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The severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) presents clinical manifestations similar to the influenza, severe acute respiratory syndrome (SARS-CoV), and Middle East respiratory syndrome (MERS-CoV). However, in the course of the coronavirus disease 2019 (COVID-19), various pathological complications of high clinical significance have remained unknown. Impaired blood supply to the visceral vascular system can cause serious life-threatening acute damage. We report a case of extensive acute mesenteric ischemia associated with SARS-CoV-2 infection confirmed in a patient hospitalized in Amin Hospital – a COVID-19 referral center in Isfahan University of Medical Sciences, Isfahan, Iran. This case highlights the importance of paying attention to serious and less common or less known clinical manifestations other than fever, dry cough, dyspnea, and myalgia.

Background and Objective: Workplace air quality is a very important factor in community health, which is measured using airborne contaminants evaluation and measurement. One of these airborne pollutants in industries is ammonia gas. Spray towers are important components of air pollution control. This study aimed to investigate the effects of dilute sulfuric acid solution on the efficiency of ammonia removal in a spray tower. Materials and Methods: This study evaluated the rate of ammonia removal from the air stream using a spray tower with laboratory criterion by altering the liquid pressure and nozzles, as well as the inlet density. The volume o f the used airstream was 3737.82 l/min; moreover, one, two, and three 20 -micron diameter nozzles were used with the dilute sulfuric acid solution. The data were analyzed in SPSS software (version 21) through one-way ANOVA. Results: An increase in the number of nozzles and washing liquid pressure of the spray tower increased the ammonia removal efficiency and enhanced the input load of the system which reduced the elimination efficiency (P

Introduction: One of the major factors that affect the employees' health and productivity in industries is the air quality of work environments. One of these pollutants is ammonia gas, which is very important from an economic and environmental points of view. Therefore, this study aimed to investigate the effect of using acidic water compound on the removal efficiency of air ammonia in a spray tower. Methods: In this study, airflow was provided by variable ventilation and water pressure through a class electropump. The rate of ammonia removal from the air stream was investigated by a spray tower with changes in water pressure, inlet gas density, and number of nozzles. For this purpose, at different inlet densities, different liquid pressures and different nozzles with water washing liquid with 0.01 mM sulfuric acid were used as the washing liquid. Results: Increased number of nozzles from one to three had a significant effect on ammonia removal (P-Value = 0.021). Increase of the inlet ammonia gas density from 24.1 to 68 parts per million significantly reduced the efficiency (P-Value = 0.058). Increase of the spray pressure from 9 bar to 12 bar also significantly increased the removal of ammonia gas from the spray tower outlet (P-Value = 0.052). Conclusion: Increased number of nozzles, increased spray pressure, and decreased density of the ammonia gas inlet gas will increase removal efficiency.

In high-speed digital wireless communication applications, the intersymbol interference channel may have spectral nulls or erasures, which may degrade the orthogonal frequency division multiplexing (OFDM) bit error rate (BER) performance. In this paper, we prove that the BER performance of the OFDM system is considerably refined if the erased symbols in erasure channel (or received symbols on the deep-faded subcarriers in Rayleigh fading channel) are estimated based on the rest symbols in each OFDM signal. Also, an oversampled OFDM scheme which is a particular form of the pre-coded OFDM schemes is considered to guarantee high enough sampling rate. Furthermore, a new iterative receiver is proposed for perfect symbol recovery. A comprehensive Monte Carlo simulation study is performed to validate the theoretical results and affirm the superior performance of the oversampled OFDM scheme with the iterative receiver, compared with the typical detector for the OFDM scheme.

Spray tower scrubbers ordinarily have low air resistance and gas removal efficiency. Although packed-bed wet scrubbers are efficient in gaseous contaminants treatment, a significant limitation of packed-bed wet scrubbers is that they have high pressure drop and primary costs. Appropriate features of the nozzle play an important role in system cost, efficiency, low operational costs, and optimization of spray towers. Operating pressure, nozzles size, and number of nozzles could increase mass transfer and removal efficiency and decrease investment and save operational costs. The objective of the present study was to develop a spray tower through optimization of the design and operating parameters for removal ammonia emissions from the air streams. Spray tower design parameters included nozzle type, number of stages of spray nozzle, and operating parameters such as operating pressure and inlet NH3 concentration. Among the studied parameters, only increasing ammonia concentration was in inverse proportion to the spray tower efficiency. The spray tower was optimized as equipped with an 8010SS spray nozzle with three stages working together, spraying 0.01% H2SO4 scrubbing liquid counter-current to the air stream with operating pressure of 12 bars and inlet NH3 concentration of 24.1 ppm. The highest removal efficiency was 97.92% at an 8010SS spray nozzle with three stages working together, H2SO4 solution, pressure 12 bars and inlet ammonia concentration of 24.1 ppm. The results of this study demonstrated that caustic spray tower could be a very effective technology for removal of NH3 from air stream.

