Conjunctive grammars and alternating pushdown automata

In this paper we introduce a variant of alternating pushdown automata, synchronized alternating pushdown automata, which accept the same class of languages as those generated by conjunctive grammars.     

Should I stay or should I switch? A cost–benefit analysis of voluntary language switching in young and aging bilinguals.

Bilinguals spontaneously switch languages in conversation even though laboratory studies reveal robust cued language switching costs. The authors investigated how voluntary-switching costs might differ when switches are voluntary. Younger (Experiments 1–2) and older (Experiment 3) Spanish–English bilinguals named pictures in 3 conditions: (a) dominant-language only, (b) nondominant-language only, and (c) using “whatever language comes to mind” (in Experiment 2, “using each language about half the time”). Most bilinguals, particularly balanced bilinguals, voluntarily mixed languages even though switching was costly. Unlike with cued switching, voluntary switching sometimes facilitated responses, switch costs were not greater for the dominant language, and age effects on language mixing and switching were limited. This suggests that the freedom to mix languages voluntarily allows unbalanced and older bilinguals to function more like balanced and younger bilinguals. Voluntary switch costs reveal an expanded role for inhibitory control in bilingual language production and imply a mandatory separation by language in bilingual lexical selection. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A New Low Temperature Device for High Resolution, In Situ Measurement and Control of Submicron Gaps

We have developed a device to investigate finite-size scaling of the thermal expansion coefficient in liquid helium near the lambda transition. Motivated by the need for a range of well known, uniform, sub-micron gaps with constant surface conditions, we have built a variable-gap parallel-plate capacitor that can be adjusted in situ. We measure the gap at three points using laser interferometry. A careful choice of the material and thickness of the reflecting surfaces results in asymmetric fringes, for which both exceptional sensitivity and a high contrast ratio can be achieved simultaneously. Both the gap size and its uniformity are actively controlled using voice coil actuators. This design has a number of additional benefits: the gap can be kept closed until low temperature use, data can be collected for all gaps with no thermal cycling, and no spacers are needed to establish the gap.     

Albumin Nanoshell Encapsulation of Near‐Infrared‐Excitable Rare‐Earth Nanoparticles Enhances Biocompatibility and Enables Targeted Cell Imaging

The use of traditional fluorophores for in vivo imaging applications is limited by poor quantum yield, poor tissue penetration of the excitation light, and excessive tissue autofluorescence, while the use of inorganic fluorescent particles that offer a high quantum yield is frequently limited due to particle toxicity. Rare‐earth‐doped nanoparticles that utilize near‐infrared upconversion overcome the optical limitations of traditional fluorophores, but are not typically suitable for biological application due to their insolubility in aqueous solution, lack of functional surface groups for conjugation of biomolecules, and potential cytotoxicity. A new approach to establish highly biocompatible and biologically targetable nanoshell complexes of luminescent rare‐earth‐doped NaYF₄ nanoparticles (REs) excitable with 920–980 nm near‐infrared light for biomedical imaging applications is reported. The approach involves the encapsulation of NaYF₄ nanoparticles doped with Yb and Er within human serum albumin nanoshells to create water‐dispersible, biologically functionalizable composite particles. These particles exhibit narrow size distributions around 200 nm and are stable in aqueous solution for over 4 weeks. The albumin shell confers cytoprotection and significantly enhances the biocompatibility of REs even at concentrations above 200 µg REs mL^?1. Composite particles conjugated with cyclic arginine‐glycine‐aspartic acid (cRGD) specifically target both human glioblastoma cell lines and melanoma cells expressing α_vβ₃ integrin receptors. These findings highlight the promise of albumin‐encapsulated rare‐earth nanoparticles for imaging cancer cells in vitro and the potential for targeted imaging of disease sites in vivo.     

Effects of a supportive or an unsupportive audience on biological and psychological responses to stress.

