Radio-Excess IRAS Galaxies: IV. Optical Spectroscopy

This is the fourth in our series of papers investigating radio-excess galaxies, which have radio emission associated with an active nucleus but which do not fit into the traditional categories of either radio-loud or radio-quiet active galaxies. In this paper, we present optical spectra of our sample of FIR-luminous radio-excess galaxies. Optical emission line diagnostics are used to determine the dominant source of the ionizing radiation. We find that radio excess is an excellent indicator of the presence of an active nucleus: the radio-excess sample contains a much higher fraction of AGN than samples selected on FIR luminosity alone, or using other criteria such as warm FIR colors. Several objects have ambiguous classifications and are likely to be composite objects with mixed excitation. The type of optical spectrum appears to be associated with the radio-loudness: radio-loud objects may be more `pure' AGN than radio-intermediate objects. We find strong evidence for interaction between the radio plasma and the surrounding gas. The jet energy fluxes of the radio-excess objects, inferred from the [O III] luminosities, are lower than in powerful radio sources, consistent with our previous results. We conclude that the jets of radio-intermediate sources are intrinsically weaker than those in sources with more powerful radio emission. A significant fraction of the sample spectra show post-starburst stellar continuum, with A-star absorption lines, consistent with the large fraction of merging or disturbed host galaxies in the sample. The ages of the radio sources are significantly less than those of A stars indicating that, if the radio sources are associated with merging activity, there is a delay between the interaction and the initiation of the radio activity. (Abridged.)Comment: Accepted for publication in AJ; version with high resolution figures available from http://www.cis.rit.edu/~clbsps/papers/paper4.pd

Age and Growth of Cobia, \u3ci\u3eRachycentron canadum\u3c/i\u3e, from the Northeastern Gulf of Mexico

We examined 1005 cobia, Rachycentron canadum, from recreational catches in the northeastern Gulf of Mexico from 1987 to 1995. Specimens ranged from 325 to 1651 mm fork length (FL); females had a mean FL of 1050 mm (n=730) and were significantly larger than males that had a mean FL of 952 mm (n=275). The over all male to female ratio was 1:2.7. Ages of 565 cobia were estimated from thin-sectioned otoliths (sagittae). Marginal-increment analysis of sagittal otoliths showed a single annual minimum during June. Male cobia (n=170; 525-1330 mm FL) ranged from age 0 to 9, and females (n=395; 493-1651 mm FL) ranged from age 0 to 11. The relationship of observed fork length and age was described by the von Bertalanffy growth equation for males FLt = 1171(1-exp [-0.432(t+1.150)]) and for females FLt = 1555(1-exp [-0.272(t+1.254)]). Growth in length for both sexes was relatively fast through age 2, after which growth slowed gradually. Estimates of the von Bertalanffy growth equation parameters L-infinity and K were significantly different for males and females, whereas estimates for t(0) were not significantly different. Sagittal otolith weight was a good predictor of age. The instantaneous rate of total mortality (Z) estimated by catch curve analysis for fully recruited ages 4-8 was 0.75

Movements of Spotted Seatrout (Cynoscion nebulosus) in Mississippi Coastal Waters Based on Tag–Recapture

Movement patterns of spotted seatrout (Cynoscion nebulosus) were evaluated in Mississippi coastal waters by an angler-based tagging study from 1995 through 1999. During this period, 505 anglers tagged 15,206 spotted seatrout, the majority of which (84%) did not meet the state\u27s legal minimum size limit of 14 inches (356 mm) total length. Overall, 408 (2.7%) tagged fish were recaptured and reported to project personnel. Over 90% of these recaptured fish moved less than 10 km from site of tagging to site of recapture (mean = 3.0 ± 0.41 km), and 82% moved less than 3 km. The greatest movement from tagging to recapture site by any fish was 60 km over a period of 200 d, and only three fish (0.7%) moved 50 km or more. Study results suggest that spotted seatrout in Mississippi waters comprise a nonmigratory fish stock, as has been found for this species in coastal waters of neighboring states along the U.S. Gulf of Mexico

