7,220 research outputs found
Agricultural Producer Cooperatives as Strategic Alliances
In this paper we examine the linkages between four bodies of business-to-business relationship theory (transaction cost analysis, the resource-based theory of the firm (RBV), social network theory and theories of trust and cooperation) to the design and governance of agricultural cooperatives. Defining a cooperative broadly as any type of alliance formed by producers for their mutual benefit, we base the discussion on three types of cooperative; traditional, "new generation" and learning networks. Our main focus is on cooperatives as an alliance between members, but we also discuss alliances between cooperatives We find that there is a gap in the literature relating to the analysis of alliances with more than two members (such as cooperatives), so the linkages between the theories and cooperative types must be seen as being somewhat tentative. We hypothesise that the RBV, social network theory and trust and cooperation theories are in fact, applicable to multiple-member alliances, but their relevance is likely to become less as the number of members increase.agricultural cooperatives, strategic alliances, transaction cost analysis, the resource-based view, social network theory, trust and cooperation, new generation cooperatives, learning networks., Agribusiness,
Creep at elevated temperatures and high vacuum Semiannual report no. 3, May 1 - Oct. 31, 1965
Creep tests on polycrystalline copper with surface reoxidized or cleaned by argon bombardment at elevated temperatures and high vacuu
Heavy Meson Physics: What have we learned in Twenty Years?
I give a personal account of the development of the field of heavy quarks.
After reviewing the experimental discovery of charm and bottom quarks, I
describe how the field's focus shifted towards determination of CKM elements
and how this has matured into a precision science.Comment: This talk was presented during the ceremony awarding the Medalla 2003
of the Division of Particles and Fields of The Mexican Phsyical Society, at
the IX Mexican Workshop on Particles and Fields; submitted for proceedings; 9
pages, 9 figures; replacement: fix multiple typo
Evaluation of SMAP Freeze/Thaw Retrieval Accuracy at Core Validation Sites in the Contiguous United States
Seasonal freeze-thaw (FT) impacts much of the northern hemisphere and is an important control on its water, energy, and carbon cycle. Although FT in natural environments extends south of 45°N, FT studies using the L-band have so far been restricted to boreal or greater latitudes. This study addresses this gap by applying a seasonal threshold algorithm to Soil Moisture Active Passive (SMAP) data (L3_SM_P) to obtain a FT product south of 45°N (âSMAP FTâ), which is then evaluated at SMAP core validation sites (CVS) located in the contiguous United States (CONUS). SMAP landscape FT retrievals are usually in good agreement with 0â5 cm soil temperature at SMAP grids containing CVS stations (\u3e70%). The accuracy could be further improved by taking into account specific overpass time (PM), the grid-specific seasonal scaling factor, the data aggregation method, and the sampling error. Annual SMAP FT extent maps compared to modeled soil temperatures derived from the Goddard Earth Observing System Model Version 5 (GEOS-5) show that seasonal FT in CONUS extends to latitudes of about 35â40°N, and that FT varies substantially in space and by year. In general, spatial and temporal trends between SMAP and modeled FT were similar
Outcomes of therapeutic community treatment for personality disorder
Purpose - The paper reviewed quantitative research since 1999 evaluating the effectiveness of democratic therapeutic community (DTC) treatment for individuals with personality disorders (PD) with reference to interpersonal and offending risk outcomes. Design/methodology/approach - A systematic search resulted in the review of ten studies. All of the studies investigated DTCs treating PD in community, inpatient residential and forensic settings. Only peer-reviewed, English-language articles employing a quantitative design were included. Findings - The majority of studies were conducted poorly and of low methodological quality, with limitations located in the representativeness of participants, limited use of control and comparison groups, follow up periods and controls