Photometric study and period analysis of the contact binary XZ Leonis

We present multi-color CCD photometry of the neglected contact binary XZ Leo. Completely covered VRI band light curves and four times of minimum light were obtained. Combining the photometric and previously published radial velocity data, a revised photometric analysis was carried out for the binary system by applying the Wilson-Devinney code. With a hot spot placed on the massive primary component near the neck region of the common envelope, the light curves were satisfactorily modeled. The photometric solution combined with the radial velocity solution reveals that XZ Leo is an A-type contact binary with a degree of contact of 24($\pm1)\%$. The absolute parameters of the components were determined as M_1 = 1.74($\pm$0.06)M_\odot, M_2 = 0.61($\pm$0.02)M_\odot, R_1 = 1.69($\pm$0.01)R_\odot, R_2 = 1.07($\pm0.01$)R_\odot, L_1 = 6.73($\pm0.08$) L_\odot, L_2 = 2.40($\pm$0.04)L_\odot. Based on all the available data, the long-term orbital period behavior of the system was investigated. It indicates that the binary system was undergoing continuous orbital period increase in the past three decades with a rate of dP/dt = + 6.12 \times {10^{-8}} days yr^{-1}, which suggests a probable mass transfer from the secondary to the primary component at a rate of dM/dt= 3.92\times 10^{-8} M_\odot yr^{-1}. The binary system is expected to evolve into the broken-contact stage in $1.56 \times 10^6$ years. This could be evidence supporting the Thermal Relaxation Oscillation theory.Comment: 8 pages, 6 figures, accepted in A

Birthrates and delay times of Type Ia supernovae

Type Ia supernovae (SNe Ia) play an important role in diverse areas of astrophysics, from the chemical evolution of galaxies to observational cosmology. However, the nature of the progenitors of SNe Ia is still unclear. In this paper, according to a detailed binary population synthesis study, we obtained SN Ia birthrates and delay times from different progenitor models, and compared them with observations. We find that the Galactic SN Ia birthrate from the double-degenerate (DD) model is close to those inferred from observations, while the birthrate from the single-degenerate (SD) model accounts for only about 1/2-2/3 of the observations. If a single starburst is assumed, the distribution of the delay times of SNe Ia from the SD model is a weak bimodality, where the WD + He channel contributes to the SNe Ia with delay times shorter than 100Myr, and the WD + MS and WD + RG channels to those with age longer than 1Gyr.Comment: 11 pages, 2 figures, accepted by Science in China Series G (Dec.30, 2009

Image segmentation Based on Chaotic Quantum Ant Colony Algorithm

Ant colony algorithm is a new type of biomimetic evolutionary algorithm, which has some outstanding characteristics like good robustness, parallelism and positive feedback. It has been widely used in many fields but it still has some weaknesses, such as slow-convergence and easily-falling into local extreme value. Therefore we propose a new algorithm which combines the quantum evolutionary algorithm and ant colony algorithm together based on these shortcomings, this new type of algorithm considers the two quantum bit probability amplitudes as ants’ current location information. The searching space will be doubled when ants’ numbers remain the same. Both introducing the pixel point gradient into quantum revolving door, and dynamically changing rotation angle are to achieve local-searching. Searching by chaotic quanta near candidates with optimal solution is to improve the global optimization. Meanwhile, adopting a NAND gate is to achieve mutating operation, and to avoid algorithm’s precocity. Compared with the traditional algorithm, the new algorithm has a better population diversity and an outstanding ability to overcome the precocity and stagnation in the optimization process. It has been proved that this improved algorithm is effectively to the problems like slow-convergence and easily-falling into local extreme value, and vividly increase the speed and accuracy of the image segmentation

Coverage based empirical modelling for EMS rescue system of Karachi (Pakistan)

