Higgs field as the gauge field corresponding to parity in the usual space-time

We find that the local character of field theory requires the parity degree of freedom of the fields to be considered as an additional dicrete fifth dimension which is an artifact emerging due to the local description of space-time. Higgs field arises as the gauge field corresponding to this discrete dimension. Hence the noncommutative geometric derivation of the standard model follows as a manifestation of the local description of the usual space-time.Comment: 14 pages, latex, no figure

Hippocampus and retrosplenial cortex combine path integration signals for successful navigation

The current study used fMRI in humans to examine goal-directed navigation in an open field environment. We designed a task that required participants to encode survey-level spatial information and subsequently navigate to a goal location in either first person, third person, or survey perspectives. Critically, no distinguishing landmarks or goal location markers were present in the environment, thereby requiring participants to rely on path integration mechanisms for successful navigation. We focused our analysis on mechanisms related to navigation and mechanisms tracking linear distance to the goal location. Successful navigation required translation of encoded survey-level map information for orientation and implementation of a planned route to the goal. Our results demonstrate that successful first and third person navigation trials recruited the anterior hippocampus more than trials when the goal location was not successfully reached. When examining only successful trials, the retrosplenial and posterior parietal cortices were recruited for goal-directed navigation in both first person and third person perspectives. Unique to first person perspective navigation, the hippocampus was recruited to path integrate self-motion cues with location computations toward the goal location. Last, our results demonstrate that the hippocampus supports goal-directed navigation by actively tracking proximity to the goal throughout navigation. When using path integration mechanisms in first person and third person perspective navigation, the posterior hippocampus was more strongly recruited as participants approach the goal. These findings provide critical insight into the neural mechanisms by which we are able to use map-level representations of our environment to reach our navigational goals

Ibuprofen Blunts Ventilatory Acclimatization to Sustained Hypoxia in Humans.

Ventilatory acclimatization to hypoxia is a time-dependent increase in ventilation and the hypoxic ventilatory response (HVR) that involves neural plasticity in both carotid body chemoreceptors and brainstem respiratory centers. The mechanisms of such plasticity are not completely understood but recent animal studies show it can be blocked by administering ibuprofen, a nonsteroidal anti-inflammatory drug, during chronic hypoxia. We tested the hypothesis that ibuprofen would also block the increase in HVR with chronic hypoxia in humans in 15 healthy men and women using a double-blind, placebo controlled, cross-over trial. The isocapnic HVR was measured with standard methods in subjects treated with ibuprofen (400 mg every 8 hrs) or placebo for 48 hours at sea level and 48 hours at high altitude (3,800 m). Subjects returned to sea level for at least 30 days prior to repeating the protocol with the opposite treatment. Ibuprofen significantly decreased the HVR after acclimatization to high altitude compared to placebo but it did not affect ventilation or arterial O2 saturation breathing ambient air at high altitude. Hence, compensatory responses prevent hypoventilation with decreased isocapnic ventilatory O2-sensitivity from ibuprofen at this altitude. The effect of ibuprofen to decrease the HVR in humans provides the first experimental evidence that a signaling mechanism described for ventilatory acclimatization to hypoxia in animal models also occurs in people. This establishes a foundation for the future experiments to test the potential role of different mechanisms for neural plasticity and ventilatory acclimatization in humans with chronic hypoxemia from lung disease

Modeling Stable Matching Problems with Answer Set Programming

The Stable Marriage Problem (SMP) is a well-known matching problem first introduced and solved by Gale and Shapley (1962). Several variants and extensions to this problem have since been investigated to cover a wider set of applications. Each time a new variant is considered, however, a new algorithm needs to be developed and implemented. As an alternative, in this paper we propose an encoding of the SMP using Answer Set Programming (ASP). Our encoding can easily be extended and adapted to the needs of specific applications. As an illustration we show how stable matchings can be found when individuals may designate unacceptable partners and ties between preferences are allowed. Subsequently, we show how our ASP based encoding naturally allows us to select specific stable matchings which are optimal according to a given criterion. Each time, we can rely on generic and efficient off-the-shelf answer set solvers to find (optimal) stable matchings.Comment: 26 page

The effect of social media communication on consumer perceptions of brands

Researchers and brand managers have limited understanding of the effects social media communication has on how consumers perceive brands. We investigated 504 Facebook users in order to observe the impact of firm-created and user-generated social media communication on brand equity, brand attitude and purchase intention by using a standardized online survey throughout Poland. To test the conceptual model, we analyzed 60 brands across three different industries: non-alcoholic beverages, clothing and mobile network operators. When analyzing the data, we applied the structural equation modeling technique to both investigate the interplay of firm-created and user-generated social media communication and examine industry-specific differences. The results of the empirical studies showed that user-generated social media communication had a positive influence on both brand equity and brand attitude, whereas firm-created social media communication affected only brand attitude. Both brand equity and brand attitude were shown to have a positive influence on purchase intention. In addition, we assessed measurement invariance using a multi-group structural modeling equation. The findings revealed that the proposed measurement model was invariant across the researched industries. However, structural path differences were detected across the models

Pluronic polymer capped biocompatible mesoporous silica nanocarriers

A facile self-assembly method is described to prepare PEGylated silica nanocarriers using hydrophobic mesoporous silica nanoparticles and a pluronic F127 polymer. Pluronic capped nanocarriers revealed excellent dispersibility in biological media with cyto- and blood compatibilities. © 2013 The Royal Society of Chemistry

