1,813 research outputs found
Availability of Credit and Loan Default: A Look at the Commercial Mortgage Supply Cycle
This study uses a structural equation approach to assess the presence of a credit supply effect in the commercial mortgage market and the lenders' ability to incorporate expectations about this effect into their lending policies. A credit supply effect is defined as the effect of mortgage supply on the level of loan defaults. The empirical analysis shows two important results. First, changes in loan defaults appear to be followed by changes in commercial mortgage supply with a lag of approximately four to five years. Second, lenders tend to behave myopically, failing to incorporate expectations about the credit supply effect into their lending policies. Additionally, a simulation suggests that adequate timing of the mortgage supply cycle is crucial in limiting the incidence of mortgage default.
Inter-Center Retail Externalities
This paper empirically examines inter-center externalities in regional shopping centers. Specifically, we use a non-linear retail share model to measure the impact that department store size and image in subject and competitive centers have on subject center in-line retail sales. Our findings reveal that department store size and image attributes have a significant and non-linear impact on subject center sales. More importantly, the results show that the effect of department store fashion image dominates that of department store size
Exposure to the leaf litter microbiome of healthy adults protects seedlings from pathogen damage
It is increasingly recognized that microbiota affect host health and physiology. However, it is unclear what factors shape microbiome community assembly in nature, and how microbiome assembly can be manipulated to improve host health. All plant leaves host foliar endophytic fungi, which make up a diverse, environmentally acquired fungal microbiota. Here, we experimentally manipulated assembly of the cacao tree (Theobroma cacao) fungal microbiome in nature and tested the effect of assembly outcome on host health. Using next-generation sequencing, as well as culture-based methods coupled with Sanger sequencing, we found that manipulating leaf litter exposure and location within the forest canopy significantly altered microbiome composition in cacao. Exposing cacao seedlings to leaf litter from healthy conspecific adults enriched the seedling microbiome with Colletotrichum tropicale, a fungal endophyte known to enhance pathogen resistance of cacao seedlings by upregulating host defensive pathways. As a result, seedlings exposed to healthy conspecific litter experienced reduced pathogen damage. Our results link processes that affect the assembly and composition of microbiome communities to their functional consequences for host success, and have broad implications for understanding plant–microbe interactions. Deliberate manipulation of the plant– fungal microbiome also has potentially important applications for cacao production and other agricultural systems in generalIt is increasingly recognized that microbiota affect host health and physiology. However, it is unclear what factors shape microbiome community assembly in nature, and how microbiome assembly can be manipulated to improve host health. All plant leaves host foliar endophytic fungi, which make up a diverse, environmentally acquired fungal microbiota. Here, we experimentally manipulated assembly of the cacao tree (Theobroma cacao) fungal microbiome in nature and tested the effect of assembly outcome on host health. Using next-generation sequencing, as well as culture-based methods coupled with Sanger sequencing, we found that manipulating leaf litter exposure and location within the forest canopy significantly altered microbiome composition in cacao. Exposing cacao seedlings to leaf litter from healthy conspecific adults enriched the seedling microbiome with Colletotrichum tropicale, a fungal endophyte known to enhance pathogen resistance of cacao seedlings by upregulating host defensive pathways. As a result, seedlings exposed to healthy conspecific litter experienced reduced pathogen damage. Our results link processes that affect the assembly and composition of microbiome communities to their functional consequences for host success, and have broad implications for understanding plant–microbe interactions. Deliberate manipulation of the plant– fungal microbiome also has potentially important applications for cacao production and other agricultural systems in genera
Comparative study of the indicated cycle of a diesel engine using simulation CFD and experimental data
En este trabajo se presenta un estudio comparativo entre la simulación numérica y datos experimentales del ciclo indicado de un motor diesel de inyección directa. Para esto se han efectuado una simulación multidimensional utilizando un paquete CFD y empleando un modelo predictivo, para varias condiciones de operación del motor. Ambos resultados se han comparado con datos experimentales medidos sobre un motor montado en banco de ensayos. El estudio se ha hecho en términos de los parámetros habituales del ciclo indicado como la evolución temporal de presión, temperatura y calor liberado, así como de la potencia, efciencia, consumo específco de combustible y presión media indicada.
