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Potential Pitfalls (potential + pitfall)
Selected AbstractsDeveloping and maintaining the therapeutic alliance with self-injuring patientsJOURNAL OF CLINICAL PSYCHOLOGY, Issue 11 2007Nira Nafisi In this article, the authors outline methods of strengthening the therapist,patient bond with individuals who self-injure. Self-injuring patients present with a host of challenges that differ from other patient populations and therefore certain approaches may be more effective than others. Among the strategies described are validation, checking in, working collaboratively toward goals, providing support, and repairing a ruptured alliance. Potential pitfalls (e.g., reinforcing maladaptive behavior, negative judging, and the fundamental attribution error) to which psychotherapists often fall prey are discussed as well. Self-injury is explained as functional rather than manipulative behavior and detailed clinical guidelines and examples are provided to better illustrate approaches that will improve the therapeutic alliance. © 2007 Wiley Periodicals, Inc. J Clin Psychol: In Session 63: 1069,1079, 2007. [source] Letters to the Editors: Potential pitfalls on the validation of liver stiffness measurement by Fibroscan with histological staging in chronic hepatitis BALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 7 2010H. L.-Y. No abstract is available for this article. [source] Potential pitfalls on the road to a process-managed organization (PMO), part 2: A road too much traveledPERFORMANCE IMPROVEMENT, Issue 5 2009Geary A. Rummler In the second part of our article, we examine the potential pitfalls in the process-managed organization (PMO) and describe the "type of journey that will lead to success." Most setbacks for a PMO are results of discrepancies found in the underlying foundation; typically the process identification is most likely to be the cause. Processes in organizations do not manage themselves,a cross silo organizational system is required to operate the organization for optimal efficiency. [source] Potential pitfalls on the road to a process-managed organization (PMO), Part 1: The organization as system lensPERFORMANCE IMPROVEMENT, Issue 4 2009Geary A. Rummler Process design and improvement over the past 20 years have yielded great gains in customer satisfaction and cost containment in organizations throughout the world. This article presents what we call the Organizations as a Systems Lens. It provides a way of looking at organizations essential to being process centered. We present a powerful framework called the Processing System Hierarchy, which makes it quite clear what must be done to successfully travel the road to the process-managed organization. [source] Capillary electrophoresis for chimerism monitoring by PCR amplification of microsatellite markers after allogeneic hematopoietic cell transplantationCLINICAL TRANSPLANTATION, Issue 3 2005Alexandros Spyridonidis Abstract:, Background:, Hematopoietic chimerism has been demonstrated to be relevant for donor cell engraftment and detection of minimal residual disease after allogeneic hematopoietic cell transplantation (aHCT). In the light of increasing numbers of non-myeloablative aHCT as a treatment modality sensitive, rapid, and accurate chimerism monitoring techniques acquire novel relevance. Methods:, We evaluated the informativeness of five microsatellite markers in 376 donor/recipient pairs and evaluated the ability of capillary electrophoresis to detect mixed chimerism after aHCT. The sensitivity for capillary electrophoresis with respect to different markers was determined by limiting dilution assays with mixed chimerism samples containing defined amounts of cells or DNA. Furthermore, capillary electrophoresis was applied in 17 retrospectively selected patients with a mixed chimerism detected previously by gel electrophoresis, having undergone aHCT for different hematologic diseases and initially achieving a complete donor chimerism. Results:, In 163 of 165 (98%) of all related and 210 of 211 (99%) unrelated transplants the microsatellites identified informative alleles. The sensitivity and accuracy was higher with capillary electrophoresis when compared with gel electrophoresis with three of five microsatellites. Potential pitfalls with the application of capillary electrophoresis was preferential amplification and the occurrence of stutter peaks in the representative area. Investigation of the selected patient samples demonstrated that detection of a mixed chimerism was earlier with capillary electrophoresis when compared with gel electrophoresis. The detected recipient genotype by capillary electrophoresis examination, despite a negative gel electrophoresis result, ranged from 0.7 