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We study the connection between the variations in the far-ultraviolet (FUV), near-ultraviolet (NUV), and X-ray band emission from NGC 4051 using 4 d long AstroSat observations performed during 5–9 June 2016. NGC 4051 showed rapid variability in all three bands with the strongest variability amplitude in the X-ray band (⁠|$F_{\mathrm{ var}} \sim 37~{{\ \rm per\ cent}}$|⁠) and much weaker variability in the UV bands (⁠|$F_{\mathrm{ var}} \sim 3{\!-\!}5~{{\ \rm per\ cent}}$|⁠). Cross-correlation analysis performed using interpolated cross-correlation functions and discrete cross-correlation functions revealed a robust correlation (∼0.75) between the UV and X-ray light curves. The variations in the X-ray band are found to lead those in the FUV and NUV bands by ∼7.4 ks and ∼24.2 ks, respectively. The UV lags favour the thermal disc reprocessing model. The FUV and NUV bands are strongly correlated (∼0.9) and the variations in the FUV band lead those in the NUV band by ∼13 ks. Comparison of the UV lags found using the AstroSat observations with those reported earlier and the theoretical model for thermal reverberation timelag suggests a possible change in either the geometry of the accretion disc/corona or the height of the corona. [ABSTRACT FROM AUTHOR]

We study accretion disc–corona connection in Seyfert 1 galaxies using simultaneous UV/X-ray observations of NGC 4593 (2016 July 14–18) and NGC 7469 (2017 October 15–19) performed with AstroSat. We use the X-ray (0.5–7.0 keV) data acquired with the Soft X-ray Telescope (SXT) and the UV (FUV: 130–180 nm, NUV: 200–300 nm) data obtained with the Ultra-Violet Imaging Telescope (UVIT). We also use the contemporaneous Swift observations of NGC 4593 and demonstrate AstroSat 's capability for X-ray/UV correlation studies. We performed UV/X-ray cross-correlation analysis using the interpolated and the discrete cross-correlation functions and found similar results. In the case of NGC 4593, we found that the variations in the X-rays lead to those in the FUV and NUV bands by ∼38 ks and ∼44 ks, respectively. These UV lags favour the disc-reprocessing model; they are consistent with the previous results within uncertainties. In contrast, we found an opposite trend in NGC 7469 where the soft X-ray variations lag those in the FUV and NUV bands by ∼41 ks and ∼49 ks, respectively. The hard lags in NGC 7469 favour the thermal Comptonization model. Our results may provide direct observational evidence for the variable intrinsic UV emission from the accretion disk, which acts as the seed for thermal Comptonization in a hot corona in a lamp-post-like geometry. The non-detection of disk reverberation photons in NGC 7469, using AstroSat data, is most likely due to a high accretion rate resulting in a hot accretion disc and large intrinsic emission. [ABSTRACT FROM AUTHOR]

We present a study of far- and near ultraviolet (UV) emission from the accretion disc in a powerful Seyfert 1 galaxy IC 4329A using observations performed with the Ultraviolet Imaging Telescope (UVIT) onboard AstroSat. These data provide the highest spatial resolution and deepest images of IC 4329A in the far- and near UV bands acquired to date. The excellent spatial resolution of the UVIT data has allowed us to accurately separate the extended emission from the host galaxy and the AGN emission in the far- and near UV bands. We derive the intrinsic AGN flux after correcting for the Galactic and internal reddening, as well as for the contribution of emission lines from the broad and narrow-line regions. The intrinsic UV continuum emission shows a marked deficit compared to that expected from the 'standard' models of the accretion disc around an estimated black hole mass of |$1-2\times 10^8\, {\rm M}_{\odot }$| when the disc extends to the innermost stable circular orbit. We find that the intrinsic UV continuum is fully consistent with the standard disc models, but only if the disc emits from distances larger than ∼80–150 gravitational radii. [ABSTRACT FROM AUTHOR]

