Prospects and Constraints for a Recreational Fishery on East Canyon Creek at the 910 Ranch

Summit County Lands and Natural Resources has retained students from Utah State University’s Management and Restoration of Aquatic Ecosystems program to evaluate current conditions of East Canyon Creek (ECC) in the 910 Ranch and propose prospects, constraints, and potential actions to establish a recreational trout fishery

Survival Rate and Growth of Fighting Fish Larvae (Betta splendens Regan) Fed on Various Live Foods

Larval of fighting fish (Betta splendens Regan) requires precise live foods for its growth and survival. In this experiment, fish larvae were fed on either Paramecium + Artemia, Paramecium + Artemia + Tubifex, Paramecium + Moina, or Paramecium + Moina + Tubifex. The fish were fed Paramecium from day-2 till day-7 after hatching. There after, the live food was changed according to the treatments till day-28.  Results showed that fish fed on Paramecium + Artemia significantly had the highest total length (12.63 mm) than other treatments (11.86 mm). On the other hand, survival rate of fish had no significant affected by the treatments. Keywords: fighting fish, Betta splendens, Paramecium, Moina, Artemia, Tubifex, larvae   ABSTRAK Larva ikan betta (Betta splendens Regan) membutuhkan jenis pakan alami yang tepat bagi kelangsungan hidup dan pertumbuhannya. Pada penelitian ini, larva ikan diberi pakan berupa Paramecium + Artemia, Paramecium + Artemia + Tubifex, Paramecium + Moina, atau Paramecium + Moina + Tubifex.  Ikan diberi pakan pakan berupa Paramecium dari hari ke-2 hingga hari ke-7. Setelah itu, pemberian pakan alami diubah berdasarkan masing-masing perlakuan hingga hari ke-28.  Hasil penelitian menunjukkan bahwa ikan yang diberi pakan Paramecium + Artemia memiliki tubuh secara signifikan lebih panjang (12,63 mm) dibandingkan perlakuan lainnya (11,86 mm).  Sementara itu, kelangsungan hidup tidak dipengatuhi oleh perlakuan. Kata kunci: ikan betta, Betta splendens, Paramecium, Moina, Artemia, Tubifex, larv

Neurovestibular Effects of Long-Duration Spaceflight: A Summary of Mir-Phase 1 Experiences

Space motion sickness and associated neurovestibular dysfunction though not completely understood - have been relatively well clinically and operationally characterized on short-duration (1-2 week) Space Shuttle missions (Oman, et al, 1984, 1986; Thornton, et al, 1987; Reschke, et al, 1994). Between March 1995 and June 1998, seven NASA astronauts flew on the Russian Mir space station, as "Phase 1" of the joint effort to build the International Space Station, and provided NASA with invaluable experience on the operational and biomedical problems associated with flights of up to six months in duration. The goal of this paper is to provide a summary of the available information on neurovestibular dysfunction, space motion sickness, and readaptation to Earth's gravity on the NASA Mir flights, based on a set of medical questionnaire data, transcripts, and interviews which are available from the NASA-Mir Phase I program. Records were incomplete and anecdotal. All references to specific crewmembers have been removed, to respect their individual privacy. Material was excerpted from multiple sources of information relating to neurologic function, sensory illusions and motion sickness of NASA-Mir Phase I Program crewmembers. Data were compiled by epoch (in-flight vs landing/postflight) and grouped by neurovestibular topic. The information was recorded either contemporaneously during or within days after landing, or retrospectively weeks to months later. Space motion sickness symptoms are more intense and longer in duration. Sense of spatial orientation takes at least a month to become "natural and instinctive" in space station structures, but mental survey knowledge is apparently not completely developed even after 3 months in some cases. Visual reorientation illusions (VRI) are more easily induced after long exposure to weightlessness. Head movements can cause illusory spinning sensations for up to 7 days postflight. Postural and balance control does not fully recover for at least a month postflight

Missing dark matter in dwarf galaxies?

