Compact Yb fiber few-cycle pulse source based on precision pulse compression and shaping with an adaptive fiber Bragg grating.

We generate bandwidth limited 10 µJ pulses of 92 fs pulse width using an adaptive fiber Bragg grating stretcher (FBG) in conjunction with a Lyot filter. The temperature controlled FBG is used to optimize the group delay, whereas the Lyot filter counteracts gain narrowing in the amplifier chain. Soliton compression in a hollow core fiber (HCF) allows for access to the few-cycle pulse regime.

Hanbury Brown-Twiss Correlations for a Driven Superatom.

Hanbury Brown-Twiss interference and stimulated emission, two fundamental processes in atomic physics, have been studied in a wide range of applications in science and technology. We study interference effects that occur when a weak probe is sent through a gas of two-level atoms that are prepared in a singly excited collective (Dicke or "superatom") state and for atoms prepared in a factorized state. We measure the time-integrated second-order correlation function g^{(2)} of the output field as a function of the delay τ between the input probe field and radiation emitted by the atoms and find that, for the Dicke state, g^{(2)} is twice as large for τ=0 as it is for γ_{e}τ≫1 (γ_{e} is an excited state decay rate), while for the product state, this ratio is equal to 3/2.

Neural activity associated with rhythmicity of song in juvenile male and female zebra finches.

Rhythm is an important aspect of both human speech and birdsong. Adult zebra finches show increased neural activity following exposure to arrhythmic compared to rhythmic song in regions similar to the mammalian auditory association cortex and amygdala. This pattern may indicate that birds are detecting errors in the arrhythmic song relative to their learned song template or to more general expectations of song structure.

ZENK induction in the zebra finch brain by song: Relationship to hemisphere, rhythm, oestradiol and sex.

Oestradiol is abundant in the zebra finch auditory forebrain and has the capacity to modulate neural responses to auditory stimuli with specificity as a result of both hemisphere and sex. Arrhythmic song induces greater ZENK expression than rhythmic song in the caudomedial nidopallium (NCM), caudomedial mesopallium (CMM) and nucleus taeniae (Tn) of adult zebra finches. The increases in the auditory regions (i.

Arrhythmic song exposure increases ZENK expression in auditory cortical areas and nucleus taeniae of the adult zebra Finch.

Rhythm is important in the production of motor sequences such as speech and song. Deficits in rhythm processing have been implicated in human disorders that affect speech and language processing, including stuttering, autism, and dyslexia. Songbirds provide a tractable model for studying the neural underpinnings of rhythm processing due to parallels with humans in neural structures and vocal learning patterns.

Norepinephrine inhibition in juvenile male zebra finches modulates adult song quality.

During development, male zebra finches learn a song that they eventually use in courtship and defense of nest sites. Norepinephrine (NE) is important for learning and memory in vertebrates, and this neuromodulator and its receptors are present throughout the brain regions that control song learning and production. The present study used the neurotoxin N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine hydrochloride (DSP4) to reduce brain levels of NE in juvenile males.

Experimental evaluation of the power balance model of speed skating.

Prediction of speed skating performance with a power balance model requires assumptions about the kinetics of energy production, skating efficiency, and skating technique. The purpose of this study was to evaluate these parameters during competitive imitations for the purpose of improving model predictions. Elite speed skaters (n = 8) performed races and submaximal efficiency tests.

Effect of competitive distance on energy expenditure during simulated competition.

Concepts of how athletes should expend their aerobic and anaerobic energetic reserves are generally based on results of tests where an "all out" strategy is imposed on/required from the athlete. We sought to determine how athletes spontaneously expend their energetic reserves when the only instruction was to finish the event in minimal time, as in competition. Well trained, and task habituated, road cyclists (N = 14) completed randomly ordered laboratory time trials of 500 m, 1000 m, 1500 m and 3000 m on a windload braked cycle ergometer.

Pattern of energy expenditure during simulated competition.

Purpose: To determine how athletes spontaneously use their energetic reserves when the only instruction was to finish in minimal time, and whether experience from repeated performance changes the strategy of recreational athletes.

Methods: Recreational road cyclists/speed skaters (N = 9) completed three laboratory time trials of 1500 m on a windload braked cycle. The pattern of energy use was calculated from total work and from the work attributable to aerobic metabolism, which allowed computation of anaerobic energy use.

The penicillin sensory transducer, BlaR, involved in the inducibility of beta-lactamase synthesis in Bacillus licheniformis is embedded in the plasma membrane via a four-alpha-helix bundle.

Prediction studies, conformational analyses and membrane-topology mapping lead to the conclusion that the penicillin sensory transducer, BlaR, involved in the inducibility of beta-lactamase synthesis in Bacillus licheniformis, is embedded in the plasma membrane bilayer via four transmembrane segments TM1-TM4 that form a four-alpha-helix bundle. The extracellular 262-amino-acid-residue polypeptide, S340-R601, that is fused at the carboxy end of TM4, possesses the amino acid sequence signature of a penicilloyl serine transferase. It probably functions as penicillin sensor.

Structure, function, and fate of the BlaR signal transducer involved in induction of beta-lactamase in Bacillus licheniformis.

The membrane-spanning protein BlaR is essential for the induction of beta-lactamase in Bacillus licheniformis. Its nature and location were confirmed by the use of an antiserum specific for its carboxy-terminal penicillin sensor, its function was studied by genetic dissection, and the structure of the penicillin sensor was derived from hydrophobic cluster analysis of the amino acid sequence by using, as a reference, the class A beta-lactamases with known three-dimensional structures. During the first 2 h after the addition of the beta-lactam inducer, full-size BlaR, bound to the plasma membrane, is produced, and then beta-lactamase is produced.

