Hanbury Brown et Twiss (HBT)

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Hanbury brown and twiss: important, anti-weird, beautiful

Hanbury brown and twiss: important, anti-weird, beautiful

I read with interest Daniel Klepp- ner’s lucid column on Hanbury Brown’s “steamroller.” Kleppner mentions an aspect of the Hanbury Brown and Twiss (HBT) effect that at first seemingly de- fied a quantum interpretation; he terms it “anti-weird,” since in certain cases a completely classical understanding is possible. Other aspects of the Hanbury Brown physics are truly weird in the

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Hanbury-Brown Twiss noise correlation with time controlled quasi-particles in ballistic quantum conductors

Hanbury-Brown Twiss noise correlation with time controlled quasi-particles in ballistic quantum conductors

2. Measuring Hanbury Brown Twiss correlations in ballistic conductors In this section we discuss the conditions to realize a HOM ex- periment with electrons. A HOM experiment measures HBT cor- relations, but contrary to the original HBT measurements the thermodynamic sources randomly emitting particles are replaced by sources providing time-resolved particle emission. Examples of such sources are the optical parametric down conversion of light creating pairs of photons and the on-demand electron sources for electrons.

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Hanbury-Brown Twiss correlations to probe the population statistics of GHz photons emitted by conductors

Hanbury-Brown Twiss correlations to probe the population statistics of GHz photons emitted by conductors

(Dated: 23rd March 2004) Abstract We present the first study of the statistics of GHz photons in quantum circuits, using Hanbury- Brown and Twiss correlations. The superpoissonian and poissonian photon statistics of thermal and coherent sources respectively made of a resistor and a radiofrequency generator are measured down to the quantum regime at milliKelvin temperatures. As photon correlations are linked to the second and fourth moments of current fluctuations, this experiment, which is based on current cryogenic electronics, may become a standard for probing electron/photon statistics in quantum conductors.
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The Hanbury Brown and Twiss Effet for Cold Atoms

The Hanbury Brown and Twiss Effet for Cold Atoms

defined 关 1 兴. The most familiar type of coherence is known as first order coherence and is related to the visibility of inter- ference fringes in an interferometer. It is proportional to the value of the correlation function of the associated field. Sec- ond order coherence is less intuitive and corresponds to the correlation function of the intensity or squared modulus of the field. From a particle point of view, second order coher- ence is a way of quantifying density correlations and is re- lated to the probability of finding one particle at a certain location given that another particle is present at some other location. Particle correlations can arise simply from ex- change symmetry effects and exist even when there is no interaction between the particles. This fact was clearly dem- onstrated in the celebrated Hanbury Brown Twiss experiment which showed a second order correlation for photons coming from widely separated points in a thermal source such as a star 关 2 兴.
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De la condensation de Bose-Einstein à l'effet Hanbury Brown & Twiss atomique de l'hélium métastable

De la condensation de Bose-Einstein à l'effet Hanbury Brown & Twiss atomique de l'hélium métastable

Fig. 2.8 – Montage optique de l’exp´ erience de Hanbury Brown et Twiss. Reproduit ` a partir de Nature(London) 177, 27(1956)[41]. Notre sch´ ema (voir 2.1.3) est tr` es proche du leur. Notre d´ etecteur est aussi l’´ equi- valent de leur photo-multiplicateur, mˆ eme si notre ´ electronique actuelle nous permet bien plus de souplesse. La diff´ erence essentielle se trouve dans la lame semi-r´ efl´ echissante qu’ils utilisent (voir figure 2.8). Cela leur permet d’´ etudier comment la corr´ elation varie avec la distance entre les d´ etecteurs. Mais en r´ ealit´ e c’est essentiel, mˆ eme ` a leur mesure de la corr´ elation pour deux d´ etecteurs superpos´ es. Ils ne peuvent le faire sur un seul d´ etecteur car le temps de corr´ elation qu’ils attendent est inf´ erieur au temps mort de leur d´ etecteur. Autrement dit, leur d´ etecteur ne se r´ earme pas assez vite apr` es l’arriv´ ee du premier photon pour d´ etecter aussi le second. C’est une difficult´ e technique qui a ´ et´ e lev´ ee depuis et qui nous permet d’utiliser un seul d´ etecteur. Autre difficult´ e qui a ´ et´ e lev´ ee : les deux auteurs de cette exp´ erience mesurent la corr´ elation en multipliant les deux signaux ´ electriques. Les exp´ eriences ult´ erieures ont pu se faire sur des signaux num´ eriques, simplifiant le probl` eme du traitement du bruit de l’´ electronique et ses d´ e- rives. Cela affecte leur rapport signal ` a bruit : malgr´ e le flux important des photons ils doivent accumuler une heure et demi pour chaque point de mesure. Et encore : « In these first experiments the quantum efficiency of the photocathodes was too low to give a satisfactory ratio of signal to noise. However, when an improved type of photomulti- plier became available with an appreciably higher quantum efficiency, it was possible to make a quantitative test of the theory. »[41]. Cette exp´ erience fondatrice est donc aussi un exploit technique autant qu’un test fondamental.
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Short-time Hanbury-Brown and Twiss correlation of a single-electron beam in ballistic conductors