We use cosmological hydrodynamical simulations of the APOSTLE project along with high-quality rotation curve observations to examine the fraction of baryons in ΛCDM haloes that collect into galaxies. This ‘galaxy formation efficiency’ correlates strongly and with little scatter with halo mass, dropping steadily towards dwarf galaxies. The baryonic mass of a galaxy may thus be used to place a lower limit on total halo mass and, consequently, on its asymptotic maximum circular velocity. A number of observed dwarfs seem to violate this constraint, having baryonic masses up to 10 times higher than expected from their rotation speeds, or, alternatively, rotating at only half the speed expected for their mass. Taking the data at face value, either these systems have formed galaxies with extraordinary efficiency – highly unlikely given their shallow potential wells – or their dark matter content is much lower than expected from ΛCDM haloes. This ‘missing dark matter’ is reminiscent of the inner mass deficit of galaxies with slowly rising rotation curves, but cannot be explained away by star formation-induced ‘cores’ in the dark mass profile, since the anomalous deficit applies to regions larger than the luminous galaxies themselves. We argue that explaining the structure of these galaxies would require either substantial modification of the standard ΛCDM paradigm or else significant revision to the uncertainties in their inferred mass profiles, which should be much larger than reported. Systematic errors in inclination may provide a simple resolution to what would otherwise be a rather intractable problem for the current paradigm

The origin of the mass discrepancy-acceleration relation in ΛCDM

We examine the origin of the mass discrepancy–radial acceleration relation (MDAR) of disc galaxies. This is a tight empirical correlation between the disc centripetal acceleration and that expected from the baryonic component. The MDAR holds for most radii probed by disc kinematic tracers, regardless of galaxy mass or surface brightness. The relation has two characteristic accelerations: a0, above which all galaxies are baryon dominated, and amin, an effective minimum acceleration probed by kinematic tracers in isolated galaxies. We use a simple model to show that these trends arise naturally in Λ cold dark matter (ΛCDM). This is because (i) disc galaxies in ΛCDM form at the centre of dark matter haloes spanning a relatively narrow range of virial mass; (ii) cold dark matter halo acceleration profiles are self-similar and have a broad maximum at the centre, reaching values bracketed precisely by amin and a0 in that mass range and (iii) halo mass and galaxy size scale relatively tightly with the baryonic mass of a galaxy in any successful ΛCDM galaxy formation model. Explaining the MDAR in ΛCDM does not require modifications to the cuspy inner mass profiles of dark haloes, although these may help to understand the detailed rotation curves of some dwarf galaxies and the origin of extreme outliers from the main relation. The MDAR is just a reflection of the self-similar nature of cold dark matter haloes and of the physical scales introduced by the galaxy formation process

The properties of ”dark” ΛCDM halos in the Local Group

We examine the baryon content of low-mass Λ cold dark matter (ΛCDM) haloes (108 < M200/M⊙ < 5 × 109) using the APOSTLE cosmological hydrodynamical simulations. Most of these systems are free of stars and have a gaseous content set by the combined effects of cosmic reionization, which imposes a mass-dependent upper limit, and of ram-pressure stripping, which reduces it further in high-density regions. Haloes mainly affected by reionization (RELHICS; REionization-Limited H I Clouds) inhabit preferentially low-density regions and make up a population where the gas is in hydrostatic equilibrium with the dark matter potential and in thermal equilibrium with the ionizing UV background. Their thermodynamic properties are well specified, and their gas density and temperature profiles may be predicted in detail. Gas in RELHICS is nearly fully ionized but with neutral cores that span a large range of H I masses and column densities and have negligible non-thermal broadening. We present predictions for their characteristic sizes and central column densities; the massive tail of the distribution should be within reach of future blind H I surveys. Local Group RELHICS (LGRs) have some properties consistent with observed Ultra Compact High Velocity Clouds (UCHVCs) but the sheer number of the latter suggests that most UCHVCs are not RELHICS. Our results suggest that LGRs (i) should typically be beyond 500 kpc from the Milky Way or M31; (ii) have positive Galactocentric radial velocities; (iii) H I sizes not exceeding 1 kpc, and (iv) should be nearly round. The detection and characterization of RELHICS would offer a unique probe of the small-scale clustering of CDM

Improving Sensorimotor Function and Adaptation using Stochastic Vestibular Stimulation