Synthesis of titanate nanostructures using amorphous precursor material and their adsorption/photocatalytic properties

This paper reports on a new and swift hydrothermal chemical route to prepare titanate nanostructures (TNS) avoiding the use of crystalline TiO2 as starting material. The synthesis approach uses a commercial solution of TiCl3 as titanium source to prepare an amorphous precursor, circumventing the use of hazardous chemical compounds. The influence of the reaction temperature and dwell autoclave time on the structure and morphology of the synthesised materials was studied. Homogeneous titanate nanotubes with a high length/diameter aspect ratio were synthesised at 160^{\circ}C and 24 h. A band gap of 3.06\pm0.03 eV was determined for the TNS samples prepared in these experimental conditions. This value is red shifted by 0.14 eV compared to the band gap value usually reported for the TiO2 anatase. Moreover, such samples show better adsorption capacity and photocatalytic performance on the dye rhodamine 6G (R6G) photodegradation process than TiO2 nanoparticles. A 98% reduction of the R6G concentration was achieved after 45 minutes of irradiation of a 10 ppm dye aqueous solution and 1 g/L of TNS catalyst.Comment: 29 pages, 10 figures, accepted for publication in Journal of Materials Scienc

Numerical 3D modeling of heat transfer in human tissues for microwave radiometry monitoring of Brown fat metabolismo

Background: Brown adipose tissue (BAT) plays an important role in whole body metabolism and could potentially mediate weight gain and insulin sensitivity. Although some imaging techniques allow BAT detection, there are currently no viable methods for continuous acquisition of BAT energy expenditure. We present a non-invasive technique for long term monitoring of BAT metabolism using microwave radiometry. Methods: A multilayer 3D computational model was created in HFSS™ with 1.5 mm skin, 3-10 mm subcutaneous fat, 200 mm muscle and a BAT region (2-6 cm3) located between fat and muscle. Based on this model, a log-spiral antenna was designed and optimized to maximize reception of thermal emissions from the target (BAT). The power absorption patterns calculated in HFSS™ were combined with simulated thermal distributions computed in COMSOL® to predict radiometric signal measured from an ultra-low-noise microwave radiometer. The power received by the antenna was characterized as a function of different levels of BAT metabolism under cold and noradrenergic stimulation. Results: The optimized frequency band was 1.5-2.2 GHz, with averaged antenna efficiency of 19%. The simulated power received by the radiometric antenna increased 2-9 mdBm (noradrenergic stimulus) and 4-15 mdBm (cold stimulus) corresponding to increased 15-fold BAT metabolism. Conclusions: Results demonstrated the ability to detect thermal radiation from small volumes (2-6 cm3) of BAT located up to 12 mm deep and to monitor small changes (0.5°C) in BAT metabolism. As such, the developed miniature radiometric antenna sensor appears suitable for non-invasive long term monitoring of BAT metabolism

New tetracyclic heteroaromatic compounds based on dehydroamino acids : photophysical and electrochemical studies of interaction with DNA

A benzothienoindole (BTIN) and a benzofuroindole (BFIN) were synthesized in high yields, as potential new target DNA compounds, using a metal-assisted intramolecular C-N cyclization, developed by us, of the methyl esters of N-(t-butoxycarbonyl)-b,b-bis(dibenzothien-4-yl or dibenzofuro-4-yl)dehydroalanines. The latter were obtained by a bis-Suzuki coupling of a b,b-dibromodehydroalanine with the corresponding heteroarylboronic acids. The absorption and fluorescence properties of the novel tetracyclic heteroaromatic compounds were studied in different solvents and in the presence of natural double-stranded (ds) salmon sperm DNA. The results in several solvents show that either BTIN or BFIN can be used as fluorescence solvent sensitive probes. Spectroscopic studies of the interaction of both compounds with dsDNA allowed to determine binding constant (Ki) values and binding site sizes (n). Fluorescence quenching experiments using iodide ion allowed the determination of the accessibilities to the quencher, showing that intercalation is the preferred mode of binding of these molecules to DNA. From the results obtained BTIN is the more intercalative compound and has a higher affinity to DNA. The interaction of this more promising compound with DNA was also studied electrochemically, by using differential pulse voltammetry (DPV) in connection with disposable pencil graphite electrode (PGE). These studies are based on the differences in the BTIN and adenine oxidation signals. After the interaction of BTIN with DNA, the oxidation signals of BTIN and adenine strongly decreased. The latter was attributed to the binding of the BTIN to DNA and the former points to a possible damage of the oxidizable groups of the compound after intercalation into DNA. Several concentrations of BTIN were tested and 50 μg/mL was found to be the optimum concentration in order to detect its interaction with DNA. In addition, the detection limit and the reproducibility were determined by using a disposable electrochemical transducer. The results of spectroscopic and electrochemical detection of BTIN interaction with DNA are in good agreement.Academy of Pharmacists and Turkish Pharmacists Association (TEB)Turkish Academy of Sciences - Young Scientist Award Program (KAE/TUBA-GEBIP/2001-2-8)FEDERFundação para a Ciência e a Tecnologia (FCT) - Projecto POCI/QUI/59407/2004. A.S.A. acknowledges a post-doc. grant SFRH/BPD/24548/2005, Bolsa SFRH/BPD/24548/2005.Scientific and Technical Research Council of Turkey (TUBITAK)