Expression in Escherichia coli of the carboxy terminal domain of the BLAR sensory-transducer protein of Bacillus licheniformis as a water-soluble Mr 26,000 penicillin-binding protein.

A cloning vector has been constructed which allows production and export by Escherichia coli of the Met346-Arg601 carboxy terminal domain of the 601 amino acid BLAR sensory-transducer involved in beta-lactamase inducibility in Bacillus licheniformis. The polypeptide, referred to as BLAR-CTD, accumulates in the periplasm of E. coli in the form of a water-soluble, Mr 26,000 penicillin-binding protein.

Identification of BlaR, the signal transducer for beta-lactamase production in Bacillus licheniformis, as a penicillin-binding protein with strong homology to the OXA-2 beta-lactamase (class D) of Salmonella typhimurium.

The blaR gene of Bacillus licheniformis encodes the signal transducer for induction of the class A beta-lactamase. The protein product, BlaR, has a hydrophilic carboxy region that binds beta-lactams and shows high sequence homology to the class D beta-lactamases, particularly the OXA-2 beta-lactamase of Salmonella typhimurium. The BlaR-beta-lactam complex is stable and may provide the continuing stimulus needed for the prolonged production of the enzyme.

Interaction of BlaI, the repressor for the beta-lactamase gene of Bacillus licheniformis, with the blaP and blaI promoters.

BlaI repressor for the beta-lactamase gene (blaP) of Bacillus licheniformis 749, was shown to repress expression of blaP and of the repressor gene (blaI), using the purified protein in a DNA-directed in vitro translation assay. Binding of BlaI to the promoter regions of blaP and blaI was examined by equilibrium and competitive binding assays. BlaI binds to the blaP promoter with an equal or only slightly higher affinity than to the blaI promoter.

Differential transcription of the bla regulatory region during induction of beta-lactamase in Bacillus licheniformis.

Induction of beta-lactamase (blaP) in Bacillus licheniformis involves the regulatory genes blaI (repressor), blaR1 (coinducer) and R2 (function unknown). Transcription of the bla genes during induction was followed by Northern hybridization. In the first 30 min 2.

A second regulatory gene, blaR1, encoding a potential penicillin-binding protein required for induction of beta-lactamase in Bacillus licheniformis.

A second regulatory locus (blaR1) required for the induction of beta-lactamase synthesis in Bacillus licheniformis 749 was cloned and sequenced. The gene was located on a 5.2-kilobase-pair SphI DNA fragment which also contained the beta-lactamase (blaP) and repressor (blaI) genes.

Repressor gene, blaI, for Bacillus licheniformis 749 beta-lactamase.

The repressor gene, blaI, for the beta-lactamase of Bacillus licheniformis 749 was functional when cloned in Escherichia coli, but addition of a beta-lactam did not lead to induction. One plasmid contained fragments from the inducible strain (source of repressor), the other carried fragments from the blaI- mutant 749/C (target). blaI lies just 5' to the promoter for the structural gene, blaP, and the target is the promoter region between the two genes.

Purification and DNA binding properties of the blaI gene product, repressor for the beta-lactamase gene, blaP, of Bacillus licheniformis.

The location of the repressor gene, blaI, for the beta-lactamase gene blaP of Bacillus licheniformis 749, on the 5' side of blaP, was confirmed by sequencing the bla region of the constitutive mutant 749/C. An amber stop codon, likely to result in a nonfunctional truncated repressor, was found at codon 32 of the 128 codon blaI open reading frame (ORF) located 5' to blaP. In order to study the DNA binding activity of the repressor, the structural gene for blaI, from strain 749, with its ribosome binding site was expressed using a two plasmid T7 RNA polymerase/promotor system (S.

Cloning and sequencing of the blaZ gene encoding beta-lactamase III, a lipoprotein of Bacillus cereus 569/H.

It has not been clear whether the membrane-bound beta-lactamase III of Bacillus cereus 569 is a separate enzyme or a modified form of the secreted beta-lactamase I. The membrane enzyme is an acyl-glyceride thioether-linked lipoprotein (J. B.

Transcriptional analysis of beta-lactamase regulation in Bacillus licheniformis.

The expression of the blaP gene for the beta-lactamase of Bacillus licheniformis was examined by transcriptional analyses. Radiolabeled probes containing the blaP gene or various regions 3' or 5' to it were used to analyze RNA samples prepared from induced and uninduced cultures of wild-type and mutant B. licheniformis strains.

Cloning and sequencing of the metallothioprotein beta-lactamase II gene of Bacillus cereus 569/H in Escherichia coli.

The structural gene for beta-lactamase II (EC 3.5.2.

"A bucket of cold water": a follow-up study in a residential special school.

This paper reports the initial findings of a follow-up study of the 75 young men who were admitted in their early teens to a residential school for maladjusted boys over a five year period. Sixty were traced and interviewed in depth, using an approach based on methods established at the Institute of Psychiatry. A structured interview was used which covered the individual's recollections of family, peer experiences, schools and adult life, with a special section on the residential therapeutic environment.

Cloning and sequencing of the beta-lactamase I gene of Bacillus cereus 5/B and its expression in Bacillus subtilis.

The beta-lactamases of Bacillus cereus have attracted interest because they are secreted efficiently, because multiple enzymes are frequently present, and because their regulation has unusual features. beta-Lactamase I of strain 5/B is produced constitutively at a high level, and the exoenzyme appears to be several thousand daltons larger than the corresponding product of strain 569/H. We have cloned the gene for 5/B beta-lactamase I in Escherichia coli and B.