Short-time Hanbury-Brown and Twiss correlation of a single-electron beam in ballistic conductors

L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignemen[r]

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Specific shifts in the endocannabinoid system in hibernating brown bears

Specific shifts in the endocannabinoid system in hibernating brown bears

(See figure on previous page.) Fig. 1 Lipidomic from summer and winter brown bear serum. The winter and summer bear serum mixes were prepared as described (Supplementary Table S 1 ). a: Total fatty acid (FA) concentration. b: Total n-6 and n-3 FA relative proportions of total lipids. c: Highest molar percent lipid species D: Molar percent of the n-3 family lipid species. e: Molar ratios of DHA/AA in summer and winter serum. Detailed lipidomic results are presented in Supplementary Tables S2 and S3. Data are expressed in mmol/L for total FAs concentration, or molar percentage of total lipids and are represented as mean ± SEM of separate extractions and quantifications from the twelve mixes (six summer and six winter serum mixes, except for EPA with data from only three summer and three winter mixes). Paired Student t-test were used to compare wummer and winter data and Benjamini-Hochberg correction was applied for multiple comparisons. * indicates BH adjusted p value < 0.05 when comparing seasons, ** for p < 0.01, *** for p < 0.001, NS: non significant. AA:arachidonic acid, ALA: alpha-linolenic acid, DHA: docosahexaenoic acid, DPA: docosapentaenoic acid, EPA: eicosapentaenoic acid, LA: linoleic acid, OA: oleic acid, PA: palmitic acid, SA: stearic acid, SBS: summer bear serum, WBS: winter bear serum
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Discovery of a brown dwarf companion to the star HIP 64892

Discovery of a brown dwarf companion to the star HIP 64892

We report the discovery of a bright, brown dwarf companion to the star HIP 64892, imaged with VLT/SPHERE during the SHINE exoplanet survey. The host is a B9.5V member of the Lower-Centaurus-Crux subgroup of the Scorpius Centaurus OB association. The measured angular separation of the companion (1.2705 ± 0.0023”) corresponds to a projected distance of 159 ± 12 AU. We observed the target with the dual-band imaging and long-slit spectroscopy modes of the IRDIS imager to obtain its spectral energy distribution (SED) and astrometry. In addition, we reprocessed archival NACO L-band data, from which we also recover the companion. Its SED is consistent with a young (<30 Myr), low surface gravity object with a spectral type of M9 γ ± 1. From comparison with the BT-Settl atmospheric models we estimate an effective temperature of T eff = 2600 ± 100 K, and comparison of the companion photometry to the COND evolutionary models yields a mass of ∼29−37 M J at the estimated age of 16 +15 −7 Myr for the system. The star HIP 64892 is a rare example of an extreme-mass ratio system (q ∼ 0.01) and will be useful for testing models relating to the formation and evolution of such low-mass objects.
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WASP-128b: a transiting brown dwarf in the dynamical-tide regime

WASP-128b: a transiting brown dwarf in the dynamical-tide regime

6 CONCLUSION We have discovered WASP-128b, a transiting brown dwarf from the WASP survey on a 2.2 d period around a G dwarf. Dynamical-tide theory predicts very few such objects should exist due to rapid orbital decay from strong stellar tidal cou- pling. Using radial velocity data collected over ∼5 years, we rule out any significant orbital decay, and we derive a value of the stellar tidal quality factor based on an assumption of dynamical stability. The derived age, mass, and size of WASP-128b suggests a mild inflation, although we can not rule out a young age.

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Do native brown trout and non-native brook trout interact reproductively?

Do native brown trout and non-native brook trout interact reproductively?

