for parsing (all or a subset of) context-free languages. Unfortunately, some programming languages are not context-free. Using standard context-free parsing techniques to parse a context-sensitive programming language poses a considerable challenge. Im- plementors of programming language parsers have adopted various techniques, such as hand-written parsers, special lex- ers, or post-processing of an ambiguous parser output to deal with that challenge. In this paper we suggest a simple extension of a top-down parser with contextual information. Contrary to the tradi- tional approach that uses only the input stream as an input to a parsing function, we use a parsing context that provides ac- cess to a stream and possibly to other context-sensitive infor- mation. At a same time we keep the context-free formalism so a grammar definition stays simple without mind-blowing context-sensitive rules. We show that our approach can be used for various purposes such as indent-sensitive parsing, a high-precision island parsing or XML (with arbitrary el- ement names) parsing. We demonstrate our solution with PetitParser, a parsing-expression grammar based, top-down, parser combinator framework written in Smalltalk.

Corneal Cross-Linking in a 4-Year-Old Child With Keratoconus and Down Syndrome

PURPOSE To describe the clinical outcome of corneal cross-linking (CXL) in a young child with keratoconus. METHODS This is a case report of a young girl with keratoconus with ophthalmologic findings and 3-year follow-up. Follow-up visits included visual acuity measurement, retinoscopy, corneal tomography, and topography. RESULTS A girl with Down syndrome was diagnosed with bilateral keratoconus and relative amblyopia at the age of 4 years. The best-corrected near visual acuity was 20/100 binocularly. Corneal tomography showed the following parameters: OD K(max) 47.2 diopters (D), thinnest location 442 μm; OS K(max) 49.6 D, thinnest location 432 μm. Three months later, the keratoconus in the left eye progressed (K(max) 50.2 D, thinnest location 424 μm), and CXL was performed. One year later, CXL was necessary also in the right eye because of progression. The girl was most recently reexamined at the age of 7 years. The corrected near visual acuity was 20/80 in both eyes. The corneal curvature slightly flattened, and the corneal thickness stabilized (OD K(max) 46.8 D, thinnest location 389 μm; OS K(max) 49.4 D, thinnest location 360 μm). CONCLUSIONS Onset of keratoconus can occur in early childhood, especially in patients with Down syndrome. In this case, CXL was performed at 4 and 5 years of age without complications and stopped further keratoconus progression.