Tensorial Reconstruction at the Integrand Level

We present a new approach to the reduction of one-loop amplitudes obtained by reconstructing the tensorial expression of the scattering amplitudes. The reconstruction is performed at the integrand level by means of a sampling in the integration momentum. There are several interesting applications of this novel method within existing techniques for the reduction of one-loop multi-leg amplitudes: to deal with numerically unstable points, such as in the vicinity of a vanishing Gram determinant; to allow for a sampling of the numerator function based on real values of the integration momentum; to optimize the numerical reduction in the case of long expressions for the numerator functions.Comment: 20 pages, 2 figure

Next-to-leading order QCD predictions for W+W+jj production at the LHC

Because the LHC is a proton-proton collider, sizable production of two positively charged W-bosons in association with two jets is possible. This process leads to a distinct signature of same sign high-pt leptons, missing energy and jets. We compute the NLO QCD corrections to the QCD-mediated part of pp -> W+W+jj. These corrections reduce the dependence of the production cross-section on the renormalization and factorization scale to about +- 10 percent. We find that a large number of W+W+jj events contain a relatively hard third jet. The presence of this jet should help to either pick up the W+W+jj signal or to reject it as an unwanted background.Comment: 15 pages, 5 (lovely) figures, v3 accepted for publication in JHEP, corrects tables in appendi

The effects of cognitive reappraisal following retrieval-procedures designed to destabilize alcohol memories in high-risk drinkers

RATIONALE: Addiction is a disorder of motivational learning and memory. Maladaptive motivational memories linking drug-associated stimuli to drug seeking are formed over hundreds of reinforcement trials and accompanied by aberrant neuroadaptation in the mesocorticolimbic reward system. Such memories are resistant to extinction. However, the discovery of retrieval-dependent memory plasticity has opened up the possibility of permanent modification of established (long-term) memories during 'reconsolidation'. OBJECTIVES: Here, we investigate whether reappraisal of maladaptive alcohol cognitions performed after procedures designed to destabilize alcohol memory networks affected subsequent alcohol memory, craving, drinking and attentional bias. METHODS: Forty-seven at-risk drinkers attended two sessions. On the first lab session, participants underwent one of two prediction error-generating procedures in which outcome expectancies were violated while retrieving alcohol memories (omission and value prediction error groups). Participants in a control group retrieved non-alcohol memories. Participants then reappraised personally relevant maladaptive alcohol memories and completed measures of reappraisal recall, alcohol verbal fluency and craving. Seven days later, they repeated these measures along with attentional bias assessment. RESULTS: Omission prediction error (being unexpectedly prevented from drinking beer), but not a value prediction error (drinking unexpectedly bitter-tasting beer) or control procedure (drinking unexpectedly bitter orange juice), was associated with significant reductions in verbal fluency for positive alcohol-related words. No other statistically robust outcomes were detected. CONCLUSIONS: This study provides partial preliminary support for the idea that a common psychotherapeutic strategy used in the context of putative memory retrieval-destabilization can alter accessibility of alcohol semantic networks. Further research delineating the necessary and sufficient requirements for producing alterations in alcohol memory performance based on memory destabilization is still required

Minimal basilar membrane motion in low-frequency hearing

Low-frequency hearing is critically important for speech and music perception, but no mechanical measurements have previously been available from inner ears with intact low-frequency parts. These regions of the cochlea may function in ways different from the extensively studied high-frequency regions, where the sensory outer hair cells produce force that greatly increases the sound-evoked vibrations of the basilar membrane. We used laser interferometry in vitro and optical coherence tomography in vivo to study the low-frequency part of the guinea pig cochlea, and found that sound stimulation caused motion of a minimal portion of the basilar membrane. Outside the region of peak movement, an exponential decline in motion amplitude occurred across the basilar membrane. The moving region had different dependence on stimulus frequency than the vibrations measured near the mechanosensitive stereocilia. This behavior differs substantially from the behavior found in the extensively studied high-frequency regions of the cochlea

Towards W b bbar + j at NLO with an automatized approach to one-loop computations

We present results for the O(alpha_s) virtual corrections to q g -> W b bbar q' obtained with a new automatized approach to the evaluation of one-loop amplitudes in terms of Feynman diagrams. Together with the O(alpha_s) corrections to q q' -> W b bbar g, which can be obtained from our results by crossing symmetry, this represents the bulk of the next-to-leading order virtual QCD corrections to W b bbar + j and W b + j hadronic production, calculated in a fixed-flavor scheme with four light flavors. Furthermore, these corrections represent a well defined and independent subset of the 1-loop amplitudes needed for the NNLO calculation of W b bbar. Our approach was tested against several existing results for NLO amplitudes including selected O(alpha_s) one-loop corrections to W + 3 j hadronic production. We discuss the efficiency of our method both with respect to evaluation time and numerical stability.Comment: 14 pages, 3 figure

