Los yacimientos del cuarzo-apatito (fosforita) en el Macizo Hespérico español: el caso de Aldea Moret-Zarza la Mayor (Cáceres)

[Resumen] Los filones de Q-Ap se hallan en zona orgánica intracontinental de reactivación de zócalos antiguos. Corresponden a yacimientos plutonogénicos relacionados con granitoides peralumínicos. Poseen estructuras y texturas de relleno, siendo su morfologia filoniana según se deduce de los planos de la mina. El tipo espectral (o tipoquímico) del apatito es característico de yacimientos hidroternales (caracter hipotermal) y su composición es la de fluorapatito. No existe un fondo geoquímico elevado en P, sino que es la presencia de mineralizadores como el F que concentra el P en un modelo halogénico.[Abstract] Since 1961, date of establishment of the firm, the investigations made gave as a result 35,000,000 Tm of reserves, being exploited 120,000 tpa. In this paper a description of benefitiation process and fina1 products is made, appearing that they are mainly for exporte In addition, considerations concerning the significance of magnesium in animal nutrition and its app1ication for it are made. Finally, difficulties and proposed solutions are quote

Effect of Land Management on Grassland Carbon Dioxide Fluxes

Grassland soils can act as both a source and sink for atmospheric carbon dioxide (CO2). Implementing grassland management practices that increase the rates of soil CO2 sequestration are urgently sought to offset Ireland’s agricultural greenhouse gas emissions. However, land management of Irish grasslands is not yet accounted for in the national inventories simultaneously posing a limitation and opportunity for refining modelled estimates of carbon sequestration. In this study, eddy covariance flux towers were established to monitor net ecosystem CO2 exchange (NEE), gross primary productivity (GPP) and ecosystem respiration (Re) in three grassland types (intensive dairy grazing, drystock grazing and zero- grazing) in geographically distinct agricultural catchments in Ireland. The initial results show larger magnitude of NEE, GPP and Re in intensively grazed and zero-grazed grasslands that are subject to frequent grazing/defoliation followed by recovery of photosynthetic potential. The continuously grazed drystock grassland exhibited lower NEE and GPP rates but smaller seasonal fluctuations in daily fluxes which may reflect the reduction in nutrient availability to support higher GPP. However, the drystock grazed grassland had significantly higher soil water content which may stimulate higher soil CO2 respiration resulting in lower NEE over time. Management practices involving defoliation and nutrient supply influenced affected season CO2 exchange but longer-term flux monitoring is required to assess the net ecosystem carbon budgets of each grassland system

Should gender be a determinant factor for granting crowdfunded microloans?

Crowdfunded microloans are a suitable tool for financing basic economic activities in developing as well as developed countries, favouring female empowerment. Despite the loans being relatively small, the widespread use of this instrument merits analyzing the factors affecting the microloan. One of these factors is gender because microloans are an important tool to finance projects promoted by women in many developing countries where microfinance is widely diffused. This research aims to determine if the gender of crowdfunded micro-borrowers is related to the main features which define the conditions of a microloan: amount, term, number of lenders, length of time to contact with borrowers and repayment system. The methodology used is the multinomial logit regression. The sample used in this study has been obtained by applying sampling techniques to a extensive public database from Kiva. This provided information on microloans from 56 countries around the world. The results based on amount, term, repayment method and recruitment period indicate that women are the best borrowers. All these variables, except the term, are significant at a 5% level. These findings may be useful to improve financial inclusion and outreach, consistently with the Sustainable Development Goals. Future research is needed to assess how “green and pink” microfinance (with environmental strategies particularly favored by women) can attract more ESG-compliant crowdfunding resources

Compressed Sigma-Protocols for bilinear circuits and applications to logarithmic-sized transparent Threshold Signature Schemes