to 7.1%. Conclusions:, We conclude that chimerism assessment with our five microsatellites identified informative alleles in 99% of all donor/recipient pairs and may therefore be of use when establishing an institutional chimerism testing procedure. Capillary electrophoresis displayed a high sensitivity and accuracy for detecting a mixed chimerism in vitro and in vivo. [source] Fine needle aspiration of a metastatic mucinous tumour of the thyroid gland from ovarian adenocarcinoma: a potential pitfall in the differential diagnosis of thyroid neoplasmsCYTOPATHOLOGY, Issue 4 2007A. D'Antonio No abstract is available for this article. [source] Idiopathic retroperitoneal fibrosis , a potential pitfall for fine needle aspiration cytologyCYTOPATHOLOGY, Issue 1 2005S. Jogai No abstract is available for this article. [source] Metastatic hepatocellular carcinoma presenting as a pancreatic mass by computed tomography scan and mimicking a primary neuroendocrine tumor: A potential pitfall in aspiration cytologyDIAGNOSTIC CYTOPATHOLOGY, Issue 12 2009Valerie A. Fitzhugh M.D. Abstract Hepatocellular carcinoma (HCC) is a highly malignant neoplasm, often presenting at late stage and portending a poor prognosis for the patient. The peripancreatic fat is a rare site of extrahepatic metastasis, and metastatic HCC can mimic primary pancreatic neoplasms, even in this location. It is crucial to be aware of this pitfall in the evaluation of aspiration cytology of pancreatic neoplasms and to develop a strategy to reach the correct diagnosis. We present an endoscopic ultrasound fine-needle aspiration diagnosis of metastatic HCC presenting as a pancreatic mass radiologically that had neuroendocrine features on various cytological and histological preparations. The metastatic lesions were located surgically in the peripancreatic adipose tissue with involvement of one peripancreatic lymph node. This case illustrates the utility of FNA for diagnosing uncommon presentations of HCC and the importance of clinical history, cell block, and an immunocytochemical panel in determining the origin of the tumor. Diagn. Cytopathol. 2009. © 2009 Wiley-Liss, Inc. [source] Metastatic hepatocellular carcinoma to the mandible masquerading as a parotid gland mass: A potential pitfall in the diagnosis by fine needle aspiration biopsyDIAGNOSTIC CYTOPATHOLOGY, Issue 10 2007Liying Han M.D., Ph.D. No abstract is available for this article. [source] Simultaneous medullary carcinoma of the thyroid gland and Hodgkin's lymphoma in bilateral lymph nodes of the neck: A potential pitfall in fine-needle aspiration cytologyDIAGNOSTIC CYTOPATHOLOGY, Issue 4 2004Jesús Acosta-Ortega M.D. Abstract The clinicopathological features and the cytological findings of Hodgkin's lymphoma (HL) and medullary carcinoma (MC) of the thyroid gland are described appearing simultaneously in different organs of the cervical region of the same patient. Although the cytological features of both entities are well known, the rare clinical presentation and the epithelium-like Hodgkin and Reed-Sternberg (HRS) cells of the syncytial variant of HL led to an erroneous cytological diagnosis of metastatic carcinoma of the upper aerodigestive tract. Diagn. Cytopathol. 2004;31:255,258. © 2004 Wiley-Liss, Inc. [source] Adenomyoepithelioma of the breast: A cytologic dilemma.DIAGNOSTIC CYTOPATHOLOGY, Issue 3 2002Report of a case, review of the literature Abstract Adenomyoepithelioma of the breast is a rare benign tumor made up of epithelial and myoepithelial cells. The cytologic features of this lesion are not well defined. This report describes the cytologic features of a case of adenomyoepthelioma characterized by hypercellularity and the presence of many atypical epithelial cells, leading to the erroneous diagnosis of adenocarcinoma. Review of the cytology literature shows that this condition frequently mimics the cytologic features of a number of benign and malignant breast lesions, thus representing not only an important potential pitfall in the diagnosis of carcinoma but also a differential diagnosis to consider in a variety of breast lesions. Diagn. Cytopathol. 