Hot Wind Research Articles

The condensation of the corona for the correlation between the hard X-ray photon index Γ and the reflection scaling factor ℜ in active galactic nuclei

Observationally, it is found that there is a strong correlation between the hard X-ray photon index $\Gamma$ and the Compton reflection scaling factor $\Re$ in active galactic nuclei. In this paper, we propose that the $\Gamma-\Re$ correlation can be explained within the framework of the condensation of the hot corona onto the cold accretion disc around a supermassive black hole. In the model, it is presumed that, initially, a vertically extended hot gas (corona) is supplied to the central supermassive black hole by capturing the interstellar medium and stellar wind. In this scenario, when the initial mass accretion rate $\dot M/ \dot M_{\rm Edd} \gtrsim 0.01$, at a critical radius $r_{\rm d}$, part of the hot gas begins to condense onto the equatorial disc plane of the black hole, forming an inner cold accretion disc. Then the matter is accreted in the form of the disc-corona structure extending down to the innermost stable circular orbits of the black hole. The size of the inner disc is determined by the initial mass accretion rate. With the increase of the initial mass accretion rate, the size of the inner disc increases, which results in both the increase of the Compton reflection scaling factor $\Re$ and the increase of the hard X-ray photon index $\Gamma$. By comparing with a sample of Seyfert galaxies with well-fitted X-ray spectra, it is found that our model can roughly explain the observations. Finally, we discuss the possibility to apply our model to high mass X-ray binaries, which are believed to be fueled by the hot wind from the companion star.

HYDRODYNAMICAL COUPLING OF MASS AND MOMENTUM IN MULTIPHASE GALACTIC WINDS

Using a set of high resolution hydrodynamical simulations run with the Cholla code, we investigate how mass and momentum couple to the multiphase components of galactic winds. The simulations model the interaction between a hot wind driven by supernova explosions and a cooler, denser cloud of interstellar or circumgalactic media. By resolving scales of $\Delta x<0.1$ pc over $>100$ pc distances our calculations capture how the cloud disruption leads to a distribution of densities and temperatures in the resulting multiphase outflow, and quantify the mass and momentum associated with each phase. We find the multiphase wind contains comparable mass and momenta in phases over a wide range of densities and temperatures extending from the hot wind ($n \approx 10^{-2.5}$ $\mathrm{cm}^{-3}$, $T \approx 10^{6.5}$ K) to the coldest components ($n \approx 10^2$ $\mathrm{cm}^{-3}$, $T \approx 10^2$ K). We further find that the momentum distributes roughly in proportion to the mass in each phase, and the mass-loading of the hot phase by the destruction of cold, dense material is an efficient process. These results provide new insight into the physical origin of observed multiphase galactic outflows, and inform galaxy formation models that include coarser treatments of galactic winds. Our results confirm that cool gas observed in outflows at large distances from the galaxy ($\gtrsim1$kpc) likely does not originate through the entrainment of cold material near the central starburst.

From APOCALIPSIXTLÁN: A DYSTOPIAN LONG POEM

from APOCALIPSIXTLÁN: A DYSTOPIAN LONG POEM Rigoberto González (bio) There’s a woman who squats on the sand the color of midnight, we don’t dare call itash. Instead, we marvel at how midnight comes and the woman appears to floatlike a boat. Her white tunic a sail blowing with the hot winds from the north, whereit is rumored water still flows. We know about boats, we broke them down to bones—a mercy killing. Since they wailed the loudest in the drought they had to be the first to go. We tossed the priests into the fire pit next for filling us with false hope. And thenthe politicians for telling us their lies. They told the truth finally but much too late tochange our minds about burning them alive. We tossed the teachers and the scholarsinside the barren wells, then dropped their wretched books on top of them and watchedthe pages swell with piss and sweat. Steam hissed as they cooked beneath the bubbling paper. We heard them boil and blister day and night until their bodies softened into mushand then hardened once again like plaster— a pool turned frieze with jaws and fingersjutting out. Those who held such wisdom and refused to use it were the guiltiest of all,and thus they earned the cruelest penance: to melt into the pulp of what they prizedthe most—worthless words, incompetent ideas. Despite our better judgment, we let the poet [End Page 26] live though with his mouth sewn shut. He alone keeps the story of our insurrection. Eachnight before we sleep we whisper in his ear our precious secrets and stick a pin into his fleshto keep them safe in case we die. If we awake we repossess what’s ours by pulling all the needles out.His eyes dart left and right in panic during visitations. We scurry down the dunes on firelike a colony of scorpions. We are legion. We are condemnation—promise land turned purgatory. [End Page 27] Rigoberto González Rigoberto González, a multifaceted creative writer, is author of four books of poems: Unpeopled Eden (Four Way Books, 2013), Black Blossoms (Four Way Books, 2011), Other Fugitives and Other Strangers (Tupelo Press, 2006), and So Often the Pitcher Goes to Water Until It Breaks (University of Illinois Press, 1999). His numerous other books include such novels and nonfiction prose as The Mariposa Club trilogy, Butterfly Boy: Memories of a Chicano Mariposa, and Red-Inked Retablos: Essays. The Lenore Marshall Poetry Prize, American Book Award, Guggenheim Fellowship, the 2014 USA Rolón Fellowship, and the Bill Whitehead Award for Lifetime Achievement (The Publishing Triangle) are some of the honors his work has garnered for him. He is Professor of English at Rutgers University, Newark, NJ, and a member of the Executive Board of Directors of the National Book Critics Circle. Copyright © 2018 Johns Hopkins University Press

