Direct and Interactive Effects of Brokerage Roles on Innovation in Clustered Firms          下载免费PDF全文

Cristina Boari  F. Xavier Molina‐Morales  Luis Martínez‐Cháfer 《Growth and change》2017,48(3):336-358

Social network analysis has generated a great number of research findings in the organizational and management literature, in which the so‐called territorial clusters have often been represented through the network metaphor. However, while scholars primarily examine the network structure and the internal heterogeneity, we have specifically analyzed the diverse types or roles of informational brokers which firms can perform. We also posit that innovation generated by these firms is moderated by their own capabilities and, more particularly, we analyze how innovation is affected by brokerage roles and the moderating effect of R&D in the Spanish ceramic tile cluster. Our results show that different brokerage roles played by clustered firms have different implications in terms of innovation. Another relevant and related result refers to the interactive effect of brokerage roles and absorptive capacity, which becomes more or less significant depending on the role being played in each case.  相似文献   

Onset of Spermatogenesis in Corriedale Ram Lambs under Extensive Rearing Conditions in Uruguay     

A. Castrillejo  A Moraha  A Bielli  T. Gastet  J.R. Molina  M. Forsberg  H. Rodriguez-Martinez 《Acta veterinaria Scandinavica》1995,36(2):161

The present study was undertaken to estimate the time for the attainment of spermatogenesis in spring-born Corriedale ram lambs under conditions of extensive grazing systems in Uruguay. Clinical (live weight, scrotal circumference, penile/preputial separation), morphologi-cal(light and electron microscopy) and endocrinological (testosterone levels) parameters were examined. Two experiments in 2 consecutive years were carried out. In Exp. I, 40 ram lambs were clinically examined, weighed, and blood-sampled at 2 week-intervals between 78 and 216 days of age. Sixteeen were castrated in 3 selected periods: 132-162 (n: 2), 145–175 (n: 6) and 186–216 days (n: 8). In Exp. II, 40 ram lambs appertaining to the next generation of the same flock were examined as above at 180–210 days of age, and castrated for morphological studies. The time for attainment of complete spermatogenesis correlated significantly with most corporal parameters (i.e. scrotal circumference (r = 0.52); testicular weight (r = 0.61), epididymal weight (r = 0.60), penile/preputial separation (r = 0.75). The age of castrated ram lambs correlated with the degree of spermatogenesis (r = 0.83), although no significant correlations were found with live weight or with levels of circulating testosterone. The histology showed major variations in the degree of development of the seminiferous epithelium. Cells undergoing degeneration were a common finding through the initial stages of spermatogenesis, coincident to the presence of sperm abnormalities and foreign cells in semen. By day 180 and onwards, both histology and seminal picture normalized. It is concluded that, under these rearing conditions, the onset of puberty (expressed as morphologically established spermatogenesis) in Corriedale ram lambs is attained at 180-216 days of age when they reach 23 cm of scrotal circumference and 191 g of testis weight. The finding of a high correlation between these parameters (r: 0.93) confirms the usefulness of the measurement of scrotal circumference during clinical examination of ram lambs in this breed.  相似文献   

Immunoprotection in goats against Haemonchus contortus after immunization with cysteine protease enriched protein fractions     

Ruiz A  Molina JM  González JF  Conde MM  Martín S  Hernández YI 《Veterinary research》2004,35(5):565-572

Haemonchus cysteine proteases, because of their apparent critical function in worm physiology, are considered important candidates in the immunological control of haemonchosis in sheep. Only limited information is, however, available on the immunoprotective properties of these molecules in goats. In the present study cysteine proteases of Haemonchus contortus adult worms isolated from a goat strain (Gran Canaria, Spain) were enriched by affinity chromatography and evaluated as immunoprotective antigens against caprine haemonchosis. The eggs per gram of faeces averaged over the whole experiment for unvaccinated goats (550 +/- 13.5) was significantly greater (P < 0.001) than that of vaccinated goats (61 +/- 2.9). Accordingly, the worm burden was significantly different between the groups (P < 0.05), with mean values of 247.5 +/- 43.8 and 762.5 +/- 78.3 worms per animal in the immunized and nonimmunized goats, respectively. The percentage of egg (89%) and worm (68%) reduction approached those attained with other immunogens used in sheep.  相似文献   