2002;26:191,196; DOI 10.1002/dc.10073 © 2002 Wiley-Liss, Inc. [source] PNET-like features of synovial sarcoma of the lung: A pitfall in the cytologic diagnosis of soft-tissue tumorsDIAGNOSTIC CYTOPATHOLOGY, Issue 4 2001Pascale Hummel M.D. Abstract Fine-needle aspiration (FNA) cytology of soft-tissue tumors is evolving. As more experience is gained, we are becoming aware of potential pitfalls. We describe 2 cases of synovial sarcoma of the lung, primary and metastatic, in patients who had FNA biopsy performed on a lung mass. The cytologic smears showed extremely cellular groups of malignant small round cells, intersected by small blood vessels, with numerous loose single cells, in a background of macrophages and mature lymphocytes. The tumors displayed monomorphic cells forming rosettes and displaying occasional mitoses. A diagnosis of neuroendocrine tumor/primitive neuroepithelial tumor (PNET) was suspected. Furthermore, this suspicion was supported by immunohistochemical stains, which showed positivity for a neuroendocrine marker, Leu 7 (case 1), and for a neural marker, CD 99 (O 13 or HBA 71) (both cases); and negativity for cytokeratins (case 1). The resection specimen of case 1 had mostly tightly packed small round cells, with occasional rosettes, similar to the FNA biopsy, and focal areas composed of spindle cells, organized in a focal fibrosarcoma-like and hemangiopericytoma-like pattern. A balanced translocation between chromosomes X and 18, demonstrated by both karyotyping and fluorescent in situ hybridization (FISH), enabled us to make a diagnosis of synovial sarcoma, which was histologically classified as poorly differentiated. Case 2 was a metastatic biphasic synovial sarcoma of the arm, with a prominent epithelial component. Synovial sarcoma, when composed mainly of small round cells on cytologic smears, is a great mimicker of neuroendocrine/PNET tumors, with light microscopic and immunohistochemical overlap. Awareness of this potential pitfall may aid in preventing a misdiagnosis. Its recognition is of major concern, especially for the poorly differentiated variant, because it is associated with a worse prognosis. Diagn. Cytopathol. 24:283,288, 2001. © 2001 Wiley-Liss, Inc. [source] Extracutaneous transformation into a high-grade lymphoma: a potential pitfall in the management of patients with Sézary syndromeINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 3 2006Sonja Michaelis MD Background, Transformation into a high-grade lymphoma in cutaneous T-cell lymphoma (CTCL) occurs in approximately 25% of cases and is associated with an aggressive clinical course. Methods, We identified four cases of transformation of Sézary syndrome (SS) into pleomorphic T-cell lymphoma. Results, In all patients, transformation occurred first in the lymph nodes, an average of 43 months after the diagnosis of SS. These high-grade lymphomas were composed of CD30-positive (two patients) and CD30-negative (two patients) pleomorphic large cells. All patients died of lymphoma an average of 29 months after nodal transformation. Conclusion, Because of an apparently poorer prognosis, the early recognition of transformation, especially by lymph node biopsy, is important for adequate therapy. [source] On estimating basal metabolic rate from body mass: A potential pitfall in predicting post operative survival,AMERICAN JOURNAL OF HEMATOLOGY, Issue 10 2010Claus Bech No abstract is available for this article. [source] Clear cell sarcoma of the small bowel: a potential pitfall,APMIS, Issue 10 2005Case report Clear cell sarcoma (soft-part melanoma) is a very rare entity with a distinctive histopathologic and molecular profile. Herein, we present the sixth reported case of a primary gastrointestinal clear cell sarcoma discovered in a 21-year-old woman. The patient underwent numerous tests prior to the diagnosis of her small bowel pathology, including the use of capsule endoscopy, which allowed for visualization and final localization of the tumour. Additionally, we discuss this rare type of sarcoma that affects young adults and has a poor prognosis characterized by the balanced chromosomal translocation t(12;22)(q13;q12) with special emphasis on the necessity for pathologists to be able to distinguish it from melanoma , potentially a major pitfall in diagnosis. [source] The art and science of oral examinationDERMATOLOGIC THERAPY, Issue 3 2010Rania Agha ABSTRACT Performing an accurate oral examination is an integral part of a complete dermatological evaluation. As dermatologists, we are frequently asked to assess and treat numerous oral pathologies, which include, but are not limited to, normal variants, infections, ulcers, granulomas, lymphomas, as well as primary and metastatic tumors of the mouth and lips. The oral mucosa can be the window through which one can see and make numerous systemic diagnoses. Some clinicians are apprehensive about performing this evaluation, or feel that this examination is outside of their realm of expertise. These concerns may reflect limited exposure and education during training. Therefore, this article aimed to educate the readers on how to complete an oral examination, demonstrate normal variants, and highlight potential pitfalls and limitations of performing oral biopsies. [source] Dilemmas of Counter-Mapping Community Resources in TanzaniaDEVELOPMENT AND CHANGE, Issue 1 2002Dorothy L. Hodgson Recent work has celebrated the