高効率空気熱源ヒートポンプ式熱風発生装置 “熱 Pu-ton”の開発

高効率空気熱源ヒートポンプ式熱風発生装置 “熱 Pu-ton”の開発

Invisible War

WORLDLIT.ORG 23 gentlemen, please excuse the inconvenience, but this young lady is a foreigner, she doesn’t have papers, and we will not move until she gets off of the bus. The murmurs grow. The driver kills the motor. Without the air-conditioning a light, hot wind enters. The woman in seat twelve approaches and the nervous and hysteric woman insists, dragging her s’s, that she is not a foreigner. Listen, don’t cause problems for us. We still have ten hours to go. We want to get there, too. But she keeps screaming that she won’t get off and then Elena gets up, joins them, and asks her to show her ID. The officer approaches them. Too late. She should sit down before the man arrives. Too late. His enormous gold watch shines when it passes before her eyes as he reaches for the foreigner’s ID. Stupid. Stupid, naïve idiot. An incautious woman is a poor imitation of a female. She hates her. She hates all the bitches who spend their money on bad replicas of voter IDs or birth certificates. She realizes that she’s the stupid one here. She should sit down and shut up. Close her eyes and let the stupid cow figure it out on her own. Turn her back and head to her seat. One second of imprudence could bring it all tumbling down. The officer’s voice is tense. Isolated babblings from around the bus demand that the woman get off and quit resisting. It’s fake, officer, the ID is fake, Elena finally blurts out, first with fear, then with the security that she couldn’t have made a better choice because no one can doubt her now. She’s released her voice with fury and burden. She turns her back on them. The officer yanks on the woman and, struggling, they both descend from the darkness of the aisle into the asphyxiating night. An empty spot remains. Elena could change seats. Stretch her legs and fall asleep with the weakness she carries in her skin. She settles in. Out the window she observes the three men and two women, in line, awaiting interrogation. She would like to have an affair with an officer. Their height attracts her. Not to mention the badge. Her hair is poorly cut and she’s a little overweight, but that, too, was pure strategy. Guats, lazy asses, stupid sheep, she says to herself, letting her barrio talk escape. She’s at peace. Some are left behind, others simply continue. This world is for the clever. And the fortunate. Surely the most difficult part of the night has passed. She moves her head. There’s no reason to be nervous. She’s practically Mexican. Four more years in Mexico and she won’t have to move. She wants to go to Juárez, no further. Once again the rattle of the motor rises, almost licking her legs. The bus’s lights advance, cutting a swath in the night, slashing it, revealing, along with the sun, the ordinariness of things. We’ll see what happens tomorrow, she thinks, yawning. Translation from the Spanish By Julie Ann Ward Editorial note: From Barcos en Houston © 2005 by Nadia Villafuerte. English translation copyright © 2017 by Julie Ann Ward. Invisible War by Gábor Schein Glints of the tram. The nondescript houses dream numb underwater dreams. Faces are transparent bubbles popping off from the windows where water used to break through. The pedestrians crossing to the other side of the street drag heavy years in their shopping bags. Better to forget them. Some ended up on the hook of a quick death. Some merely fell ill and when they healed, let ivy run over the balcony railings and grew flowers in a case. While continuing to write, on and off, less and less. The screech of brakes can’t wake you now from sleep. Cartilage calcifies, an uninhabitable archipelago sediments on the frontal lobe. And nothing can dull the metronome beats of fear. The tram gets stuck on an octagonal square. The passengers scream and bang the doors. No help in sight. They’re slowly overgrown by...