for confounders. Heterogeneity remained in use of measures and limited consideration was given to the validity of interpersonal measures used. While improved interpersonal outcomes post DTC treatment were noted in forensic and residential settings, results were mixed in day and mini TC settings. Inconsistent findings in offending risk outcomes were also indicated. A study with increased methodological rigour indicated residential treatment had limited effects on interpersonal outcomes, when compared to combination treatment (residential TC and step-down treatment). Originality/value - The study provided an evaluation of the limitations of DTC research across a range of settings and highlighted a combination of residential TC and step-down treatment may achieve superior outcomes to residential TC treatment alone in a community inpatient population. Recommendations are made for future research to contribute to the treatment of PD
Deep levels in a-plane, high Mg-content MgxZn1-xO epitaxial layers grown by molecular beam epitaxy
Deep level defects in n-type unintentionally doped a-plane MgxZn1âxO, grown by molecular beam epitaxy on r-plane sapphire were fully characterized using deep level optical spectroscopy (DLOS) and related methods. Four compositions of MgxZn1âxO were examined with xâ=â0.31, 0.44, 0.52, and 0.56 together with a control ZnO sample. DLOS measurements revealed the presence of five deep levels in each Mg-containing sample, having energy levels of Ecâââ1.4âeV, 2.1âeV, 2.6âV, and Evâ+â0.3âeV and 0.6âeV. For all Mg compositions, the activation energies of the first three states were constant with respect to the conduction band edge, whereas the latter two revealed constant activation energies with respect to the valence band edge. In contrast to the ternary materials, only three levels, at Ecâââ2.1âeV, Evâ+â0.3âeV, and 0.6âeV, were observed for the ZnO control sample in this systematically grown series of samples. Substantially higher concentrations of the deep levels at Evâ+â0.3âeV and Ecâââ2.1âeV were observed in ZnO compared to the Mg alloyed samples. Moreover, there is a general invariance of trap concentration of the Evâ+â0.3âeV and 0.6âeV levels on Mg content, while at least and order of magnitude dependency of the Ecâââ1.4âeV and Ecâââ2.6âeV levels in Mg alloyed samples
Human Adenovirus come indicatore di contaminazione biologica in matrici idriche
In Italia la normativa vigente non prevede virus come indicatori di contaminazione biologica. Nello specifico per le acque reflue, in uscita dallâimpianto di recupero, gli unici indicatori presi in considerazione sono E. Coli e Salmonella (Allegato D.M. 185/03). Mentre per le acque di balneazione sono E. Coli ed Enterococchi (2006/7/CE), cosĂŹ come per le acque destinate al consumo umano (D.lgs. n. 31/2001). Per aerosol e superfici non vi sono normative a riguardo. Numerosi studi hanno però fatto emergere che la presenza di questi indicatori non è esaustiva per predire la contaminazione biologica delle matrici idriche in esame. Se da un lato sono in grado di rivelare una contaminazione e quindi un rischio per la salute, dallâaltro non sono parametri correlabili con la presenza di virus e protozoi. Infatti, laddove E. Coli ed Enterococchi sono assenti, possono essere presenti virus umani come Human Adenovirus, Rotavirus, Epatite A (HAV), Enterovirus, Norovirus GII. Tra questi Human Adenovirus risulta essere ritrovato con maggior frequenza nelle matrici. In studi effettuati su acqua di mare tale virus risulta presente nel 21% dei campioni in cui invece erano totalmente assenti E. Coli ed Enterococchi (patogeni indice suggeriti dalla normativa). Tale dato si è riscontrato anche nelle acque di fiume dove il 72% dei campioni, negativo per E. Coli ed Enterococchi, è per il 63% positivo per Human Adenovirus. Nelle acque trattate il 46% dei campioni che è negativo per E. Coli ed Enterococchi è invece positivo invece per il 57% a Human Adenovirus. Questo lavoro si è concentrato appunto su Human Adenovirus, un virus della famiglia di Adenoviridae, genere Mastadenovirus, che conta 51 diversi sierotipi in grado di infettare lâuomo, divisi in 6 sottogeneri ( indicati con le lettere da A a F) e 51 sierotipi ( indicati con i numeri). Eâ un virus a doppio filamento di DNA, formato da un capside icosaedrico privo di envelope e con un diametro di circa 35-40 nm. La