political potential of ,counter-mapping', that is, mapping against dominant power structures, to further seemingly progressive goals. This article briefly reviews the counter-mapping literature, and compares four counter-mapping projects from Maasai areas in Tanzania to explore some potential pitfalls in such efforts. The cases, which involve community-based initiatives led by a church-based NGO, ecotourism companies, the Tanzanian National Parks Authority, and grassroots pastoralist rights advocacy groups, illustrate the broad range of activities grouped under the heading of counter-mapping. They also present a series of political dilemmas that are typical of many counter-mapping efforts: conflicts inherent in conservation efforts involving territorialization, privatization, integration and indigenization; problems associated with the theory and practice of ,community-level' political engagement; the need to combine mapping efforts with broader legal and political strategies; and critical questions involving the agency of ,external' actors such as conservation and development donors, the state and private business interests. [source] Curiosity and cure: Translational research strategies for neural repair-mediated rehabilitationDEVELOPMENTAL NEUROBIOLOGY, Issue 9 2007Bruce H. Dobkin Abstract Clinicians who seek interventions for neural repair in patients with paralysis and other impairments may extrapolate the results of cell culture and rodent experiments into the framework of a preclinical study. These experiments, however, must be interpreted within the context of the model and the highly constrained hypothesis and manipulation being tested. Rodent models of repair for stroke and spinal cord injury offer examples of potential pitfalls in the interpretation of results from developmental gene activation, transgenic mice, endogeneous neurogenesis, cellular transplantation, axon regeneration and remyelination, dendritic proliferation, activity-dependent adaptations, skills learning, and behavioral testing. Preclinical experiments that inform the design of human trials ideally include a lesion of etiology, volume and location that reflects the human disease; examine changes induced by injury and by repair procedures both near and remote from the lesion; distinguish between reactive molecular and histologic changes versus changes critical to repair cascades; employ explicit training paradigms for the reacquisition of testable skills; correlate morphologic and physiologic measures of repair with behavioral measures of task reacquisition; reproduce key results in more than one laboratory, in different strains or species of rodent, and in a larger mammal; and generalize the results across several disease models, such as axonal regeneration in a stroke and spinal cord injury platform. Collaborations between basic and clinical scientists in the development of translational animal models of injury and repair can propel experiments for ethical bench-to-bedside therapies to augment the rehabilitation of disabled patients. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007 [source] PNET-like features of synovial sarcoma of the lung: A pitfall in the cytologic diagnosis of soft-tissue tumorsDIAGNOSTIC CYTOPATHOLOGY, Issue 4 2001Pascale Hummel M.D. Abstract Fine-needle aspiration (FNA) cytology of soft-tissue tumors is evolving. As more experience is gained, we are becoming aware of potential pitfalls. We describe 2 cases of synovial sarcoma of the lung, primary and metastatic, in patients who had FNA biopsy performed on a lung mass. The cytologic smears showed extremely cellular groups of malignant small round cells, intersected by small blood vessels, with numerous loose single cells, in a background of macrophages and mature lymphocytes. The tumors displayed monomorphic cells forming rosettes and displaying occasional mitoses. A diagnosis of neuroendocrine tumor/primitive neuroepithelial tumor (PNET) was suspected. Furthermore, this suspicion was supported by immunohistochemical stains, which showed positivity for a neuroendocrine marker, Leu 7 (case 1), and for a neural marker, CD 99 (O 13 or HBA 71) (both cases); and negativity for cytokeratins (case 1). The resection specimen of case 1 had mostly tightly packed small round cells, with occasional rosettes, similar to the FNA biopsy, and focal areas composed of spindle cells, organized in a focal fibrosarcoma-like and hemangiopericytoma-like pattern. A balanced translocation between chromosomes X and 18, demonstrated by both karyotyping and fluorescent in situ hybridization (FISH), enabled us to make a diagnosis of synovial sarcoma, which was histologically classified as poorly differentiated. Case 2 was a metastatic biphasic synovial sarcoma of the arm, with a prominent epithelial component. Synovial sarcoma, when composed mainly of small round cells on cytologic smears, is a great mimicker of neuroendocrine/PNET tumors, with light microscopic and immunohistochemical overlap. Awareness of this potential pitfall may aid in preventing a misdiagnosis. Its recognition is of major concern, especially for the poorly differentiated variant, because it is associated with a worse prognosis. Diagn. Cytopathol. 