Hot planetary winds near a star: dynamics, wind–wind interactions, and observational signatures

Signatures of "evaporative" winds from exo-planets on short (hot) orbits around their host star have been observed in a number of systems. In this paper we present global AMR simulations that track the launching of the winds, their expansion through the circumstellar environment, and their interaction with a stellar wind. We focus on purely hydrodynamic flows including the anisotropy of the wind launching and explore the orbital/fluid dynamics of the resulting flows in detail. In particular we find that a combination of the tidal and Coriolis forces strongly distorts the planetary "Parker" wind creating "up-orbit" and "down-orbit" streams. We characterize the flows in terms of their orbital elements which change depending on their launch position on the planet. We find that the anisotropy in the atmospheric temperature leads to significant backflow on to the planet. The planetary wind interacts strongly with the stellar wind creating instabilities that cause eventual deposition of planetary gas onto the star. We present synthetic observations of both transit and absorption line-structure for our simulations. For our initial conditions, we find that the orbiting wind material produces absorption signatures at significant distances from the planet and substantial orbit to orbit variability. Ly-{\alpha} absorption shows red and blueshifted features out to 70 km/s. Finally, using semi-analytic models we constrain the effect of radiation pressure, given the approximation of uniform stellar absorption.

THE LINK BETWEEN RARE-EARTH PEAK FORMATION AND THE ASTROPHYSICAL SITE OF THE R PROCESS

ABSTRACT The primary astrophysical source of the rare-earth elements is the rapid neutron capture process (r process). The rare-earth peak that is seen in the solar r-process residuals has been proposed to originate as a pile-up of nuclei during the end of the r process. We introduce a new method utilizing Monte Carlo studies of nuclear masses in the rare-earth region, that includes self-consistently adjusting β-decay rates and neutron capture rates, to find the mass surfaces necessary for the formation of the rare-earth peak. We demonstrate our method with two types of astrophysical scenario, one corresponding to conditions typical of hot winds from core-collapse supernovae and stellar-mass accretion disks, and one corresponding to conditions typical of the ejection of the material from the tidal tails of neutron star mergers. In each type of astrophysical condition, this method successfully locates a region of enhanced stability in the mass surface that is responsible for the rare-earth peak. For each scenario, we find that the change in the mass surface has qualitatively different features, thus future measurements can shed light on the type of environment in which the r process occurred.

What tree rings can tell us about the competition between trees and lianas? A case study based on growth, anatomy, density, and carbon accumulation

In tropical forest, landscape fragmentation and the consequent degradation of disturbed forests increase the incidence of light and dry hot winds, causing a disturbance on natural regeneration. Under these conditions, lianas (woody vines) development is stimulated instead of other species, which are more suited to mature forest and under less influence of the edge effect. For this, lianas colonization is an important variable for assessing the disturbance level of a forest. In this context, it becomes important to understand the nature of the competitive relationships between hyper-abundant lianas and ring growth of the host trees. Here, we selected trees with occupation or absence of lianas from two tropical species – Pinus caribaea var. hondurensis (Caribbean pine) and Tectona grandis (teak) – localized in a semideciduous forest fragment in southeastern Brazil, aiming to compare growth, climatic response, anatomy (vessels and intra-annual density fluctuations), wood density and carbon, by tree-ring analysis. The results showed that the lianas caused a change in tree-ring anatomy of host trees in last 10 years, mainly. We observed that trees occupied by lianas had a decrease the radial growth and carbon in the two species, an increase of the vessels size in teak and a decrease of the IADF frequency in Caribbean pine. In teak, the climate-tree relationship indicated that trees with lianas had lower response to rainfall and higher response to temperature in the summer (rainy and hottest period); in Caribbean pine, we observed that trees with lianas had a 2-month delay in the radial growth response to rainfall in the dry season. In the teak group, we observed that host trees had higher wood density values than liana-free tree in the outer rings, and the opposite was showed for pine. These findings show that tree-ring growth of host trees are a strong bioindicator of forest disturbance caused by aggressive colonization of lianas. We believe that these methods are applicable to future studies relating to the effects of habitat fragmentation and forest degradation on biodiversity and ecosystem services, particularly in the context of global climate change.