Although social support is related to substantial benefits for health and well-being, research has uncovered qualifications to its benefits. In a test of the psychological and biological impact of an audience on responses to laboratory stress challenges, 183 participants going through the Trier Social Stress Test experienced either (a) an unsupportive audience, (b) a supportive audience, or (c) no audience. Both audience conditions produced significantly stronger cortisol, heart rate, and blood pressure responses to the stress tasks, relative to the no-audience control, even though the supportive audience was rated as supportive. Contrary to hypotheses offered by several theories, these effects were not moderated by self-esteem, individual differences in psychological resources, or baseline social support. Psychological resources and baseline social support were, however, tied to more beneficial biological and psychological profiles at baseline and at recovery in some cases. It was concluded that when one must perform stressful tasks in front of an audience, evaluative concerns may outweigh the potential benefits of a supportive audience. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Transboundary atmospheric lead pollution

A high-temporal resolution collection technique was applied to refine aerosol sampling in Jerusalem, Israel. Using stable lead isotopes, lead concentrations, synoptic data, and atmospheric modeling, we demonstrate that lead detected in the atmosphere of Jerusalem is not only anthropogenic lead of local origin but also lead emitted in other countries. Fifty-seven percent of the collected samples contained a nontrivial fraction of foreign atmospheric lead and had 206Pb/207Pb values which deviated from the local petrol-lead value (206Pb/207Pb = 1.113) by more than two standard deviations (0.016). Foreign 206Pb/207Pb values were recorded in Jerusalem on several occasions. The synoptic conditions on these dates and reported values of the isotopic composition of lead emitted in various countries around Israel suggest that the foreign lead was transported to Jerusalem from Egypt, Turkey, and East Europe. The average concentration of foreign atmospheric lead in Jerusalem was 23 +/- 17 ng/m3, similar to the average concentration of local atmospheric lead, 21 +/- 18 ng/ m3. Hence, the load of foreign atmospheric lead is similar to the load of local atmospheric lead in Jerusalem.     

Photosensitizer method to determine rate constants for the reaction of carbonate radical with organic compounds

Carbonate radical (CO3*-) is a powerful oxidant that is present in sunlit surface waters and in waters treated by advanced oxidation processes. The production of CO3*- in aqueous solution through oxidation of carbonate anion by excited triplet states of aromatic ketones was investigated in this study to provide new methods for the determination of rate constants and to explore a possible photoinduced pathway of CO3*- formation in the aquatic environment. Rate constants for triplet quenching by carbonate anion of up to 3.0 x 10(7) M(-1) s(-1) and CO3*- yields approaching unity, determined using laser flash photolysis, allowed us to conclude that such a formation mechanism might be significant in sulit natural waters. Kinetic methods based on either flash photolysis or steady-state irradiation and on the use of aromatic ketones as photosensitizers gave bimolecular rate constants in the range of 4 x 10(6) to 1 x 10(8) M(-1) s(-1) for the reaction of CO3*- with several s-triazine and phenylurea herbicides. For various anilines and phenoxide anions, rate constants determined by these methods agreed well with published values. Moreover, it could be shown for the first time by a direct method that dissolved natural organic matter (DOM) reduces the lifetime of CO3*- and a second-order rate constant of (280 +/- 90) (mg of C/L)(-1) s(-1) was obtained for Suwannee River fulvic acid.     

Characterization of endothelin-1 and nitric oxide generating systems in corpus luteum-derived endothelial cells

Endothelium-derived endothelin-1 (ET-1) and nitric oxide (NO) are pivotal regulators of corpus luteum (CL) function. To have a better insight into their synthesis and action, members of the ET system (ET-1, ET converting enzyme (ECE-1) isoforms a-d, ETA and ETB receptors) along with NO synthase (NOS) isoforms--endothelial (e)NOS and inducible (i)NOS--were quantified in CL-derived endothelial cells (CLEC). The expression of these genes in microvascular CLEC, obtained by lectin-coated magnetic beads, was compared with cells removed from the luteal microenvironment and maintained in culture for different durations, and with endothelial cells (EC) derived from a large blood vessel (i.e. bovine aortic endothelial cells, BAEC). The profile of gene expression in the different EC types was determined by quantitative real-time PCR. Freshly isolated EC from mid-cycle CL exhibited high ET-1 receptor expression (both ETA and ETB), low ET-1 synthesizing ability (both prepro (pp) ET-1 and ECE-1), but elevated iNOS - the high throughput NOS isoform. The distinct phenotype of CLEC was lost soon after an overnight culture. ETA and ETB receptor levels declined, ppET-1 levels increased while iNOS was reduced. These changes were extenuated during long-term culture of CLEC. The general pattern of gene expression in BAEC and long-term cultured CLEC was similar yet some differences, reminiscent of freshly isolated CLEC, remained: ECE-1c, ETB receptor and NOS isoforms were expressed differently in BAEC as compared with lines of CLEC. This study suggests that the luteal microenvironment is necessary to sustain the selective phenotype of its resident endothelial cells. The inverse relationship between ppET-1 and iNOS observed in freshly isolated CLEC and in cultured cells is physiologically significant and suggests that ET-1 and NO may modulate the production of each other.     