Background and aims: Spray tower is a cost effective and simple equipment for ammonia gas purification. But its’ appropriate performance in the removal of ammonia gas is under question. In this study, the effect of nozzle number, concentration of input ammonia gas and scrubbing liquid pressure over the removal efficiency of spray tower was studied. Methods: In present study, a spray tower was used to remove ammonia from air at room temperature and barometric pressure of Tehran. Ammonia gas at average concentration of 24.1, 52 and 68 parts per million was injected into the tower. Water was applied at a volumetric flow rate of 5 liters per minute and at 9, 10 and 12 bar head as the scrubbing liquid. The air flow rate in 3737.8 liters per minute was adjusted by a variable speed fan. Scrubbing liquid was sprayed using 1, 2 and 3 nozzle settings with a 20 μm size. The collected data were analyzed using the SPSS software. Results: The highest removal efficiency of 88.38% and the lowest removal efficiency of 51.47% Were obtained. Increasing the number of nozzles did not increase the removal efficiency significantly (P-Value = 0.06). Conclusion: Removal efficiency of spray tower decreased by increasing the input ammonia gas concentration. Increasing the number of nozzles mounted on the spray tower from 1 to 3 increased the removal efficiency. Increasing the scrubbing liquid pressure increased the removal efficiency of ammonia gas by spray tower. It is advisable to increase the size of the nozzle outlet and apply caustic scrubbing solution to get removal efficiencies of higher than 90%.

This paper proposes an iterative detector for uncoded OFDM signals in cooperative networks, where the information symbols are simply partitioned through a time-domain matrix at the OFDM transmitter. We analytically show that our proposed iterative detector at the partner node converges and can completely recover the user’s data from its partitioned version, if sufficient redundancy is inserted in the user’s data. For efficient use of the redundancy in the user’s data, a coded cooperative transmission based on superposition modulation is proposed. Additionally, a closed-form input–output relationship for the partitioning and reconstruction algorithm in the proposed cooperative scenario is derived. We also obtain closed-form expressions for symbol error rate performance of the proposed coded cooperative scenario over Rayleigh frequency-selective fading channels. Numerical comparisons shed light on the relative merits of the proposed coded cooperation under various inter-user and uplink channel conditions.

We examine the properties of atomic hydrogen (HI) associated with galaxies in the EAGLE simulations of galaxy formation. EAGLE's feedback parameters were calibrated to reproduce the stellar mass function and galaxy sizes at $z=0.1$, and we assess whether this calibration also yields realistic HI properties. We estimate the self-shielding density with a fitting function calibrated using radiation transport simulations, and correct for molecular hydrogen with empirical or theoretical relations. The `standard-resolution' simulations systematically underestimate HI column densities, leading to an HI deficiency in low-mass ($M_\star < 10^{10}M_\odot$) galaxies and poor reproduction of the observed HI mass function. These shortcomings are largely absent from EAGLE simulations featuring a factor of 8 (2) better mass (spatial) resolution, within which the HI mass of galaxies evolves more mildly from $z=1$ to $0$ than in the standard-resolution simulations. The largest-volume simulation reproduces the observed clustering of HI systems, and its dependence on HI-richness. At fixed $M_\star$, galaxies acquire more HI in simulations with stronger feedback, as they become associated with more massive haloes and higher infall rates. They acquire less HI in simulations with a greater star formation efficiency, since the star formation and feedback necessary to balance the infall rate is produced by smaller gas reservoirs. The simulations indicate that the HI of present-day galaxies was acquired primarily by the smooth accretion of ionized, intergalactic gas at $z\simeq1$, which later self-shields, and that only a small fraction is contributed by the reincorporation of gas previously heated strongly by feedback. HI reservoirs are highly dynamic: over $40$ percent of HI associated with $z=0.1$ galaxies is converted to stars or ejected by $z=0$., Accepted for publication by MNRAS. v2: minor changes from submitted manuscript

Increasing urban population and organizations have introduced many problems in urban life. In a city there are a lot of organizations like municipalities, Roads and Urban Development organizations, etc. Which have made their own segmentations for servicing their customers. All of these configurations have been made for responding to specific requirements and reaching specific goals. But Most of the time these segmentations have functional overlap and in many cases are in conflict with each other.This has caused inefficiency, and dissatisfaction of people, because they have to go to lots of organizations to get their work done. Therefore all the organizations in a city must clearly specify their responsibilities and territories.To do this, we aim to suggest a new system of regionalization using REDCAP algorithms in Tehran City. Research type is descriptive/analytical and the data has been collected from different organization. We designed 22 indexes to reshape new regions. These indices have been generated by aggregating raw data in primary spatial units. Primary spatial units have been designed by converting road network of Tehran city to polygons.After that we applied REDCAP algorithm by defining three parameters (number of regions, minimum population and REDCAP algorithms) to generate new regions. Then to prove our new regions are superior to formal regions of Tehran municipality we utilized Moran’s I index by measuring homogeneity of new regions in comparison with formal regions. Results showed us that new regions best fit our aims and are more homogenous than formal regions.

