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We build a model that, according to the empirical evidence, gives rise to oscillations in wealth within a dynasty while keeping intergenerational persistence in education attainment. We propose a mechanism based on the interaction between wealth and effort as suggested by the Carnegie conjecture, according to which wealthier individuals devote less effort in their job occupations than poorer. Oscillations in wealth arise from changes in the occupation chosen by different generations of the same dynasty as a response to both inherited wealth and college premium. Our mechanism generates a rich social stratification with several classes in the long run due to the combination of different levels of education and occupation types. Furthermore, we generate a large mobility in wealth among classes even in the long run. Our model highlights the role played by the minimum cost on education investment, the borrowing constraints, and the complementarity between education and occupational effort.
Applications of job crafting are widespread in the professional practice. In an attempt to measure this phenomenon, Tims, Bakker and Derks (2012) developed a Job Crafting Scale based on the Job Demand-Resources model (JD-R) and validated it in a Dutch sample. However, its application to other cultural contexts presented some difficulties. The present work aimed to validate a shorter version of scale by Tims et al. (2012) in a Spanish sample (n = 1,647). The data were randomly split in two independent subsamples (Sample 1: Explorative; Sample 2: Confirmative). The exploratory factor analysis showed a three-factor structure. Through a confirmatory factor analysis, the four-dimensionality structure of the original scale was replicated. In fact, the four-factor solution presented better goodness of fit indices than the alternative one-factor model, χ2(48) = 192.70, p < .01; AGFI = .94; NNFI = .93; RMR = .05; RMSEA = .06. Alpha reliabilities were acceptable for increasing structural job resources (α = .75), decreasing hindering job demands (α = .64), increasing social job resources (α = .78) and increasing challenging job demands (α = .77). Convergent validity was appropriate for three of the four dimensions, because each construct’s AVE were around .50 and each construct’s Composite Reliability were around .70. Decreasing hindering job demands presented more limited values (CR = .65; AVE = .40). In addition, the four job crafting dimensions presented significant correlations with job performance (range –.09 to .42) and personal growth (ranging from –.09 to .45). Finally, the squared correlations between factors were lower than the square root of AVE, which confirmed discriminant validity.
Prevention of Shiga toxin-producing Escherichia coli (STEC) foodborne outbreaks is hampered by its complex epidemiology. We assessed the distribution of virulence genes (VGs), main serogroups/serotypes for public health [haemolytic uraemic syndrome (HUS)-related], antimicrobial resistance (AMR) profiles and pulsed-field gel electrophoresis (PFGE) patterns in a collection of STEC isolates obtained from cattle hide (n = 149) and faecal (n = 406) samples collected during a national survey conducted in Spain in 2011 and 2013. Isolates were cultured using McConkey and CT-SMAC agar after enrichment, and confirmed as STEC by PCR. STEC prevalence in hides (15·4%) was higher than in faeces (10·7%) and O157:H7 was more frequent in the former (2·7% vs. 0·99%). Non-O157 HUS-related serogroups were present albeit at low frequencies. The non-O157 isolates were more heterogeneous than O157:H7 in their VG patterns, with 25/64 presenting VGs from both STEC and enterotoxigenic pathotypes (hybrid isolates). Of the STEC isolates, 62·5% were resistant at least to one antimicrobial, and no differences in AMR between O157:H7 and non-O157 were detected. All isolates had different profiles by PFGE and did not form a cluster. Overall, our results demonstrated that STEC in the cattle reservoir is still a matter of concern for human health due to the presence of HUS-related serogroups, the occurrence of certain VGs, AMR and the additional risks that hybrid isolates may pose, and thus warrants further investigation.
Movement between host plants during the growing season is a common behaviour among insect herbivores, although the mechanisms promoting these movements are poorly understood for many systems. Two possible reasons why insect herbivores relocate include compensating for host plant quantity and/or quality changes and the avoidance of natural enemies. The Arctic caterpillar (Gynaephora groenlandica (Wocke); Lepidoptera: Lymantriidae) moves several metres each day, feeds on its patchily distributed host plant, Arctic willow (Salix arctica Pallas; Salicaceae), and has two main natural enemies, the parasitoids Exorista thula Wood (Diptera: Tachinidae) and Hyposoter diechmanni (Nielsen) (Hymenoptera: Ichneumonidae). We physically moved caterpillars between Arctic willows and restricted other caterpillar individuals each to a single willow throughout the active period of Arctic caterpillars. We found that growth rate, herbivory rate, and the proportion of available leaf fascicles eaten were higher for experimentally moved caterpillars. Parasitoid abundances were low and did not differ between experimentally moved and stationary caterpillars. Taken together, our study addresses the bottom–up and top–down controls on insect herbivore movement during the short duration of the growing season in the Arctic. Our results suggest that caterpillars are likely moving to new willow shrubs to access high quality resources.
