Toward Understanding Astrophysical Phenomena

Fast radio bursts (FRBs), a novel type of radio pulse, whose physics is not yet understood at all. Only a handful of FRBs had been detected when we started this project. Taking account of the scant observations, we put physical constraints on FRBs. We excluded proposals of a galactic origin for their extraordinarily high dispersion measures (DM), in particular stellar coronas and HII regions. Therefore our work supports an extragalactic origin for FRBs. We show that the resolved scattering tail of FRB 110220 is unlikely to be due to propagation through the intergalactic plasma. Instead the scattering is probably caused by the interstellar medium in the FRB's host galaxy, and indicates that this burst sits in the central region of that galaxy. Pulse durations of order $\ms$ constrain source sizes of FRBs implying enormous brightness temperatures and thus coherent emission. Electric fields near FRBs at cosmological distances would be so strong that they could accelerate free electrons from rest to relativistic energies in a single wave period. When we worked on FRBs, it was unclear whether they were genuine astronomical signals as distinct from `perytons', clearly terrestrial radio bursts, sharing some common properties with FRBs. Recently, in April 2015, astronomers discovered that perytons were emitted by microwave ovens. Radio chirps similar to FRBs were emitted when their doors opened while they were still heating. Evidence for the astronomical nature of FRBs has strengthened since our paper was published. Some bursts have been found to show linear and circular polarizations and Faraday rotation of the linear polarization has also been detected. I hope to resume working on FRBs in the near future. But after we completed our FRB paper, I decided to pause this project because of the lack of observational constraints.

The pulsar triple system, J0733+1715, has its orbital parameters fitted to high accuracy owing to the precise timing of the central $\ms$ pulsar. The two orbits are highly hierarchical, namely $P_{\mathrm{orb,1}}\ll P_{\mathrm{orb,2}}$, where 1 and 2 label the inner and outer white dwarf (WD) companions respectively. Moreover, their orbital planes almost coincide, providing a unique opportunity to study secular interaction associated purely with eccentricity beyond the solar system. Secular interaction only involves effect averaged over many orbits. Thus each companion can be represented by an elliptical wire with its mass distributed inversely proportional to its local orbital speed. Generally there exists a mutual torque, which vanishes only when their apsidal lines are parallel or anti-parallel. To maintain either mode, the eccentricity ratio, $e_1/e_2$, must be of the proper value, so that both apsidal lines precess together. For J0733+1715, $e_1\ll e_2$ for the parallel mode, while $e_1\gg e_2$ for the anti-parallel one. We show that the former precesses $\sim 10$ times slower than the latter. Currently the system is dominated by the parallel mode. Although only a little anti-parallel mode survives, both eccentricities especially $e_1$ oscillate on $\sim 10^3\yr$ timescale. Detectable changes would occur within $\sim 1\yr$. We demonstrate that the anti-parallel mode gets damped $\sim 10^4$ times faster than its parallel brother by any dissipative process diminishing $e_1$. If it is the tidal damping in the inner WD, we proceed to estimate its tidal quantity parameter ($Q$) to be $\sim 10^6$, which was poorly constrained by observations. However, tidal damping may also happen during the preceding low-mass X-ray binary (LMXB) phase or hydrogen thermal nuclear flashes. But, in both cases, the inner companion fills its Roche lobe and probably suffers mass/angular momentum loss, which might cause $e_1$ to grow rather than decay.

Several pairs of solar system satellites occupy mean motion resonances (MMRs). We divide these into two groups according to their proximity to exact resonance. Proximity is measured by the existence of a separatrix in phase space. MMRs between Io-Europa, Europa-Ganymede and Enceladus-Dione are too distant from exact resonance for a separatrix to appear. A separatrix is present only in the phase spaces of the Mimas-Tethys and Titan-Hyperion MMRs and their resonant arguments are the only ones to exhibit substantial librations. When a separatrix is present, tidal damping of eccentricity or inclination excites overstable librations that can lead to passage through resonance on the damping timescale. However, after investigation, we conclude that the librations in the Mimas-Tethys and Titan-Hyperion MMRs are fossils and do not result from overstability.

Rubble piles are common in the solar system. Monolithic elements touch their neighbors in small localized areas. Voids occupy a significant fraction of the volume. In a fluid-free environment, heat cannot conduct through voids; only radiation can transfer energy across them. We model the effective thermal conductivity of a rubble pile and show that it is proportional the square root of the pressure, $P$, for $P\leq \epsy^3\mu$ where $\epsy$ is the material's yield strain and $\mu$ its shear modulus. Our model provides an excellent fit to the depth dependence of the thermal conductivity in the top $140\,\mathrm{cm}$ of the lunar regolith. It also offers an explanation for the low thermal inertias of rocky asteroids and icy satellites. Lastly, we discuss how rubble piles slow down the cooling of small bodies such as asteroids.