trasmissione del virus avviene per via oro-fecale e respiratoria, mediante secrezioni respiratorie e oculari. Si localizza a livello di del tratto respiratorio, intestinale e della congiuntiva provocando molte patologie come: gastroenteriti, congiuntiviti, patologie respiratorie e infezioni del tratto urinario. Eâ eliminato allâesterno mediante feci, urina, secrezioni oro-faringee e liquido congiuntivale. Lo scopo di questo lavoro è proporre Human Adenovirus come patogeno indice di contaminazione biologica in differenti matrici idriche da affiancare agli indicatori tradizionali. Tale scelta deriva dal fatto che Human Adenovirus è ubiquitario, ha elevata resistenza ambientale e ai trattamenti di disinfezione chimico-fisici. Inoltre ha elevata specificitĂ per lâospite umano il quale rilascia nellâambiente unâalta concentrazione di particelle virali anche dopo molto tempo dallâinfezione. Sono stati analizzati campioni di liquame in entrata e uscita dal depuratore, acqua sperimentalmente trattata, acqua di mare e acqua di fiume. I campioni successivamente sono stati esaminati con procedure standardizzate in house per passare poi allâanalisi molecolare mediante la qPCR (Real Time PCR) con protocollo specifico per Human Adenovirus. Nella maggior parte dei campioni analizzati si è riscontrata la presenza del genoma di Human Adenovirus a concentrazioni variabili (liquame in entrata(1,7 x 1010 Âą 7,9) e uscita dal depuratore(4,7 x 108 Âą 11), acqua sperimentalmente trattata(1,6 x 102 Âą 31), acqua di mare(9,3 x 103 Âą 2,4) e acqua di fiume(8,5 x 102 Âą 27), confermando la sua diffusione ubiquitaria nellâambiente. I risultati ottenuti con questo lavoro concordano con quelli di precedenti monitoraggi confermano che Human Adenovirus potrebbe essere un ottimo candidato come indicatore di contaminazione biologica da affiancare a quelli tradizionali, per diverse matrici idriche, grazie anche alla facilitĂ con cui, tramite qPCR, si può rilevare e quantificare la sua presenza
Ultrafast Optical Excitation of a Persistent Surface-State Population in the Topological Insulator Bi2Se3
Using femtosecond time- and angle- resolved photoemission spectroscopy, we
investigated the nonequilibrium dynamics of the topological insulator Bi2Se3.
We studied p-type Bi2Se3, in which the metallic Dirac surface state and bulk
conduction bands are unoccupied. Optical excitation leads to a meta-stable
population at the bulk conduction band edge, which feeds a nonequilibrium
population of the surface state persisting for >10ps. This unusually long-lived
population of a metallic Dirac surface state with spin texture may present a
channel in which to drive transient spin-polarized currents
Time series of high resolution spectra of SN 2014J observed with the TIGRE telescope
We present a time series of high resolution spectra of the Type Ia supernova
2014J, which exploded in the nearby galaxy M82. The spectra were obtained with
the HEROS echelle spectrograph installed at the 1.2 m TIGRE telescope. We
present a series of 33 spectra with a resolution of R = 20, 000, which covers
the important bright phases in the evolution of SN 2014J during the period from
January 24 to April 1 of 2014. The spectral evolution of SN 2014J is derived
empirically. The expansion velocities of the Si II P-Cygni features were
measured and show the expected decreasing behaviour, beginning with a high
velocity of 14,000 km/s on January 24. The Ca II infrared triplet feature shows
a high velocity component with expansion velocities of > 20, 000 km/s during
the early evolution apart from the normal component showing similar velocities
as Si II. Further broad P-Cygni profiles are exhibited by the principal lines
of Ca II, Mg II and Fe II. The TIGRE SN 2014J spectra also resolve several very
sharp Na I D doublet absorption components. Our analysis suggests interesting
substructures in the interstellar medium of the host galaxy M82, as well as in
our Milky Way, confirming other work on this SN. We were able to identify the
interstellar absorption of M82 in the lines of Ca II H & K at 3933 and 3968 A
as well as K I at 7664 and 7698 A. Furthermore, we confirm several Diffuse
Interstellar Bands, at wavelengths of 6196, 6283, 6376, 6379 and 6613 A and
give their measured equivalent widths.Comment: 11 pages, 10 figures, accepted for publication in MNRA
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