Monte Carlo (MC) simulations have been used extensively for benchmarking photon dose calculations in modern radiotherapy using linear accelerators (linacs). Moreover, a major barrier to widespread clinical implementation of MC dose calculation is the difficulty in characterising the radiation source using data reported from manufacturers.
This work aims to develop a generalised full MC histogram source model of an Elekta Precise SL-25 linac (electron exit window, target, flattening filter, monitor chambers and collimators) for 6 MV photon beams used in standard therapies. The inclusion of many different probability processes such as scatter, nuclear reactions, decay, capture cross-sections and more led to more realistic dose calculations in treatment planning and quality assurance.
Materials and methods
Two different codes, MCNPX 2·6 and EGSr-BEAM, were used for the calculation of particle transport, first in the geometry of the internal/external accelerator source, and then followed by tracking the transport and energy deposition in phantom-equivalent tissues. A full phase space file was scored directly above the upper multilayer collimator’s jaws to derive the beam characteristics such as planar fluence, angular distribution and energy spectrum. To check the quality of the generated photon beam, its depth dose curves and cross-beam profiles were calculated and compared with measured data.
In-field dose distributions calculated using the accelerator models were tuned to match measurement data with preliminary calculations performed using the accelerator information provided by the manufacturer. Field sizes of 3×3, 5×5, 10×10, 15×15 and 20×20 cm2 were analysed. Local differences between calculated and measured curve doses beneath 2% were obtained for all the studied field sizes. Higher discrepancies were obtained in the air–water interface, where measurements of dose distributions with the ionisation chamber need to be shifted for the effective point of measurement.
The agreements between MC-calculated and measured dose distributions were excellent for both codes, showing the strength and stability of the proposed model. Beam reconstruction methods as direct input to dose-calculation codes using the recorded histograms can be implemented for more accurate patient dose estimation.
A new Scyllaeidae of the genus Notobryon is described from Guadeloupe, in the Lesser Antilles. Notobryon caribbaeus sp. nov. is characterized by having the anterior pair of body lobes remarkably bigger than the posterior pair, a stomach with eight triangular plates, a black and very wide ampulla, a lemon-shaped bursa copulatrix and a complex and well-differentiated sponge-like prostate. The first Caribbean records of Notobryon were provisionally assigned to the Australian species Notobryon cf. wardi and later transferred to Notobryon panamica. However, the structure of the male genital system is one of the main morphological characters to discriminate species in the genus and the presence of a prostate in N. caribbaeus sp. nov. distinguishes it from N. panamica, which remains confined to the eastern Pacific. Of the remaining four species in the world, only Notobryon bijecurum shares this character, but its external anatomy is different: it lacks a bursa copulatrix and the deferent duct is much shorter. Notobryon caribbaeus sp. nov. was captured in the context of an intensive expedition (‘Karubenthos’) organized by the Muséum National d'Histoire Naturelle, Paris and its description raises the total inventory of sea slugs in Guadeloupe to 150.