24:283,288, 2001. © 2001 Wiley-Liss, Inc. [source] Reconstructing ancestral ecologies: challenges and possible solutionsDIVERSITY AND DISTRIBUTIONS, Issue 1 2006Christopher R. Hardy ABSTRACT There are several ways to extract information about the evolutionary ecology of clades from their phylogenies. Of these, character state optimization and ,ancestor reconstruction' are perhaps the most widely used despite their being fraught with assumptions and potential pitfalls. Requirements for robust inferences of ancestral traits in general (i.e. those applicable to all types of characters) include accurate and robust phylogenetic hypotheses, complete species-level sampling and the appropriate choice of optimality criterion. Ecological characters, however, also require careful consideration of methods for accounting for intraspecific variability. Such methods include ,Presence Coding' and ,Polymorphism Coding' for discrete ecological characters, and ,Range Coding' and ,MaxMin Coding' for continuously variable characters. Ultimately, however, historical inferences such as these are, as with phylogenetic inference itself, associated with a degree of uncertainty. Statistically based uncertainty estimates are available within the context of model-based inference (e.g. maximum likelihood and Bayesian); however, these measures are only as reliable as the chosen model is appropriate. Although generally thought to preclude the possibility of measuring relative uncertainty or support for alternative possible reconstructions, certain useful non-statistical support measures (i.e. ,Sharkey support' and ,Parsimony support') are applicable to parsimony reconstructions. [source] 5 DIAGNOSTIC PITFALLS IN THE ECHOCARDIOGRAPHIC EVALUATION OF HYPERTROPHIC OBSTRUCTIVE CARDIOMYOPATHY (HOCM) REFERRED FOR CATHETER INTERVENTIONAL THERAPYECHOCARDIOGRAPHY, Issue 1 2004G. Beer Introduction: Generally, the diagnosis of typical HOCM with subaortic obstruction and a dynamic pressure gradient across the left ventricular outflow tract is made by noninvasive diagnostic procedures with great certainty by employing transthoracic (TTE) and/or transoesophageal (TEE) echocardiography. However, in patients with asymmetric septal hypertrophy pitfalls in echocardiographic examination may arise from several additional diseases as described in casuistic reports. To date systematic investigations in patients referred for catheter interventional therapy of HOCM are lacking. Patients and Methods: Therefore we investigated for the first time in a systematic study 200 symptomatic patients. (180 consecutive and 20 nonconsecutive patients; functional class 3 or 4 according to NYHA) with HOCM who were referred for this new catheter interventional therapy. In all patients TTE, bicycle exercise Doppler echocardiography and multiplane TEE were performed. Results: In 4 of 180 consecutive patients. (2.2%) discrete subvalvular membranous aortic stenosis (DSAS) (3 female patients and 1 male patient; age 20 to 58 years; mean septal diameter 19 mm; Sam-like motion in all 4 patients) was made. In all cases the diagnosis could be confirmed by surgical treatment. TEE evaluation was of crucial importance with demonstration of a typical subvalvular membrane that was situated a few millimeters below the aortic valve. In all cases a typical asymmetric septal hypertrophy mimicking HOCM was seen. Additionally, in 2 patients there was a conincidence of severe symptomatic valvular aortic stenosis and HOCM and in 1 patient a tunnel type of subvalvular aortic stenosis was present. Conclusion: These results show the potential pitfalls in echocardiographic diagnosis of HOCM. Especially, the frequency of DSAS in symptomatic patients referred for HOCM is unexpectedly high (2.2%). Especially in patients in whom TTE is of insufficient quality, investigation employing multiplane TEE with careful evaluation of the small poststenotic subvalvular area in HOCM is of crucial importance. This is of special significance prior to catheter interventional therapy, because in these patients surgical treatment is mandatory. [source] Uses and abuses of fractal methodology in ecologyECOLOGY LETTERS, Issue 3 2004J. M. Halley Abstract Fractals have found widespread application in a range of scientific fields, including ecology. This rapid growth has produced substantial