Electromagnetic (EM) follow-up observations of gravitational wave (GW) events will help shed light on the nature of the sources, and more can be learned if the EM follow-ups can start as soon as the GW event becomes observable. In this paper, we propose a computationally efficient time-domain algorithm capable of detecting gravitational waves (GWs) from coalescing binaries of compact objects with nearly zero time delay. In case when the signal is strong enough, our algorithm also has the flexibility to trigger EM observation {\it before} the merger. The key to the efficiency of our algorithm arises from the use of chains of so-called Infinite Impulse Response (IIR) filters, which filter time-series data recursively. Computational cost is further reduced by a template interpolation technique that requires filtering to be done only for a much coarser template bank than otherwise required to sufficiently recover optimal signal-to-noise ratio. Towards future detectors with sensitivity extending to lower frequencies, our algorithm's computational cost is shown to increase rather insignificantly compared to the conventional time-domain correlation method. Moreover, at latencies of less than hundreds to thousands of seconds, this method is expected to be computationally more efficient than the straightforward frequency-domain method.

The Atmospheric Dynamics of Pulsar Companions

Pulsars emit radiation over an extremely wide frequency range, from radio through gamma. Recently, systems in which this radiation significantly alters the atmospheres of low-mass pulsar companions have been discovered. These systems, ranging from ones with highly anisotropic heating to those with transient X-ray emissions, represent an exciting opportunity to investigate pulsars through the changes they induce in their companions. In this work, we present both analytic and numerical work investigating these phenomena, with a particular focus on atmospheric heat transport, transient phenomena, and the possibility of deep heating via gamma rays. We find that certain classes of binary systems may explain decadal-timescale X-ray transient phenomena, as well as the formation of so-called redback companion systems. We also posit an explanation for the formation of high-eccentricity millisecond pulsars with white dwarf companions. In addition, we examine the temperature anisotropy induced by the Pulsar in its companion, and demonstrate that this may be used to infer properties of both the companion and the Pulsar wind. Finally, we explore the possibility of spontaneously generated banded winds in rapidly rotating convecting objects.

A Multiwavelength Study of the Intracluster Medium and the Characterization of the Multiwavelength Sub/millimeter Inductance Camera

The first part of this thesis combines Bolocam observations of the thermal Sunyaev-Zel’dovich (SZ) effect at 140 GHz with X-ray observations from Chandra, strong lensing data from the Hubble Space Telescope (HST), and weak lensing data from HST and Subaru to constrain parametric models for the distribution of dark and baryonic matter in a sample of six massive, dynamically relaxed galaxy clusters. For five of the six clusters, the full multiwavelength dataset is well described by a relatively simple model that assumes spherical symmetry, hydrostatic equilibrium, and entirely thermal pressure support. The multiwavelength analysis yields considerably better constraints on the total mass and concentration compared to analysis of any one dataset individually. The subsample of five galaxy clusters is used to place an upper limit on the fraction of pressure support in the intracluster medium (ICM) due to nonthermal processes, such as turbulent and bulk flow of the gas. We constrain the nonthermal pressure fraction at r500c to be less than 0.11 at 95% confidence, where r500c refers to radius at which the average enclosed density is 500 times the critical density of the Universe. This is in tension with state-of-the-art hydrodynamical simulations, which predict a nonthermal pressure fraction of approximately 0.25 at r500c for the clusters in this sample.

The second part of this thesis focuses on the characterization of the Multiwavelength Sub/millimeter Inductance Camera (MUSIC), a photometric imaging camera that was commissioned at the Caltech Submillimeter Observatory (CSO) in 2012. MUSIC is designed to have a 14 arcminute, diffraction-limited field of view populated with 576 spatial pixels that are simultaneously sensitive to four bands at 150, 220, 290, and 350 GHz. It is well-suited for studies of dusty star forming galaxies, galaxy clusters via the SZ Effect, and galactic star formation. MUSIC employs a number of novel detector technologies: broadband phased-arrays of slot dipole antennas for beam formation, on-chip lumped element filters for band definition, and Microwave Kinetic Inductance Detectors (MKIDs) for transduction of incoming light to electric signal. MKIDs are superconducting micro-resonators coupled to a feedline. Incoming light breaks apart Cooper pairs in the superconductor, causing a change in the quality factor and frequency of the resonator. This is read out as amplitude and phase modulation of a microwave probe signal centered on the resonant frequency. By tuning each resonator to a slightly different frequency and sending out a superposition of probe signals, hundreds of detectors can be read out on a single feedline. This natural capability for large scale, frequency domain multiplexing combined with relatively simple fabrication makes MKIDs a promising low temperature detector for future kilopixel sub/millimeter instruments. There is also considerable interest in using MKIDs for optical through near-infrared spectrophotometry due to their fast microsecond response time and modest energy resolution. In order to optimize the MKID design to obtain suitable performance for any particular application, it is critical to have a well-understood physical model for the detectors and the sources of noise to which they are susceptible. MUSIC has collected many hours of on-sky data with over 1000 MKIDs. This work studies the performance of the detectors in the context of one such physical model. Chapter 2 describes the theoretical model for the responsivity and noise of MKIDs. Chapter 3 outlines the set of measurements used to calibrate this model for the MUSIC detectors. Chapter 4 presents the resulting estimates of the spectral response, optical efficiency, and on-sky loading. The measured detector response to Uranus is compared to the calibrated model prediction in order to determine how well the model describes the propagation of signal through the full instrument. Chapter 5 examines the noise present in the detector timestreams during recent science observations. Noise due to fluctuations in atmospheric emission dominate at long timescales (less than 0.5 Hz). Fluctuations in the amplitude and phase of the microwave probe signal due to the readout electronics contribute significant 1/f and drift-type noise at shorter timescales. The atmospheric noise is removed by creating a template for the fluctuations in atmospheric emission from weighted averages of the detector timestreams. The electronics noise is removed by using probe signals centered off-resonance to construct templates for the amplitude and phase fluctuations. The algorithms that perform the atmospheric and electronic noise removal are described. After removal, we find good agreement between the observed residual noise and our expectation for intrinsic detector noise over a significant fraction of the signal bandwidth.