Recently, there has been a great development in communication-efficient zero-knowledge (ZK) protocols for arithmetic circuit relations. Since any relation can be translated into an arithmetic circuit relation, these primitives are extremely powerful and widely applied. However, this translation often comes at the cost of losing conceptual simplicity and modularity in cryptographic protocol design.For this reason, Lai et al. (CCS 2019), show how Bulletproof’s communication-efficient circuit zero-knowledge protocol (Bootle et al., EUROCRYPT 2016 and Bünz et al., S&P 2018) can be generalized to work for bilinear group arithmetic circuits directly, without requiring these circuits to be translated into arithmetic circuits. For many natural relations their approach is actually more efficient than the indirect circuit ZK approach. We take a different approach and show that the arithmetic circuit model can be generalized to any circuit model in which (a) all wires take values in (possibly different) Zq-modules and (b) all gates have fan-in2and are either linear or bilinear mappings. We follow a straightforward generalization of Compressed Σ-Protocol Theory (CRYPTO 2020). We compress the communication complexity of a basic Σ-protocol for proving linear statements down to logarithmic. Then, we describe a linearization strategy to handle non-linearities. Besides its conceptual simplicity our approach also has practical advantages; we reduce the constant of the logarithmic component in the communication complexity of the CCS 2019 approach from 16 down to 6 and that of the linear component from 3 down to 1. Moreover, the generalized commitment scheme required for bilinear circuit relations is also advantageous to standard arithmetic circuit ZK protocols, since its application immediately results in a square root reduction of public parameters size. The implications of this improvement can be significant, because many application scenarios result in very large sets of public parameters. As an application of our compressed protocol for proving linear statements we construct the first k-out-of-n threshold signature scheme (TSS) with both transparent setup and threshold signatures of size O(κlog(n)) bits for security parameter κ. Each individual signature is of a so-called BLS type, the threshold signature hides the identities of the k signers and the threshold k can be dynamically chose n at aggregation time. Prior TSSs either result in sub-linear size signatures at the cost of requiring a trusted setup or the cost of the transparent setup amounts to linear (ink) size signatures.</p

Determinants of Repayment among Male and Female Microcredit Clients in the USA. An Approach Based on Managers’ Perceptions

Research on microfinance institutions (MFIs) has normally been focused on developing and emerging markets. However, an analysis of developed countries is also important for foreign MFIs wishing to take advantage of the growth potential of those markets. Therefore, the aim of this article is to determine whether MFIs working in the USA’s market should change or adapt their microcredit policies with respect to women. In effect, there are no studies in the USA supporting the argument that women are a better risk of microcredit than men, or that there are differences in microcredit repayment behavior between women and men. Additionally, it was investigated if the payment behavior of women and men is related to variables such as their age, ethnicity, academic level, marital status, or the characteristics of the microcredits, like purposes, amounts, and payment terms. In the USA, there are not—as in other countries—strong incentives, motivations, or external pressures, other than those that men also have, which influence women to pay their microloans better than men. Then, domestic and international MFIs attracted to enter the USA’s market should review their microcredit policies in relation to women. More research is needed about the microfinance market in the USA

Brief announcement: Malicious security comes for free in consensus with leaders

We consider consensus protocols in the model that is most commonly considered for use in state machine replication, as initiated by Dwork-Lynch-Stockmeyer, then by Castro-Liskov in 1999 with "PBFT."Such protocols guarantee, assuming n players out of which t < n/3 are maliciously corrupted, that the honest players output the same valid value within a finite number of messages, after the (unknown) point in time where both: the network becomes synchronous, and a designated player (the leader) is honest. The state of the art (Hotstuff, PODC'19), achieves linear communication complexity, but at the cost of additional latency, due to one more round-trip with the leader. Furthermore, it relies on constant-size threshold signatures schemes (TSS), for which all prior-known constructions require a costly interactive (or trusted) setup. We remove all of these limitations. The communication bottleneck of PBFT lies in the subprotocol, denoted as "view change,"in which the leader forwards 2t+1 signed messages to each player. Then, each player checks that these 2t+1 messages satisfy some predicate, which we denote "non-supermajority''. We replace this with a responsive subprotocol, with linear communication complexity, that enables players to check this predicate. Its construction is elementary, since it requires only black box use of any TSS. In the full version of our paper \citemalicious2 we achieve three things. Firstly, we further optimize this subprotocol from succinct arguments of many signed messages, which we instantiate from Attema-Cramer-Rambaud \cite[2021-3-9 version]ACR20. As an introduction to these methods, we discuss here the simplest case, which is the construction in \citeACR20 of the first logarithmic-sized TSS with transparent setup. Second, we also address another complexity challenge pointed in Hotstuff, namely, that protocols with fast termination in favorable runs, have so far quadratic complexity, due to an even more complex view change. Third, we enable halting in finite time with (amortized) linear complexity, which was an unsolved question so far when external validity is required

