5,432 research outputs found
Thermal entanglement witness for materials with variable local spin lengths
We show that the thermal entanglement in a spin system using only magnetic
susceptibility measurements is restricted to the insulator materials. We
develop a generalization of the thermal entanglement witness that allows us to
get information about the system entanglement with variable local spin lengths
that can be used experimentally in conductor or insulator materials. As an
application, we study thermal entanglement for the half-filled Hubbard model
for linear, square and cubic clusters. We note that it is the itinerancy of
electrons that favors the entanglement. Our results suggest a weak dependence
between entanglement and external spin freedom degrees.Comment: 4 pages, 3 figure
Peshtasar basalts: An example of post-collision basalts in sedimentary Basin of Moghan, NW Iran
With an eastâwest exposure trend, Peshtasar Complex, which is located in the sedimentary basin of Moghan, northwestern Iran, is lithologically varied. The main constituent minerals are plagioclase, clinopyroxene and iddingsitised olivine in basalts and plagioclase megacryst, clinopyroxene and leucite in tephrite. The studied rocks are plotted in the fields of basaltic trachy-andesite, trachy-andesite and tephri-phonolite in the total alkali-silica (TAS) diagram as well as high-K to calc-alkaline and shoshonite fields. The chondrite normalised pattern of rare earth elements indicates the enrichment of LILE and LREE as well as the depletion of HFSE and HREE. Nb and Ti have a negative anomaly in the spider diagram. Eu/Eu* represents a positive anomaly for Eu indicating the frequency of calcic plagioclase and low oxygen fugacity in rocks. Geochemical parameters and diagrams predict a magmatic evolution via assimilation â fractional crystallisation process. According to the Ce/Yb vs. Ce diagram, partial melting has happened within the garnetâlherzolite field in the depth of âŒ100 km. Based on 87Sr/86Sr, Shahyourdi samples have EM1 sources, whereas Germi and Tazehkand basalts have EM11 sources that are indicative of different mantle sources for basalts in the western Moghan of the central and eastern areas. Basalts are found in active continental margins associated with the post-collision arcs.publishe
Zircon U-Pb geochronology, geochemistry, Sr-Nd isotopic compositions, and tectonomagmatic implications of Nay (NE Iran) postcollisional intrusives in the Sabzevar zone
The mafic to felsic intrusive rocks of Nay (IRN) are located in the northeast of the central Iranian block. In this study, we present new major and trace element geochemistry, U-Pb zircon ages, and Sr-Nd isotopic data to discuss the origin of the IRN postcollisional units. The oldest units in the Nay area belong to Paleoceneâearly Eocene volcanic and pyroclastic series including basalt-andesite, latite, dacite, and tuff. These series are crosscut by subvolcanic and granitoid rocks with lithological composition varying from quartz gabbro to K-feldspar granite. The youngest igneous activity is represented by quartz monzodiorite dikes. Hornblende-biotite quartz monzonite from Nay granitoids was dated at 40 Ma (zircon U-Pb). The IRN rocks are metaluminous to peraluminous with high-K calc-alkaline and shoshonitic affinities. They display enrichment in light REEs [(La/Yb)N = 3.79â8.71] and LILEs (such as Ba, Th, Rb, U, and K), with depletion in HFSEs (such as Nb, Zr, Y, and Ti). All rocks have negative Eu anomalies [(Eu/Eu*)N = 0.17â0.88] and relatively flat heavy REE patterns [(Gd/Yb)N = 1.12â1.69]. Granitoids have initial 87Sr/86Sr values from 0.7053 to 0.7061 and ΔNd values from â1.65 to â0.02 calculated at 40 Ma. The geochemical composition of IRN rocks along with the low ISr and positive ΔNd values and mantle model ages of 0.6â0.8 Ga indicate that two end-members, enriched mantle and a continental crust, were involved in the magma generation. We argue that the Eocene IRN magmatism occurred as a postcollisional product by asthenospheric upwelling owing to the convective removal of the lithosphere during an extensional collapse of the central Iranian block.publishe
U-Pb zircon geochronology, geochemistry, and petrogenesis of the Hamech intrusions in the Kuh-e-Shah volcano-plutonic complex, Eastern Iran