Two long AstroSat Soft X-ray Telescope observations were taken of the third recorded outburst of the symbiotic recurrent nova V3890 Sgr. The first observing run, 8.1–9.9 d after the outburst, initially showed a stable intensity level with a hard X-ray spectrum that we attribute to shocks between the nova ejecta and the pre-existing stellar companion. On day 8.57, the first, weak, signs appeared of supersoft source (SSS) emission powered by residual burning on the surface of the white dwarf. The SSS emission was observed to be highly variable on time-scales of hours. After day 8.9, the SSS component was more stable and brighter. In the second observing run, on days 15.9–19.6 after the outburst, the SSS component was even brighter but still highly variable. The SSS emission was observed to fade significantly during days 16.8–17.8 followed by re-brightening. Meanwhile, the shock component was stable, leading to increase in hardness ratio during the period of fading. AstroSat and XMM–Newton observations have been used to study the spectral properties of V3890 Sgr to draw quantitative conclusions even if their drawback is model dependent. We used the xspec to fit spectral models of plasma emission, and the best fits are consistent with the elemental abundances being lower during the second observing run compared to the first for spectra ≥1 keV. The SSS emission is well fitted by non-local thermal equilibrium model atmosphere used for white dwarfs. The resulting spectral parameters, however, are subject to systematic uncertainties such as completeness of atomic data. [ABSTRACT FROM AUTHOR]

Our nearest stellar neighbour, Proxima Centauri, is a low-mass star with spectral type dM5.5 and hosting an Earth-like planet orbiting within its habitable zone. However, the habitability of the planet depends on the high-energy radiation of the chromospheric and coronal activity of the host star. We report the AstroSat, Chandra , and HST observation of Proxima Centauri carried out as part of the multiwavelength simultaneous observational campaign. Using the soft X-ray data, we probe the different activity states of the star. We investigate the coronal temperatures, emission measures and abundance. Finally, we compare our results with earlier observations of Proxima Centauri. [ABSTRACT FROM AUTHOR]

Star clusters are ideal platforms for categorizing X-ray emitting stars and to study X-ray emission as a function of stellar age and activity. We present a comprehensive study of an open star cluster, NGC 2527, by combining data from XMM-UVOT- Gaia. Cluster membership of stars and their photometry are taken from Gaia and cross-matched with XMM and UVOT detections. We estimate the age of NGC 2527 as ∼630 Myr, reddening as E (B − V) = 0.13 mag, and a distance of 642 ± 30 pc using PARSEC isochrones. We detect five sub-subgiants and five bandgap stars, which defy single star evolution. We estimate the temperature, mass, radius, and luminosity of 53 single stars and 10 potential binary stars using a python code that fits single and composite Kurucz spectra to broad-band spectral energy distribution. Among the 12 X-ray emitting members, we find that five are potential RS CVn-type binaries, two are potential FK Comae type of red giant branch (RGB) stars, and five are main sequence (MS) stars with high coronal activity. Members with strong UV emission comprise one RGB star and several MS stars with UV excess suggestive of chromospheric activity. Based on comparison with other clusters, we tentatively suggest that X-ray luminosity of both RS CVn and contact binaries increases with age, suggesting that more active binaries are present in older clusters as compared to younger clusters. This study suggests possible presence of W UMa and FK Comae-type stars in younger (age ≃ 630 Myr) clusters. [ABSTRACT FROM AUTHOR]

We report the analysis of simultaneous multiwavelength data of the high-energy-peaked blazar RGB J0710 + 591 from the Large Area X-ray Proportional Counters, Soft X-ray focusing Telescope, and Ultraviolet Imaging Telescope (UVIT) instruments onboard AstroSat. The wide band X-ray spectrum (0.35–30 keV) is modelled as synchrotron emission from a non-thermal distribution of high-energy electrons. The spectrum is unusually curved, with a curvature parameter βp ∼ 6.4 for a log parabola particle distribution, or a high-energy spectral index p 2 > 4.5 for a broken power-law distribution. The spectrum shows more curvature than an earlier quasi-simultaneous analysis of Swift– XRT/ Nu STAR data where the parameters were βp ∼ 2.2 or p 2 ∼ 4. It has long been known that a power-law electron distribution can be produced from a region where particles are accelerated under Fermi process and the radiative losses in acceleration site decide the maximum attainable Lorentz factor, γmax. Consequently, this quantity decides the energy at which the spectrum curves steeply. We show that such a distribution provides a more natural explanation for the AstroSat data as well as the earlier XRT/ Nu STAR observation, making this as the first well-constrained determination of the photon energy corresponding to γmax. This in turn provides an estimate of the acceleration time-scale as a function of magnetic field and Doppler factor. The UVIT observations are consistent with earlier optical/UV measurements and reconfirm that they plausibly correspond to a different radiative component than the one responsible for the X-ray emission. [ABSTRACT FROM AUTHOR]

