Perfect single-photon sources

We introduce the "gapped coherent state" in the form of a single-photon source (SPS) that consists of uncorrelated photons as a background, except that we demand that no two photons can be closer in time than a time gap $t_\mathrm{G}$. While no obvious quantum mechanism is yet identified to produce exactly such a photon stream, a numerical simulation is easily achieved by first generating an uncorrelated (Poissonian) signal and then for each photon in the list, either adding such a time gap or removing all successive photons that are closer in time from any photon that is kept than $t_\mathrm{G}$. We study the statistical properties of such a hypothetical signal, which exhibits counter-intuitive features. This provides a neat and natural connection between continuous-wave (stationary) and pulsed single-photon sources, with also a bearing on what it means for such sources to be perfect in terms of single-photon emission

A modern study of HD166734: a massive supergiant system

Aims. HD166734 is an eccentric eclipsing binary system composed of two supergiant O-type stars, orbiting with a 34.5-day period. In this rare configuration for such stars, the two objects mainly evolve independently, following single-star evolution so far. This system provides a chance to study the individual parameters of two supergiant massive stars and to derive their real masses. Methods. An intensive monitoring was dedicated to HD166734.We analyzed mid- and high-resolution optical spectra to constrain the orbital parameters of this system. We also studied its light curve for the first time, obtained in the VRI filters. Finally, we disentangled the spectra of the two stars and modeled them with the CMFGEN atmosphere code in order to determine the individual physical parameters. Results. HD166734 is a O7.5If+O9I(f) binary. We confirm its orbital period but we revise the other orbital parameters. In comparison to what we found in the literature, the system is more eccentric and, now, the hottest and the most luminous component is also the most massive one. The light curve exhibits only one eclipse and its analysis indicates an inclination of 63.0{\deg} $\pm$ 2.7{\deg}. The photometric analysis provides us with a good estimation of the luminosities of the stars, and therefore their exact positions in the Hertzsprung-Russell diagram. The evolutionary and the spectroscopic masses show good agreement with the dynamical masses of 39.5 Msun for the primary and 33.5 Msun for the secondary, within the uncertainties. The two components are both enriched in helium and in nitrogen and depleted in carbon. In addition, the primary also shows a depletion in oxygen. Their surface abundances are however not different from those derived from single supergiant stars, yielding, for both components, an evolution similar to that of single stars.Comment: 13 pages, 13 figures, A&A accepte

HD 152246 - a new high-mass triple system and its basic properties

Analyses of multi-epoch, high-resolution (R ~ 50.000) optical spectra of the O-type star HD 152246 (O9 IV according to the most recent classification), complemented by a limited number of earlier published radial velocities, led to the finding that the object is a hierarchical triple system, where a close inner pair (Ba-Bb) with a slightly eccentric orbit (e = 0.11) and a period of 6.0049 days revolves in a 470-day highly eccentric orbit (e = 0.865) with another massive and brighter component A. The mass ratio of the inner system must be low since we were unable to find any traces of the secondary spectrum. The mass ratio A/(Ba+Bb) is 0.89. The outer system has recently been resolved using long-baseline interferometry on three occasions. The interferometry confirms the spectroscopic results and specifies elements of the system. Our orbital solutions, including the combined radial-velocity and interferometric solution indicate an orbital inclination of the outer orbit of 112{\deg} and stellar masses of 20.4 and 22.8 solar masses. We also disentangled the spectra of components A and Ba and compare them to synthetic spectra from two independent programmes, TLUSTY and FASTWIND. In either case, the fit was not satisfactory and we postpone a better determination of the system properties for a future study, after obtaining observations during the periastron passage of the outer orbit (the nearest chance being March 2015). For the moment, we can only conclude that component A is an O9 IV star with v*sin(i) = 210 +\- 10 km/s and effective temperature of 33000 +\- 500 K, while component Ba is an O9 V object with v*sin(i) = 65 +/- 3 km/s and T_eff = 33600 +\- 600 K.Comment: 9 pages, 6 figures, accepted for publication in Astronomy and Astrophysic

Co- delivery of Venlafaxine and Doxycycline by films of Cellulose Nanofibers for diabetic foot ulcers