Pathogenesis of hypoxic-ischemic brain injury in a perinatal rodent model

Exposure of immature rats to 8% oxygen after unilateral carotid artery ligation (UCL) causes metabolic, neurochemical and histopathological changes in the ipsilateral forebrain that resemble those in human perinatal hypoxic-ischemic encephalopathy. Regional cerebral perfusion in this model was examined by visual analysis of India ink trapped in cerebral vessels and measurement of [14C]iodoantipyrine ([14C]IAP) and [3H]flunitrazepam extraction into the brain. UCL alone reduced [14C]IAP accumulation in the ipsilateral hemisphere by 20% and hypoxia superimposed on UCL progressively reduced ipsilateral hemisphere perfusion by 71% at 2 h. Hypoxia probably injures neurons in this model by causing a critical reduction in cerebral perfusion, an effect which also appears to be important in the human disorder.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24718/1/0000140.pd

Screening volatile organics by direct sampling ion trap and glow discharge mass spectrometry

Two different types of direct sampling mass spectrometers are currently being evaluated in our laboratory for use as rapid screening tools for volatile organics in a wide range of environmental matrices. These include a commercially available ITMS ion trap mass spectrometer and a specially designed tandem source glow discharge quadrupole mass spectrometer. Both of these instruments are equipped with versatile sampling interfaces which enable direct monitoring of volatile organics at part-per-billion (ppb) levels in air, water, and soil samples. Direct sampling mass spectrometry does not utilize chromatographic or other separation steps prior to admission of samples into the analyzer. Instead, individual compounds are measured using one or more of the following methods: spectral subtraction, selective chemical ionization, and tandem mass spectroscopy (MS/MS). For air monitoring applications, an active sniffer'' probe is used to achieve instantaneous response. Water and soil samples are analyzed by means of high speed direct purge into the mass spectrometer. Both instruments provide a range of ionization options for added selectivity and the ITMS can also provide high efficiency collision induced dissociation MS/MS for target compound analysis. Detection limits and response factors have been determined for a large number volatile organics in air, water, and number of different soil types. 4 refs., 14 figs., 3 tabs

Pelagic calcium carbonate production and shallow dissolution in the North Pacific Ocean

Funding was provided by NSF Grants OCE1220600 and OCE1220302 awarded to JA and WB, respectively, MINECO PID2020-113526RB-I00, the Generalitat de Catalunya MERS (#2017 SGR-1588) awarded to PZ and NERC grant NE/N011716/1 awarded to JR.Planktonic calcifying organisms play a key role in regulating ocean carbonate chemistry and atmospheric CO2. Surprisingly, references to the absolute and relative contribution of these organisms to calcium carbonate production are lacking. Here we report quantification of pelagic calcium carbonate production in the North Pacific, providing new insights on the contribution of the three main planktonic calcifying groups. Our results show that coccolithophores dominate the living calcium carbonate (CaCO3) standing stock, with coccolithophore calcite comprising ~90% of total CaCO3 production, and pteropods and foraminifera playing a secondary role. We show that pelagic CaCO3 production is higher than the sinking flux of CaCO3 at 150 and 200 m at ocean stations ALOHA and PAPA, implying that a large portion of pelagic calcium carbonate is remineralised within the photic zone; this extensive shallow dissolution explains the apparent discrepancy between previous estimates of CaCO3 production derived from satellite observations/biogeochemical modeling versus estimates from shallow sediment traps. We suggest future changes in the CaCO3 cycle and its impact on atmospheric CO2 will largely depend on how the poorly-understood processes that determine whether CaCO3 is remineralised in the photic zone or exported to depth respond to anthropogenic warming and acidification.Publisher PDFPeer reviewe