We present optical photometric and spectroscopic observations, and an analysis of archival X-ray data of three polars: RX J0859.1+0537, RX J0749.1–0549, and RX J0649.8–0737. Optical light curves of these three polars reveal eclipse-like features that are deep, total, and variable in shape. The optical and X-ray modulations of RX J0859.1+0537, RX J0749.1–0549, and RX J0649.8–0737 are both found to occur at the orbital periods of 2.393 ± 0.003 h, 3.672 ± 0.001 h, and 4.347 ± 0.001 h, respectively. RX J0859.1+0537 is found to be a polar that lies in the region of the period gap, whereas RX J0749.1–0549 and RX J0649.8–0737 are found to be long-period polars above the period gap. The eclipse length is found to be 61 min for RX J0749.1–0549 in the R band, which is the highest among the long-period eclipsing polars. The radius of the eclipsed light source is found to be more than the actual size of the white dwarf for these three systems, indicating that the eclipsed component is not only the white dwarf but also appears to include the presence of an extended accretion region. Optical spectra of these systems show the presence of high-ionization emission lines along with the strong Balmer emission lines with an inverted Balmer decrement. Cyclotron harmonics are also detected in the optical spectra from which we infer magnetic field strength of the surface of the white dwarf to be 49 ± 2 MG, 43.5 ± 1.4 MG, and 44 ± 1 MG for RX J0859.1+0537, RX J0749.1–0549, and RX J0649.8–0737, respectively. [ABSTRACT FROM AUTHOR]

We report the results from analysis of six observations of Cygnus X-1 by Large Area X-ray Proportional Counter (LAXPC) and Soft X-ray Telescope (SXT) onboard AstroSat , when the source was in the hard spectral state as revealed by the broad-band spectra. The spectra obtained from all the observations can be described by a single-temperature Comptonizing region with disc and reflection components. The event mode data from LAXPC provides unprecedented energy dependent fractional root mean square (rms) and time-lag at different frequencies which we fit with empirical functions. We invoke a fluctuation propagation model for a simple geometry of a truncated disc with a hot inner region. Unlike other propagation models, the hard X-ray emission (>4 keV) is assumed to be from the hot inner disc by a single-temperature thermal Comptonization process. The fluctuations first cause a variation in the temperature of the truncated disc and then the temperature of the inner disc after a frequency dependent time delay. We find that the model can explain the energy dependent rms and time-lag at different frequencies. [ABSTRACT FROM AUTHOR]

Abstract: Aim: The aim of this study was to develop polymerase spiral reaction (PSR) for rapid, sensitive and specific detection of Brucella sp. Methods and Results: Polymerase spiral reaction assay was developed using specifically designed primers targeting the conserved multicopy IS711 gene of Brucella sp. The assay could be performed within 60 min at an isothermal temperature of 64°C. The lower limit of detection of PSR was 11·8 fg and conventional PCR was 1·18 pg of Brucella abortus genomic DNA. Thus, PSR was found to be 100‐fold more sensitive than conventional PCR and was comparable to real‐time PCR. The specificity of PSR was tested with other non‐Brucella bacteria and also with some bacterial and viral pathogens causing abortions. The assay was found to be specific as it did not detect any putative pathogens other than Brucella sp. Fifty‐six clinical samples suspected for brucellosis (aborted fetal stomach content) were screened with PSR to validate the applicability of the test to detect Brucella DNA. The same samples were also screened with conventional PCR and real‐time PCR. Of 56 samples, 25 samples were found to be positive with both PSR as well as real‐time PCR, whereas only 20 samples were found positive with conventional PCR. Conclusions: The results of this study indicated that the PSR assay is a simple, rapid, sensitive and specific method for the detection of Brucella sp. that may improve diagnostic potential in clinical laboratories or can be used at diagnostic laboratories with minimal infrastructure. Significance and Impact of the Study: The PSR assay, because of its simplicity and low cost, can be preferred to other molecular methods in the diagnosis of infectious diseases. [ABSTRACT FROM AUTHOR]