Blade-coated sol-gel indium-gallium-zinc-oxide for inverted polymer solar cell

The inverted organic solar cell was fabricated by using sol-gel indium-gallium-zinc-oxide (IGZO) as the electron-transport layer. The IGZO precursor solution was deposited by blade coating with simultaneous substrate heating at 120 °C from the bottom and hot wind from above. Uniform IGZO film of around 30 nm was formed after annealing at 400 °C. Using the blend of low band-gap polymer poly[(4,8-bis-(2-ethylhexyloxy)-benzo(1,2-b:4,5-b’)dithiophene)-2,6-diyl-alt- (4-(2-ethylhexanoyl)-thieno [3,4-b]thiophene-)-2-6-diyl)] (PBDTTT-C-T) and [6,6]-Phenyl C71 butyric acid methyl ester ([70]PCBM) as the active layer for the inverted organic solar cell, an efficiency of 6.2% was achieved with a blade speed of 180 mm/s for the IGZO. The efficiency of the inverted organic solar cells was found to depend on the coating speed of the IGZO films, which was attributed to the change in the concentration of surface OH groups. Compared to organic solar cells of conventional structure using PBDTTT-C-T: [70]PCBM as active layer, the inverted organic solar cells showed significant improvement in thermal stability. In addition, the chemical composition, as well as the work function of the IGZO film at the surface and inside can be tuned by the blade speed, which may find applications in other areas like thin-film transistors.

Clumping in stellar winds and interiors

AbstractThe uncertain clumping properties pose a major problem for the quantitative analysis and the modelling of hot star winds. New results suggest that also the outer envelopes of massive stars may be affected by clumping, with important consequences for their observable radii and ionising properties. In this talk I will discuss how clumping is incorporated in stellar interior and wind/atmosphere models, how current theoretical results compare with observations, and what we can learn from a combination of stellar interior models and winds.

Investigating the Magnetospheres of Rapidly Rotating B-type Stars

AbstractRecent spectropolarimetric surveys of bright, hot stars have found that ~10% of OB-type stars contain strong (mostly dipolar) surface magnetic fields (~kG). The prominent paradigm describing the interaction between the stellar winds and the surface magnetic field is the magnetically confined wind shock (MCWS) model. In this model, the stellar wind plasma is forced to move along the closed field loops of the magnetic field, colliding at the magnetic equator, and creating a shock. As the shocked material cools radiatively it will emit X-rays. Therefore, X-ray spectroscopy is a key tool in detecting and characterizing the hot wind material confined by the magnetic fields of these stars. Some B-type stars are found to have very short rotational periods. The effects of the rapid rotation on the X-ray production within the magnetosphere have yet to be explored in detail. The added centrifugal force due to rapid rotation is predicted to cause faster wind outflows along the field lines, leading to higher shock temperatures and harder X-rays. However, this is not observed in all rapidly rotating magnetic B-type stars. In order to address this from a theoretical point of view, we use the X-ray Analytical Dynamical Magnetosphere (XADM) model, originally developed for slow rotators, with an implementation of new rapid rotational physics. Using X-ray spectroscopy from ESA’s XMM-Newton space telescope, we observed 5 rapidly rotating B-types stars to add to the previous list of observations. Comparing the observed X-ray luminosity and hardness ratio to that predicted by the XADM allows us to determine the role the added centrifugal force plays in the magnetospheric X-ray emission of these stars.

Loop thermosiphon as a feasible cooling method for the stators of gas turbine

A stator sample of a gas turbine was developed with loop thermosiphon structure to seek a feasible cooling method for high-temperature stators of gas turbine. The sample was comprised by 8 hollow vanes and a cooling tube. Its inner space was filled by sodium-potassium alloy (Na-K) to become a loop thermosiphon stator sample (LTSS). The thermosiphon structure could transfer the heat from the hot surfaces of the vanes heated by the high-temperature gas mainstream to its own cooling tube, which would be blown by the cold air in the external duct of a gas turbine. Heatproof ability of the LTSS was experimented at 1230°C in a hot wind tunnel to judge whether loop thermosiphon is a feasible cooling method. Results indicated the average wall temperature of 8 vanes was about 340°C lower than 1230°C.