new insights, but has also spawned confusion and a host of methodological problems. In this paper, we review the value of fractal methods, in particular for applications to spatial ecology, and outline potential pitfalls. Methods for measuring fractals in nature and generating fractal patterns for use in modelling are surveyed. We stress the limitations and the strengths of fractal models. Strictly speaking, no ecological pattern can be truly fractal, but fractal methods may nonetheless provide the most efficient tool available for describing and predicting ecological patterns at multiple scales. [source] Anatomy of an overfill: a reflection on the processENDODONTIC TOPICS, Issue 1 2007ALAN H. GLUSKIN The design and implementation of shaping, cleaning and sealing objectives in root canal therapy are fraught with real and potential pitfalls when the anatomic complexity of the space and technical considerations for its instrumentation, disinfection and obturation are contemplated. This review will focus on the genesis of results that lead to endodontic overfills. We will look at how the literature defines overfill and overextension; attempt to address the consensus opinion on the definition of working length; and determine the effects of shaping geometry on overfill as well as the biological impact of obturation materials that go beyond the root canal space. In addition, this manuscript will highlight evidence for the prevention of overfills as well as focus on the local factors that affect repair and healing. [source] The pros and cons of noninferiority trialsFUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 4 2003Stuart J. Pocock Abstract Noninferiority trials comparing new treatment with an active standard control are becoming increasingly common. This article discusses relevant issues regarding their need, design, analysis and interpretation: the appropriate choice of control group, types of noninferiority trial, ethical considerations, sample size determination and potential pitfalls to consider. [source] Think tanks with deliverables: How communities of practice helped LPL financial manage rapid growth and organizational complexityGLOBAL BUSINESS AND ORGANIZATIONAL EXCELLENCE, Issue 3 2010Jack Regan In the wake of acquisitions, new hiring, and a shift from a functional to a customer channel structure, the company pulled its best and brightest talent into practice centers (PCs) to share knowledge, transfer best practices, standardize policies and practices across the channels, drive key initiatives, and cement collaborative relationships. The authors present the business case for communities of practice; describe LPL's vision and process for implementing its PCs, including strategies for enhancing success and avoiding potential pitfalls; and highlight the PCs' accomplishments. They also share how the PCs facilitated the company's response to the 2008,2009 financial crisis. © 2010 Wiley Periodicals, Inc. [source] Amyloidosis: a rheumatological perspective on diagnosis, further investigation and treatmentINTERNATIONAL JOURNAL OF RHEUMATIC DISEASES, Issue 1 2008S. K. L. LAM Abstract In this Grand Round, we present a 58-year-old man with a presumptive diagnosis of rheumatoid arthritis (RA) who was being managed by a plastic surgery unit for a dorsal swelling of his right hand. While awaiting surgery for this lesion, he sustained a pathological fracture of his left neck of femur. This necessitated a total hip joint replacement and pathology revealed amyloidosis. Excision of the hand swelling also revealed amyloidosis as the cause. We discuss the ways in which amyloidosis can mimic musculoskeletal disease as well as the importance and some potential pitfalls of further investigation and management once the diagnosis of amyloidosis has been made. [source] Fishes as models in studies of sexual selection and parental careJOURNAL OF FISH BIOLOGY, Issue 2003T. Amundsen Fishes are by far the most diverse group of vertebrates. This fact is in no way, however, reflected in their use as model organisms for understanding sexual selection or parental care. Why is this so? Is it because fishes are actually poor models? The usefulness of fishes as models for sexual selection and parental care is discussed by emphasizing some problems inherent in fish studies, along with a number of reasons why fishes are indeed excellently suited. The pros and cons of fishes as models are discussed mainly by comparison with birds, the most popular model organisms in animal behaviour. Difficulties include a lack of background knowledge for many species, and the problems of marking and observing fishes in their natural environment. Positive attributes include the diversity of lifestyles among fishes, and the ease with which they can be