Astronauts experience sensorimotor changes during adaption to G-transitions that occur when entering and exiting microgravity. Post space flight, these sensorimotor disturbances can include postural and gait instability, visual performance changes, manual control disruptions, spatial disorientation, and motion sickness, all of which can hinder the operational capabilities of the astronauts. Crewmember safety would be significantly increased if sensorimotor changes brought on by gravitational changes could be mitigated and adaptation could be facilitated. The goal of this research is to investigate and develop the use of electrical stochastic vestibular stimulation (SVS) as a countermeasure to augment sensorimotor function and facilitate adaptation. For this project, SVS will be applied via electrodes on the mastoid processes at imperceptible amplitude levels. We hypothesize that SVS will improve sensorimotor performance through the phenomena of stochastic resonance, which occurs when the response of a nonlinear system to a weak input signal is optimized by the application of a particular nonzero level of noise. In line with the theory of stochastic resonance, a specific optimal level of SVS will be found and tested for each subject [1]. Three experiments are planned to investigate the use of SVS in sensory-dependent tasks and performance. The first experiment will aim to demonstrate stochastic resonance in the vestibular system through perception based motion recognition thresholds obtained using a 6-degree of freedom Stewart platform in the Jenks Vestibular Laboratory at Massachusetts Eye and Ear Infirmary. A range of SVS amplitudes will be applied to each subject and the subjectspecific optimal SVS level will be identified as that which results in the lowest motion recognition threshold, through previously established, well developed methods [2,3,4]. The second experiment will investigate the use of optimal SVS in facilitating sensorimotor adaptation to system disturbances. Subjects will adapt to wearing minifying glasses, resulting in decreased vestibular ocular reflex (VOR) gain. The VOR gain will then be intermittently measured while the subject readapts to normal vision, with and without optimal SVS. We expect that optimal SVS will cause a steepening of the adaptation curve. The third experiment will test the use of optimal SVS in an operationally relevant aerospace task, using the tilt translation sled at NASA Johnson Space Center, a test platform capable of recreating the tilt-gain and tilt-translation illusions associated with landing of a spacecraft post-space flight. In this experiment, a perception based manual control measure will be used to compare performance with and without optimal SVS. We expect performance to improve in this task when optimal SVS is applied. The ultimate goal of this work is to systematically investigate and further understand the potential benefits of stochastic vestibular stimulation in the context of human space flight so that it may be used in the future as a component of a comprehensive countermeasure plan for adaptation to G-transitions

Gonad Maturation of Clown Loach (Botia macracanthus) in Pond

The objective of this research is to know the gonad maturation of clown loach {Botia macracanthus) reared in pond. Two groups contain 4 female broodstock; I) carried and II) non-carried egg broodstock were reared in two separated hapas which placed in pond. Each hapa was also stocked nine males. The fish were fed pellet (32,33% protein) 10% biomass, daily in three times. After 20 days, the broodstocks were implanted by LHRH-a 100 u.g/kg of body weight. In the group I, diameter of egg in gonad were developed from 1,028 mm at the beginning of implantation to 1,071 and 1,106 mm at day of 15 and 30 after implantation respectively. In the group II, only one female has developed her gonad successfully. The egg was developed to 0,937 and 1,026 mm after 15 and 30 day implantation respectively. Key words : Gonad maturation, clown loach, Botia macracanthus, pond   ABSTRAK Penelitian ini bertujuan untuk mengetahui pematangan gonad induk ikan botia (Botia macracanthus) yang dipelihara di kolam. Dua kelompok induk betina; I) sudah mengandung telur dan II) belum mengandung telur masing-masing sebanyak 4 ekor dipelihara masing-masing dalam 2 hapa. Ke dalam setiap hapa juga ditempatkan induk jantan sebanyak 9 ekor. Induk diberi pakan berupa pelet (protein, 32,33%) sebanyak 10% dari bobot biomasa per hari, 3 kali sehari, dan diberi LHRH-a dengan dosis 100 ng/kg bobot tubuh secara implantasi pada hari ke 20 pemeliharaan. Induk dalam kelompok pertama telurnya berkembang dari rata-rata 1,028 pada saat pemberian LHRH-a menjadi rata-rata 1,071 dan 1,106 mm masing-masing pada hari ke 15 dan 30 setelah pemberian. Pada kelompok kedua hanya satu ekor induk yang berkembang gonadnya setelah diberi LHRH-a. telur induk ikan tersebut berkembang dari 0,937 menjadi 1,026 mm masing pada hari ke 15 dan 30 setelah implantasi. Kata kunci : Pematangan gonad, ikan botia, Botia macracanthus, kola

Optimizing the vertebrate vestibular semicircular canal: could we balance any better?

The fluid-filled semicircular canals (SCCs) of the vestibular system are used by all vertebrates to sense angular rotation. Despite masses spanning seven decades, all mammalian SCCs are nearly the same size. We propose that the SCC represents a sensory organ that evolution has `optimally designed'. Four geometric parameters are used to characterize the SCC, and `building materials' of given physical properties are assumed. Identifying physical and physiological constraints on SCC operation, we find that the most sensitive SCC has dimensions consistent with available data.Comment: 4 pages, 3 figure