Estrelas dantescas nas galáxias de Haroldo de Campos

Uma constante no trabalho plural de Haroldo de Campos é o apreço pela intertextualidade. Em um percurso que toca as mais distantes e distintas galáxias, destacamos uma constelação: quatro textos literários (Finismundo: a última viagem, Signância quase céu, Galáxias e A máquina do mundo repensada) que entram em diálogo com a Commedia, de Dante Alighieri, e uma tradução de Haroldo de seis cantos do paraíso. Desdobrando o interesse de Haroldo de Campos pelo concreto da obra, partimos de algumas soluções formais dos textos em questão para pensar a experiência estética e a diferença entre as visões de mundo das obras comparadas.O estudo da Commedia permite perceber configurações formais que aproximam o leitor da experiência mística da personagem ao apresentá-la como experiência estética. O interesse de Haroldo de Campos está no potencial estético da obra de Dante. Confrontando o texto do poeta italiano com a tradução e com os quatro poemas citados acima, mostramos as semelhanças e diferenças dos processos de tradução e mimesis nas diversas metamorfoses pelas quais a Commedia passa nas criações de Haroldo de Campos

Bartonella species detection in captive, stranded and free-ranging cetaceans

We present prevalence of Bartonella spp. for multiple cohorts of wild and captive cetaceans. One hundred and six cetaceans including 86 bottlenose dolphins (71 free-ranging, 14 captive in a facility with a dolphin experiencing debility of unknown origin, 1 stranded), 11 striped dolphins, 4 harbor porpoises, 3 Risso's dolphins, 1 dwarf sperm whale and 1 pygmy sperm whale (all stranded) were sampled. Whole blood (n = 95 live animals) and tissues (n = 15 freshly dead animals) were screened by PCR (n = 106 animals), PCR of enrichment cultures (n = 50 animals), and subcultures (n = 50 animals). Bartonella spp. were detected from 17 cetaceans, including 12 by direct extraction PCR of blood or tissues, 6 by PCR of enrichment cultures, and 4 by subculture isolation. Bartonella spp. were more commonly detected from the captive (6/14, 43%) than from free-ranging (2/71, 2.8%) bottlenose dolphins, and were commonly detected from the stranded animals (9/21, 43%; 3/11 striped dolphins, 3/4 harbor porpoises, 2/3 Risso's dolphins, 1/1 pygmy sperm whale, 0/1 dwarf sperm whale, 0/1 bottlenose dolphin). Sequencing identified a Bartonella spp. most similar to B. henselae San Antonio 2 in eight cases (4 bottlenose dolphins, 2 striped dolphins, 2 harbor porpoises), B. henselae Houston 1 in three cases (2 Risso's dolphins, 1 harbor porpoise), and untyped in six cases (4 bottlenose dolphins, 1 striped dolphin, 1 pygmy sperm whale). Although disease causation has not been established, Bartonella species were detected more commonly from cetaceans that were overtly debilitated or were cohabiting in captivity with a debilitated animal than from free-ranging animals. The detection of Bartonella spp. from cetaceans may be of pathophysiological concern.

Abundance of cetaceans in the oceanic northern Gulf of Mexico from 2003 and 2004 ship surveys

The Gulf of Mexico (GMx) is a subtropical marginal sea of the western North Atlantic Ocean with a diverse cetacean community. Ship-based, line-transect abundance surveys were conducted in oceanic waters (>200 m deep) of the northern GMx within U.S. waters (380,432 square km) during summer 2003 and spring 2004. Data from these surveys were pooled and minimum abundance estimates were based on 10,933 km of effort and 433 sightings of at least 17 species.The most commonly sighted species (number of groups) were pantropical spotted dolphin, Stenella attenuata (115); sperm whale, Physeter macrocephalus (85); dwarf/pygmy sperm whale, Kogia sima/breviceps (27); Risso’s dolphin, Grampus griseus (26); and bottlenose dolphin, Tursiops truncatus (26). The most abundant species (number of individuals; coefficient of variation) were S. attenuata (34,067; 0.18); Clymene dolphin, S. clymene (6,575; 0.36); T. truncatus (3,708; 0.42); and striped dolphin, S. coeruleoalba (3,325; 0.48). The only large whales sighted were P. macrocephalus (1,665; 0.20) and Bryde’s whale, Balaenoptera edeni (15; 1.98). Abundances for other species or genera ranged from 57 to 2,283 animals. Cetaceanswere sighted throughout the oceanic northern GMx, and whereas many species were widely distributed, some had more regional distributions. Compared to abundance estimates for this area based on 1996-2001 surveys, the estimate for S. attenuata was significantly smaller (P <0.05) and that for the spinner dolphin, S. longirostris, appeared much smaller. Also, P. macrocephalus estimates were based on less negatively biased estimates of group-size using 90-minute counts during 2003 and 2004.