E-MERLIN 21 cm constraints on the mass-loss rates of OB stars in Cyg OB2

We present e-MERLIN 21 cm (L-band) observations of single luminous OB stars in the Cygnus OB2 association, from the COBRaS Legacy programme. The radio observations potentially offer the most straightforward, least model-dependent, determinations of mass-loss rates, and can be used to help resolve current discrepancies in mass-loss rates via clumped and structured hot star winds. We report here that the 21 cm flux densities of O3 to O6 supergiant and giant stars are less than ~ 70 microJy. These fluxes may be translated to `smooth' wind mass-loss upper limits of ~ 4.4 - 4.8 x 10^(-6) M_sol/yr for O3 supergiants and < 2.9 x 10^(-6) M_sol/yr for B0 to B1 supergiants. The first ever resolved 21 cm detections of the hypergiant (and LBV candidate) Cyg OB2 #12 are discussed; for multiple observations separated by 14 days, we detect a ~ 69% increase in its flux density. Our constraints on the upper limits for the mass-loss rates of evolved OB stars in Cyg OB2 support the model that the inner wind region close to the stellar surface (where Halpha forms) is more clumped than the very extended geometric region sampled by our radio observations.

Conjugate heat transfer investigation on the cooling performance of air cooled turbine blade with thermal barrier coating

A hot wind tunnel of annular cascade test rig is established for measuring temperature distribution on a real gas turbine blade surface with infrared camera. Besides, conjugate heat transfer numerical simulation is performed to obtain cooling efficiency distribution on both blade substrate surface and coating surface for comparison. The effect of thermal barrier coating on the overall cooling performance for blades is compared under varied mass flow rate of coolant, and spatial difference is also discussed. Results indicate that the cooling efficiency in the leading edge and trailing edge areas of the blade is the lowest. The cooling performance is not only influenced by the internal cooling structures layout inside the blade but also by the flow condition of the mainstream in the external cascade path. Thermal barrier effects of the coating vary at different regions of the blade surface, where higher internal cooling performance exists, more effective the thermal barrier will be, which means the thermal protection effect of coatings is remarkable in these regions. At the designed mass flow ratio condition, the cooling efficiency on the pressure side varies by 0.13 for the coating surface and substrate surface, while this value is 0.09 on the suction side.

Optimization Analysis on Distribution of Temperature of a Corn Based on Fluent

Traditional method of drying corn is using higher temperature to dry quickly. But high drying temperature can make the corn lost nutrients. Provide the foundation of designing a new corn drier which can dry corn efficient as well as sustain nutrition.Optimization analysis on distribution of temperature of a corn by Fluent. It shows that:1).Hot winds is 0.8m/s，temperature is 343K. Temperature distributions of corn is evenlier. The highest temperature is below 333K.2).More fluid inlet make corn evenlier. Change the angle between corn and velocity vector will not impact the temperature distributions of corn.

Heat wave over India during summer 2015: an assessment of real time extended range forecast

Hot winds are the marked feature of summer season in India during late spring preceding the climatological onset of the monsoon season in June. Some years the conditions becomes very vulnerable with the maximum temperature (T max) exceeding 45 °C for many days over parts of north-western, eastern coastal states of India and Indo-Gangetic plain. During summer of 2015 (late May to early June) eastern coastal states, central and northwestern parts of India experienced severe heat wave conditions leading to loss of thousands of human life in extreme high temperature conditions. It is not only the loss of human life but also the animals and birds were very vulnerable to this extreme heat wave conditions. In this study, an attempt is made to assess the performance of real time extended range forecast (forecast up to 3 weeks) of this scorching T max based on the NCEP’s Climate Forecast System (CFS) latest version coupled model (CFSv2). The heat wave condition was very severe during the week from 22 to 28 May with subsequent week from 29 May to 4 June also witnessed high T max over many parts of central India including eastern coastal states of India. The 8 ensemble members of operational CFSv2 model are used once in a week to prepare the weekly bias corrected deterministic (ensemble mean) T max forecast for 3 weeks valid from Friday to Thursday coinciding with the heat wave periods of 2015. Using the 8 ensemble members separately and the CFSv2 corresponding hindcast climatology the probability of above and below normal T max is also prepared for the same 3 weeks. The real time deterministic and probabilistic forecasts did indicate impending heat wave over many parts of India during late May and early June of 2015 associated with strong northwesterly wind over main land mass of India, delaying the sea breeze, leading to heat waves over eastern coastal regions of India. Thus, the capability of coupled model in providing early warning of such killer heat wave can be very useful to the disaster managers to take appropriate actions to minimize the loss of life and property due to such high T max.