We present a multiwavelength temporal analysis of the blazar 3C 454.3 during the high ? -ray active period from May to December, 2014. Except for X-rays, the period is well sampled at near-infrared (NIR)-optical by the Small and Moderate Aperture Research Telescope System (SMARTS) facility, and the source is detected continuously on daily time-scale in the Fermi- Large Area Telescope γ-ray band. The source exhibits diverse levels of variability with many flaring/active states in the continuously sampled γ-ray light curve which are also reflected in the NIR-optical light curves and the sparsely sampled X-ray light curve by the Swift-XRT. Multiband correlation analysis of this continuous segment during different activity periods shows a change of state from no lags between IR and γ-ray, optical and γ-ray, and IR and optical to a state where γ-ray lags the IR/optical by ~3 d. The results are consistent with the previous studies of the same during various γ-ray flaring and active episodes of the source. This consistency, in turn, suggests an extended localized emission region with almost similar conditions during various γ-ray activity states. On the other hand, the delay of γ-ray with respect to IR/optical and a trend similar to IR/optical in X-rays along with strong broadband correlations favour magnetic field related origin with X-ray and γ-ray being inverse Comptonization of IR/optical photons and external radiation field, respectively. [ABSTRACT FROM AUTHOR]

We present an X-ray analysis of a 4 Gyr old open cluster, M67, using archival XMM-Newton data. The aim of this study was to find new X-ray members of M67, and to use the updated member list for studying X-ray variability, and derive the X-ray luminosity functions (XLFs) of different stellar types and compare them with other star clusters of similar age. We report the detection of X-ray emission from 25 members of M67, with membership based primarily on their proper motion, of which one X-ray source is a new member. Supplementing this study with previous ROSAT and Chandra studies of M67, and using the most recent proper motion study by Vereshchagin et al., we have compiled a revised list of X-ray emitting members of M67 consisting of 43 stars. 16 of these are known RS CVn type binaries having orbital periods < 10 d, and near-circular orbits, five are contact binaries with orbital periods < 6 h, five are yellow and blue stragglers, two are Algol-type binaries, and one source is a cataclysmic variable. 14 members do not have any orbital information and cannot be classified. 14 of the X-ray sources detected do not have any optical counterpart down to a magnitude of V ≃ 22, and their membership is uncertain. Finally, we report the XLFs of RS CVn type and other types of stars in M67 and compare them with other open clusters of intermediate-to-old age. [ABSTRACT FROM AUTHOR]

The γ-ray flare of PKS 1222+216, observed in 2010 June, is interpreted as an outcome of jet dynamics at recollimation zone. We obtained the γ-ray light curves in three different energy bands, namely 100–300 MeV, 300 MeV–1 GeV and 1–3 GeV from observations by the Fermi-LAT (Large Area Telescope). We also use the Swift-XRT (X-Ray Telescope) flux from 0.3–10 keV obtained from archival data. We supplement these with the 0.07–0.4 TeV observations with MAGIC (Major Atmospheric Gamma-ray Imaging Cherenkov) telescope, available in the literature. The detection of source at very high energy (E > 100 GeV) with a differential photon spectral index of 2.7 ± 0.3 and the rapid variability associated with it suggests that the emission arises from a compact region located beyond the broad line emitting region. The plausible γ-ray emission mechanism can then be inverse Compton scattering of IR photons from obscuring torus. Further, the decay time of LAT flare cannot be explained by considering simple radiative loss mechanisms. Hence, to interpret the LAT light curves, we develop a model where the broad-band emission originates from a compact region, arising plausibly from the compression of jet matter at the recollimation zone. The flare is then expressed as an outcome of jet deceleration probably associated with this focusing effect. Based on this model, the rise of the LAT flare is attributed to the opening of emission cone followed by the decay resulting from jet deceleration. The parameters of the model are further constrained by reproducing the broad-band spectral energy distribution of the source obtained during the flare episode. Our study suggests that the particle energy density exceeds magnetic energy density by a large factor which in turn may cause rapid expansion of the emission region. However, near equipartition can be achieved towards the end of LAT flare during which the compact emission region would have expanded to the size of jet cross-section. [ABSTRACT FROM AUTHOR]