The Hudson-Raritan Estuary as a crossroads for distribution of blue (Callinectes sapidus), lady (Ovalipes ocellatus), and Atlantic rock (Cancer irroratus) crabs

Blue (Callinectes sapidus)(Portunidae),lady (Ovalipes ocellatus)(Portunidae), and Atlantic rock (Cancer irroratus) (Cancridae) crabs inhabit estuaries on the northeast United States coast for parts or all of their life cycles. Their distributions overlap or cross during certain seasons. During a 1991–1994 monthly otter trawl survey in the Hudson-Raritan Estuary between New York and New Jersey, blue and lady crabs were collected in warmer months and Atlantic rock crabs in colder months. Sex ratios, male:female, of mature crabs were 1:2.0 for blue crabs, 1:3.1 for lady crabs, and 21.4:1 for Atlantic rock crabs. Crabs, 1286 in total, were subsampled for dietary analysis, and the dominant prey taxa for all crabs, by volume of foregut contents, were mollusks and crustaceans. The proportion of amphipods and shrimp in diets decreased as crab size increased. Trophic niche breadth was widest for blue crabs, narrower for lady crabs, and narrowest for Atlantic rock crabs. Trophic overlap was lowest between lady crabs and Atlantic rock crabs, mainly because of frequent consumption of the dwarf surfclam (Mulinia lateralis) by the former and the blue mussel (Mytilus edulis) by the latter. The result of cluster analysis showed that size class and location of capture of predators in the estuary were more influential on diet than the species or sex of the predators.

小麦春化相关基因元件克隆分析与小麦矮化突变体的研究

一、 春化相关基因全长cDNA序列及其启动子的克隆与分析研究 通过建立小麦（Triticum aestivum. L. cv Jingdong No.1）胚芽春化cDNA文库，以春化相关基因VER2的3’端序列为探针，筛选获得全长1195 bp cDNA序列，它编码300个氨基酸。在VER2中存在植物疾病抗性反应蛋白和茉莉酸诱导凝集素两种蛋白的结构域。另外在VER2蛋白中存在核定位信号和多种磷酸酶的作用位点，VER2可能参与了多种调控途径。 以VER2基因的cDNA为探针，利用改进的池式PCR以及高密度膜杂交筛选的方法，从小麦TAC基因组文库中获得41,788 bp的基因组克隆，该序列含有11个基因，其中VER2基因位于第三个基因。VER2基因组序列含有3个内含子，4个外显子与cDNA序列100%同源。通过对转录起始点和转录终止点的分析，进一步证明从cDNA文库筛选得到的VER2基因为全长序列。 对VER2基因的上游启动子区域进行分析，发现基因上游启动子区存在三个小的重复序列，每个片段有482 bp，另有两个较大的重复序列，每个片段有2,161 bp。对上游2.8 kb启动子区（不含重复序列）的响应元件分析，其包括ABA响应元件（ABRE）、茉莉酸甲酯响应元件（Me-JARE）、胚乳特异性表达元件、参与淀粉酶合成的元件以及存在类似GA响应元件（ATAACAAAC）如ATAACATAC等等。根据VER2基因上游6 kb序列结构特点，将VER2启动子区域进行缺失突变形成10个片段，分别以GUS和GFP为报告基因构建成瞬间表达载体和植物表达载体等四类质粒。通过基因枪方法将最大片段（6 kb）驱动GFP报告基因的瞬间表达载体转入经春化处理或未春化处理的小麦幼叶中，结果发现GFP在春化处理的幼叶中表达，而在未春化处理的幼叶中不表达，说明VER2基因的启动子驱动基因转录受春化处理调控。 二、 小麦矮化突变体的研究 通过对小麦矮化突变体gaid遗传生理分析发现该突变体为半显性阻断GA信号途径，由此发现在赤霉素信号途径中，α-淀粉酶的诱导一定程度上通过某些与株高相关的基因控制。突变体gaid呈现对高浓度的脱落酸更敏感，当ABA浓度达到10-6M时，突变体的生长几乎完全受到了抑制，而野生型的生长需要ABA浓度达到10-5M时才能完全受到抑制。通过突变体gaid对乙烯等抑制型生长调节剂的响应实验研究，首次提出GA调控植物伸长生长存在两条信号途径，即GA基础水平信号途径（GA basal level signaling pathway）和GA正常水平信号途径（GA normal level signaling pathway），而乙烯以及高浓的GA合成抑制剂（如PAC）是通过第一条途径（GA基础水平信号途径）起作用。光形态建成中对植株生长的抑制作用存在独立于GA的信号途径。 突变体gaid的根系在强光照（63.5 Es-1m-2）和培养基内（低氧）的生长条件下，表现出弯曲、变短、加粗等异常性状，而随光照强度的减弱，这种根系异常生长的表型也减弱，在暗培养中则完全消失，但无论在哪种环境条件下，相对野生型对照而言，突变体的种子根短、侧根少。低浓度的ABA（10-8M）可以恢复突变体gaid根系在强光低氧条件下的正常生长发育。然而利用IAA及其极性运输的抑制剂（TIBA）、乙烯生物合成前提物（ACC）及合成抑制剂（AOA）处理突变体gaid，并没有发现突变体根系的生长发育得到恢复。 突变体gaid可能是一个新的属于小麦GA信号途径中的负调控基因（GAID）发生了突变或超表达，导致其负调控作用增强，呈现半显性的矮化突变。在与另一已知小麦GA信号途径中的负调控基因RHT的关系研究上发现，GAID可能对RHT蛋白磷酸化后的降解途径起抑制作用。通过双向电泳发现突变体gaid与野生型对照（京冬1号）在生长过程中存在差异蛋白，这将有助于对GA信号途径分子机理的深入研究。