Longevity of granular iron in groundwater treatment processes: corrosion product development

Permeable reactive barriers employing iron as a reactive surface have received extensive attention. A remaining issue, however, relates to their longevity. As an integral part of a long-term column study conducted to examine the influence of inorganic cosolutes on iron reactivity toward chlorinated solvents and nitroaromatic compounds, Master Builder iron grains were characterized via scanning and transmission electron microscopy, electron energy loss spectroscopy (EELS), micro-Raman spectroscopy, and X-ray diffraction. Prior to exposure to carbonate solutions, the iron grains were covered by a surface scale that consisted of fayalite (Fe2SiO4), wüstite (FeO), magnetite (Fe3O4), maghemite (gamma-Fe2O3), and graphite. After 1100 days of exposure to solutions containing carbonate, other inorganic solutes, and organic contaminants, the wüstite, fayalite, and graphite of the original scale partially dissolved, and magnetite and iron carbonate hydroxide (Fe3(OH)2.2CO3) precipitated on top of the scale. Raman results indicate the presence of green rust (e.g., [Fe4(2+)Fe2(3+)(OH)12]-[CO3 x 2H2O]) toward the column outlet after 308 days of operation, although this mineral phase disappears at longer operation times. Grains extracted from a column exposed to a high concentration (20 mM) of sodium bicarbonate were more extensively weathered than those from columns exposed to 2 mM sodium bicarbonate. An iron carbonate hydroxide layer up to 100 microm thick was observed. Even though EELS analysis of iron carbonate hydroxide indicates that this is a redox-active phase, the thickness of this layer is presumed responsible for the previously observed decline in the reactivity of this column relative to low-bicarbonate columns. A silica-containing feed resulted in reduced reactivity toward TCE. Grains from this column had a strong enrichment of silicon in the precipitates, although no distinct silica-containing mineral phases were identified. The substitution of 2 mM calcium carbonate for 2 mM sodium bicarbonate in the feed did not produce a measurable reactivity loss, asthe discrete calcium carbonate precipitates that formed in this system did not severely restrict access to the reactive surface.     

Protein kinases of cultured chicken osteoblasts that phosphorylate extracellular bone proteins

Cytosolic and microsomal protein kinase preparations from cultured chicken osteoblasts were found to phosphorylate up to six major proteins with Mrs 66, 58, 50, 36, 32, and 22 kDa in chicken bone extract. Use of heparin led to the conclusion that these proteins were predominantly phosphorylated by factor-independent protein kinase (FIPK) present both in microsomal and cytosolic preparations. It was confirmed that microsomal preparation contained predominantly FIPK, whereas cytosolic preparation contained additional kinases, that can phosphorylate the bone proteins. Use of purified chicken bone osteopontin (OPN) (58 kDa) and recombinant OPN led to the same conclusions. The identify of the protein kinases was clearly established by using a series of synthetic peptide substrates. Quantitative analysis utilizing pure protein kinases and purified chicken bone OPN, recombinant mouse OPN, and bovine bone OPN and BSP led to introduction of approximately 9 moles of phosphate/mole of OPN and 6.6 moles phosphate/mole bovine bone sialoprotein (BSP) by casein kinase II. cGMP-dependent protein kinase and protein kinase C both introduced 0.5-1.2 moles phosphate/mole of OPN and BSP, whereas cAMP-dependent protein kinase led to no significant phosphorylation of OPN or BSP. Consistent with the above results, sites of phosphorylation identified for OPN (metabolically labeled) and BSP (labeled by casein kinase II) revealed that predominant phosphorylated sites have recognition sequences for FIPK.