Background: Antineoplastic drugs as chemotherapy agents are used for various therapeutic purposes. Occupational exposure to antineoplastic drugs is possible through inhalation, skin contact, skin absorption, and digestive or injection. Assessment of occupational exposure of staff working with anti-neoplastic drugs has been a major concern among practitioners and occupational health and safety managers. Objectives: Considering the importance of safeguarding oncology personnel against antineoplastic drugs, the aim of this study was to validate a method for analysing cyclophosphamide (CPA) in urine samples as the biomarker of the exposure of oncology personnel of two hospitals in Tehran. Methods: Standard urine samples were obtained from a healthy man without having any exposure to CPA drug. The standards urine samples of CPA within the concentration range of 0.02 to 50 microgram per liter (µg/L) were prepared by diluting the urine stock solution. Ifosfamide (IFO) was added as an internal standard at a concentration of 20 µg/L. CPA and IFO analysis by gas chromatography-electron capture detector (GC-ECD) in this study was confirmed by gas chromatography-mass spectrometry (GC-MS) for verification of their peak retention times and MS signature at 95% confidence. Results: Urinary CPA concentrations as the biomarker of the exposure of the oncology personnel were detected within the range of 0.52 to 21.4 µg/L. The drug presence in the urine of 31% (10 of 32) of two hospital staff indicate the biological monitoring potential to recognition of worker’s exposure. Conclusions: In general, biological monitoring of oncology personnel could be a useful tool for assessing occupational exposure through all routes and efficacy of the current safety measures. Owing to higher values of urinary CPA in this study compared to the studies of their colleagues abroad stringent control measures were deemed necessary.

Background: Formaldehyde (FA) is a reactive carcinogenic compound and is used routinely in anatomy theatres. Recently, biological monitoring is introduced as a method of choice for monitoring of exposed workers to hazardous chemicals with systemic absorption. Objectives: Considering the toxicity of formaldehyde and lack of a comprehensive method for its biological monitoring, the aim of this study was to explore a new and non-invasive method for biological monitoring of formaldehyde exposure in the staffs of anatomy theatre. Methods: This study was a cross-sectional investigation and the population of this study was comprised of 20 exposed staffs in an anatomy theatre in Tehran, Iran. The personal monitoring of 20 staff was carried out during the early winter, according to a method from the National Institute of Occupational Safety and Health No. 2016. Biological monitoring was conducted by measuring FA in staff’s exhaled breath after termination of the work shift. The data obtained were statistically analyzed using correlation analysis. Results: The mean FA personal exposure and its concentration in the exhaled breath of anatomy’s staffs were 698 ± 34 and 195 ± 17 as ppb, respectively. Correlation of staff’s personal exposures to formaldehyde with the excreted formaldehyde in their exhaled breath was statistically significant (P < 0.001). Conclusions: The present study showed that the personal exposure of staffs to the FA was higher than the permissible exposure limit. Statistically significant positive correlation of staff exposure with the content of FA in their exhaled breath indicated the potential of biological monitoring of exposed group to FA through exhaled breath.

The present study was conducted, based on scenario modeling approach, in the Do-hezar and Se-hezar forested landscape in the Mazandaran Province in Northern Iran in order to detect spatial-temporal changes of carbon storage and sequestration in four different carbon pools, i.e., aboveground and belowground biomasses, dead organic matter, and organic soils. For this purpose, firstly, the changing trend of land use/land cover (LULC) was detected by analyzing and comparing remotely sensed data of the landscape during the period of 1984-2016. Then, the impacts of future LULC changes on carbon storage and sequestration were predicted and valued using the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model under two future plausible scenarios of business as usual (BAU) and balanced development (BD). According to the results of BAU scenario, continuation of the current trend will lead to a significant reduction in the carbon sequestration and a huge amount of social cost due to the loss of carbon stored in the landscape and its release to the atmosphere. The BD scenario which refers to the principled and under control development of human settlements simultaneously with forest conservational and restoration activities, could potentially reverse the downtrend of carbon sequestration service and avoid future socioeconomic costs, hence add to the economic value of the forest landscape in terms of providing a better sink for carbon storage. The results of this research can facilitate the quantitative and accurate assessment of carbon storage and sequestration relying on more precise biophysical and economic data as well as provide insight for effective land-use planning.

The metallicity of strong HI systems, spanning from damped Lyman-alpha absorbers (DLAs) to Lyman-limit systems (LLSs) is explored between z = 5->0 using the EAGLE high-resolution cosmological hydrodynamic simulation of galaxy formation. The metallicities of LLSs and DLAs steadily increase with time in agreement with observations. DLAs are more metal rich than LLSs, although the metallicities in the LLS column density range (NHI = 10^17 -10^20 cm^-2) are relatively flat, evolving from a median HI-weighted metallicity of Z 3 that are not observed, which may indicate more widespread early enrichment in the real Universe compared to EAGLE., 8 pages, 6 figures, accepted by MNRAS

The observed high covering fractions of neutral hydrogen (HI) with column densities above $\sim 10^{17} \rm{cm}^{-2}$ around Lyman-Break Galaxies (LBGs) and bright quasars at redshifts z ~ 2-3 has been identified as a challenge for simulations of galaxy formation. We use the EAGLE cosmological, hydrodynamical simulation, which has been shown to reproduce a wide range of galaxy properties and for which the subgrid feedback was calibrated without considering gas properties, to study the distribution of HI around high-redshift galaxies. We predict the covering fractions of strong HI absorbers ($N_{\rm{HI}} \gtrsim 10^{17} \rm{cm}^{-2}$) inside haloes to increase rapidly with redshift but to depend only weakly on halo mass. For massive ($M_{200} \gtrsim 10^{12} {\rm M_{\odot}}$) halos the covering fraction profiles are nearly scale-invariant and we provide fitting functions that reproduce the simulation results. While efficient feedback is required to increase the HI covering fractions to the high observed values, the distribution of strong absorbers in and around halos of a fixed mass is insensitive to factor of two variations in the strength of the stellar feedback. In contrast, at fixed stellar mass the predicted HI distribution is highly sensitive to the feedback efficiency. The fiducial EAGLE simulation reproduces both the observed global column density distribution function of HI and the observed radial covering fraction profiles of strong HI absorbers around LBGs and bright quasars., Accepted for publication in MNRAS. V2: Very minor changes