Hitne slučajeve uglavnom rješava služba hitne pomoći (EMS). U većini se slučajeva radi o jednom pacijentu. Osnovni sustavi nisu u stanju reagirati kod hitnih slučajeva s više unesrećenih. EMS je u zadnje dvije godine morao prilagoditi svoje planove takvim slučajevima zbog sve većeg broja nesreća i terorističkih napada. Ali takvi bi se planovi mogli osujetiti smanjenim proračunom i izvorima financiranja, a i brojem ambulantnih kola i njihovim položajem/lokacijom, te strategijom njihova slanja, što sve utječe na EMS. Dodatni faktor je promjenljivost u broju slobodnih ambulantnih kola u različito vrijeme tijekom dana. U svrhu održavanja pokrivenosti potrebno je pripaziti i da su ambulantna kola uvijek u stanju pripravnosti. U radu predlažemo model optimalizacije u EMS-u koji će pomoći kod medicinskih postupaka u regiji Karachi, Pakistan (uporabom podataka iz dvije godine, 2010. i 2011.). Također smo proveli i empirijsku analizu vremena reagiranja ambulantnih kola, njihovo vrijeme dolaska u bolnicu i vrijeme provedeno u bolnici. Korištene su Google mape kako bi se olakšalo praćenje i analiziranje mjesta nesreće uz pomoć GPSa ili nekog drugog izvora informacija. Fizikalna simulacija i rezultati su korišteni kao dio procesa planiranja što pokazuje integritet i učinkovitost vremenske granice temeljene na hitnosti pacijenta u vrijeme poziva (Spasilačka ekipa 15).Emergency Medical Services (EMS) is a major source of handling emergencies. Most of the emergencies have one patient. The routine systems are not able to respond to emergencies in which there are many casualties. The mass-casualty disaster response and EMS services plans have become more popular in case of ordinary disasters and terrorist attacks over the past decades. But it might not be possible to construct such plans due to limited resources and budget. There may be such more factors including the number of ambulances deployed, their position/location, and dispatching strategies that affect the EMS system. One more factor is the variation in number of vacant ambulances at different time of the day. In order to sustain coverage, it is necessary to locate ambulances at the station in functional states. In this paper we proposed an optimization model dealing with EMS to assist the medical treatment in the region of Karachi, Pakistan (by using two years data from the year 2010 to 2011). We also conducted and estimated an empirical analysis of ambulance response times, travel times to a hospital and the time spent at the hospital. Google maps are used to facilitate EMS’s provider to view and analyse the entire scene of the accident with the help of GPS or other sources of information. Physical simulation and results are used as part of the planning process, which shows the integrity and efficiency of the time threshold based on the acuity of the patient at the time when the 15 call is made (Rescue 15)

Unveiling hidden stellar aggregates in the Milky Way: 1656 new star clusters found in Gaia EDR3

We report 1,656 new star clusters found in the Galactic disk (|b|<20 degrees) beyond 1.2 kpc, using Gaia EDR3 data. Based on an unsupervised machine learning algorithm, DBSCAN, and followed our previous studies, we utilized a unique method to do the data preparation and obtained the clustering coefficients, which proved to be an effective way to search blindly for star clusters. We tabulated the physical parameters and member stars of the new clusters, and presented some interesting examples, including a globular cluster candidate. The cluster parameters and member stars are available at CDS via anonymous ftp to https://cdsarc.cds.unistra.fr/ftp/vizier.submit//he22c. We examined the new discoveries and discussed their statistical properties. The proper motion dispersions and radii of the new clusters were the same as the previously reported ones. The new star clusters beyond 1.2 kpc were older than those in the solar neighborhood, and the new objects found in the third Galactic quadrant presented the lowest line-of-sight extinctions. Combined with our previous results, the total population of new clusters detected through our method was 2,541, corresponding to 55% of all newly published clusters in the Gaia era. The number of cataloged Gaia star clusters was also increased to nearly six thousand. In the near future, it is necessary to make a unified confirmation and member star determination for all reported clusters.Comment: 16 pages, 11 figures, 3 tables with full clusters/members data link in CDS, accepted for publication in ApJ