ABSTRACT We present the analysis of archival X-ray data obtained with the XMM-Newton and Suzaku for a new intermediate polar identified as a counterpart of an INTEGRAL discovered γ-ray source, IGR J17195−4100. We report a new period of 1053.7 ± 12.2 s in X-rays. A new binary orbital period of 3.52 [ABSTRACT FROM AUTHOR]

ABSTRACT We present an analysis of seven flares detected from five RS CVn-type binaries (UZ Lib, σ Gem, λ And, V711 Tau and EI Eri) observed with XMM-Newton observatory. The quiescent state X-ray luminosities in the energy band of 0.3-10.0 keV of these stars were found to be 1030.7-30.9 erg s−1. The exponential decay time in all the sample of flares range from ∼1 to 8 h. The luminosity at peak of the flares in the energy band of 0.3-10.0 keV was found to be in the range of 1030.8-1031.8 erg s−1. The great sensitivity of the XMM-European Photon Imaging Camera instrument allowed us to perform time resolved spectral analysis during the flares and also in the subsequent quiescent phases. The derived metal abundances of coronal plasma were found to vary during the flares observed from σ Gem, V771 Tau and EI Eri. In these flares elemental abundances found to be enhanced by factors of ∼1.3-1.5 to the quiescent states. In most of the flares, the peak temperature was found to be more than 100 MK, whereas emission measure increased by factors of 1.5-5.5. Significant sustained heating was present in the majority of flares. The loop lengths ( L) derived for flaring structure were found to be in the order of 1010-11 cm and are smaller than the stellar radii ( R★), i.e. L/ R★≲ 1. The flare from σ Gem showed a high and variable absorption column density during the flare. [ABSTRACT FROM AUTHOR]

Using data from observations made with XMM–Newton, we present an X-ray analysis of two Wolf–Rayet (WR) binaries: V444 Cyg and CD Cru. The X-ray light curves show the phase-locked variability in both binaries, where the flux increased by a factor of ∼2 for V444 Cyg and ∼1.5 for CD Cru, from minimum to maximum. The maximum luminosities in the 0.3–7.5 keV energy band were found to be and for V444 Cyg and CD Cru, respectively. The X-ray spectra of these stars confirmed large extinction and revealed hot plasma with prominent emission-line features of highly ionized Ne, Mg, Si, S, Ar, Ca and Fe; these are found to be consistent with a two-temperature plasma model. At a temperature of ∼0.6 keV, the cooler plasma was found to be constant at all phases for both binaries, which could be the result of a distribution of small-scale shocks in radiation-driven outflows. The hot components in these binaries were found to be phase-dependent. They varied from 1.85 to 9.61 keV for V444 Cyg and from 1.63 to 4.27 keV for CD Cru. The absorption of the hard component varied with the orbital phase and was found to be maximum during the primary eclipse of V444 Cyg. The high plasma temperature and variability with orbital phase suggest that the hard-component emission is caused by a colliding wind shock between the binary components. [ABSTRACT FROM AUTHOR]

Using new CCD photometric observations and the archival infrared and X-ray data, we have carried out a multiwavelength study of a Perseus arm young open star cluster NGC 7419. An age of Myr and a distance of pc are derived for the cluster. Our photometric data indicate a higher value of colour excess ratio than the normal one. There is an evidence for mass segregation in this dynamically relaxed cluster and in the range , the mass function slope is in agreement with the Salpeter value. Excess emissions in near-infrared and Hα support the existence of a young (≤2 Myr) stellar population of Herbig Ae/Be stars indicating a second episode of star formation in the cluster region. Using XMM–Newton observations, we found several X-ray sources in the cluster region but none of the Herbig Ae/Be stars is detected in X-rays. We compare the distribution of upper limits for Herbig Ae/Be stars with the X-ray distribution functions of the T Tauri and the Herbig Ae/Be stars from previous studies, and found that the X-ray emission level of these Herbig Ae/Be stars is not more than , which is not significantly higher than for the T Tauri stars. Therefore, X-ray emission from Herbig Ae/Be stars could be the result of either unresolved companion stars or a process similar to T Tauri stars. We report an extended X-ray emission from the cluster region NGC 7419, with a total X-ray luminosity estimate of . If the extended emission is due to unresolved emission from the point sources then we estimate ∼288 T Tauri stars in the cluster region each having X-ray luminosity . Investigation of dust attenuation and12CO emission map of a square degree region around the cluster indicates the presence of a foreground dust cloud which is most likely associated with the local arm star-forming region (Sh2−154). This cloud harbours uniformly distributed pre-main-sequence stars , with no obvious trend of their distribution with either excess or . This suggests that the star formation in this cloud depend mostly upon the primordial fragmentation. [ABSTRACT FROM AUTHOR]

