Controlling the Kondo Effect in CoCu_n Clusters Atom by Atom

Clusters containing a single magnetic impurity were investigated by scanning tunneling microscopy, spectroscopy, and ab initio electronic structure calculations. The Kondo temperature of a Co atom embedded in Cu clusters on Cu(111) exhibits a non-monotonic variation with the cluster size. Calculations model the experimental observations and demonstrate the importance of the local and anisotropic electronic structure for correlation effects in small clusters.Comment: 4 pages, 4 figure

Gamma-Ray Spectral States of Galactic Black Hole Candidates

OSSE has observed seven transient black hole candidates: GRO J0422+32, GX339-4, GRS 1716-249, GRS 1009-45, 4U 1543-47, GRO J1655-40, and GRS 1915+105. Two gamma-ray spectral states are evident and, based on a limited number of contemporaneous X-ray and gamma-ray observations, these states appear to be correlated with X-ray states. The former three objects show hard spectra below 100 keV (photon number indices Gamma < 2) that are exponentially cut off with folding energy ~100 keV, a spectral form that is consistent with thermal Comptonization. This "breaking gamma-ray state" is the high-energy extension of the X-ray low, hard state. In this state, the majority of the luminosity is above the X-ray band, carried by photons of energy ~100 keV. The latter four objects exhibit a "power-law gamma-ray state" with a relatively soft spectral index (Gamma ~ 2.5-3) and no evidence for a spectral break. For GRO J1655-40, the lower limit on the break energy is 690 keV. GRS 1716-249 exhibits both spectral states, with the power-law state having significantly lower gamma-ray luminosity. The power-law gamma-ray state is associated with the presence of a strong ultrasoft X-ray excess (kT ~ 1 keV), the signature of the X-ray high, soft (or perhaps very high) state. The physical process responsible for the unbroken power law is not well understood, although the spectra are consistent with bulk-motion Comptonization in the convergent accretion flow.Comment: 27 pages, 3 figures, uses aaspp.sty and psfig.st

Qualitätsvergleich von Regenbogenforellen aus konventioneller und ökologisch zertifizierter Aufzucht als Voraussetzung für eine Verbesserung der Wettbewerbsfähigkeit von Bioforellen

Die Studie umfasste die Untersuchung der Aufzuchtsbedingungen sowie Futterversuche und vergleichende Untersuchungen zur Produktqualität. Es wurden 2 ökologisch zertifizierte und 3 konventionelle Forellenzuchtbetriebe verglichen. Tagesgänge verschiedener wasserchemischer Parameter an Zu- und Ablauf der Teiche umfassten die Bestimmung von Temperatur, Sauerstoff, pH-Wert, Ammonium-, Nitrit-, Gesamt- und ortho-Phosphatgehalt sowie CSB- und Feststoffgehalt. In zwei Futterversuchen wurden Ökofutter für Forellen mit konventionellen Futtern hinsichtlich Wachstum, Futterverwertung und Proteinausnutzung verglichen. Die zwei untersuchten ökologischen Futtermittel zeigten im Vergleich ein schlechteres Protein-/Energieverhältnis, das sich in niedrigeren Rohfettgehalten ausdrückte. Zusätzlich wurden futterbedingte Stickstoffexkretionsmuster von Forellen im Tagesgang untersucht. Im Ergebnis zeigte sich, dass die Ökofutter im Vergleich zu den konventionellen Futtern zu einer stärkeren Umweltbelastung und einem geringerem Wachstum bei schlechterer Futterverwertung führten. Die Qualitätsuntersuchungen der Forellen beinhalteten die Erfassung der biologischen Para-meter, die mikrobiologische und sensorische Beurteilung der Ware, Farb- und Texturmessun-gen, die Bestimmung der chemischen Zusammensetzung einschließlich der Rückstände sowie bildverarbeitende Methoden und die Aufnahme des Aromaprofils. Insgesamt waren die Produktqualität und der mikrobiologische Status aller untersuchten Forellen sehr gut. In ihrer chemischen Zusammensetzung unterschieden sich die Fische vor allem im Fettgehalt. Alle ermittelten Rückstandsgehalte lagen weit unter den zulässigen Höchstwerten. Ein Zusammenhang zwischen der Aufzuchtsform und der Qualität konnte nicht festgestellt werden. Bei den Projektergebnissen handelt es sich um eine Abschätzung der Situation ausgewählter Forellenzuchtbetriebe, repräsentative Aussagen können aus den Ergebnissen nicht abgeleitet werden