The Hamech area is located in the west of Kuh-e-Shah volcano-plutonic complex, close to the boundary between the Lut Block and Sistan Suture Zone (SSZ), and is composed of monzonite to diorite porphyries and rare gabbro that intruded into older volcanic rocks. U-Pb zircon dating indicates an age of 36.9 ± 1 Ma for gabbro (Late Eocene, Priabonian) and 38.6 ± 0.5 Ma for dacite (Late Eocene, Bartonian). Geochemically, the studied intrusions are dominantly I-type, high-K calc-alkaline, and metaluminous features. Primitive mantle-normalized trace-element spider diagrams of these rocks present enrichment in ion lithophile elements such as Cs, Rb, Ba, K, and Sr and depletion in high field strength elements such as Nb, Ti, Zr, and heavy rare earth elements. Besides, chondrite-normalized rare earth elements plots of the rocks show enrichment in light rare earth elements (6.85 < LaN/YbN < 9.72) and a lack or weak negative Eu anomaly (Eu/Eu* = 0.81â1.02). The initial 87Sr/86Sr and 143Nd/144Nd ratios for the rocks from 0.704541 to 0.704880 and from 0.512633 to 0.512691, respectively, when recalculated to an age of 39 Ma. The ΔNd(i) values vary from +0.87 to +1.99, which fits into a suprasubduction mantle wedge source for the parental melts. All data suggest that the Hamech intrusions developed in a low maturity continental margin arc setting related to the convergence of the Afghan and Lut Blocks and subduction of Sistan oceanic crust during the Eocene.publishe
Geochronological and geochemical characteristics of the Dehzaman intrusive and volcanic rocks (NE Iran): Implication for a Cadomian magmatism
Cadomian magmatism is interpreted to indicate fragments of late Neoproterozoic-Early Cambrian continental arcs bordering the northern margin of Gondwana. Cadomian rocks constitute the main elements of the continental crust of central Iranian block (including the Lut block). An example of such Cadomian rocks from NE Iran is studied here: the Dehzaman igneous rocks within the Kashmar- Kerman Tectonic Zone (KKTZ). The Cadomian exposure in NE Iran includes intrusive rocks with a thick sequence of felsic volcanic rocks. Zircon U-Pb dating of syenogranites and ryholites yielded 238U/206Pb
crystallization ages of â521.3 to â524.3 Ma, respectively and the age of 557 Ma to Biosyenogranites already was obtained by Rossetti et al. (2015) (Ediacaran-Early Cambrian). Geochemically, the intrusive rocks are mostly characterized by high-K content and are similar to the I-type granites. These rocks are characterized by enrichment in large ion lithophile elements (LILEs) and light rare earth elements (LREEs) along with depletion in high field strength elements (HFSEs). Their initial ΔNd (t) ranges from -0.6 to -2.1 at 86Sr/87Sr (i)=0.7045-0.7073. The Cadomian rocks from NE Iran, along with similaraged rocks from Turkey and Iran are suggested to form in an early stage of an active continental margin.publishe
Preliminary petrological inferences on the high-grade metamorphic rocks exhumed by the South Rif Thrust, Prerif, Northern Morocco
The exhumation of deep crustal rocks along major shear zones is common, yet a highly debated subject, particularly when occurring during recent tectonic events. This is the case of the South Rif Thrust (SRT), a significant shear zone analogous to those described at the Betic Cordillera in Spain.
The SRT separates two major geodynamic domains in Northern Morocco: a) the Prerif, to the North, mostly composed of Miocenic sedimentary units on top of a stratigraphic sequence continuously deposited since the Triassic; and b) the Western Meseta, to the South, mostly composed of Paleozoic metasedimentary units, correlated with the Iberian Variscan Belt [1]. Associated to the SRT, and exhumed by its activity, there is a dismembered and exotic high-grade metamorphic belt representative of the middle and lower crust. Also in this region, several thermo-mineral waters occur, whose deep circulation can be traced back to the SRT [2].
Detailed geological mapping, structural, stratigraphic and petrographic analyses on this dismembered and highly deformed exotic sequence reveal the presence of low- to high-grade metasediments (including migmatites and felsic granulites), but mostly high-grade metabasic and basic rocks, including amphibolites, mafic granulites and gabbros. Preliminary geothermobarometry in the mafic granulites provides an important characterization of the infra-crustal conditions of the pre-Alpine geodynamics and of the activity and exhumation along the SRT since the Miocene: a) the mafic granulites endured M1 metamorphic peak conditions of T
= 1030 ÂșC at P = 8.5 kbar, which is consistent with typical conductive continental crust geothermal gradients (~30 ÂșC.km-1); b) M2 retrogression occurred by near isothermal decompression at T = 820 ÂșC and P = 3.5 kbar, implying an initial vertical uplift of >18 km of the granulite-facies rocks to very shallow levels; c) during this period, the geothermal gradient in the region surpassed 60 ÂșC.km-1; d) exhumation and retrogression continued by almost isobaric cooling at T < 750 ÂșC and P = 1.7 â 3.0 kbar with an M3 amphibolitization of the granulites after late water inflow.