Emplacement styles within the Land's End Granite, West Cornwall

The Land's End Granite is the youngest of the major plutons of the Cornubian batholith and comprises a number of discrete bodies of both coarse-grained granite (CGG) and fine-grained granite (FGG). Detailed re-mapping of selected parts of the composite Land's End pluton indicates that individual granite intrusions take a variety of forms, including dykes and sub-horizontal sheets. U-Pb (monazite) and 40Ar-39Ar (muscovite) age data have been interpreted elsewhere to indicate that the CGG and FGG of the northern "Zennor lobe" were emplaced c. 2-3 m.y. before the CGG and FGG of the southern "St Buryan lobe". Separating the two lobes is a large body of aphyric granite, the "St Just wedge", which is as yet undated. Relationships at Porth Nanven, where an irregular contact is discordant to a magmatic-state fabric in CGG of the St Buryan lobe, and at Porth Ledden, where sheets of aphyric granite intrude CGG, suggest that the St Just wedge is younger than the two main lobes. The composite nature of the pluton is exemplified by variations in grainsize and texture and in the size, abundance and alignment of alkali-feldspar phenocrysts. The subtle nature of petrographic variation in such felsic rocks makes identification of contacts between CGGs difficult, but those between CGG and FGG are more easily recognizable. At Bosigran, there is a laterally persistent northwest dipping sheet of CGG which exhibits a sharp, planar contact with underlying MGG. Immediately to the north, at Carn Veslan, the same MGG has a gradational contact with non-porphyritic FGG. At Sennen and Land's End, contacts between slightly different CGGs are denoted by the presence of distinct mafic zones, planar at Sennen and much more irregular at Land's End. The contrasting nature of these contacts suggests different time-intervals between intrusive events. At Porth Nanven, granite dykes with sharp, planar margins intrude the aphyric granite of the St Just wedge. Throughout the pluton, bodies of FGG demonstrate a variety of temporal relationships with adjoining CGG, including contemporaneous, sub-rounded masses and later sub-horizontal sheets. These and other examples within the Land's End Granite demonstrate that, rather than having originated as a large, diapirically emplaced magma body, as suggested in earlier models, the pluton is composed of a series of discrete intrusions

Influence of Particle Size on Optical Constants From Pellets Measured With Terahertz Pulsed Spectroscopy

Particle size is shown to influence both the overall value and the measurement precision of the refractive index and absorption coefficient of a sample diluted with high density polyethylene (HDPE) powder and compressed in a pellet. However, excessive grinding of a sample before it is mixed with HDPE powder can result in the formation of large particle clusters. These aggregates can induce internal scattering of the terahertz pulse within the pellet as well as lead to different mechanical properties of the pellet, which may change the distribution of air pores. These phenomena result in extracted optical constants with low accuracy and precision. The present work introduces a simple experimental procedure to improve the precision and accuracy of optical constants from spectroscopic pellets. This procedure consists of moderately grinding the sample powder in fine HDPE powder with a pestle and mortar. The standard deviation of the refractive index of Prussian blue has been observed to reduce from 0.14 to 0.02 following this procedure

Controlling surface plasmon polaritons in transformed coordinates

Transformational optics allow for a markedly enhanced control of the electromagnetic wave trajectories within metamaterials with interesting applications ranging from perfect lenses to invisibility cloaks, carpets, concentrators and rotators. Here, we present a review of curved anisotropic heterogeneous meta-surfaces designed using the tool of transformational plasmonics, in order to achieve a similar control for surface plasmon polaritons in cylindrical and conical carpets, as well as cylindrical cloaks, concentrators and rotators of a non-convex cross-section. Finally, we provide an asymptotic form of the geometric potential for surface plasmon polaritons on such surfaces in the limit of small curvature.Comment: 14 pages, 9 figure

Dexmedetomidine an adjuvant to levobupivacaine in supraclavicular brachial plexus block: A randomized double blind prospective study

BACKGROUND: Apha-2 agonists are combined with local anesthetics to extend the duration of regional anesthesia. We evaluated the effect of combining dexmedetomidine with levobupivacine with respect to duration of motor and sensory block and duration of analgesia.METHODS: Sixty patients scheduled for elective forearm and hand surgery were divided into two equal groups in a randomized double blind fashion. The patients received brachial plexus block via supraclavicular route with the help of nerve stimulator. In group L (n=30) 35cc of levobupivacaine with 1ml of isotonic saline and in group LD (n=30) 35cc of levobupivacine with 1 ml of (100 microgram) of dexmedetomidine was given. Duration of motor and sensory block and time to first rescue analgesia were recorded. Data analysis was done by SPSS version 16.0 [SPSS Inc ILLINOIS, USA, 2008]. Categorical variables were analyzed using Pearson”s Chi-square test. Normally distributed numerical variables were analyzed using unpaired “t” test. Skewed numerical variables within the group were analyzed usingMan-Whitney “U” test. All tests were two tailed. Statistical significance was defined as P<0.05.RESULTS: Sensory and motor block durations were longer in group LD as compared to L (P<0.01). Duration of analgesia was significantly longer in group LD as compared to group L (p<0.05).CONCLUSION: Dexmedetomidine added to levobupivacaine in supraclavicular brachial plexus block prolongs the duration of block and the duration of postoperative analgesia.KEYWORDS: Dexmedetomidine, levobupivacaine, supraclavicular bloc

Antimicrobial Activity of Actinomycetes Against Multidrug Resistant Staphylococcus aureus, E. coli and Various Other Pathogens

Purpose: The rapid emergence of drug resistance among pathogenic bacteria, especially multidrugresistant bacteria, underlines the need to look for new antibiotics.Methods: In the present study, 134 different actinomycetes, isolated from the soil samples collected from different localities of Punjab and Himachal Pradesh, were screened for antimicrobial activity against various test organisms including multidrug-resistant methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli in order to identify potential antibiotic producers.Results: Among these isolates, 51 (38 %) showed antimicrobial activity against one or more test organisms and six exhibited promising broad-spectrum activity against all the tested organisms. The observed cultural, morphological, physiological and biochemical characteristics confirmed that these isolates are species of the genus, Streptomyces.Conclusion: Further studies on the bioactive metabolites from these cultures will be useful for discovering novel compounds of clinical and agricultural use.Keywords: Actinomycetes, Broad spectrum antibiotics, Multidrug-resistant Staphylococcus aureus, Streptomyces