Biofisch – Qualitätsvergleich zwischen konventionellen und ökologisch produzierten Forellen

Die Studie umfasste die Untersuchung der Aufzuchtsbedingungen sowie Futterversuche und vergleichende Untersuchungen zur Produktqualität an Portionsforellen. Es wurden 2 ökologisch zertifizierte und 3 konventionelle Forellenzuchtbetriebe verglichen. In dieser Arbeit werden nur die Ergebnisse der Qualitätsuntersuchungen wiedergegeben. Die Untersuchungen der Portionsforellen beinhalteten die Erfassung der biologischen Parameter, die mikrobiologische und sensorische Beurteilung der Ware, Farb- und Texturmessungen, die Bestimmung der chemischen Zusammensetzung einschließlich der Rückstände sowie bildverarbeitende Methoden und die Aufnahme des Aromaprofils. Insgesamt waren die Qualität und der mikrobiologische Status aller untersuchten Forellen sehr gut. In ihrer chemischen Zusammensetzung unterschieden sich die Fische vor allem im Fettgehalt. Alle ermittelten Rückstandsgehalte lagen weit unter den zulässigen Höchstwerten. Unterschiede zwischen den Aufzuchtsformen wurden nicht gefunden

Galactic Black Hole Binaries: Multifrequency Connections

We review the recent multifrequency studies of galactic black hole binaries, aiming at revealing the underlying emission processes and physical properties in these systems. The optical and infrared observations are important for determining their system parameters, such as the companion star type, orbital period and separation, inclination angle and the black hole mass. The radio observations are useful for studying high energy electron acceleration process, jet formation and transport. X-ray observations can be used to probe the inner accretion disk region in order to understand the fundamental physics of the accretion disk in the strongest gravitational field and the properties of the black hole. Future higher sensitivity and better resolution instrumentation will be needed to answer the many fundamental questions that have arisen.Comment: Revised on August 6, 1997, 22 pages, 6 figures, 1 table. Invited review paper for the 4th Compton Symposium, eds. C. D. Dermer and J. D. Kurfess, Williamsburg, VA, April, 1997. AIP Conference Proceeding

Environmental controls, emergent scaling, and predictions of greenhouse gas (GHG) fluxes in coastal salt marshes

Author Posting. © American Geophysical Union, 2018. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Biogeosciences 123 (2018): 2234-2256, doi:10.1029/2018JG004556.Coastal salt marshes play an important role in mitigating global warming by removing atmospheric carbon at a high rate. We investigated the environmental controls and emergent scaling of major greenhouse gas (GHG) fluxes such as carbon dioxide (CO2) and methane (CH4) in coastal salt marshes by conducting data analytics and empirical modeling. The underlying hypothesis is that the salt marsh GHG fluxes follow emergent scaling relationships with their environmental drivers, leading to parsimonious predictive models. CO2 and CH4 fluxes, photosynthetically active radiation (PAR), air and soil temperatures, well water level, soil moisture, and porewater pH and salinity were measured during May–October 2013 from four marshes in Waquoit Bay and adjacent estuaries, MA, USA. The salt marshes exhibited high CO2 uptake and low CH4 emission, which did not significantly vary with the nitrogen loading gradient (5–126 kg · ha−1 · year−1) among the salt marshes. Soil temperature was the strongest driver of both fluxes, representing 2 and 4–5 times higher influence than PAR and salinity, respectively. Well water level, soil moisture, and pH did not have a predictive control on the GHG fluxes, although both fluxes were significantly higher during high tides than low tides. The results were leveraged to develop emergent power law‐based parsimonious scaling models to accurately predict the salt marsh GHG fluxes from PAR, soil temperature, and salinity (Nash‐Sutcliffe Efficiency = 0.80–0.91). The scaling models are available as a user‐friendly Excel spreadsheet named Coastal Wetland GHG Model to explore scenarios of GHG fluxes in tidal marshes under a changing climate and environment.National Oceanic and Atmospheric Administration Grant Numbers: NA09NOS4190153, NA14NOS4190145; National Science Foundation (NSF) Grant Numbers: 1705941, 1561941/1336911; USGS LandCarbon Program; NOAA National Estuarine Research Reserve Science Collaborative Grant Number: NA09NOS4190153 and NA14NOS41901452019-01-2