Nowadays, the fibre diameter (FD) is considered the main selection objective in alpaca populations all over the world. International Committee for Animal Recording recommendations define the FD and its CV as the first two traits to be considered in breeding programmes for this specie. In addition to these main criteria, other selection criteria of economic value used are comfort factor (CF) or standard deviation (s.d.); also other less important traits being used as selection objectives are these morphological traits: density (DE), crimp (CR) or lock structure (LS) for, respectively, Huacaya (HU) and Suri (SU) ecotypes, head (HE), coverage (CO) and balance (BA). The goal of this study was to establish how to implement a combined selection index starting from genetic parameters and to study the expected correlation between genetic trends by considering different alternative procedures of weighting all the involved traits, and the consequences of a wrongly proceeding way. Heritabilities and genetic and phenotypic correlations were estimated from the data set belonging to the PACOMARCA experimental farm for SU and HU. Two approaches were used to check the consequences of a set of subjective weights essayed. The coefficients of selection indexes were obtained for two sets of reference weights. In addition, equivalent weights were drawn if applied those reference values as coefficients of hypothetical selection indexes directly on phenotypes; relative expected genetic responses were computed in different cases. Results showed that almost in all cases for both ecotypes, the weight applied to CF should be surprisingly negative. Concerning genetic responses, only CO was compromised in some cases for the HU ecotype. The essayed methodology allowed explaining the differences between ecotypes in the genetic trends. The proposed methodology was shown to be effective to study the relative importance of the traits granted by the manager of a breeding scheme.
In recent decades, transformations in organizations and the labour market have produced an increase in employee job insecurity. In response to this situation, workers present different negative reactions. However, the intensity of these reactions varies across studies that have investigated the outcomes of job insecurity. One possible explanation for this inconsistency may lie in the influence of other factors, such as the occupational group (Sverke et al., 2002). The aim of this study is to provide additional evidence about the relationship between job insecurity and its outcomes (i.e., life satisfaction, job satisfaction, perceived performance and organizational commitment), and examine the moderator role of occupational group in this relationship. The sample was composed of 321 employees from different Spanish organizations. The results showed that job insecurity was directly and negatively related to life satisfaction, job satisfaction and organizational commitment, and they suggest that occupational group moderated relations between job insecurity and three studied outcomes. In the case of life satisfaction and perceived performance, this relationship was stronger among blue collar workers. The relationship between job insecurity and job satisfaction was stronger in white collar workers. The implications and limitations of this study are discussed.
The analyses of the performance of a complete photovoltaic system require precise
measuring equipment in order to obtain reliable comparative results. This paper presents a
computer-based instrumentation system suitable for a characterization of photovoltaic
conversion chains. Consisting in a data acquisition stage, a data processor, photovoltaic
generators and power conditioners, the system evaluates the respective efficiency of
maximum power point tracker (MPPT) and power conditioner. The efficiency of unknown MPPT
functions is estimated with great accuracy by means of an extremum control-based MPPT used
as a reference. Efficiency evaluations of two photovoltaic battery chargers during 4 days
illustrate the estimation procedure and the system test facilities.
Demarcated to the north by the Shannon and its estuary and to the south by the Kenmare river and the Caha mountains, the south-western territories of Kerry and Desmond provide a microcosm of the tensions and interactions characteristic of early modern Ireland. Although historically divided into roughly two corresponding halves representing the outcome of thirteenth-century Gaelic/Anglo-Norman conflict, the area approximating to the modern administrative division of Kerry was defined by Gaelic cultural ascendancy and by the similar (though differing in scale) seigneurial ambitions of successive Fitzgerald and MacCarthy magnates. Significantly, a territorial division configured along ethnic lines was not replicated at a cultural level, where a remarkable level of homogeneity prevailed in terms of the currency of Gaelic language and literature. However, the defeat and execution of the fourteenth earl of Desmond and the distribution of his lands among English settlers under the auspices of the government-sponsored Munster plantation inaugurated profound political, social and religious turmoil in the province. In Kerry, also, consolidation of the New English military, social and legal presence in the wake of the redistribution of the earl of Desmond’s lands precipitated levels of political and cultural dissonance unparalleled since the twelfth and thirteenth centuries.
Pacomarca is an experimental ranch founded by the INCA group to act as a selection nucleus from which basic genetic improvement of alpaca fibre can spread throughout the rural communities in the Peruvian Altiplano. State-of-art techniques in animal science, such as performance recording or assisted reproduction including embryo transfer, are applied to demonstrate their usefulness in the Altiplano conditions. Pacomarca has developed useful software (Paco Pro) to carry out the integral processing of production and reproduction data. Mating is carried out individually, and gestation is diagnosed via ultrasound. Breeding values estimated from a modern genetic evaluation are used for selection, and embryo transfer is applied to increase the selection intensity. However, the objective of Pacomarca goes beyond, extending its advances to the small rural communities. Training courses for farmers are organised while searching for new ways of improving the performance of alpacas both technically and scientifically.