756 research outputs found

    Competition, restructuring and firm performance: evidence of an inverted-U relationship from a cross-country survey of firms in transition economies

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    This paper examines the importance of competition in the growth anddevelopment of firms. We draw on a survey of 3,300 firms in 25transition countries to shed light on the factors that influencerestructuring by firms and their subsequent performance. These datahave three main advantages over those used in previous work. First,they measure directly the degree of competition perceived by each firmin its principal market rather than attempting to infer this from marketdata as measured by statistical agencies. Second, the fact that transitioncountries have market structures inherited from the past avoids some ofthe endogeneity problems associated with measures of competition inmarket economies. Third, the breadth of cross-country variationprovides a method of dealing with the fact that firm-level measures ofthe external environment will not be independent of the firm?s ownperformance. We find evidence of a robust inverted-U effect ofcompetition on performance that is both statistically and economicallysignificant. This paper examines the importance of competition in the growth anddevelopment of firms. We draw on a survey of 3,300 firms in 25transition countries to shed light on the factors that influencerestructuring by firms and their subsequent performance. These datahave three main advantages over those used in previous work. First,they measure directly the degree of competition perceived by each firmin its principal market rather than attempting to infer this from marketdata as measured by statistical agencies. Second, the fact that transitioncountries have market structures inherited from the past avoids some ofthe endogeneity problems associated with measures of competition inmarket economies. Third, the breadth of cross-country variationprovides a method of dealing with the fact that firm-level measures ofthe external environment will not be independent of the firm?s ownperformance. We find evidence of a robust inverted-U effect ofcompetition on performance that is both statistically and economicallysignificant

    An electrically driven, computer controlled robotics platform for orchard use

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    As automation in agriculture progresses, more automation systems will be placed into farms & orchards. Systems that service the crops directly are likely to have positioning requirements that make traditional tractor-trailer units unsuitable. This paper introduces a platform built for transporting robotics modules through a kiwifruit orchard. Performance figures, design considerations and a general hardware overview are presented. The platform is controlled either by remote or computer generated drive commands - facilitating autonomous navigation. In-orchard testing shows the system is well suited for the target application, achieving stable speed control and repeatable positioning

    Evolutionary Roots of Property Rights; The Natural and Cultural Nature of Human Cooperation

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    Debates about the role of natural and cultural selection in the development of prosocial, antisocial and socially neutral mechanisms and behavior raise questions that touch property rights, cooperation, and conflict. For example, some researchers suggest that cooperation and prosociality evolved by natural selection (Hamilton 1964, Trivers 1971, Axelrod and Hamilton 1981, De Waal 2013, 2014), while others claim that natural selection is insufficient for the evolution of cooperation, which required in addition cultural selection (Sterelny 2013, Bowles and Gintis 2003, Seabright 2013, Norenzayan 2013). Some scholars focus on the complexity and hierarchical nature of the evolution of cooperation as involving different tools associated with lower and the higher levels of competition (Nowak 2006, Okasha 2006); others suggest that humans genetically inherited heuristics that favor prosocial behavior such as generosity, forgiveness or altruistic punishment (Ridley 1996, Bowles and Gintis 2004, Rolls 2005). We argue these mechanisms are not genetically inherited; rather, they are features inherited through cultural selection. To support this view we invoke inclusive fitness theory, which states that individuals tend to maximize their inclusive fitness, rather than maximizing group fitness. We further reject the older notion of natural group selection - as well as more recent versions (West, Mouden, Gardner 2011) – which hold that natural selection favors cooperators within a group (Wynne-Edwards 1962). For Wynne-Edwards, group selection leads to group adaptations; the survival of individuals therefore depends on the survival of the group and a sharing of resources. Individuals who do not cooperate, who are selfish, face extinction due to rapid and over-exploitation of resources

    Comparative Chromosome Maps of Neotropical Rodents Necromys lasiurus and Thaptomys nigrita (Cricetidae) Established by ZOO-FISH

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    This work presents chromosome homology maps between Mus musculus (MMU) and 2 South American rodent species from the Cricetidae group: Necromys lasiurus (NLA, 2n = 34) and Thaptomys nigrita (TNI, 2n = 52), established by ZOO-FISH using mouse chromosome-specific painting probes. Extending previous molecular cytogenetic studies in Neotropical rodents, the purpose of this work was to delineate evolutionary chromosomal rearrangements in Cricetidae rodents and to reconstruct the phylogenetic relationships among the Akodontini species. Our phylogenetic reconstruction by maximum parsimony analysis of chromosomal characters confirmed one consistent clade of all Neotropical rodents studied so far. In both species analyzed here, we observed the syntenic association of chromosome segments homologous to MMU 8/13, suggesting that this chromosome form is a synapomorphic trait exclusive to Neotropical rodents. Further, the previously described Akodontini-specific syntenic associations MMU 3/18 and MMU 6/12 were observed in N. lasiurus but not in T. nigrita, although the latter species is considered a member of the Akodontini tribe by some authors. Finally, and in agreement with this finding, N. lasiurus and Akodon serrensis share the derived fission of MMU 13, which places them as basal sister clades within Akodontini. Copyright (C) 2011 S. Karger AG, Base

    Clonal karyotype evolution involving ring chromosome 1 with myelodysplastic syndrome subtype RAEB-t progressing into acute leukemia