Although the number of observed mixed groups was relatively low (n=S, representing 7.8% of the total number of active redds), wc round that these groups were principally comp[r]

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Transcriptome analysis during defense response in the brown alga Laminaria digitata

Transcriptome analysis during defense response in the brown alga Laminaria digitata

Host-pathogen interactions in terrestrial plants are well described at the physiological, metabolic or molecular levels. However, defense induction and regulation have hardly been studied in marine macroalgae. In the brown alga Laminaria digitata, studies have shown that oligoguluronates elicit defense responses. Significant progress has been made in understanding the signalling events which produce an oxidative burst and confer late resistance. The halogenated metabolism is particularly active in this species. It seems to be involved in defense responses as indicated by the emission of molecular iodine and volatile halogenated organic compounds after elicitation. In this context, this thesis investigated the transcriptome regulation in response to the perception of oligoluronates by substractive suppressive hybridization, macroarray and real time PCR. Differential expression was confirmed for ten genes encoding haloperoxidases, thioredoxins and pentose phosphate pathway enzymes. Theses results suggest that L. digitata has developed an original strategy to cope with oxidative stress. The importance of halogenated metabolism in defense responses was highlighted by differential expression of haloperoxidase members. The specific regulation of a few members of this multigenic family represents the first report confirming that some haloperoxidase members have evolved toward specialized functions. Identification of these defense molecular markers led to the first identification of the intracellular pathway involving defense genes activation in L. digitata. Hydrogen peroxide was found to be a key actor in different pathways of this signaling cascade. The tools developed and the molecular markers identified in this study should make possible to extend the understanding of defense responses in macroalgae in the context of biotic interactions and long- distance signaling.
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Brown adipose tissue thermogenic adaptation requires Nrf1-mediated proteasomal activity

Brown adipose tissue thermogenic adaptation requires Nrf1-mediated proteasomal activity

Results Non-shivering thermogenesis requires proteasomal activity The ER is a critical organelle for coordinating cellular homeostasis during states of high metabolism, but the specific pathways and ER-resident proteins that contribute to the adaptation of BAT to a cold environment remain elusive. In line with previous results 23 , we did not find differences in thermogenic energy expenditure stimulated by CL316,243 (CL), an adipocyte-specific β3-adrenergic agonist 25 , in mice with either adipocyte-specific Inositol-requiring enzme-1 α (Ire1α) or Xbp1 deficiency (Supplementary Fig. 1a,b), indicating that this branch of the UPR is dispensable for BAT-mediated respiration. As ERAD supports ER function by removing damaged or dispensable proteins 14,15 , we focused on protein degradation through the UPS as a potential alternate mechanism by which brown adipocytes secure ER homeostasis and ameliorate metabolic stress. To investigate whether cold adaptation is linked to proteasome function we first measured proteasomal activity in BAT from wild-type (WT) mice adapted to thermoneutrality (30 °C), room temperature (22 °C) or cold (4 °C) for 7 days. We found that cold adaptation either to 22 °C or 4 °C was associated with higher proteasomal activity in BAT compared to 30 °C (Fig. 1a). In contrast, in the liver proteasomal activity remained unchanged after cold adaptation (Supplementary Fig. 1c). To determine the physiological significance of this observation for non-shivering thermogenesis, we treated mice housed at 30 °C or 22 °C with bortezomib, a clinical proteasome inhibitor 26,27 . We observed that at 22 °C, a setting in which non-shivering thermogenesis in BAT is active, mice treated with bortezomib were less able to defend their core body temperature compared to controls treated with dimethyl sulfoxide (DMSO), while mice adapted to 30 °C and treated with bortezomib or DMSO
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On the Brown--Shields conjecture for cyclicity in the Dirichlet space

On the Brown--Shields conjecture for cyclicity in the Dirichlet space

A subspace M of D is called invariant if f (z) ∈ M =⇒ zf (z) ∈ M . Given f ∈ D, we denote by [f ] the smallest closed, invariant subspace containing f , namely the closure in D of the set {pf : p is a polynomial}. We say that f is cyclic if [f ] = D. It is a long-standing open problem to characterize the cyclic functions in D. Brown and Shields showed in [2] that, if f ∈ D is cyclic, then necessarily f is an outer function and the set {ζ ∈ T : lim r→1 − f (rζ) = 0} is of logarithmic capacity zero. They conjectured that these two necessary

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Brown Field System Architecting: Driving Commonality Across Unmanned Aircraft Systems

Brown Field System Architecting: Driving Commonality Across Unmanned Aircraft Systems

• As more systems are fielded, logistics tails for independent systems must be maintained at costs of inventory, transportation, training, repair, and more • Literature focus is on developing commonality from “clean sheet” designs for product families instead of the case of existing (brown field) architectures and systems

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Effects of regional climate change on brown rust disease in winter wheat

Effects of regional climate change on brown rust disease in winter wheat

Table 2 Infection periods of wheat leaf rust (WLR), severity of predominant fungal diseases, and grain yield loss at Burmerange and Reuler during the 2003 –2013 period.. The predominant [r]

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Histone modifications during the life cycle of the brown alga Ectocarpus