A substantial fraction of all ionizing photons originate from radiative recombinations. However, in radiative transfer calculations this recombination radiation is often assumed to be absorbed 'on-the-spot' because for most methods the computational cost associated with the inclusion of gas elements as sources is prohibitive. We present a new, CPU and memory efficient implementation for the transport of ionizing recombination radiation in the TRAPHIC radiative transfer scheme. TRAPHIC solves the radiative transfer equation by tracing photon packets at the speed of light and in a photon-conserving manner in spatially adaptive smoothed particle hydrodynamics simulations. Our new implementation uses existing features of the TRAPHIC scheme to add recombination radiation at no additional cost in the limit in which the fraction of the simulation box filled with radiation approaches 1. We test the implementation by simulating an HII region in photoionization equilibrium and comparing to reference solutions presented in the literature, finding excellent agreement. We apply our implementation to discuss the evolution of the HII region to equilibrium. We show that the widely used case A and B approximations yield accurate ionization profiles only near the source and near the ionization front, respectively. We also discuss the impact of recombination radiation on the geometry of shadows behind optically thick absorbers. We demonstrate that the shadow region may be completely ionized by the diffuse recombination radiation field and discuss the important role of heating by recombination radiation in the shadow region., Comment: 16 pages, 10 figures, accepted for publication in MNRAS

Background: In many industries, noise is attributed as the most prevalent harmful agent threatening workers' health. Geographic Information System (GIS) is an applicable surveying tool in civil engineering. But, the use of GIS for noise and hearing loss screening seems to be partly a new approach. Objectives: This study aimed to apply GIS in noise and hearing loss screening in the production hall of a publishing industry. Patients and Methods: A cross-sectional study was conducted on 46 employees working in the production hall of a publishing industry in Iran. First, workers' hearing threshold was examined by Pure-Tone Audiometry (PTA) at 250-8000 Hz frequencies. Then, the production hall area was divided into squares (6 × 6 m 2 ), taking sound pressure levels (SPL) in each square center by a sound level meter (SLM) according to ISO-9612; 2009. Noise and hearing loss maps were drawn, by Arc GIS-9.2, for different areas of the production hall. Results: Noise measurements revealed that total sound pressure levels (SPL) in the production hall ranged from 72.3to 94.5 dBA. From the total area of production hall, 20% of it was found to be exceeding the threshold limit value (SPL ≥ 85 dBA) on the GIS-prepared noise map. Fisher exact test showed a significant difference between hearing losses (HL ≥ 25 dB) in the danger zone (SPL ≥ 85 dB) and the warning zone (85 > SPL ≥ 65 dB) (P = 0.005). Among the workers, 50% of them were in the danger zone and 8.8% of those who were in warning zone had varying degrees of hearing losses. Conclusions: GIS can play an important role in better noise and hearing loss screening through providing a set of facilities such as: converting point data to area ones, possibility of classification in different domains of prepared area data, generation of reports on map, graphic, and table, etc.

It is often assumed that local sources of ionizing radiation have little impact on the distribution of HI in the post-reionization Universe. While this is a good assumption for the IGM, analytic arguments suggest that local sources may typically be more important than the background radiation for high column density absorbers (N_HI > 10^17 /cm^2). We post-process cosmological simulations with accurate radiation transport to investigate the impact of local stellar sources on the HI distribution. We demonstrate that the limited numerical resolution and the simplified treatment of the ISM that are typical of current cosmological simulations provide significant challenges, but that many of the problems can be overcome by taking two steps. First, using ISM particles rather than stellar particles as sources results in a much better sampling of the source distribution. Second, by rescaling the source luminosities so that the amount of radiation escaping into the IGM agrees with that required to produce the observed background, many of the results become insensitive to errors in the predicted fraction of the radiation that escapes the immediate vicinity of the sources. By adopting this strategy and by varying the assumptions about the structure of the unresolved ISM, we conclude that we can robustly estimate the effect of local sources for column densities N_HI << 10^21 /cm^2. However, neither the escape fraction of ionizing radiation nor the effect of local sources on the abundance of N_HI >~ 10^21 systems can be predicted with confidence. We find that local stellar radiation is unimportant for N_HI << 10^17, but that it can affect Lyman Limit and DLA systems. For 10^18 < N_HI < 10^21 the impact of local sources increases with redshift. At z = 5 the abundance of absorbers with N_HI >> 10^17 is substantially reduced, but at z = 0 the reduction only becomes significant for N_HI >~ 10^21 /cm^2., 19 pages, 12 figures; Accepted for publication in MNRAS