Glyphosate and AMPA in human urine of HBM4EU-aligned studies: part B adults

Within HBM4EU, human biomonitoring (HBM) studies measuring glyphosate (Gly) and aminomethylphosphonic acid (AMPA) in urine samples from the general adult population were aligned and quality-controlled/assured. Data from four studies (ESB Germany (2015-2020); Swiss HBM4EU study (2020); DIET-HBM Iceland (2019-2020); ESTEBAN France (2014-2016)) were included representing Northern and Western Europe. Overall, median values were below the reported quantification limits (LOQs) (0.05-0.1 microg/L). The 95th percentiles (P95) ranged between 0.24 and 0.37 microg/L urine for Gly and between 0.21 and 0.38 microg/L for AMPA. Lower values were observed in adults compared to children. Indications exist for autonomous sources of AMPA in the environment. As for children, reversed dosimetry calculations based on HBM data in adults did not lead to exceedances of the ADI (proposed acceptable daily intake of EFSA for Gly 0.1 mg/kg bw/day based on histopathological findings in the salivary gland of rats) indicating no human health risks in the studied populations at the moment. However, the controversy on carcinogenicity, potential endocrine effects and the absence of a group ADI for Gly and AMPA induce uncertainty to the risk assessment. Exposure determinant analysis showed few significant associations. More data on specific subgroups, such as those occupationally exposed or living close to agricultural fields or with certain consumption patterns (vegetarian, vegan, organic food, high cereal consumer), are needed to evaluate major exposure sources

Detectability of testosterone esters and estradiol benzoate in bovine hair and plasma following pour-on treatment

The abuse of synthetic esters of natural steroids such as testosterone and estradiol in cattle fattening and sports is hard to detect via routine urine testing. The esters are rapidly hydrolysed in vivo into substances which are also endogenously present in urine. An interesting alternative can be provided by the analysis of the administered synthetic steroids themselves, i.e., the analysis of intact steroid esters in hair by liquid chromatography tandem mass spectrometry (LC/MS/MS). However, retrospective estimation of the application date following a non-compliant finding is hindered by the complexity of the kinetics of the incorporation of steroid esters in hair. In this study, the incorporation of intact steroid esters in hair following pour-on treatment has been studied and critically compared with results from intramuscular treatment. To this end animals were pour-on treated with a hormone cocktail containing testosterone cypionate, testosterone decanoate and estradiol benzoate in different carriers. The animals were either treated using injection and pour-on application once or three times having 1 week between treatments using injection and pour-on application. Animals were slaughtered from 10–12 weeks after the last treatment. Both hair and blood plasma samples were collected and analysed by LC/MS/MS. From the results, it is concluded that after single treatment the levels of steroid esters in hair drop to CCβ levels (5–20 µg/kg) after 5–7 weeks. When treatment is repeated two times, the CCβ levels are reached after 9–11 weeks. Furthermore, in plasma, no steroid esters were detected; not even at the low microgramme per litre level but—in contrast with the pour-on application—after i.m. injection, significant increase of 17β-testosterone and 17β-estradiol were observed. These observations suggest that transport of steroid esters after pour-on application is not only performed by blood but also by alternative fluids in the animal so probably the steroid esters are already hydrolysed and epimerized before entering the blood