Introduction: About 15-25% of diabetic patients suffer from foot ulcers. Diabetic foot ulcers often require specialized treatment and multidisciplinary approach. the choice  of appropriate drug delivery system for antibiotics and pain refiner is an important remedy. Venlafaxine is an antidepressant drug of the serotonin-norepinephrine reuptake inhibitor (SNRI) class which is a safe and well-tolerated analgesic drug for neuropathic pain in diabetic’s foot ulcers.  On the other hand Doxycycline inhibits metalloproteinases activity through the chelation of calcium and zinc ions which inhibits extra cellular matrix destruction mediated by metalloproteinases. Films of cellulose nanofibers are biocompatible with excellent physical properties and can be appropriate choice for wound dressing in diabetic foot ulcers. In the present study, films of cellulose nanofibers were loaded by Venlafaxine and Doxycycline for simultaneous delivery to diabetic foot ulcers. Methods and Results: Doxycycline and Venlafaxine were dissolved in 10 cc water and then Films were putted on them and stirred for 24 hours to reach or until drugs are loaded drugs loading. Drug loading efficiency and release profiles were investigated by UV spectroscopy in 275 and 225 nm, respectively. The influence of the pH from 3 to 9 and the ratio of the drugs to carrier (1:1, 1:2 and 1:3) were assessed on the drug loading and release profiles. Efficiency of drugs loading was decreased by increase in  pH possibly due to the negative charge of cellulose and positive charge of Venlafaxine and Doxycycline in lower pH. On the other hand, the ratio of 1:2 of drugs to carrier was the most efficient ratio for drug loading that was 20% and 69% and also, 60% and 35% release for Venlafaxine and Doxycycline respectively. Conclusions: Films of cellulose nanofibers proved to be an appropriate carrier for co-delivery of Venlafaxine and Doxycycline as wound dressing. Further clinical studies are needed to evaluate their effectiveness in alleviating the inflammation and neuropathic pain of the diabetic foot ulcers

A new investigation of the binary HD 48099

With an orbital period of about 3.078 days, the double-lined spectroscopic binary HD 48099 is, still now, the only short-period O+O system known in the Mon OB2 association. Even though an orbital solution has already been derived for this system, few information are available about the individual stars. We present, in this paper, the results of a long-term spectroscopic campaign. We derive a new orbital solution and apply a disentangling method to recover the mean spectrum of each star. To improve our knowledge concerning both components, we determine their spectral classifications and their projected rotational velocities. We also constrain the main stellar parameters of both stars by using the CMFGEN atmosphere code and provide the wind properties for the primary star through the study of IUE spectra. This investigation reveals that HD 48099 is an O5.5 V((f))+O9 V binary with M_1 sin^3 i = 0.70 M_{\sun} and M_2 sin^3 i = 0.39 M_{\sun}, implying a rather low orbital inclination. This result, combined with both a large effective temperature and log g, suggests that the primary star (v sini ~ 91 km s^-1) is actually a fast rotator with a strongly clumped wind and a nitrogen abundance of about 8 times the solar value.Comment: 12 pages, 7 figures, accepted by Ap

Biomarkers of systemic inflammation and growth in early infancy are associated with stunting in young Tanzanian children

Stunting can afflict up to one-third of children in resource-constrained countries. We hypothesized that low-grade systemic inflammation (defined as elevations in serum C-reactive protein or alpha-1-acid glycoprotein) in infancy suppresses the growth hormone–insulin-like growth factor (IGF) axis and is associated with subsequent stunting. Blood samples of 590 children from periurban Dar es Salaam, Tanzania, were obtained at 6 weeks and 6 months of age as part of a randomized controlled trial. Primary outcomes were stunting, underweight, and wasting (defined as length-for-age, weight-for-age and weight-for-length z-scores < −2) between randomization and endline (18 months after randomization). Cox proportional hazards models were constructed to estimate hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) of time to first stunting, underweight, and wasting as outcomes, with measures of systemic inflammation, insulin-like growth factor-1 (IGF-1) and insulin-like growth factor binding protein-3 (IGFBP-3) as exposures, adjusting for numerous demographic and clinical variables. The incidences of subsequent stunting, underweight, and wasting were 26%, 20%, and 18%, respectively. In multivariate analyses, systemic inflammation at 6 weeks of age was significantly associated with stunting (HR: 2.14, 95% CI: 1.23, 3.72; p = 0.002). Children with higher levels of IGF-1 at 6 weeks were less likely to become stunted (HR: 0.58, 95% CI: 0.37, 0.93; p for trend = 0.019); a similar trend was noted in children with higher levels of IGF-1 at 6 months of age (HR: 0.50, 95% CI: 0.22, 1.12; p for trend = 0.07). Systemic inflammation occurs as early as 6 weeks of age and is associated with the risk of future stunting among Tanzanian children.This research was funded by the National Institutes of Health (R01 HD048969, 2P30 DK040561, K24 DK104676-Dr. Duggan) and the Bill and Melinda Gates Foundation (OPP1066203-Dr. Duggan). (R01 HD048969 - National Institutes of Health; 2P30 DK040561 - National Institutes of Health; K24 DK104676 - National Institutes of Health; OPP1066203 - Bill and Melinda Gates Foundation)Accepted manuscrip