Eprinomectin 'pour-on' and the shedding of Haemonchus contortus eggs in experimentally infected goats     

Molina JM  Ruiz A  Hernández B  González JF  Martín S  Hernández YI 《Australian veterinary journal》2008,86(11):444-445

The effect of eprinomectin on goats experimentally infected with the nematode Haemonchus contortus was investigated. Faecal analysis showed that a single dose of eprinomectin 'pour-on' delayed the onset of shedding of eggs for 10 to 17 days.  相似文献   

Occurrence and genotype characterization of Giardia duodenalis in goat kids from the Canary Islands, Spain     

Ruiz A  Foronda P  González JF  Guedes A  Abreu-Acosta N  Molina JM  Valladares B 《Veterinary parasitology》2008,154(1-2):137-141

Giardia duodenalis (syn. Giardia lamblia, Giardia intestinalis) is a wide-spread intestinal protozoa of both humans and animals. Although giardiosis in goat is commonly asymptomatic, young kids may bear an enteric disease associated with persistent diarrhoea and delayed weight gain. In the present study we have analysed the occurrence of Giardia in 315 young goat kids (2–6 months old) from Gran Canaria Island (Spain) through visualization of faecal cysts. The identification of genotypes of G. duodenalis among the farms was attained by nested PCR of the triophosphate isomerase (TPI) and single PCR of β-giardin genes and subsequent sequencing. Positive samples were found in 42.2% of the animals and 95.5% of the farms. Goat faecal specimens were positive for only livestock-associated G. duodenalis assemblage E genotype for both TPI and β-giardin genes. The genetic analysis of these two loci revealed the presence of different haplotypes among the farms included in the survey and high homology with homologous genes from cattle and sheep. Altogether, the data presented here provide additional information to the prevalence and genetic characterization of Giardia isolates. The absence of assemblages A and B in this study suggests that zoonotic transmission of Giardia from goats could be of low epidemiological significance, although these findings should be validated in studies including other geographical areas, age groups and larger number of samples.  相似文献   

Application of individual increase in inbreeding to estimate realized effective sizes from real pedigrees     

I Cervantes  F Goyache  A Molina  M Valera  J P Gutiérrez 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2008,125(5):301-310

The objective of this study was to test the performance of a recently proposed methodology for the estimation of realized effective size (N(e)) based on individual increase in inbreeding (DeltaF(i)) on several real pedigrees: (a) an experimental mice population; (b) a closed pedigree of fighting bulls; (c) the Spanish Purebred (SPB, Andalusian) horse pedigree; (d) the Carthusian strain of SPB pedigree; (e) the Spanish Arab horse pedigree; and (f) the Spanish Anglo-Arab horse pedigree. Several reference subpopulations were defined on the basis of generation length in order to consider only animals in the last generation, to assess the influence of the pedigree content on the estimates of N(e). The estimates of realized N(e) computed from DeltaF(i) (Ne) tended to be higher than those obtained from regression on equivalent generations. The new parameter Ne remained approximately stable when pedigree depth achieved about five equivalent generations. Estimates of take into account the genetic history of the populations, the size of their founder population, and the mating policy or bottlenecks caused by poor use of reproducing individuals. The usefulness of the realized N(e) computed from individual increase in inbreeding in real pedigrees is also discussed.  相似文献   

Dog sperm swimming parameters analysed by computer‐assisted semen analysis of motility reveal major breed differences     

Anthony Valverde  Sandra Arnau  Almudena García‐Molina  Daznia Bompart  Marcos Campos  Eduardo Raúl S. Roldn  Carles Soler 《Reproduction in domestic animals》2019,54(5):795-803