Life Histories, Demography, and Distribution of a Fluvial Bull Trout Population

To describe the life histories and demography of a fluvial population of Bull Trout Salvelinus confluentus, we PIT-tagged and radio-tagged Bull Trout captured in Mill Creek, a tributary of the Walla Walla River (Washington–Oregon), during 1998–2009. Adult abundance declined 63% during 2006–2010, driven primarily by a 10-fold reduction in subadult-to-adult returns. Larger subadults and fall–winter emigrants survived at higher rates, but they were a small proportion of the subadult migrants. The survival rates of larger, generally older adults were also more than 40% greater than those of smaller adults. Changes in abundance influenced other characteristics of the population. For example, adult upstream movement into spawning areas during 1999–2005 peaked in late July, whereas the smaller runs observed during 2006–2010 peaked in early September, and the relationship between fish size and migration timing shifted. Unlike many adfluvial populations, more than 90% of the adults in Mill Creek spawned annually. Bull Trout that spawned in main-stem Mill Creek were primarily larger migratory adults; however, about 20% of the large adults were strictly or intermittently resident, remaining in the spawning area year-round. The downstream extent of individuals' migratory distributions varied greatly—from just downstream of the spawning area to the mouth of the Walla Walla River and potentially hundreds of kilometers into the Columbia River. Despite a large sample size of radio-tagged fish, radiotelemetry substantially underestimated the distribution and range that were evident from PIT tag detections. Life history terms such as “migratory,” “resident,” and “fluvial” and their associations with body size, movement, and distribution are useful for describing general patterns, but they fail to reflect the diversity and complexity within and among populations. For Bull Trout in Mill Creek, that life history diversity, including small, resident adult forms in the tributaries and a continuum of distribution for large adults, maximizes the use of available habitat and likely contributes to the population's persistence

Measurement and Theory of Gas-Phase Ion Mobility Shifts Resulting from Isotopomer Mass Distribution Changes

The unanticipated discovery of recent ultra-high-resolution ion mobility spectrometry (IMS) measurements revealing that isotopomers—compounds that differ only in the isotopic substitution sites—can be separated has raised questions as to the physical basis for their separation. A study comparing IMS separations for two isotopomer sets in conjunction with theory and simulations accounting for ion rotational effects provides the first-ever prediction of rotation-mediated shifts. The simulations produce observable mobility shifts due to differences in gas−ion collision frequency and translational-to-rotational energy transfer. These differences can be attributed to distinct changes in the moment of inertia and center of mass between isotopomers. The simulations are in broad agreement with the observed experiments and consistent with relative mobility differences between isotopomers. These results provide a basis for refining IMS theory and a new foundation to obtain additional structural insights through IMS

Biological measurement beyond the quantum limit

Quantum noise places a fundamental limit on the per photon sensitivity attainable in optical measurements. This limit is of particular importance in biological measurements, where the optical power must be constrained to avoid damage to the specimen. By using non-classically correlated light, we demonstrated that the quantum limit can be surpassed in biological measurements. Quantum enhanced microrheology was performed within yeast cells by tracking naturally occurring lipid granules with sensitivity 2.4 dB beyond the quantum noise limit. The viscoelastic properties of the cytoplasm could thereby be determined with a 64% improved measurement rate. This demonstration paves the way to apply quantum resources broadly in a biological context

Topological spin memory of antiferromagnetically coupled skyrmion pairs in Co/Gd/Pt multilayers

Antiferromagnetically (AFM) coupled skyrmions offer potential advantages for spintronic devices, including reduced dipolar fields that may enable smaller skyrmion sizes and a reduction of the skyrmion Hall effect. However, the topological stability of AFM-coupled skyrmions subjected to dramatic spin deformation through low-temperature cycling has not been investigated. Here we report the discovery of a topological spin memory effect for AFM-coupled skyrmion pairs in [Co/Gd/Pt]10 multilayered films. Photoemission electron microscopy imaging shows that bubble skyrmions in the multilayer that are stable at room temperature evolve into complex in-plane spin textures as the temperature is lowered and reform completely when the sample is warmed back up. Simulations demonstrate that Dzyaloshinskii-Moriya interactions play a key role in this spin memory effect, and furthermore reveal that the topological charge is preserved throughout the dramatic spin texture rearrangement and recovery. These results highlight a key aspect of topological protection—the preservation of the topological properties under continuous deformation—and also provide a promising avenue for information encryption and recovery