The Three body system delta Circini

Delta Cir is known as an O7.5 III eclipsing and spectroscopic binary with an eccentric orbit. Penny et al. discovered the presence of a third component in the IUE spectra. The eclipsing binary and the third body revolve around a common centre of gravity with a period of 1644 days in an eccentric orbit with the semimajor axis of 10 AU. We demonstrate the presence of the apsidal-line rotation with a period of about 141 years, which is considerably longer than its theoretically predicted value, based on the published radii of the binary components derived from the Hipparchos Hp light curve. However, our new solution of the same light curve resulted in smaller radii and a better agreement between the observed and predicted period of the apsidal- line advance. There are indications that the third body is a binary. The object was resolved by VLTI with the PIONIER combiner; in June 2012 the separation was 3.78 mas, magnitude difference in the H region 1.75 mag. This result means that (assuming the distance 770 pc) the inclination of the long orbit is 87.7 degrees.Comment: Accepted for publication in the Astronomical Journa

Web-Based Communities as a Tool for Extension and Outreach

The Internet has become a common tool for facilitating business transactions, fostering communication, and aiding for-profit and non-profit companies and organizations to better compete. An additional benefit of the Internet is the ability to create sector-specific Web-based communities that can facilitate outreach and Extension efforts. Communities in general can be any group with a common interest or goal and can include a number of actions such as information sharing, real-time dialog, and transaction facilitation. In this article, we discuss a background of Web-based communities and forest-sector Web-based communities developed by Cooperative Extension faculty members at two U.S. universities

Collective evolution of submicron hillocks during the early stages of anisotropic alkaline wet chemical etching of Si(100) surfaces

We address experimentally the large-scale dynamics of Si(100) surfaces during the initial stages of anisotropic wet (KOH) chemical etching, which are characterized through atomic force microscopy. These systems are known to lead to the formation of characteristic pyramids, or hillocks, of typical sizes in the nanometric/micrometer scales, thus with the potential for a large number of applications that can benefit from the nanotexturing of Si surfaces. The present pattern formation process is very strongly disordered in space. We assess the space correlations in such a type of rough surface and elucidate the existence of a complex and rich morphological evolution, featuring at least three different regimes in just 10 min of etching. Such a complex time behavior cannot be consistently explained within a single formalism for dynamic scaling. The pyramidal structure reveals itself as the basic morphological motif of the surface throughout the dynamics. A detailed analysis of the surface slope distribution with etching time reveals that the texturing process induced by the KOH etching is rather gradual and progressive, which accounts for the dynamic complexity. The various stages of the morphological evolution can be accurately reproduced by computer-generated surfaces composed by uncorrelated pyramidal structures. To reach such an agreement, the key parameters are the average pyramid size, which increases with etching time, its distribution and the surface coverage by the pyramidal structures.We gratefully acknowledge discussions with David Nečas, leader of the Gwyddion project. This work was supported by Council of Scientific and Industrial Research (India) Scheme No. 03(1289)/13/EMR-II, and by MINECO/FEDER (Spain/UE) Grants Nos. FIS2012-38866-C05-01, MAT2014-54231-C4-1-P, BIO2016-79618-R, and FIS2015-66020-C2-1-P, as well as by Comunidad Autónoma de Madrid (Spain) Grant NANOAVANSENS S2013/MIT-3029