Marketing of small indigenous species of fish (SIS) in three selected fish markets of Mymensingh

A socio-economic survey was conducted round the year in three fish markets at Mymensingh, Bangladesh. The selected markets were categorized as rural market (Sutiakhali market), a peri-urban market (Kamal Ranjeet market, BAU) and an urban market (Notun Bazar market, Mymensingh town). It was learnt from the survey that the availability of Small Indigenous Fish Species (SIS) declined to a great extent over the last few years and at presently many of such fish species are either threatened or at the edge of extinction. The supply of SIS was highest in KR market (37% of total) and more or less similar in Notun Bazar and Sutiakhali fish market (25 and 27% respectively). The total supply of SIS fluctuated from 25% to 35% throughout the year in these markets. About 48 SIS were found in the sampled markets over the survey period. The highest number of species (45) was found in KR market followed by Notun Bazar (42) and Sutiakhali (37) fish markets. During the survey, three critically endangered species namely, schilbid catfish, garua catfish and rita were found in these markets. Beside these, other 11 and 10 species were listed to be endangered and vulnerable respectively. The biodiversity of 21 SIS found in three markets were no threat at all. Three species (guntea loach, Indian glass barb and flying barb) were 'data deficient' as reported by the IUCN Red Book (IUCN-Bangladesh 2000). From the supply point of view small prawn, spotted snakehead, stinging catfish, pool barb, striped dwarf catfish, Gangetic mystus, walking catfish and tank goby were the prominent fish. The least available species found in this survey were lesser spiny eel, barred spiny eel, Gangetic ailia, freshwater garfish, zig-zag eel, flying barb, Ganges river sprat, freshwater river shad and dwarf gourami. The weight of SIS available in Notun bazar was highest and nearly double than other two markets. There was no significant difference recorded in the supply of SIS in Sutiakhali and KR markets. The average monthly SIS supply was 185, 192 and 467 kg in KR, Sutiakhali and Notun Bazar, respectively; therefore, the cumulative average supply was 844 kg per month in three markets. The price of SIS ranged widely from taka 50-450/kg depending on species, location of market, time of purchase and the condition of fish. In general small prawn, ticto barb, dwarf gourami, Gangetic leaffish, and Annandale loach were sold at a lower price (ranged taka 50-100/kg) and these species could be considered at the bottom of the market-price list. Other SIS like walking catfish, climbing parch, butter catfish, cotio and schilbid catfish valued as highest price (ranged taka 150-450/kg). There was no specific marketing chain for SIS in Mymensingh region. The components of marketing channels and their expansion varied with seasons and locations. The general pattern, however, was as this - after buying fish from fish farmer/fishermen, middlemen (locally known as Foria) used to buy fish to wholesale market and sell to the wholesalers. The retailers used to buy fish from wholesaler through auction to the highest bidders. The retailers then send the fish to particular market where the fish reached the consumers. The livelihood strategy of SIS retailers in three fish markets showed that socio-economic constraints such as low income, poor educational background, low economic status and lack of capital are the main constrains [sic]. Most of the retailers proposed that government should control the fish price throughout the year, so that the producers can get reasonable and stable price. Construction of cold storage and preservation facilities at market sites, improvement of road and communication, improvement of physical market facilities and reduction of market chain is essential. Credit facilities, improvement of their standard of living, health and sanitary condition, housing condition, children education and access to drinking water facilities were identified as additional aspects to improve socio-economic condition of SIS retailers.

Study ectoparasite infestation of 10 common imported freshwater ornamental fish species

In the present study, ectoparasite infestation of common freshwater ornamental fish species imported into Iran including: Dwarf gourami (Colisa lalia), Angelfish (Pterophyllum scalare), Oscar (Astronatus ocellatus), Red eye Tetra ( Moenkhansia Sanctaefilomenae), Barb( Capoeta tetrazona), Arowana (Osteoglossum bicirrhosum), Goldfish(Carassius auratus), Red fin Shark (Lebeo elythrurus, Catfish (Hypostomus plecostomus) and Pangasius sutchi ( Pangasius hypophthalmus) from May until April was investigated.A total of 6 specimens sample of each fish species) randomly were obtained and taken alive to the lab. After observing gill and skin wet smear under the microscope , gill was dissected and examined carefully .Photo and films were taken from the isolated parasites and parasite identification was performed according to Yamaguti AP1), Bychowsky (■Y).From a total of examined fishes 1\ ► sample (YY.V.) were parasitized .Parasite groups that were observed consisting ciliated protozoan myxosporidian , monogenean Digenean metacercaria and crustacean .The only non-parasitized fish was Barb. Monogenea Trianchoratus sp. , Cleidodiscus sp. , Ancylodiscoides sp. , Thaparocleidus sp. , Centrocestus formosanus metacercaria and Myxobolus longisporus report for the first time in ornamental fish which imported from Southeast of Asia to Iran. According to the results, it seems that severe quarantine and sanitary rules are necessary.