The overall metamorphic evolution of these deep crustal rocks is compatible with a clockwise P-T path, involving initial fast tectonic exhumation, followed by thermal readjustment to shallower levels. This is consistent with the currently observed geothermal gradients in the area (†42 ÂșC.km-1) [2] which may still be a reflection of the events during the Miocene. These petrological constrains on the tectonic processes associated with the exhumation of this lower crust segment and the activity of the SRT during the closure of the Alboran Basin are key to understanding the circulation of deep hot waters, which are an important part of the economy of this region in Northern Morocco.publishe
Bats and hawkmoths form mixed modules with flowering plants in a nocturnal interaction network
Based on the conceptual framework of pollination syndromes, pollination networks should be composed of well-delimited subgroups formed by plants that diverge in floral phenotypes and are visited by taxonomically different pollinators. Nevertheless, floral traits are not always accurate in predicting floral visitors. For instance, flowers adapted to bat-pollination are larger and wider, enabling the exploitation by other nocturnal animals, such as hawkmoths. Thus, should an interaction network comprising bats and hawkmoths, the most important nocturnal pollinators in the tropics, be formed of mixed-taxon modules due to cross-syndrome interactions? Here, we analyzed such a network to test whether resource plants are shared between the two taxa, and how modules differ in terms of species morphologies. We sampled interactions through pollen grains collected from floral visitors in a Caatinga dry forest in northeastern Brazil. The network was modular yet interwoven by cross-syndrome interactions. Hawkmoths showed no restriction to visit the wider chiropterophilous flowers. Furthermore, bats represented a subset of a hawkmoth-dominated network, as they were restricted to chiropterophilous flowers due to constraints in accessing narrower sphingophilous flowers. As such, the bat-dominated module encompassed relatively wider flowers, but hawkmoths, especially long-tongued ones, were unrestricted by floral width or length. Thus, pollination of flowers with open architectures must be investigated with caution, as they are accessible to a wide array of floral visitors, which may result in mixed-pollination systems. Future research should continue to integrate different syndromes and pollinator groups in order to reach a better understanding of how pollination-related functions emerge from community-level interactions. Abstract in Portuguese is available with online material.Fil: Queiroz, Joel A.. Universidade Estadual da Paraiba; BrasilFil: Diniz, Ugo M.. Universidade do BrasĂlia; BrasilFil: Vazquez, Diego P.. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Ăridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Ăridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Ăridas; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Quirino, Zelma M.. Universidade Estadual da Paraiba; BrasilFil: Santos, Francisco A. R.. Universidade Estadual de Feira de Santana; BrasilFil: Mello, Marco A. R.. Universidade de Sao Paulo; BrasilFil: Machado, Isabel. Universidade Federal de Pernambuco; Brasi
Computer code for double beta decay QRPA based calculations
The computer code developed by our group some years ago for the evaluation of nuclear matrix elements, within the QRPA and PQRPA nuclear structure models, involved in neutrino-nucleus reactions, muon capture and Îȱ processes, is extended to include also the nuclear double beta decay.Publicado en AIP Conference Proceedings, vol. 1625Facultad de Ciencias ExactasInstituto de FĂsica La Plat
Water quality on small ruminantsâ dairy farms in Castelo Branco region
The importance of providing quality water for cleaning milking machines and other equipment is perhaps one of the most overlooked factors in ensuring milk quality on most dairy farms. Water for cleaning in the dairy barn is used for different situations, including for the process of milking, which requires cleaning and disinfection of the milking equipment, the milking parlour, and the milk cooling tank. Many factors on dairy farms can contribute to
contamination of the raw milk, and one of the major factors responsible for this contamination is the water used to clean the milking and storage equipment.This work was financially supported by QRural Research Unit/IPCB and CERNAS-IPCB (UIDB/00681/2020, FCT).info:eu-repo/semantics/publishedVersio
Deficit irrigation in Mediterranean vineyards - a tool to increase water use efficiency and to control grapevine and berry growth
IHC - IS Viti&Climate: Effect of Climate Change on Production and Quality of Grapevines and their Products, 28 th, 2012Water is increasingly scarce in Mediterranean Europe and irrigated agriculture
is one of the largest and most inefficient users of this natural resource.
Ecological topics such as the âwater foot printâ have become more relevant for the
academy, consumers, governments and food industry. The wine sector needs solutions
to improve its economical and environmental sustainability. Agronomical solutions,
such as deficit irrigation (water supply below full crop evapotranspiration) have
emerged as a tool for more efficient water use in irrigated viticulture and with likely
positive effects on berry quality. Improving our understanding on the physiological
and molecular basis of grapevine responses to water stress is an important task for
research on irrigated viticulture. Better knowledge of the different genotypic
responses (e.g., leaf gas exchange) to water stress can help to optimize crop/soil
management and improve yield as well as berry quality traits under unfavourable
climate conditions. Mild water deficits have direct and/or indirect (via the light
environment in the cluster zone) effects on berry growth and composition. Another
important challenge is to determine how soil water deficit regulate genes and proteins
of the various metabolic pathways influencing berry composition and consequently
wine quality
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