RTA Analysis & Existing Modelling for Emergency Medical Service

Prevention of accidents is extremely difficult in absence of present situation analysis, as the aim to identify the incident locations and safety deficiency area is the key to work out the effective solution. To access the feasibility of using Geographic Information System (GIS) for mapping of incident locations with an existing data source is vital to estimate variation of RTAs (Road Traffic Accidents) pattern by interpolating. Generally, accident particulars like location, date, time, sex and suspect are included in GIS database. Here, Arc GIS (10.2.1) software is applied to identify incident locations in Karachi district. To reduce the accidents in particular area/study area and in order to sustain coverage for emergency response, there may be such more factors including the number of ambulances deployed, their position/location, and dispatching strategies that affect the EMS system, authors strictly recommended covering based probabilistic model for (Rescue-15) solving the problem of ambulance locations. GIS facilitates the respective authority to do assessment and to analyze the entire position of the accident with the help of GPS or additional sources of information while consequences are utilized as part of the preparation progression is based on the acuity of the patient in time

Multi-mode delta Sct stars from the Zwicky Transient Facility Survey

We obtain the largest catalog of multi-mode $\delta$ Sct stars in the northern sky to date using the Zwicky Transient Facility (ZTF) Data Release 20 (DR20). The catalog includes 2254 objects, of which 2181 are new to our study. Among these multi-mode $\delta$ Sct stars, 2142 objects are double-mode $\delta$ Sct, while 109 objects are triple-mode $\delta$ Sct and 3 are quadruple-mode $\delta$ Sct. By analyzing the light curves in the $r$ and $g$ bands of the ZTF, we determine the basic parameters of multi-mode $\delta$ Sct stars, including the periods and amplitudes. Periods are checked by comparison with the OGLE catalog of double-mode $\delta$ Sct stars. On the Petersen diagram, multi-mode $\delta$ Sct stars form six sequences. We find that in Galactic coordinates, the periods of 1O/F double-mode $\delta$ Sct stars at high latitudes are shorter than those of 1O/F double-mode $\delta$ Sct stars in the disk, due to metallicity variations. In the future, our catalog can be used to establish the period--luminosity relation and the period--metallicity relation of double-mode $\delta$ Sct stars, and to study the Galactic structure.Comment: 18 pages, 7 figures, accepted for publication in ApJ

Estimating realized heritability for growth in Zhikong scallop (Chlamys farreri) using genome-wide complex trait analysis

In selective breeding, a central parameter in summarizing the proportion of variance due to genetics for the purpose of predicting gains from selection is realized heritability (h2). We applied the genome-wide complex trait analysis (GCTA) method to genome-wide SNP data obtained by 2b-RAD reduced-representation genotyping and phenotypic data for four traits (shell length, shell height, shell width and whole wet weight) with the aim of establishing the heritability for growth in Zhikong scallop (Chlamys farreri) in a selective breeding program. The GCTA-based heritabilities of 0.42 (S.E. 0.09) for shell length, 0.47 (S.E. 0.07) for shell height, 0.54 (S.E. 0.11) for shell width and 0.28 (S.E. 0.03) for whole wet weight, which were estimated with uncommon SNPs (26,471 SNPs with MAF &gt;2%), were close to and strongly correlated (r = 0.957) with traditional estimates of realized heritability and in the moderate-to-high range, in line with values previously obtained for growth rates in bivalves. hGCTA 2 with 20,000 and 10,000 SNPs were very close to estimates with uncommon SNPs and appeared relatively robust to SNP number. Removing causal SNPs had little effect on obtaining reliable estimates of hGCTA 2, suggesting that causal SNPs is not necessary for accurate estimates of h2. Chromosome-wise heritability estimates suggested that the genetic contribution to growth complex traits is scattered across the genome and driven by many loci with small effect rather than a few causal loci with a large effect. These results indicate that the genome-wide complex trait analysis method may be useful for estimating realized heritability for growth in Zhikong scallop with SNPs obtained by reduced-representation genotyping approaches, which is less expensive and faster than full-genome sequencing for non-model species growing in natural environments.</p