Los resultados muestran que las curvas de presiones simuladas son bastante próximas a las medidas en todos los casos analizados, con las mayores diferencias en los modos de baja carga en torno a un 5% como mucho en el pico de máxima presión, aunque si se encuentran diferencias en las curvas de temperatura y de tasa de calor liberado, debido en parte a la calidad de los modelos de combustión y transferencia de calor empleados en la simulación. No obstante, queda demostrada la conveniencia del uso de herramientas basadas en CFD aplicadas al estudio de la combustión en motores.In this paper, a comparative study between numerical simulations and experimental data of the indicated cycle of a direct injection diesel engine is presented. A CFD package and a predictive model were used to simulate several engine operating conditions. Results were compared with experimental data obtained from an engine test bench. The comparison was based on indicated-cycle parameters such as pressure, temperature, heat release, power, effciency, specifc fuel consumption and mean effective pressure. Results show that in all cases simulated cylinder-pressure curves are in very good agreement with the experimental results. For the low-load mode, differences are around 5% at maximum pressure peak. On the other hand, temperature and heat release rate curves present signifcant differences between simulations and experiments. This could be a consequence of the combustion and heat transfer models used for the simulations. However, it is shown that the use of CFD tools for studying combustion phenomena in diesel engines is highly convenient
Comparative study of the indicated cycle of a diesel engine using simulation CFD and experimental data
En este trabajo se presenta un estudio comparativo entre la simulación numérica y datos experimentales del ciclo indicado de un motor diesel de inyección directa. Para esto se han efectuado una simulación multidimensional utilizando un paquete CFD y empleando un modelo predictivo, para varias condiciones de operación del motor. Ambos resultados se han comparado con datos experimentales medidos sobre un motor montado en banco de ensayos. El estudio se ha hecho en términos de los parámetros habituales del ciclo indicado como la evolución temporal de presión, temperatura y calor liberado, así como de la potencia, efciencia, consumo específco de combustible y presión media indicada.
Los resultados muestran que las curvas de presiones simuladas son bastante próximas a las medidas en todos los casos analizados, con las mayores diferencias en los modos de baja carga en torno a un 5% como mucho en el pico de máxima presión, aunque si se encuentran diferencias en las curvas de temperatura y de tasa de calor liberado, debido en parte a la calidad de los modelos de combustión y transferencia de calor empleados en la simulación. No obstante, queda demostrada la conveniencia del uso de herramientas basadas en CFD aplicadas al estudio de la combustión en motores.In this paper, a comparative study between numerical simulations and experimental data of the indicated cycle of a direct injection diesel engine is presented. A CFD package and a predictive model were used to simulate several engine operating conditions. Results were compared with experimental data obtained from an engine test bench. The comparison was based on indicated-cycle parameters such as pressure, temperature, heat release, power, effciency, specifc fuel consumption and mean effective pressure. Results show that in all cases simulated cylinder-pressure curves are in very good agreement with the experimental results. For the low-load mode, differences are around 5% at maximum pressure peak. On the other hand, temperature and heat release rate curves present signifcant differences between simulations and experiments. This could be a consequence of the combustion and heat transfer models used for the simulations. However, it is shown that the use of CFD tools for studying combustion phenomena in diesel engines is highly convenient
Erratum to: Theobroma cacao L. pathogenesis-related gene tandem array members show diverse expression dynamics in response to pathogen colonization
The original version of the manuscript [1] contained an incorrectly named Criollo gene ID on chromosome 1 in the first sentence, under the subheading “Organization of PR gene families into tandem arrays”. The second gene on chromosome 1, Tc##_g######, should therefore be Tc01_g000020.The original version of the manuscript [1] contained an incorrectly named Criollo gene ID on chromosome 1 in the first sentence, under the subheading “Organization of PR gene families into tandem arrays”. The second gene on chromosome 1, Tc##_g######, should therefore be Tc01_g000020
Freshwater Prawns (Palaemonidae: Macrobrachium) with Abbreviated Larval Development in Rivers of Mexico: Uses, Management, and Conservation Opportunities