Simultaneous multiwavelength observations of sagittarius A

We observed Sgr A* using the Very Large Array (VLA) and the Giant Metrewave Radio Telescope (GMRT) at multiple centimeter and millimeter wavelengths on 2003 June 17. The measured flux densities of Sgr A*, together with those obtained from the Submillimeter Array (SMA) and the Keck II 10 m telescope on the same date, are used to construct a simultaneous spectrum of Sgr A* from 90 cm to 3.8 mu m. The simultaneous spectrum shows a spectral break at about 3.6 cm, a possible signature of synchrotron self-absorption of the strong radio outburst that occurred near epoch 2003 July 17. At 90 cm, the flux density of Sgr A* is 0.22 +/- 0.06 Jy, suggesting a sharp decrease in flux density at wavelengths longer than 47 cm. The spectrum at long cm wavelengths appears to be consistent with free-free absorption by a screen of ionized gas with a cutoff similar to 100 cm. This cutoff wavelength appears to be three times longer than that of similar to 30 cm suggested by Davies, Walsh, & Booth based on observations in 1974 and 1975. Our analysis suggests that the flux densities of Sgr A* at wavelengths longer than 30 cm could be attenuated and modulated by stellar winds from massive stars close to Sgr A*.

The radio counter-jet of the QSO 3C 48

We present multi- frequency radio observational results of the quasar 3C 48. The observations were carried out with the Very Large Array ( VLA) at five frequencies, 0.33, 1.5, 4.8, 8.4, and 22.5 GHz, and with the Multi- Element Radio Linked Interferometer Network ( MERLIN) at the two frequencies of 1.6 and 5 GHz. The source shows a one- sided jet to the north within 1", which then extends to the northeast and becomes diffuse. Two bright components ( N2 and N3), containing most of the flux density, are present in the northern jet. The spectral index of the two components is alpha(N2) similar to -0.99 +/- 0.12 and alpha(N3) similar to - 0.84 +/- 0.23 ( S proportional to nu(alpha)). Our images show the presence of an extended structure surrounding component N2, suggestive of strong interaction between the jet and the interstellar medium ( ISM) of the host galaxy. A steep- spectrum component, labelled S, located 0.25 " southwest to the flat- spectrum component which could be the core of 3C 48, is detected at a significance of > 15 sigma. Both the location and the steepness of the spectrum of component S suggest the presence of a counter- jet in 3C 48.

Bending of jets in the QSO NRAO 530

We present radio images of NRAO 530 on scales ranging from pc to kpc. The observations include the EVN at 5 GHz, the VLBA at 1.6, 8.6 and 15 GHz, the MERLIN at 1.6 and 5 GHz, and the VLA at 5, 8.4, 15, 22, and 43 GHz. The VLBI images show a core-jet structure with an oscillating trajectory on a scale of about 30 mas north of the strongest compact component (core). Superluminal motions are detected in five of the jet components with apparent velocities in the range of 13.6 to 25.2c. A new component is detected at 15 GHz with the VLBA observations, which appears to be associated with the outburst in 2002. Significant polarized emission is detected around the core with the VLBA observations at 15 GHz. Rapid variations of the polarization intensity and angle are found between the epochs in 2002 and 2004. On the kpc-scale, a distant component (labelled as WL) located 11 aresec west (PA=-86 degrees) of the core is detected beyond the core-jet structure which extended to several hundreds of mas in the north-west direction (-50 degrees). A significant emission between the core-jet structure and the WL is revealed. A clump of diffuse emission (labelled EL, 12 arcsec long) at PA 70 degrees to the core, is also detected in the VLA observations, suggesting the presence of double lobes in the source. The core component shows a flat spectrum, while the distant components WL and EL have steep spectra. The steep spectra of the distant components and the detection of the arched emission suggest that the distant components are lobes or hot-spots powered by the core of NRAO 530. The morphologies from pc- to kpc-scales and the bending of jets are investigated. The observed radio morphology from pc to kcp appears to favor the model in which precession or wobbling of the nuclear disk drives the helical motion of the radio plasma and produces the S-shaped structure on kpc scale.