Approaches to the development of durum wheat cultivars (Triticum durum Desf.) with a wide variability of the growth season

Differentiation in the duration of the growth season is an inherent and, in many respects, decisive factor of the task-oriented formation of the cultivar pool in the region. This is because one cannot develop a universal cultivar that would be equally effective in utilization of environmental resources and equally responsive to precipitation at different stages of plant growth, to temperature backgrounds, and to the hot wind pattern. That is why the aim of the research was to find ways to extend the range of parameters of the durum wheat growth season in the Middle Volga region. Experiments were conducted to study the effects of Vrn genes (1, 2) on the structure and duration of the growth season. The chief parameters of the integral production processes were determined with regard to the early ripening. The formation of the yield components and the parameters of the growth season were tested in Harman’s system of principal components in the context of cultivar adaptability. The experiments showed the following results. (1) The diversity of durum wheat in early ripening in the Middle Volga region was determined by the predominance of genetic systems other than the system of Vrn genes. (2) Mid-ripening and mid–late genotypes had higher productivity potentials compared to early-ripening ones. In the climatic conditions of the Middle Volga region, it was due to the production of a large foliage surface and photosynthetic potential. (3) The duration of the emergence–heading time span was greatly influenced by the interaction of the cultivar–air temperature. Opposing responses were recorded in cultivars of different ecological and geographic origins, and this should be taken into account in breeding programs. (4) The strongest correlation of the yield components and duration of the growth season was observed in groups of nonadapted genotypes. (5) The variation limits of the durum wheat growth season in the Middle Volga region can be extended mainly due to the late-ripening components of cultivar pools.

Investigation of the environment around close-in transiting exoplanets using cloudy

It has been suggested that hot stellar wind gas in a bow shock around an exoplanet is sufficiently opaque to absorb stellar photons and give rise to an observable transit depth at optical and UV wavelengths. In the first part of this paper, we use the CLOUDY plasma simulation code to model the absorption from X-ray to radio wavelengths by 1-D slabs of gas in coronal equilibrium with varying densities ($10^{4}-10^{8} \, {\rm cm^{-3}}$) and temperatures ($2000-10^{6} \ {\rm K}$) illuminated by a solar spectrum. For slabs at coronal temperatures ($10^{6} \ {\rm K}$) and densities even orders of magnitude larger than expected for the compressed stellar wind ($10^{4}-10^{5} \, {\rm cm^{-3}}$), we find optical depths orders of magnitude too small ($> 3\times10^{-7}$) to explain the $\sim3\%$ UV transit depths seen with Hubble. Using this result and our modeling of slabs with lower temperatures ($2000-10^4 {\rm K}$), the conclusion is that the UV transits of WASP-12b and HD 189733b are likely due to atoms originating in the planet, as the stellar wind is too highly ionized. A corollary of this result is that transport of neutral atoms from the denser planetary atmosphere outward must be a primary consideration when constructing physical models. In the second part of this paper, additional calculations using CLOUDY are carried out to model a slab of planetary gas in radiative and thermal equilibrium with the stellar radiation field. Promising sources of opacity from the X-ray to radio wavelengths are discussed, some of which are not yet observed.