studied experimentally in the laboratory. How useful fish models can be is briefly illustrated by the impressive and broadly relevant advances derived from studies of guppies Poecilia reticulata and three-spined sticklebacks Gasterosteus aculeatus. A selection of topics is highlighted where fish studies have either advanced or could greatly enhance, the understanding of processes fundamental to animal reproductive dynamics. Such topics include sex role dynamics, the evolution of female ornamentation and mate choice copying. Finally, a number of potential pitfalls in the future use of fish as models for sexual selection and parental care are discussed. Researchers interested in these issues are recommended to make much more extensive use of fish models, but also to adopt a wider range of models among fishes. [source] Can forecasting performance be improved by considering the steady state?JOURNAL OF FORECASTING, Issue 1 2008An application to Swedish inflation, interest rate Abstract This paper investigates whether the forecasting performance of Bayesian autoregressive and vector autoregressive models can be improved by incorporating prior beliefs on the steady state of the time series in the system. Traditional methodology is compared to the new framework,in which a mean-adjusted form of the models is employed,by estimating the models on Swedish inflation and interest rate data from 1980 to 2004. Results show that the out-of-sample forecasting ability of the models is practically unchanged for inflation but significantly improved for the interest rate when informative prior distributions on the steady state are provided. The findings in this paper imply that this new methodology could be useful since it allows us to sharpen our forecasts in the presence of potential pitfalls such as near unit root processes and structural breaks, in particular when relying on small samples.,,Copyright © 2008 John Wiley & Sons, Ltd. [source] Short and long-run returns to agricultural R&D in South Africa, or will the real rate of return please stand up?AGRICULTURAL ECONOMICS, Issue 1 2000David Schimmelpfennig Abstract This paper briefly presents the results of a total factor productivity (TFP) study of South African commercial agriculture, for 1947-1997, and illustrates some potential pitfalls in rate of return to research (ROR) calculations. The lag between R&D and TFP is analyzed and found to be only 9 years, with a pronounced negative skew, reflecting the adaptive focus of the South African system. The two-stage approach gives a massive ROR of 170%. The predetermined lag parameters are then used in modeling the knowledge stock, to refine the estimates of the ROR from short- and long-run dual profit functions. In the short run, with the capital inputs treated as fixed, the ROR is a more reasonable 44%. In the long run, with adjustment of the capital stocks, it rises to 113%, which would reflect the fact that new technology is embodied in the capital items. However, the long-run model raises a new problem since capital stock adjustment takes 11 years, 2 years longer than the lag between R&D and TFP. If this is assumed to be the correct lag, the ROR falls to 58%, a best estimate. The paper draws attention to the possible sensitivity of rate of return calculations to assumed lag structure, particularly when the lag between changes in R&D and TFP is skewed. [source] Ultrafast imaging: Principles, pitfalls, solutions, and applicationsJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 2 2010Jeffrey Tsao PhD Abstract Ultrafast MRI refers to efficient scan techniques that use a high percentage of the scan time for data acquisition. Often, they are used to achieve short scan duration ranging from sub-second to several seconds. Alternatively, they may form basic components of longer scans that may be more robust or have higher image quality. Several important applications use ultrafast imaging, including real-time dynamic imaging, myocardial perfusion imaging, high-resolution coronary imaging, functional neuroimaging, diffusion imaging, and whole-body scanning. Over the years, echo-planar imaging (EPI) and spiral imaging have been the main ultrafast techniques, and they will be the focus of the review. In practice, there are important challenges with these techniques, as it is easy to push imaging speed too far, resulting in images of a nondiagnostic quality. Thus, it is important to understand and balance the trade-off between speed and image quality. The purpose of this review is to describe how ultrafast imaging works, the potential pitfalls, current solutions to overcome the challenges, and the key applications. J. Magn. Reson. Imaging 2010;32:252,266. © 2010 Wiley-Liss, Inc. [source] | ||||||||||||||||||||||||||||||||||||||||