We use a set of cosmological simulations combined with radiative transfer calculations to investigate the distribution of neutral hydrogen in the post-reionization Universe. We assess the contributions from the metagalactic ionizing background, collisional ionization and diffuse recombination radiation to the total ionization rate at redshifts z=0-5. We find that the densities above which hydrogen self-shielding becomes important are consistent with analytic calculations and previous work. However, because of diffuse recombination radiation, whose intensity peaks at the same density, the transition between highly ionized and self-shielded regions is smoother than what is usually assumed. We provide fitting functions to the simulated photoionization rate as a function of density and show that post-processing simulations with the fitted rates yields results that are in excellent agreement with the original radiative transfer calculations. The predicted neutral hydrogen column density distributions agree very well with the observations. In particular, the simulations reproduce the remarkable lack of evolution in the column density distribution of Lyman limit and weak damped Ly\alpha\ systems below z = 3. The evolution of the low column density end is affected by the increasing importance of collisional ionization with decreasing redshift. On the other hand, the simulations predict the abundance of strong damped Ly\alpha\ systems to broadly track the cosmic star formation rate density., Comment: 21 pages (including 6 pages for references and appendixes), 13 figures; Accepted for publication in MNRAS

High-resolution simulations of star-forming massive galactic discs have shown that clumps form with a characteristic baryonic mass in the range $10^7-10^8~M_{\odot}$, with a small tail exceeding $10^9~M_{\odot}$ produced by clump-clump mergers. This is in contrast with the observed kpc-size clumps with masses up to $10^{10}~M_{\odot}$ in high-redshift star-forming galaxies. In this paper we show that the comparison between simulated and observed star-forming clumps is hindered by limited observational spatial resolution and sensitivity. We post-process high-resolution hydrodynamical simulations of clumpy discs using accurate radiative transfer to model the effect of ionizing radiation from young stars and to compute H$\alpha$ emission maps. By comparing the intrinsic clump size and mass distributions with those inferred from convolving the H$\alpha$ maps with different gaussian apertures, we mimick the typical resolution used in observations. We found that with 100 pc resolution, mock observations can recover the intrinsic clump radii and stellar masses, in agreement with those found by lensing observations. Instead, using a 1 kpc resolution smears out individual clumps, resulting in their apparent merging. This causes significant overestimations of the clump radii and, therefore, masses derived using methods that use their observed sizes. We show that limited sensitivity can also force observations to significantly overestimate the clump masses. We conclude that a significant fraction of giant clumps detected in the observations may result from artificially inflated radii and masses, and that $\approx 100$ pc spatial resolution is required to capture correctly the physical characteristics of star-forming clumps if they are coherent structures produced by disc fragmentation., Comment: submitted to MNRAS on 07.10.2016. New reference to Dessauges et al. 2016 added post submission. Comments are welcome

We model the evolution of IR galaxies using a phenomenological approach to match the observed source counts at different IR wavelengths. We introduce a new algorithm for reproducing source counts based on direct integration of probability distributions rather than Monte-Carlo sampling. We construct a simple model for the evolution of the luminosity function and the colour distribution of IR galaxies which utilizes a minimum number of free parameters. Moreover we analyze how each of these parameters is constrained by observational data. The model is based on pure luminosity evolution and adopts the Dale & Helou SED templates. We find that the 850um source counts and their redshift distribution depend strongly on the shape of the luminosity evolution function, but only weakly on the details of the SEDs. We derive the best-fit evolutionary model using the 850um counts and redshift distribution as constraints. Moreover our best-fit shows a flattening of the faint end of the luminosity function towards high redshifts and requires a colour evolution which implies the typical dust temperatures of objects with the same luminosities to decrease with redshift. We compare our best-fit model to observed source counts at shorter and longer wavelengths which indicates our model reproduces the 70um and 1100um source counts remarkably well, but under-produces the counts at intermediate wavelengths. Analysis reveals that the discrepancy arises at low redshifts, indicating that revision of the adopted SED library towards lower dust temperatures (at a fixed infrared luminosity) is required. This modification is equivalent to a population of cold galaxies existing at low redshifts, as also indicated by recent Herschel results, which are underrepresented in IRAS sample. We show that the modified model successfully reproduces the source counts in a wide range of IR and submm wavelengths.

Recently, user-cooperation diversity has been introduced as an effective scheme that can bring about antenna diversity in wireless networks. In this paper, we introduce a coded cooperation diversity technique for single antenna uncoded orthogonal frequency division multiplexing (OFDM) systems, in which implementation of coded cooperation is provided by the oversampling potential in OFDM, instead of using extra channel coding. In fact, zero-padding followed by IFFT in OFDM is similar to oversampling and could be an alternative to applying correction codes. Furthermore, we use this oversampling to implement an iterative receiver at the partner terminal. This receiver works based on the nonuniform sampling theorem for reconstructing of lost symbols. The lost symbols appear at the partner terminal of cooperative network because of dividing each OFDM block into two segments through the puncturing at the user terminal of the cooperative network. We provide simulation results for our proposed scenario, and observe significant gains over the non-cooperative oversampled OFDM systems without any need whatever for using extra channel coding.

