51 research outputs found
Is empirical imagination a constraint on adaptationist theory construction? (Commentary)
Andrews et al. present a form of instrumental adaptationism that is designed to test the hypothesis that a given trait is an adaptation. This epistemological commitment aims to make clear statements about behavioural natural kinds. The instrumental logic is sound, but it is the limits of our empirical imagination that can cause problems for theory construction
Symbols, Stimulus Equivalence and the Origins of Language
Recent interest in the origins of language, within the strongly cognitive field of Evolutionary Psychology, has predominantly focused upon the origins of syntax (cf. Hurford, Knight and Studdert-Kennedy, 1998). However, Ullin Place's (2000a) theory of the gestural origins of language also addresses the more fundamental issue of the antecedents of symbols, and does so from a behaviourist perspective, stressing the importance of the peculiarly human ability to form stimulus equivalence classes. The rejection by many developmental psychologists of a behaviourist account of language acquisition has led to a modular and distinctly nativist psychology of language (cf. Pinker, 1994, 1997; Pinker and Bloom, 1990). Little has been said about the role or nature of learning mechanisms in the evolution of language. Although Place does not provide any defence of a behaviourist linguistic ontogeny this is no reason to rule out his phylogenetic speculations. We aim to outline Place's evolutionarily parsimonious view of symbol origins and their relation to stimulus equivalence. We applaud Ullin Place for bringing symbols into focus within the broader discipline of language origins and suggest that he has raised an interesting set of questions to be discussed in future work
Is this conjectural phenotypic dichotomy a plausible outcome of genomic imprinting? (Commentary)
What is the status of the dichotomy proposed and the nosological validity of the contrasting pathologies described? How plausibly can dysregulated imprinting explain the array of features described, compared with other genetic models? We believe that considering alternative models is more likely to lead in the long term to the correct classification and explanation of the component behaviours
Survey of Medium and Large Mammals in an Urban Park (Murray Park), Little Rock, Pulaski County, Arkansas
Because of increased environmental awareness by city planning commissions, there are more urban parks and greenbelt areas. These areas often result in increased human and wildlife contacts, thus resulting in the need for management plans regarding urban wildlife. From September 1998 to March 1999, we conducted mammal surveys of the urban greenspace Murray Park, Little Rock, Pulaski County, Arkansas. Surveys were conducted using five methods: direct observations; spot lighting; live trapping; animal sign; and scent posts. Species recorded included, opossum (Didelphis virginiana), nine-banded armadillo (Dasypus novemcinctus), fox squirrel (Sciurus niger), gray squirrel (Sciurus carolinensis), beaver (Castor canadensis), woodchuck (Marmota monax), muskrat (Ondatra zibethicus), eastern cottontail rabbit (Sylvilagus floridanus), swamp rabbit (Sylvilagus aquaticus), coyote (Canis latrans), red fox (Vulpes vulpes), raccoon (Procyon lotor), mink (Mustela vison), river otter (Lontra canadensis), bobcat (Lynx rufus), skunk sp., white-tailed deer (Odocoileus virginianus) and domestic dog (Canis familiaris) and cat (Felis sylvestris). These species represent 19 of the 23 mammals expected in surrounding natural areas. Management plans for urban wildlife need to include all mammals that potentially occur in the area
Earnings management and audit quality:stakeholders’ perceptions
This paper examines the perceptions of Libyan Commercial Banks’ (LCBs) stakeholders regarding the role of the external auditor in relation to earnings management (EM). A total of 28 semi-structured interviews were carried out with a range of LCB stakeholders comprising preparers of financial statements, users, regulators and academics. A questionnaire survey of stakeholders which yielded 102 Responses (response rate 53%) was also carried out. A variety of views were held which varied to some extent according to stakeholder group. A widely held perception amongst interviewees was that the auditor has the ability to detect EM practices but may not be able to prevent it. However questionnaire respondents were, in aggregate, more confident of the auditor’s ability to deter EM due to the influence of the audit report. The paper provides insights into stakeholders’ perceptions of the quality of bank audits. The findings are of particular relevance to regulators, and specifically, the Central Bank of Libya. Perceptions of audit quality raise questions about its guidance and regulations especially in connection with audit firm rotation. Perceptions of audit quality, and therefore, of the credibility of financial statements should be of interest to all stakeholders. The importance of the banking sector for society has been amply demonstrated in recent years. A well-functioning audit function is a key component of its regulation. To the best of our knowledge, this paper is the first to examine issues related to banks’ audit quality and audit firm rotation in Libya
Suppression of Lung Adenocarcinoma Progression by Nkx2-1
Despite the high prevalence and poor outcome of patients with
metastatic lung cancer the mechanisms of tumour progression and
metastasis remain largely uncharacterized. Here we modelled
human lung adenocarcinoma, which frequently harbours activating
point mutations in KRAS and inactivation of the p53 pathway,
using conditional alleles in mice. Lentiviral-mediated somatic
activation of oncogenic Kras and deletion of p53 in the lung epithelial
cells of Kras[superscript LSL-G12D/+];p53[superscript flox/flox] mice initiates lung adenocarcinoma
development4. Although tumours are initiated synchronously
by defined genetic alterations, only a subset becomes malignant,
indicating that disease progression requires additional alterations.