高产抗旱优质谷子新品种辐谷7号的选育与推广利

利用400Gy 60Co γ射线处理87070谷子品系干种子,选育出辐谷7号新品种。该品种具有株型紧凑、茎秆矮、高产抗旱优质并且适应种植地区广等特点。2002年2月通过陕西省农作物品种审定委员会审定,截止2008年在黄土高原地区累计推广10.8万hm2。

簇毛麦（ Dasypyrum villosum）矮秆突变体的研究

株高是农作物的重要农艺性状之一，适度矮化有利于农作物的耐肥、抗倒、高产等。20世纪50年代，以日本的赤小麦为矮源的半矮秆小麦的培育和推广，使得世界粮食产量显著增长，被誉为“绿色革命”。迄今为止，已报到的麦类矮秆、半矮秆基因已达70多个，但由于某些矮源极度矮化或者矮化的同时伴随不利的农艺性状，使得真正运用于育种实践的矮源较少。因此，发掘和鉴定新的控制麦类作物株高的基因，开展株高基因定位、克隆及作用机理等方面的研究，对实现麦类作物株高的定向改良，具有重要的理论意义和应用价值。簇毛麦(Dasypyrum villosum，2n＝14，VV)是禾本科簇毛麦属一年生二倍体异花授粉植物，为栽培小麦的近缘属。本课题组在不同来源的簇毛麦杂交后代中发现了一株自然突变产生的矮秆突变体。观察分析了该突变体的生物学特性，对矮秆性状进行了遗传分析，对茎节细胞长度、花粉的活力进行了细胞学观察，考察了该突变体内源赤霉素含量及不同浓度外施赤霉素对突变体的作用，分析了赤霉素生物合成途径中的内根贝壳杉烯氧化酶（KO）和赤霉素20氧化酶(GA20ox)的转录水平，对赤霉素20氧化酶和赤霉素3-β羟化酶(GA3ox)进行了克隆和序列分析，并对GA20ox进行了原核表达和表达的组织特异性研究。主要研究结果如下：1. 该突变体与对照植株在苗期无差异，在拔节后期才表现出植株矮小，相对对照植株，节间伸长明显受到抑制，叶鞘长度基本不变。在成熟期，对照植株的平均株高为110cm，而突变株的平均株高为32cm，仅为对照植株的1/3 左右。除了株高变矮以外，在成熟后期，突变株还表现一定程度的早衰和雄性不育。I2-KI染色法观察花粉活力结果表明，对照植株花粉90%以上都是有活力的，而突变植株的花粉仅20%左右有活力。2. 突变株与对照植株的杂交F1代均表现正常株高，表明该突变性状为隐性突变。F1代植株相互授粉得到的168株F2代植株中，株高出现分离，正常株高（株高高于80cm）与矮秆植株（株高矮于40cm）的株数比为130：38，经卡方检验，其分离比符合3：1的分离比，因此推测该突变体属于单基因的隐性突变。3. 用ELISA方法检测突变株和对照植株的幼嫩种子中内源性生物活性赤霉素（GA1＋3）含量，结果表明突变株的赤霉素含量为36 ng/ml，而对照植株的赤霉素含量为900 ng/ml。对突变株外施赤霉素，发现矮秆突变株的株高和花粉育性均可得到恢复。这些结果表明该突变株为赤霉素缺陷型突变。4. 用荧光定量PCR方法比较突变株与对照植株中内根贝壳杉烯氧化酶和赤霉素20氧化酶的转录水平，结果表明突变株的KO转录水平比对照植株分别提高了6倍（苗期）和16倍（成熟期），突变株的GA20ox转录水平与对照植株在苗期无明显差异，在成熟期突变株较对照植株则提高了10倍左右。这些结果表明该矮秆突变体与赤霉素的生物合成途径密切相关，而且极有可能在赤霉素的生物合成途径早期就发生了改变。5. 以簇毛麦总基因组为模板，同源克隆了GenBank登录号为EU142950，RT-PCR分离克隆了簇毛麦的GA3ox基因cDNA全长序列，分析结果表明该cDNA全长1206bp，含完整编码区1104bp，推测该序列编码蛋白含368个氨基酸残基，分子量为40.063KD，等电点为6.27。预测的氨基酸序列含有双加氧酶的活性结构，在酶活性中心2个Fe离子结合的氨基酸残基非常保守。该序列与小麦、大麦和水稻的GA3ox基因一致性分别为98%、96%、86%。基因组序列与cDNA序列在外显子部分一致，在478-715bp和879-1019bp处分别含238bp和140bp的内含子。6. 通过RT-PCR技术克隆了簇毛麦的GA20ox基因全长，命名为DvGA20ox，GenBank登录号为EU142949。该基因全长1080个碱基，编码359个氨基酸，具有典型的植物GA20ox基因结构。该基因编码的蛋白质与小麦、大麦、黑麦草等GA20ox蛋白的同源性分别为98%，97% 和91%。该序列重组到原核表达载体pET-32a(+)上，将获得的重组子pET-32a(+)-DvGA20ox转化大肠杆菌BL21pLysS后用IPTG进行诱导表达。SDS-PAGE分析表明，DvGA20ox基因在大肠杆菌中获得了高效表达，融合蛋白分子量为55kDa。定量PCR分析表明，该基因在簇毛麦不同器官中的表达差异明显：叶片中表达水平最高，根部表达水平次之，茎部和穗中表达较弱。在外施赤霉素后，该基因的表达水平在两小时以后急剧下降，表明该基因的表达受自身的反馈调节。本研究结果认为，(1)该簇毛麦矮秆突变体为单基因的隐性突变；(2)该矮秆突变体为赤霉素敏感突变，内源赤霉素含量检测表明突变体的内源性赤霉素含量仅为对照植株的1/30；(3)荧光定量PCR结果表明突变株的赤霉素生物合成途径的关键酶基因表达水平比对照植株高，而且突变植株的赤霉素生物合成改变很可能发生在赤霉素生物合成途径的早期；(4)GA20ox有表达的组织特异性，且受到自身产物的反馈调节。 Plant height is an impotrant agronomic trait of triticeae crops.Semi-dwarf cropcultivars, including those of wheat, maize and rice, have significantly increased grainproduction that has been known as “green revolution”. The new dwarf varieties couldraise the harvest Index at the expense of straw biomass, and, at the sametime, improvelodging resistance and responsiveness to nitrogen fertilizer. Moreover, dwarf traits ofplant are crucial for elucidating mechanisms for plant growth and development aswell. In many plant species, various dwarf mutants have been isolated and theirmodles of inheritance and physiology also have been widely investigated.The causesfor their dwarf phenotypes were found to be associated with plant hormones,especially, gibberellins GAs.Dasypyrum villosum Candargy (syn.Haynaldia villosa) is a cross-pollinating,diploid (2n = 2x = 14) annual species that belongs to the tribe Triticeae. It is native toSouthern Europe and West Asia, especially the Caucasuses, and grows underconditions unfavorable to most cultivated crops. The genome of D. villosum,designated V by Sears, is considered an important donor of genes to wheat for improving powdery mildew resistance, take-all, eyespot, and plant and seed storageprotein content. A spontaneous dwarf mutant was found in D. villosum populations.The biological character and modles of inheritance of this dwarf mutant are studied.The cell length of stem cell is observed. The influence of extraneous gibberellin tothe dwarf mutant is also examined; the transcript level of key enzyme of gibberellinbiosynthesis pathway in mutant and control plants is