We introduce a series of 20 cosmological hydrodynamical simulations of Lstar (M_200 =10^11.7 - 10^12.3 Msol) and group-sized (M_200 = 10^12.7 - 10^13.3 Msol) haloes run with the model used for the EAGLE project, which additionally includes a non-equilibrium ionization and cooling module that follows 136 ions. The simulations reproduce the observed correlation, revealed by COS-Halos at z~0.2, between O VI column density at impact parameters b < 150 kpc and the specific star formation rate (sSFR=SFR/Mstar) of the central galaxy at z~0.2. We find that the column density of circumgalactic O VI is maximal in the haloes associated with Lstar galaxies, because their virial temperatures are close to the temperature at which the ionization fraction of O VI peaks (T~10^5.5 K). The higher virial temperature of group haloes (> 10^6 K) promotes oxygen to higher ionization states, suppressing the O VI column density. The observed NO VI-sSFR correlation therefore does not imply a causal link, but reflects the changing characteristic ionization state of oxygen as halo mass is increased. In spite of the mass-dependence of the oxygen ionization state, the most abundant circumgalactic oxygen ion in both Lstar and group haloes is O VII; O VI accounts for only 0.1% of the oxygen in group haloes and 0.9-1.3% with Lstar haloes. Nonetheless, the metals traced by O VI absorbers represent a fossil record of the feedback history of galaxies over a Hubble time; their characteristic epoch of ejection corresponds to z > 1 and much of the ejected metal mass resides beyond the virial radius of galaxies. For both Lstar and group galaxies, more of the oxygen produced and released by stars resides in the circumgalactic medium (within twice the virial radius) than in the stars and ISM of the galaxy., 25 pages, 14 figures, 2 tables. Accepted in MNRAS

The use of background quasars provides a powerful tool to probe the cool gas in the circum-galactic medium of foreground galaxies. Here, we present new observations with SINFONI and X-Shooter of absorbing-galaxy candidates at z=0.7-1. We report the detection with both instruments of the H-alpha emission line of one sub-DLA at z_abs=0.94187 with log N(HI)=19.38^+0.10_-0.15 towards SDSS J002133.27+004300.9. We estimate the star formation rate: SFR=3.6+/-2.2 solar masses per year in that system. A detailed kinematic study indicates a dynamical mass M_dyn=10^9.9+/-0.4 solar masses and a halo mass M_halo=10^11.9+/-0.5 solar masses. In addition, we report the OII detection with X-Shooter of another DLA at z_abs=0.7402 with log N(HI)=20.4+/-0.1 toward Q0052+0041 and an estimated SFR of 5.3+/-0.7 solar masses per year. Three other objects are detected in the continuum with X-Shooter but the nature and redshift of two of these objects are unconstrained due to the absence of emission lines, while the third object might be at the redshift of the quasar. We use the objects detected in our whole N(HI)-selected SINFONI survey to compute the metallicity difference between the galaxy and the absorbing gas, delta_HI(X), where a positive (negative) value indicates infall (outflow). We compare this quantity with the quasar line of sight alignment with the galaxy's major (minor) axis, another tracer of infall (outflow). We find that these quantities do not correlate as expected from simple assumptions. Additional observations are necessary to relate these two independent probes of gas flows around galaxies., 16 pages, 8 figures, accepted for publication in MNRAS

We study the distribution and evolution of highly ionised intergalactic metals in the Evolution and Assembly of Galaxies and their Environment (EAGLE) cosmological, hydrodynamical simulations. EAGLE has been shown to reproduce a wide range of galaxy properties while its subgrid feedback was calibrated without considering gas properties. We compare the predictions for the column density distribution functions (CDDFs) and cosmic densities of SiIV, CIV, NV, OVI and NeVIII absorbers with observations at redshift z = 0 to ~ 6 and find reasonable agreement, although there are some differences. We show that the typical physical densities of the absorbing gas increase with column density and redshift, but decrease with the ionization energy of the absorbing ion. The typical metallicity increases with both column density and time. The fraction of collisionally ionized metal absorbers increases with time and ionization energy. While our results show little sensitivity to the presence or absence of AGN feedback, increasing/decreasing the efficiency of stellar feedback by a factor of two substantially decreases/increases the CDDFs and the cosmic densities of the metal ions. We show that the impact of the efficiency of stellar feedback on the CDDFs and cosmic densities is largely due to its effect on the metal production rate. However, the temperatures of the metal absorbers, particularly those of strong OVI, are directly sensitive to the strength of the feedback., 25 pages, 20 figures, 2 tables; Accepted for publication in MNRAS after minor changes

We present a sample of 45 Damped Ly-Alpha system [DLA; H I-N is greater than or equal to 2 x 10(exp. 20) cm(exp. -2)] counterparts (33 detections, 12 upper limits) which host gamma-ray bursts (GRB-DLAs) in order to investigate star formation and metallicity within galaxies hosting DLAs. Our sample spans z is approx. 2 - 6 and is nearly three times larger than any previously detected DLA counterparts survey based on quasar line-of-sight searches (QSO-DLAs). We report star formation rates (SFRs) from rest-frame UV photometry and spectral energy distribution modeling. We find that DLA counterpart SFRs are not correlated with either redshift or H I column density. Thanks to the combination of Hubble Space Telescope and ground-based observations, we also investigate DLA host star formation efficiency. Our GRB-DLA counterpart sample spans both higher efficiency and low efficiency star formation regions compared to the local Kennicutt-Schmidt relation, local star formation laws, and z is approximately 3 cosmological simulations. We also compare the depletion times of our DLA hosts sample to other objects in the local universe; our sample appears to deviate from the star formation efficiencies measured in local spiral and dwarf galaxies. Furthermore, we find similar efficiencies as local inner disks, SMC, and Lyman-break galaxy outskirts. Finally, our enrichment time measurements show a spread of systems with under- and over-abundance of metals, which may suggest that these systems had episodic star formation and a metal enrichment/depletion as a result of strong stellar feedback and/or metal inflow/outflow.