The Macrobrachium genus in Mexico is represented by two big groups: the first one, where the larval stages are extended, and the second one, has an abbreviated larval development. There are three main slopes in Mexico or exorheic basins and several endorheic basins such as lakes and inner lagoons. The species with extended larval stage are M. carcinus, M. heterochirus, M. acanthurus, M. olfersii, M. hobbsi, and M. faustinum in the Atlantic and Caribbean slope, while in the Pacific slope, these species are M. americanum, M. occidentale, M. digueti, M. michoacanus, M. acanthochirus, and M. tenellum. These species have important fishery activities on different basins because they live from oasis in desert to main rivers in the bigger basins. However, there are some rivers that have an extended region on their upstream such as Usumacinta, Grijalva, Papaloapan, and Coatzacoalcos basins that in general are considered as hydrological regions. Just in these extended regions, there are more caves in freshwater, springs, and primary or secondary streams, which are covered by short area rivers, and in these places, there are the following species: M. totonacum, M. tuxtlaense, M. oaxacae, M. cosolapaense, M. oaxacae, M. jacatepecense, M. mazatecum, and M. vicconi, while in the cave are M. villalobosi, M. acherontium, and M. sbordonii. However, for these species, the uses are more for the local groups mainly indigenous cultures such as Mayan, Lacandon, Zapotecs and Mixtecs, and others, and their commercial use is only in the local region depending on where these species are distributed
ECOLOGICAL IMPLICATIONS OF ANTI-PATHOGEN EFFECTS OF TROPICAL FUNGAL ENDOPHYTES AND MYCORRHIZAE
We discuss studies of foliar endophytic fungi (FEE) and arbuscular mycorrhizal fungi (AMF) associated with Theobroma cacao in Panama. Direct, experimentally controlled comparisons of endophyte free (E—) and endophyte containing (E+) plant tissues in T. cacao show that foliar endophytes (FEE) that commonly occur in healthy host leaves enhance host defenses against foliar damage due to the pathogen (Phytophthora palmivora). Similarly, root inoculations with commonly occurring AMF also reduce foliar damage due to the same pathogen. These results suggest that endophytic fungi can play a potentially important mutualistic role by augmenting host defensive responses against pathogens. There are two broad classes of potential mechanisms by which endophytes could contribute to host protection: (1) inducing or increasing the expression of intrinsic host defense mechanisms and (2) providing additional sources of defense, extrinsic to those of the host (e.g., endophytebased chemical antibiosis). The degree to which either of these mechanisms predominates holds distinct consequences for the evolutionary ecology of host-endophyte-pathogen relationships. More generally, the growing recognition that plants are composed of a mosaic of plant and fungal tissues holds a series of implications for the study of plant defense, physiology, and genetics.We discuss studies of foliar endophytic fungi (FEE) and arbuscular mycorrhizal fungi (AMF) associated with Theobroma cacao in Panama. Direct, experimentally controlled comparisons of endophyte free (E—) and endophyte containing (E+) plant tissues in T. cacao show that foliar endophytes (FEE) that commonly occur in healthy host leaves enhance host defenses against foliar damage due to the pathogen (Phytophthora palmivora). Similarly, root inoculations with commonly occurring AMF also reduce foliar damage due to the same pathogen. These results suggest that endophytic fungi can play a potentially important mutualistic role by augmenting host defensive responses against pathogens. There are two broad classes of potential mechanisms by which endophytes could contribute to host protection: (1) inducing or increasing the expression of intrinsic host defense mechanisms and (2) providing additional sources of defense, extrinsic to those of the host (e.g., endophytebased chemical antibiosis). The degree to which either of these mechanisms predominates holds distinct consequences for the evolutionary ecology of host-endophyte-pathogen relationships. More generally, the growing recognition that plants are composed of a mosaic of plant and fungal tissues holds a series of implications for the study of plant defense, physiology, and genetics
A novel procedure to measure the antioxidant capacity of Yerba maté extracts
Yerba maté extracts have in vitro antioxidant capacity attributed to the presence of polyphenolic compounds, mainly chlorogenic acids and dicaffeoylquinic acid derivatives. DPPH is one of the most used assays to measure the antioxidant capacity of pure compounds and plant extracts. It is difficult to compare the results between studies because this assay is applied in too many different conditions by the different research groups. Thus, in order to assess the antioxidant capacity of yerba maté extracts, the following procedure is proposed: 100 µL of an aqueous dilution of the extracts is mixed in duplicate with 3.0 mL of a DPPH 'work solution in absolute methanol (100 µM.L-1), with an incubation time of 120 minutes in darkness at 37 ± 1 °C, and then absorbance is read at 517 nm against absolute methanol. The results should be expressed as ascorbic acid equivalents or Trolox equivalents in mass percentage (g% dm, dry matter) in order to facilitate comparisons. The AOC of the ethanolic extracts ranged between 12.8 and 23.1 g TE % dm and from 9.1 to 16.4 g AAE % dm. The AOC determined by the DPPH assay proposed in the present study can be related to the total polyphenolic content determined by the Folin-Ciocalteu assay
Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis
BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London
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