Effects of initiation system and mulch on the production of melon in the south of Buenos Aires province, Argentine

Con el fin de evaluar el rendimiento semanal y total en cultivos de melón (Cucumis melo L.) iniciados por siembra directa y trasplante, en suelo desnudo o con acolchado plástico (negro o cristal), se realizaron ensayos en la zona sur de la provincia de Buenos Aires, Argentina, durante las campañas agrícolas 1994/95 y 1995/96.Se utilizó el híbrido "Magnum 45" del tipo reticulado, cultivado en camellones a una densidad teórica de 6.897 pl.ha-1 y riego por surco. Los sistemas de iniciación ensayados fueron dos: siembra directa y trasplante. Los tratamientos de acolchado de suelo fueron tres: suelo desnudo, acolchado con polietileno cristal de 100µ y con polietileno negro de 50µ. Los mayores valores de producción total se obtuvieron en los tratamientos de suelo con acolchado (tanto negro como cristal) e iniciados por trasplante. La mayor precocidad se observó en el cultivo realizado con acolchado plástico cristal e iniciado por trasplante, con un pico de producción muy marcado en la segunda semana de cosecha.The aim of this comunication was to evaluate the weekly and total yield in melon cropping (Cucumis melo L.) initiated by direct sowing and transplanting in bare soil or covered with polyethylene mulch (black or transparent). Assays were carried out during the field seasons 1994/95 and 1995/96, in the south area of the province of Buenos Aires, Argentina. The hybrid Magnum 45 of the netted type was cultivated in ridges to a theoretical density of 6.897 pl.ha-1 and watered by furrows. The assayed initiation systems were: direct sowing and transplanting while the treatments of soil coverage were: bare soil, mulched with 100µ transparent polyethylene or with 50µ black polyethylene. The greatest values of total production were obtained in the polyethylene-mulched treatments (both black and transparent) and initiated by transplanting. The greatest precocity was observed under the treatment with transparent polyethylene mulch and initiated by transplanting, with a peak in the second week of cropping.Facultad de Ciencias Agrarias y Forestale

Effects of initiation system and mulch on the production of melon in the south of Buenos Aires province, Argentine

Con el fin de evaluar el rendimiento semanal y total en cultivos de melón (Cucumis melo L.) iniciados por siembra directa y trasplante, en suelo desnudo o con acolchado plástico (negro o cristal), se realizaron ensayos en la zona sur de la provincia de Buenos Aires, Argentina, durante las campañas agrícolas 1994/95 y 1995/96.Se utilizó el híbrido "Magnum 45" del tipo reticulado, cultivado en camellones a una densidad teórica de 6.897 pl.ha-1 y riego por surco. Los sistemas de iniciación ensayados fueron dos: siembra directa y trasplante. Los tratamientos de acolchado de suelo fueron tres: suelo desnudo, acolchado con polietileno cristal de 100µ y con polietileno negro de 50µ. Los mayores valores de producción total se obtuvieron en los tratamientos de suelo con acolchado (tanto negro como cristal) e iniciados por trasplante. La mayor precocidad se observó en el cultivo realizado con acolchado plástico cristal e iniciado por trasplante, con un pico de producción muy marcado en la segunda semana de cosecha.The aim of this comunication was to evaluate the weekly and total yield in melon cropping (Cucumis melo L.) initiated by direct sowing and transplanting in bare soil or covered with polyethylene mulch (black or transparent). Assays were carried out during the field seasons 1994/95 and 1995/96, in the south area of the province of Buenos Aires, Argentina. The hybrid Magnum 45 of the netted type was cultivated in ridges to a theoretical density of 6.897 pl.ha-1 and watered by furrows. The assayed initiation systems were: direct sowing and transplanting while the treatments of soil coverage were: bare soil, mulched with 100µ transparent polyethylene or with 50µ black polyethylene. The greatest values of total production were obtained in the polyethylene-mulched treatments (both black and transparent) and initiated by transplanting. The greatest precocity was observed under the treatment with transparent polyethylene mulch and initiated by transplanting, with a peak in the second week of cropping.Facultad de Ciencias Agrarias y Forestale