We present temporal and spectral characteristics of X-ray flares observed from six late-type G–K active dwarfs (V368 Cep, XI Boo, IM Vir, V471 Tau, CC Eri and EP Eri) using data from observations with the XMM–Newton observatory. All the stars were found to be flaring frequently and altogether a total of 17 flares were detected above the ‘quiescent’ state X-ray emission which varied from 0.5 to . The largest flare was observed in a low-activity dwarf XI Boo with a decay time of 10 ks and ratio of peak flare luminosity to ‘quiescent’ state luminosity of 2. We have studied the spectral changes during the flares by using colour–colour diagram and by detailed spectral analysis during the temporal evolution of the flares. The exponential decay of the X-ray light curves, and time evolution of the plasma temperature and emission measure are similar to those observed in compact solar flares. We have derived the semiloop lengths of flares based on the hydrodynamic flare model. The size of the flaring loops is found to be less than the stellar radius. The hydrodynamic flare decay analysis indicates the presence of sustained heating during the decay of most flares. [ABSTRACT FROM AUTHOR]

Background  Impetigo is a common skin infection, primarily caused by Staphylococcus aureus and mainly occurring in children. It is usually treated topically with antibiotics to achieve a quick cure and prevent spread of the infection. Worldwide, resistance rates of S. aureus against commonly used antibiotics are rising. Retapamulin belongs to a newly developed class of antibiotics for the treatment of uncomplicated skin infections. Objectives  Our aim was to compare the efficacy and safety of topical application of retapamulin ointment with topical placebo ointment in the treatment of primary impetigo. Methods  In a randomized, double-blind, multicentre study, patients received either topical retapamulin ointment 1% twice daily for 5 days or topical placebo. Patients were enrolled into the study for 14 days and attended the clinic for three visits during which clinical and laboratory evaluations were performed. Results  Two hundred and thirteen patients were randomized, with 139 evaluable patients in the retapamulin group and 71 in the placebo group. Based on the primary efficacy endpoint of clinical response after 7 days (intention to treat), retapamulin ointment was superior to placebo (success rate 85·6% vs. 52·1%; P < 0·0001). Similar results were found in the per protocol analysis and in the subgroup of patients who had a pathogen isolated at baseline. The most common adverse effect, pruritus at the application site, was reported by 6% and 1% of patients in the retapamulin and placebo groups, respectively. Conclusions  This study shows that topical retapamulin is effective and safe in the treatment of primary impetigo, offering a new treatment option. [ABSTRACT FROM AUTHOR]

•Background and Aims In the dry tropics, vegetative phenology varies widely with tree characteristics and soil conditions. The present work aims to document the phenological diversity of flowering and fruiting with reference to leafing events in Indian dry-tropical tree species.•Methods Nine tree species, including one leaf-exchanging and eight deciduous showing varying leafless periods, were studied. Monthly counts of leaves, flowers and fruits were made on 160 tagged twigs on ten individuals of each species for initiation, completion and duration of different phenological events through two annual cycles.•Key Results Variation in flowering relative to leaf flushing (which occurred just prior to or during a hot, dry summer) revealed five flowering types: summer flowering (on foliated shoots), rainy-season flowering (on foliated shoots following significant rains), autumn flowering (on shoots with mature leaves), winter flowering (on shoots undergoing leaf fall) and dry-season flowering (on leafless shoots). Duration of the fruiting phenophase was shortest (3–4 months) in dry-season and winter-flowering species, 6–9 months in rainy-and autumn-flowering species, and maximum (11 months) in summer-flowering species. A wide range of time lag (<1 to >8 months) between the start of vegetative (first-leaf flush) and reproductive (first-visible flower) phases was recorded in deciduous species; this time lag was correlated with the extent of the leafless period. A synthesis of available phenological information on 119 Indian tropical trees showed that summer-flowering species were most abundant (56 % of total species) amongst the five types recognized.•Conclusions The wide diversity of seasonal flowering and fruiting with linkages to leaf flush time and leafless period reflect the fact that variable reproductive and survival strategies evolved in tree species under a monsoonic bioclimate. Flowering periodicity has evolved as an adaptation to an annual leafless period and the time required for the fruit to develop. The direct relationship between leafless period (inverse of growing period) and time lag between onset of vegetative and reproductive phases reflects the partitioning of resource use for supporting these phases. Predominance of summer flowering coupled with summer leaf flushing seems to be a unique adaptation in trees to survive under a strongly seasonal tropical climate. [ABSTRACT FROM AUTHOR]