In this paper, we present basic equation of efficient recursive least square algorithm based on GMSK modulation by linear superposition of amplitude modulated pulses for reduction complexity in equalizer. In this here, the DFE method be improved using of signal processing technique and soft decision which is called ''generalized DFE or GDFEmethod''. We compare the performance and complexity GDFE with MLSE method for different channels used in GSM systems. The GDFE differs from the conventional DFE in its tap values and value of tap feedback filter related with channel length, which discussed in simulation result. Our simulation results, obtained for fading multi path channels, show that the GDFE scheme improves the performance 1 dB approximately in comparison with conventional DFE. The GDFE method is robust to errors channel and this is a good specific beside low complexity, which is applicable in practical systems.

This paper proposes an image watermarking scheme for copyright protection based on Independent Component Analysis (ICA). In the suggested scheme, embedding is carried out in cumulative form in spatial domain and ICA is used for watermark extraction. For extraction there is no need to access the original image or the watermark, and extraction is carried out only with two watermarked images. Experimental results show that the new method has better quality than famous methods [1], [2], [3] in spatial or frequency domain and is robust against various attacks. Noise addition, resizing, low pass filtering, multiple marks, gray-scale reduction, rotation, JPEG compression, and cropping are some attacks which a reconsidered in our extensive simulations to demonstrate the proposed algorithm performance.

A precise method for calculating the bit error probability (BEP) of an iterative equalization-based oversampled OFDM system on fading channels in the presence of spectral nulls is derived. Several signaling formats, such as binary phase-shift keying, quaternary phase-shift keying, and M-ary quadrature amplitude modulation are considered.

This paper shows that the oversampled OFDM system performance is significantly improved if the deep faded symbols on the subcarriers of each oversampled OFDM signal are discarded and then reconstructed from the remaining OFDM signal by a novel time domain iterative algorithm. A precise method for calculating the probability of error (POE) of the proposed iterative equalization-based oversampled OFDM system on fading channels in the presence of spectral nulls is derived. An extensive Monte Carlo simulation study is presented to corroborate the analytical results and reveal the oversampled OFDM system performance valuable merits. Index Terms—Orthogonal Frequency Division Multiplexing (OFDM) systems, Iterative detection.

We use the weighted integral form of spherical Bessel functions, and introduce a new analytical set of complete and biorthogonal potential--density basis functions. The potential and density functions of the new set have finite central values and they fall off, respectively, similar to $r^{-(1+l)}$ and $r^{-(4+l)}$ at large radii where $l$ is the latitudinal quantum number of spherical harmonics. The lowest order term associated with $l=0$ is the perfect sphere of de Zeeuw. Our basis functions are intrinsically suitable for the modeling of three dimensional, soft-centred stellar systems and they complement the basis sets of Clutton-Brock, Hernquist & Ostriker and Zhao. We test the performance of our functions by expanding the density and potential profiles of some spherical and oblate galaxy models., 8 pages, 6 figures, Accepted for publication in Monthly Notices of the Royal Astronomical Society

Conventional OFDM symbol detection at the receiver becomes difficult if multipath fading channels have spectral nulls. In this paper, we consider an oversampled OFDM system which is a special case of the precoded OFDM systems. We show that the system performance is significantly improved if the deep faded symbols on the subcarriers of each oversampled OFDM signal are discarded and then reconstructed from the remaining ones. In fact, dropping the weak symbols at the receive side results in a nonuniform sampled version of the oversampled OFDM signal and as the nonuniform sampling theorem guarantees, as long as the average symbol rate of the symbols on the remaining subcarriers stays above the Nyquist rate, the perfect OFDM signal recovery is possible. For reconstructing the symbols on the weak subcarriers from the symbols on the remaining subcarriers at the receiver, we consider an iterative receiver for its fast convergence rate and its simple implementation. Simulation results reveal the oversampled OFDM system performance valuable merits as compared to that of the conventional detector for the OFDM system.

A set of bi-orthogonal potential-density basis functions is introduced to model the density and its associated gravitational field of three dimensional stellar systems. Radial components of our basis functions are weighted integral forms of spherical Bessel functions. We discuss the properties of our basis functions and demonstrate their shapes for the latitudinal Fourier number $l=2$., Comment: 2 pages. To appear in the proceedings of IAU Symposium 245, "Formation and Evolution of Galaxy Bulges," M. Bureau, E. Athanassoula, and B. Barbuy, eds