Identification of the lentiviral integration sites allowed us to distinguish
metastatic from non-metastatic tumours and determine the
gene expression alterations that distinguish these tumour types.
Cross-species analysis identified the NK2-related homeobox transcription
factor Nkx2-1 (also called Ttf-1 or Titf1) as a candidate
suppressor of malignant progression. In this mouse model, Nkx2-1
negativity is pathognomonic of high-grade poorly differentiated
tumours. Gain- and loss-of-function experiments in cells derived
from metastatic and non-metastatic tumours demonstrated that
Nkx2-1 controls tumour differentiation and limitsmetastatic potential
in vivo. Interrogation of Nkx2-1-regulated genes, analysis of
tumours at defined developmental stages, and functional complementation
experiments indicate that Nkx2-1 constrains tumours in
part by repressing the embryonically restricted chromatin regulator
Hmga2. Whereas focal amplification of NKX2-1 in a fraction of
human lung adenocarcinomas has focused attention on its oncogenic
function, our data specifically link Nkx2-1 downregulation
to loss of differentiation, enhanced tumour seeding ability and
increased metastatic proclivity. Thus, the oncogenic and suppressive
functions ofNkx2-1 in the sametumourNational Institutes of Health (U.S.) (grant U01-CA84306 )National Institutes of Health (U.S.) (grant K99-CA151968)Howard Hughes Medical InstituteLudwig Center for Molecular OncologyNational Cancer Institute (U.S.) (Cancer Center Support (core) grant P30-CA14051
Autonomous role of medullary thymic epithelial cells in central CD4+ T cell tolerance
International audienceMedullary thymic epithelial cells (mTECs) serve an essential function in central tolerance through expressing peripheral tissue-antigens. These antigens may be transferred to and presented by dendritic cells. Therefore, it is unclear whether mTECs, besides being an 'antigen-reservoir', also serve a mandatory function as antigen presenting cells. Here, we reduced MHC class II on mTECs through transgenic expression of a C2TA-specific 'designer miRNA'. This resulted in an enlarged polyclonal CD4 single-positive compartment and, among thymocytes specific for model-antigens expressed in mTECs, enhanced selection of regulatory T cells (Treg) at the expense of deletion. Our data document an autonomous contribution of mTECs to dominant and recessive mechanisms of CD4+ T cell tolerance and support an avidity model of Treg development versus deletion
Symbols, Stimulus Equivalence and the Origins of Language
Recent interest in the origins of language, within the strongly cognitive field of Evolutionary Psychology, has predominantly focused upon the origins of syntax (cf. Hurford, Knight and Studdert-Kennedy, 1998). However, Ullin Place's (2000a) theory of the gestural origins of language also addresses the more fundamental issue of the antecedents of symbols, and does so from a behaviourist perspective, stressing the importance of the peculiarly human ability to form stimulus equivalence classes. The rejection by many developmental psychologists of a behaviourist account of language acquisition has led to a modular and distinctly nativist psychology of language (cf. Pinker, 1994, 1997; Pinker and Bloom, 1990). Little has been said about the role or nature of learning mechanisms in the evolution of language. Although Place does not provide any defence of a behaviourist linguistic ontogeny this is no reason to rule out his phylogenetic speculations. We aim to outline Place's evolutionarily parsimonious view of symbol origins and their relation to stimulus equivalence. We applaud Ullin Place for bringing symbols into focus within the broader discipline of language origins and suggest that he has raised an interesting set of questions to be discussed in future work
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