In order to study systematically the soft X-ray emission of active galactic nuclei (AGNs) at medium to high redshifts, we have analysed ROSAT PSPC and HRI data of QSOs at 0.26 ≤ z ≤ 3.43 selected from the second deepest ROSAT PSPC survey carried out in 19911993 by McHardy et al. Our sample of 22 type 1 QSOs is nearly complete above a flux limit of 1.4 × 10[sup -14] erg cm[sup -2] s[sup -1] in the 0.1-2 keV band. Of these, nine QSOs show long-term (∼2 yr) X-ray variability by a factor of 1.5-3.5. Significant excess absorption above the Galactic column is seen in three QSOs. The soft X-ray photon index of the QSOs ranges from 1.4 to 3.7. Three QSOs have steep soft X-ray spectra (Γ[sub X] > 3.0), one of which is a narrow-line QSO a high-luminosity version of narrow-line Seyfert 1 galaxies. The average photon index (〈Γ[sub X]〉) is 2.40 ± 0.09 (with a dispersion of 0.57) in the 0.1-2 keV band. The average QSO spectra in four redshift bins flatten from an average photon index of 〈Γ[sub X]〉 ∼ 2.53 at 0.25 ≤ z ≤ 1 to 〈Γ[sub X]〉 ∼ 2 at 2 ≤ z ≤ 3.4. The flattening of the average photon index can be understood in terms of the redshift effect of the mean intrinsic QSO spectrum consisting of two components — a soft X-ray excess and a power-law component. We have also studied optical spectra of 12 of the 22 QSOs. [ABSTRACT FROM AUTHOR]

Embryonic stem cells derived from various derivatives of the murine 129/J strain are commonly used in the generation of knockout mice. Topical twice-weekly treatment of the 129/SvEv subline with either 2 or 5 microg of 12-O-tetradecanoylphorbol-13-acetate (TPA) for 4 weeks resulted in a sustained inflammation and hyperplasia. Identically treated C57BL/6 mice developed weaker inflammatory and hyperplastic responses over the same treatment course, and did not exhibit a sustained hyperplasia. SSIN mice treated with either 0.5 or 2 microg of TPA developed a sustained hyperplasia comparable to that seen in 129/SvEv mice, but a weak inflammatory response. Myeloperoxidase (MPO) measurements indicated dramatic infiltrations of the skins of all three murine strains by neutrophils within 48 h of a single TPA application. MPO activities remained significantly elevated in the skins of 129/SvEv mice and C57BL/6 mice following eight TPA treatments. In contrast, MPO activities in 8 X treated SSIN skins were comparable to those measured in solvent controls. 129/SvEv mice readily developed papillomas in two-stage skin carcinogenesis protocols employing DMBA as the initiator and TPA as the promoter. Papilloma incidences and multiplicities were dose-responsive with respect to promoter (using twice weekly applications of 1, 2 or 5 microg of TPA). With a promoting dose of 5 microg of TPA > or = 90% of the mice developed papillomas within 13 weeks, and maximum tumor multiplicities were reached within 18 weeks. These latter results, when compared to the published responses of other murine stocks and strains, demonstrate that 129/SvEv mice are very sensitive to TPA promotion in two-stage skin carcinogenesis protocols. [ABSTRACT FROM PUBLISHER]