The density of the warm ionized gas in high-redshift galaxies is known to be higher than what is typical in local galaxies on similar scales. At the same time, the mean global properties of the high- and low-redshift galaxies are quite different. Here, we present a detailed differential analysis of the ionization parameters of 14 star-forming galaxies at redshift 2.6-3.4, compiled from the literature. For each of those high-redshift galaxies, we construct a comparison sample of low-redshift galaxies closely matched in specific star formation rate (sSFR) and stellar mass, thus ensuring that their global physical conditions are similar to the high-redshift galaxy. We find that the median log [OIII] 5007/ [OII] 3727 line ratio of the high-redshift galaxies is 0.5 dex higher than their local counterparts. We construct a new calibration between the [OIII] 5007/ [OII] 3727 emission line ratio and ionization parameter to estimate the difference between the ionization parameters in the high and low-redshift samples. Using this, we show that the typical density of the warm ionized gas in star-forming regions decreases by a median factor of $7.1^{+10.2}_{-5.4}$ from z ~ 3.3 to z ~ 0 at fixed mass and sSFR. We show that metallicity differences cannot explain the observed density differences. Because the high- and low-redshift samples are comparable in size, we infer that the relationship between star formation rate density and gas density must have been significantly less efficient at z ~2-3 than what is observed in nearby galaxies with similar levels of star formation activity., 16 pages, 6 figures, accepted for publication in ApJ

We introduce the Virgo Consortium's EAGLE project, a suite of hydrodynamical simulations that follow the formation of galaxies and black holes in representative volumes. We discuss the limitations of such simulations in light of their finite resolution and poorly constrained subgrid physics, and how these affect their predictive power. One major improvement is our treatment of feedback from massive stars and AGN in which thermal energy is injected into the gas without the need to turn off cooling or hydrodynamical forces, allowing winds to develop without predetermined speed or mass loading factors. Because the feedback efficiencies cannot be predicted from first principles, we calibrate them to the z~0 galaxy stellar mass function and the amplitude of the galaxy-central black hole mass relation, also taking galaxy sizes into account. The observed galaxy mass function is reproduced to $\lesssim 0.2$ dex over the full mass range, $10^8 < M_*/M_\odot \lesssim 10^{11}$, a level of agreement close to that attained by semi-analytic models, and unprecedented for hydrodynamical simulations. We compare our results to a representative set of low-redshift observables not considered in the calibration, and find good agreement with the observed galaxy specific star formation rates, passive fractions, Tully-Fisher relation, total stellar luminosities of galaxy clusters, and column density distributions of intergalactic CIV and OVI. While the mass-metallicity relations for gas and stars are consistent with observations for $M_* \gtrsim 10^9 M_\odot$, they are insufficiently steep at lower masses. The gas fractions and temperatures are too high for clusters of galaxies, but for groups these discrepancies can be resolved by adopting a higher heating temperature in the subgrid prescription for AGN feedback. EAGLE constitutes a valuable new resource for studies of galaxy formation., Accepted for publication in MNRAS. V2: Minor changes. For images and videos, see http://eagle.strw.leidenuniv.nl/ and http://icc.dur.ac.uk/Eagle/

We introduce a new suite of radiation-hydrodynamical simulations of galaxy formation and reionization called Aurora. The Aurora simulations make use of a spatially adaptive radiative transfer technique that lets us accurately capture the small-scale structure in the gas at the resolution of the hydrodynamics, in cosmological volumes. In addition to ionizing radiation, Aurora includes galactic winds driven by star formation and the enrichment of the universe with metals synthesized in the stars. Our reference simulation uses 2x512^3 dark matter and gas particles in a box of size 25 comoving Mpc/h with a force softening scale of at most 0.28 kpc/h. It is accompanied by simulations in larger and smaller boxes and at higher and lower resolution, employing up to 2x1024^3 particles, to investigate numerical convergence. All simulations are calibrated to yield simulated star formation rate (SFR) functions in close agreement with observational constraints at redshift z = 7 and to achieve reionization at z = 8.3, which is consistent with the observed optical depth to reionization. We focus on the design and calibration of the simulations and present some first results. The median stellar metallicities of low-mass galaxies at z = 6 are consistent with the metallicities of dwarf galaxies in the Local Group, which are believed to have formed most of their stars at high redshifts. After reionization, the mean photoionization rate decreases systematically with increasing resolution. This coincides with a systematic increase in the abundance of neutral hydrogen absorbers in the IGM., Comment: 16 pages, 8 figures, accepted for publication in MNRAS

We use the Aurora radiation-hydrodynamical simulations to study the mean free path (MFP) for hydrogen ionizing photons during the epoch of reionization. We directly measure the MFP by averaging the distance 1 Ry photons travel before reaching an optical depth of unity along random lines-of-sight. During reionization the free paths tend to end in neutral gas with densities near the cosmic mean, while after reionizaton the end points tend to be overdense but highly ionized. Despite the increasing importance of discrete, over-dense systems, the cumulative contribution of systems with $N_{\rm{HI}} \lesssim 10^{16.5}~{\rm cm^{-2}}$ suffices to drive the MFP at $z \approx 6$, while at earlier times higher column densities are more important. After reionization the typical size of HI systems is close to the local Jeans length, but during reionization it is much larger. The mean free path for photons originating close to galaxies, $\rm{MFP_{gal}}$, is much smaller than the cosmic MFP. After reionization this enhancement can remain significant up to starting distances of $\sim 1$ comoving Mpc. During reionization, however, $\rm{MFP_{gal}}$ for distances $\sim 10^2 - 10^3$ comoving kpc typically exceeds the cosmic MFP. These findings have important consequences for models that interpret the intergalactic MFP as the distance escaped ionizing photons can travel from galaxies before being absorbed and may cause them to under-estimate the required escape fraction from galaxies, and/or the required emissivity of ionizing photons after reionization., 13 pages, 9 figures, 1 table; submitted to MNRAS