Histone modifications during the life cycle of the brown alga Ectocarpus

3 usually diploid. However, there is clear evidence that the identity of each life cycle generation is not determined by its ploidy because haploid sporophytes (partheno-sporophytes) can be produced by parthenogenetic development of haploid gametes [8,9] and diploid gametophytes can be constructed using mutants that are unable to deploy the sporophyte developmental pathway [3,7]. These observations indicate that epigenetic processes play an important role during the Ectocarpus life cycle. Recent work has shown that the deployment of the sporophyte program requires two different three amino acid loop extension homeodomain transcription factors (TALE HD TFs), OUROBOROS (ORO) and SAMSARA (SAM) [7]. Remarkably, TALE HD TFs appear to have been recruited convergently to regulate sporophyte development in both the brown algal and the land plant lineages [7]. In land plants, the PRC2 polycomb complex has also been implicated in life cycle regulation [10–17], indicating that chromatin modification processes play an important role in life cycle regulation in that lineage. Chromatin modification has been proposed to play a similar role in the brown algae [2] but this hypothesis has not been investigated experimentally.
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Probabilistic analysis of shallow foundations on rocks obeying Hoek-Brown failure Criterion

Probabilistic analysis of shallow foundations on rocks obeying Hoek-Brown failure Criterion

INTRODUCTION Traditionally, the stability analysis of shallow foundations resting on rocks is based on deterministic approaches. The present paper aims at determining the ultimate bearing capacity of a centrally loaded shallow strip footing (i.e. a footing subjected to a vertical or an inclined load) using a probabilistic analysis. The footing rests on a rock mass that follows the modified Hoek-Brown failure criterion. The deterministic models are based on the kinematic approach of limit analysis theory using translational multiblock failure mechanisms. The Polynomial Chaos Expansion (PCE) method (Huang et al. 2009) is used for the probabilistic analysis. Four uncertain parameters related to the modified Hoek-Brown failure criterion are modeled as random variables. These are the Geological Strength Index (GSI), the uniaxial compressive strength of the intact rock (σ c ), the intact rock material constant
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Radical Depolymerization of Alginate Extracted from Moroccan Brown Seaweed Bifurcaria bifurcata

Radical Depolymerization of Alginate Extracted from Moroccan Brown Seaweed Bifurcaria bifurcata

4 Institut Universitaire de France (IUF), 1 Rue Descartes, 75005 Paris, France * Correspondence: cedric.delattre@uca.fr Received: 16 May 2020; Accepted: 12 June 2020; Published: 17 June 2020    Abstract: The degradation of alginate extracted from Moroccan Bifurcaria bifurcata has not been fully established to date. In this work, we report the extraction and the characterization of alginate (ASBB) from the brown algae B. bifurcata, as well as the production of oligo-alginates (OGABs) by using a green chemistry process. The depolymerization of ASBB was carried out by controlled radical hydrolysis through our green chemistry process using a hydrogen peroxide (H 2 O 2 ) catalyst. The molecular
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Finding ultracool brown dwarfs with MegaCam on CFHT: method and first results

Finding ultracool brown dwarfs with MegaCam on CFHT: method and first results

(3) Statistics of brown dwarfs of intermediate temper- ature (1000 to 1500 K). Current estimates of the substellar Galactic mass function suggest that in the disk of the Galaxy brown dwarfs are about as numerous as stars (e.g Chabrier 2001; Cruz et al. 2007). That mass function however has significant statistical noise, which reduces its power as a constraint on star formation and galactic structure theories. At these low effective temperatures the final luminosity functions from the DENIS, 2MASS and SDSS surveys will all retain significant Poisson noise The samples from individual searches are not easily com- bined since they are affected by different selection biases, so only a fraction can be used to define a robust luminosity function (e.g. Cruz et al. 2007). By almost doubling the number of known brown dwarfs, from a single survey with a well understood se- lection function, we will provide significantly tighter constraints on the luminosity function.
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Radical Depolymerization of Alginate Extracted from Moroccan Brown Seaweed Bifurcaria bifurcata

Radical Depolymerization of Alginate Extracted from Moroccan Brown Seaweed Bifurcaria bifurcata

4 Institut Universitaire de France (IUF), 1 Rue Descartes, 75005 Paris, France * Correspondence: cedric.delattre@uca.fr Received: 16 May 2020; Accepted: 12 June 2020; Published: 17 June 2020    Abstract: The degradation of alginate extracted from Moroccan Bifurcaria bifurcata has not been fully established to date. In this work, we report the extraction and the characterization of alginate (ASBB) from the brown algae B. bifurcata, as well as the production of oligo-alginates (OGABs) by using a green chemistry process. The depolymerization of ASBB was carried out by controlled radical hydrolysis through our green chemistry process using a hydrogen peroxide (H 2 O 2 ) catalyst. The molecular
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