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    s Karyotypic evolution is a well-known phenomenon in patients with malignant hernatological disorders during disease progression. We describe a 50-year-old male patient who had originally presented with pancytopenia in October 1992. The diagnosis of a myelodysplastic syndrome (MDS) FAB subtype RAEB-t was established in April 1993 by histological bone marrow (BM) examination, and therapy with low-dose cytosine arabinoside was initiated. In a phase of partial hernatological remission, cytogenetic assessment in August 1993 revealed a ring chromosome 1 in 13 of 21 metaphases beside BM cells with normal karyotypes {[}46,XY,r(1)(p35q31)/46,XY]. One month later, the patient progressed to an acute myeloid leukemia (AML), subtype M4 with 40% BM blasts and cytogenetic examination showed clonal evolution by the appearance of additional numerical aberrations in addition to the ring chromosome{[}46,XY,r(1),+8,-21/45,XY,r(1),+8,-21,-22/46, XY]. Intensive chemotherapy and radiotherapy was applied to induce remission in preparation for allogeneic bone marrow transplantation (BMT) from the patient's HLA-compatible son. After BMT, complete remission was clinically, hematologically and cytogenetically (normal male karyotype) confirmed. A complete hematopoietic chimerism was demonstrated. A relapse in January 1997 was successfully treated using donor lymphocyte infusion and donor peripheral blood stem cells (PB-SC) in combination with GM-CSF as immunostimulating agent in April 1997, and the patient's clinical condition remained stable as of January 2005. This is an interesting case of a patient with AML secondary to MDS. With the ring chromosome 1 we also describe a rare cytogenetic abnormality that predicted the poor prognosis of the patient, but the patient could be cured by adoptive immunotherapy and the application of donor's PB-SC. This case confirms the value of cytogenetic analysis in characterizing the malignant clone in hernatological neoplasias, the importance of controlling the quality of an induced remission and of the detection of a progress of the disease. Copyright (c) 2006 S. Karger AG, Basel

    Karyology of the Atlantic forest rodent Juliomys (Cricetidae): A new karyotype from southern Brazil

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    Juliomys is a small rodent from the family Cricetidae which inhabits the Atlantic forest and forests from Argentina to eastern Brazil. The three species recognized so far have different karyotypes. In this paper, we describe a new karyotype with 2n = 32, FN = 48 found in Juliomys specimens from a high-altitude area in the Atlantic forest of southern Brazil. The karyotype was analyzed after G- and C-banding and silver staining of the nucleolus organizer regions (Ag-NOR) and its G-banding patterns were compared with those of the newly described species Juliomys ossitenuis (2n = 20, FN = 36). The 2n = 32 karyomorph presented peculiar features and was very different from those of the other species of the genus: J. pictipes (2n = 36, FN = 34), J. rimofrons (2n = 20, FN = 34) and J. ossitenuis (2n = 20, FN = 36). Differences were mostly due to centric and tandem fusions, pericentric inversion and loss of heterochromatin. The karyotype represents a powerful tool to differentiate Juliomys species and our data suggest that the karyotype described herein belongs to a new species

    Entrepreneurship and social capital: examining the association in deprived urban neighbourhoods

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    Spatial approaches to examining entrepreneurship have increasingly built on theories of social capital. However, the nature and extent of local social capital in less successful deprived communities remains under-researched and inadequately understood. The paper examines the association between social capital and entrepreneurship in a deprived urban neighbourhood in the city of Leeds, UK as a means of contributing to an improved theoretical understanding of how space moderates this association. It is found that social capital has a strong association with patterns of entrepreneurship in deprived urban neighbourhoods, with the potential impacts being both positive and negative. The forms of social capital are found to differ from that found in more affluent localities, with a prevalence of bonding social capital as the key facilitator of entrepreneurship, which may help in the early stages of venture development, but which over time may become a constraint. Also, a lack of the bridging social capital associated with entrepreneurial success is found within the locality. From a policy perspective, it is recommended that policy makers responsible for entrepreneurship in deprived urban neighbourhoods should seek to enhance initiatives for developing social capital which incorporate local businesses, residents and local government agencies

    Y chromosome microdeletions in infertile men with idiopathic oligo- or azoospermia

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    About 30–40% of male infertility is due to unknown reasons. Genetic contributions to the disruption of spermatogenesis are suggested and amongst the genetic factors studied, Y chromosome microdeletions represent the most common one. Screening for microdeletions in AZFa, b and c region of Y chromosome showed a big variation among different studies. The purpose of this study was to investigate the prevalence of such deletions in Saudi men. A total of 257 patients with idiopathic oligo- or azoospermia were screened for Y chromosome microdeletions by 19 markers in AZF region. Ten (3.9%) patients had chromosomal rearrangements, six of them showed sex chromosome abnormalities and four patients had apparently balanced autosomal rearrengements. Eight of the remaining 247 patients (3.2%) with a normal karyotype and no known causes of impaired spermatogenesis had Y chromosome microdeletions. Among these, six patients had deletions in AZFc region, one case had a deletion in AZFb and another had both AZFa and AZFc deletions. In conclusion, our study shows that Y chromosome microdeletions are low in our population. We also report for the first time a case with unique point deletions of AZFa and AZFc regions. The lower frequency of deletions in our study suggest that other genetic, epigenetic, nutritional and local factors may be responsible for idiopathic oligo- or azoospermia in the Saudi population
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