SGR A* AND ITS ENVIRONMENT: LOW-MASS STAR FORMATION, THE ORIGIN OF X-RAY GAS AND COLLIMATED OUTFLOW

ABSTRACT We present high-resolution multiwavelength radio continuum images of the region within 150″ of Sgr A*, revealing a number of new extended features and stellar sources in this region. First, we detect a continuous 2″ east–west ridge of radio emission, linking Sgr A* and a cluster of stars associated with IRS 13 N and IRS 13E. The ridge suggests that an outflow of east–west blob-like structures is emerging from Sgr A*. In particular, we find arc-like radio structures within the ridge with morphologies suggestive of photoevaporative protoplanetary disks. We use infrared K s and L′ fluxes to show that the emission has similar characteristics to those of a protoplanetary disk irradiated by the intense radiation field at the Galactic center. This suggests that star formation has taken place within the S-cluster 2″ from Sgr A*. We suggest that the diffuse X-ray emission associated with Sgr A* is due to an expanding hot wind produced by the mass loss from B-type main sequence stars, and/or the disks of photoevaporation of low mass young stellar objects (YSOs) at a rate of ∼10−6 M &CircleDot; ?> yr−1. The proposed model naturally reduces the inferred accretion rate and is an alternative to the inflow–outflow style models to explain the underluminous nature of Sgr A*. Second, on a scale of 5″ from Sgr A*, we detect new cometary radio and infrared sources at a position angle PA ∼ 50° which is similar to that of two other cometary sources X3 and X7, all of which face Sgr A*. In addition, we detect a striking tower of radio emission at a PA ∼ 50°–60° along the major axis of the Sgr A East supernova remnant shell on a scale of 150″ from Sgr A*. We suggest that the cometary sources and the tower feature are tracing interaction sites of a mildly relativistic jet from Sgr A* with the atmosphere of stars and the nonthermal Sgr A East shell at a PA ∼ 50°–60° with M &DiacriticalDot; &sim; 1 &times; 10 &minus; 7 M &CircleDot; yr - 1 ?> , and opening angle 10°. Lastly, we suggest that the east–west ridge of radio emission traces an outflow that is potentially associated with past flaring activity from Sgr A*. The position angle of the outflow driven by flaring activity is close to −90°.

Human thermal perception related to Föhn winds due to Saharan dust outbreaks in Crete Island, Greece

Crete Island is located in the southmost border of East Mediterranean basin, facing exacerbating atmospheric conditions (mainly concentrations of particulates) due to Saharan dust outbreaks. It is worth to note that these episodes are more frequent during spring and autumn, when mild biometeorological conditions become intolerable due to the synergy of the so called Fohn winds. Cretan mountains, especially Psiloritis Mt. (summit at 2456 m), are orientated perpendicularly to the southwest air mass flow, generating the Fohn winds. Propagating from the leeward of the mountains, these dry, hot winds have an effect on prevailing biometeorological conditions. While descending to the lowlands on the leeward side of the range, the wind becomes strong, gusty, and desiccating. This wind often lasts less than an hour to several days, with gradual weakening after the first or the second day. Sometimes, it stops very abruptly. In this work, the authors examined and analyzed the abrupt changes of human thermal perception within specific case studies during which Fohn winds appeared in Heraklion city at the leeward of Psiloritis Mt, associated with extreme Saharan dust episodes, observed within the period 2006–2010. In order to verify the development of Fohn winds, Meteorological Terminal Aviation Routine Weather Reports (METARs, meteorological observations every half hour), were acquired from the Heraklion meteorological station installed by the Hellenic National Meteorological Service (HNMS). The biometeorological conditions analyzed are based on human thermal bioclimatic indices such as the Physiologically equivalent temperature (PET) and the Universal Thermal Climate Index (UTCI). METAR recordings of meteorological variables, such as air temperature, vapor pressure, wind speed, and cloudiness, were used as input variables in modeling the aforementioned thermal indices, so that to interpret the grade of the thermo-physiological stress. The PET and UTCI analysis was performed by the use of the radiation and bioclimate model, “RayMan,” which is well-suited to calculate radiation fluxes and human biometeorological indices. The results of the performed analysis showed even an increase of air temperature from 20 to 30 °C within 5 h, associated with a decrease in the vapor pressure from 11.5 to 9.3 hPa. In addition, the wind speed at 10 m increased from 5.1 to 20.1 m/s, 3.7 to 14.3 m/s with respect to 1.1 m height, during the events of Fohn winds. The biometeorological analysis has given evidence that slight/moderate heat stress classes of the examined thermal indices appear during Saharan dust episodes. Such conditions are uncommon at the beginning of spring season, indicating that Saharan dust episodes are not only responsible for acute health impacts but also for adverse biometeorological conditions, due to the very likely development of Fohn winds towards the wider area of Heraklion, a coastal city in the eastern Mediterranean.