Dogs have undergone an intensive artificial selection process ever since the beginning of their relationship with humans. As a consequence, a wide variety of well‐defined breeds exist today. Due to the enormous variation in dog phenotypes and the unlikely chance of gene exchange between them, the question arises as to whether they should still be regarded as a single species or, perhaps, they be considered as different taxa that possess different reproductive traits. The aim of this study was therefore to characterize some male reproductive traits, focusing on kinematic characteristics of dog spermatozoa from several breeds. Thirty‐seven dogs from the following breeds were used: Staffordshire Bull Terrier, Labrador Retriever, Spanish Mastiff, Valencian Rat Hunting Dog, British Bulldog and Chihuahua. Semen samples were obtained via manual stimulation and diluted to a final sperm concentration of 50 million/ml, and they were subsequently analysed by the computer assisted semen analysis (CASA‐Mot) ISAS^®v1 system. Eight kinematic parameters were evaluated automatically. All parameters showed significant different values among breeds and among individuals within each breed. The fastest sperm cells were those of Staffordshire Bull Terriers and the slowest were recorded in Chihuahuas. The intra‐male coefficient of variation (CV) was higher than the inter‐male CV for all breeds with the Staffordshire Bull Terrier showing the lowest values. When taking into consideration the cells by animal and breed, discriminant analyses showed a high capability to predict the breed. Cluster analyses showed a hierarchical classification very close to that obtained after phylogenetic studies with genome markers. In conclusion, future workers on dog spermatozoa should bear in mind major differences between breeds and realize that results cannot be extrapolated from one to another. Because sperm characteristics are associated with breed diversity, dogs may represent a good model to examine changes in reproductive parameters associated with selection processes.  相似文献   

Endothelial cell density and characterization of corneal endothelial cells in the Tawny Owl (Strix aluco) using specular microscopy     

Natlia Coyo  Marta Leiva  Daniel Costa  Rafael Molina  Olga Nicols  Jose Ríos  Maria Teresa Pea 《Veterinary ophthalmology》2019,22(2):177-182

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Plasma biochemistry RIs and age effect in European Strigiformes          下载免费PDF全文

Susana Agusti Montolio  Rafaela Cuenca Valera  Santiago Lavín González  Carolyn Cray  Rafael Molina López  Emmanuel Serrano Ferron  Olga Nicolás Francisco  Ignasi Marco Sánchez  Encarna Casas‐Díaz 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2018,47(1):78-93

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Quantitative analysis of short‐ and long‐distance racing performance in young and adult horses and association analysis with functional candidate genes in Spanish Trotter horses          下载免费PDF全文

S. Negro Rama  M. Valera  A. Membrillo  M.D. Gómez  M. Solé  A. Menendez‐Buxadera  G. Anaya  A. Molina 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2016,133(5):347-356

The association of five candidate genes with sporting performance in young and adult Spanish Trotter horses (STHs) was performed according to a previous selection based on quantitative analysis of the trait time per kilometre (TPK). A total of 334 516 records of TPK from 5958 STHs were used to estimate the estimated breeding values (EBVs) at different age groups (young and adults horses) throughout the range of distances (1600–2700 m) using a bicharacter random regression model. The heritability estimated by distance ranged from 0.16 to 0.40, with a different range for the two age groups. Considering the animals with the best and the worst deregressed EBV, 321 STHs were selected for SNP genotyping in MSTN, COX4I2, PDK4, DMRT3 and CKM genes. An association analysis based on ridge and logistic regression revealed that the young trotters with genotype GG in PDK4 (p < 0.05) and AA of DMRT3 (p < 0.001) SNPs show the best potential in short‐distance races, while those carrying the genotype AA in DMRT3 (p < 0.001) and CC in CKM (p < 0.05) genes seem to be the best in long‐distance races. Adult trotters with genotype AA in DMRT3 also display greater speed (p < 0.05) and endurance (p < 0.001).  相似文献