compared. GA3ox and GA20oxare cloned and its expression pattern is researched.1. The dwarf mutant showed no difference with control plants at seedlingstage.At mature stage, the average height of control plants were 110cm and the dwarfplants were 33cm. The height of the mutant plant was only one third of the normalplants due to the shortened internodes. Cytology observation showed that theelongation of stem epidermal and the parenchyma cells were reduced. The dwarfmutant also shows partly male sterile. Pollen viability test indicates that more than80% of the pollen of the mutant is not viable.2. The inheritance modle of this dwarf mutant is studied. All The F1 plantsshowed normal phenotype indicating that the dwarfism is controlled by recessivealleles. Among the 168 F2 plants, there are 130 normal plants and 30 dwarf plants, thesegregation proportion accord with Mendel’s 3:1 segregation. We therefore proposethat this dwarf phenotype is controlled by a single recessive gene.3. Quantitative analyses of endogenous GA1+3 in the young seeds indicated thatthe content of GA1+3 was 36ng/ml in mutant plants and 900ng/ml in normal plants.The endogenous bioactive GA1+3 in mutant plants are only about 1/30 of that innormal plants. In addition, exogenously supplied GA3 could considerably restore themutant plant to normal phenotype. These results showed that this mutant wasdefective in the GA biosynthesis.4. More than ten enzymes are involved in GA biosynthesis. KO catalyzes thefirst cytochrome P450-mediated step in the gibberellin biosynthetic pathway and themutant of KO lead to a gibberellin-responsive dwarf mutant. GA20ox catalyze therate-limited steps so that their transcript level will influence the endogenous GAbiosynthesis and modifies plant architecture. The relative expression levels of genesencoding KO and GA20ox were quantified by real time PCR to assess whether thechanges in GA content correlated with the expression of GA metabolism genes andwhere the mutant occurred during the GA biosynthesis pathway. In mutant plants,the transcript levels of KO increased about 6-fold and 16-fold at the seedling stage and elongating stage respectively comparing with the normal plants. For theseedlings, there was no notable difference in the expression of GA20ox betweenmutant and normal plants. At the elongating stage, GA20ox transcript increased 10times in mutant plants, suggesting that the GA biosynthesis pathway in mutant plantshad changed from the early steps rather than the late steps.5. A full length cDNA of D. villosum gibberellin 3β-hydroxylase homology(designated as DvGA3ox) was isolated and consisted of 1206bp containing an openreading frame of 1104bp encoding 368 predicted amino acid residues. Identityanalysis showed that the gibberellin 3β-hydroxylase nucleotide sequence shared 98%,96% and 86% homology with that of wheat, barley and rice. The predicted peptidecontained the active-site Fe of known gibberellin 3β-hydroxylase and the regionhomologous to wheat, barley and Arabidopsis. The genomic clone of gibberellin3β-hydroxylase has two introns.6. The full-length cDNA of D. villosum gibberellin 20 oxidase (designated asDvGA20ox) was isolated and consisted of 1080-bp and encoded 359 amino acidresidues with a calculated mol wt of 42.46 KD. Comparative and bio-informaticsanalyses revealed that DvGA20ox had close similarity with GA20ox from otherspecies and contained a conserved LPWKET and NYYPXCQKP regions. Tissueexpression pattern analysis revealed DvGA20ox expressed in all the tissues that wereexamined and the highest expression of DvGA20ox in expanding leaves followed byroots. Heterologous expression of this cDNA clone in Escherichia coli gave a fusionprotein that about 55KD. Transcript levels of DvGA20ox dramatically reduced twohours after application of biologically active GA3, suggesting that the biosynthesis ofthis enzymes might be under feedback control.