Soil carbon consequences of historic hydrologic impairment and recent restoration in coastal wetlands

© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Eagle, M. J., Kroeger, K. D., Spivak, A. C., Wang, F., Tang, J., Abdul-Aziz, O. I., Ishtiaq, K. S., O’Keefe Suttles, J., & Mann, A. G. Soil carbon consequences of historic hydrologic impairment and recent restoration in coastal wetlands. The Science of the Total Environment, 848, (2022): 157682, https://doi.org/10.1016/j.scitotenv.2022.157682.Coastal wetlands provide key ecosystem services, including substantial long-term storage of atmospheric CO2 in soil organic carbon pools. This accumulation of soil organic matter is a vital component of elevation gain in coastal wetlands responding to sea-level rise. Anthropogenic activities that alter coastal wetland function through disruption of tidal exchange and wetland water levels are ubiquitous. This study assesses soil vertical accretion and organic carbon accretion across five coastal wetlands that experienced over a century of impounded hydrology, followed by restoration of tidal exchange 5 to 14 years prior to sampling. Nearby marshes that never experienced tidal impoundment served as controls with natural hydrology to assess the impact of impoundment and restoration. Dated soil cores indicate that elevation gain and carbon storage were suppressed 30–70 % during impoundment, accounting for the majority of elevation deficit between impacted and natural sites. Only one site had substantial subsidence, likely due to oxidation of soil organic matter. Vertical and carbon accretion gains were achieved at all restored sites, with carbon burial increasing from 96 ± 33 to 197 ± 64 g C m−2 y−1. The site with subsidence was able to accrete at double the rate (13 ± 5.6 mm y−1) of the natural complement, due predominantly to organic matter accumulation rather than mineral deposition, indicating these ecosystems are capable of large dynamic responses to restoration when conditions are optimized for vegetation growth. Hydrologic restoration enhanced elevation resilience and climate benefits of these coastal wetlands.This project was supported by the U.S. Geological Survey Coastal and Marine Hazards and Resources Program and the USGS Land Change Science Program's LandCarbon program, NOAA National Estuarine Research Reserve Science Collaborative NA14NOS4190145, and MIT Sea Grant 2015-R/RC-141. Contributions of Abdul-Aziz were also supported by NSF CBET Environmental Sustainability Award No. 1705941. Our stakeholder partners, including the Cape Cod National Seashore, Waquoit Bay National Estuarine Research Reserve, and the Bringing Wetlands to Market project team, and Towns and Conservation Commissions, including Eastham, Barnstable, Brewster, Yarmouth, Denis, Sandwich and Orleans, were instrumental in providing research support and site access

The electronic state of vortices in YBa2Cu3Oy investigated by complex surface impedance measurement

The electromagnetic response to microwaves in the mixed state of YBa2Cu3Oy(YBCO) was measured in order to investigate the electronic state inside and outside the vortex core. The magnetic-field dependence of the complex surface impedance at low temperatures was in good agreement with a general vortex dynamics description assuming that the field-independent viscous damping force and the linear restoring force were acting on the vortices. In other words, both real and imaginary parts of the complex resistivity, \rho_1, and \rho_2, were linear in B. This is explained by theories for d-wave superconductors. Using analysis based on the Coffey-Clem description of the complex penetration depth, we estimated that the vortex viscosity \eta at 10 K was (4 \sim 5) \times 10^{-7} Ns/m^2. This value corresponds to \omega_0 \tau \sim 0.3 - 0.5, where \omega_0 and \tau are the minimal gap frequency and the quasiparticle lifetime in the vortex core, respectively. These results suggest that the vortex core in YBCO is in the moderately clean regime. Investigation of the moderately clean vortex core in high-temperature superconductors is significant because physically new effects may be expected due to d-wave characteristics and to the quantum nature of cuprate superconductors. The behavior of Z_s as a function of B across the first order transition (FOT) of the vortex lattice was also investigated. Unlike Bi2Sr2CaCu2Oy (BSCCO), no distinct anomaly was observed around the FOT in YBCO. Our results suggest that the rapid increase of X_s due to the change of superfluid density at the FOT would be observed only in highly anisotropic two-dimensional vortex systems like BSCCO. We discuss these results in terms of the difference of the interlayer coupling and the energy scale between the two materials.Comment: 10 pages, 6 figures, to be published in Phys. Rev. B, one reference adde