bluuebunny/crossref_metadata_2025 huggingface dataset:
Bioartificial Sinus Node Constructed via In Vivo Gene Transfer of an Engineered Pacemaker HCN Channel Reduces the Dependence on Electronic Pacemaker in a Sick-Sinus Syndrome Model
Authors: Tse Hung-Fat , Xue Tian , Lau Chu-Pak , Siu Chung-Wah , Wang Kai , Zhang Qing-Yong , Tomaselli Gordon F. , Akar Fadi G. , Li Ronald A.
Published: August 2006

Background—

The normal cardiac rhythm originates in the sinoatrial (SA) node that anatomically resides in the right atrium. Malfunction of the SA node leads to various forms of arrhythmias that necessitate the implantation of electronic pacemakers. We hypothesized that overexpression of an engineered HCN construct via somatic gene transfer offers a flexible approach for fine-tuning cardiac pacing in vivo.

Methods and Results—

Using various electrophysiological and mapping techniques, we examined the effects of in situ focal expression of HCN1-ΔΔΔ, the S3-S4 linker of which has been shortened to favor channel opening, on impulse generation and conduction. Single left ventricular cardiomyocytes isolated from guinea pig hearts preinjected with the recombinant adenovirus Ad-CMV-GFP-IRES-HCN1-ΔΔΔ in vivo uniquely exhibited automaticity with a normal firing rate (237±12 bpm). High-resolution ex vivo optical mapping of Ad-CGI-HCN1-ΔΔΔ–injected Langendorff-perfused hearts revealed the generation of spontaneous action potentials from the transduced region in the left ventricle. To evaluate the efficacy of our approach for reliable atrial pacing, we generated a porcine model of sick-sinus syndrome by guided radiofrequency ablation of the native SA node, followed by implantation of a dual-chamber electronic pacemaker to prevent bradycardia-induced hemodynamic collapse. Interestingly, focal transduction of Ad-CGI-HCN1-ΔΔΔ in the left atrium of animals with sick-sinus syndrome reproducibly induced a stable, catecholamine-responsive in vivo “bioartificial node” that exhibited a physiological heart rate and was capable of reliably pacing the myocardium, substantially reducing electronic pacing.

Conclusions—

The results of the present study provide important functional and mechanistic insights into cardiac automaticity and have further refined an HCN gene–based therapy for correcting defects in cardiac impulse generation.
Different Effects of Angiotensin Receptor Blockade on End-Organ Damage in Salt-Dependent and Salt-Independent Hypertension
Authors: Maitland Karlene , Bridges LaKeesha , Davis Wendell P. , Loscalzo Joseph , Pointer Mildred A.
Published: August 2006

Background—

Although angiotensin II type 1 receptor blockers have emerged as effective antihypertensive agents, it is not known how efficacious these agents are in treating hypertension-associated target organ damage.

Methods and Results—

The present study was undertaken to compare the effect of angiotensin type 1 receptor inhibition on the progression of the organ damage observed in 2 models of hypertension, namely, salt-sensitive and nitric oxide synthase inhibition–mediated hypertension. Effective (16.4 μmol/kg) and ineffective (0.8 to 4.9 μmol/kg) antihypertensive doses of candesartan cilexetil were initiated after hypertension was established. Both low- and high-dose candesartan cilexetil significantly reduced cardiac and renal damage in the nitric oxide synthase inhibitor model of hypertension (
P
<0.05 versus untreated); however, high-dose candesartan caused a significant increase in renal damage in the Dahl salt-sensitive model of hypertension (
P
<0.05 versus untreated). Interestingly, the beneficial end-organ effects of candesartan in the nitric oxide synthase inhibition model were independent of sustained antihypertensive actions of candesartan, whereas the exacerbation of renal injury with candesartan in the Dahl salt-sensitive model was inversely related to its blood pressure–lowering effect.

Conclusions—

These data show that angiotensin type 1 blockade reduces injury in the
l
-nitroarginine methyl ester model but increases tissue injury in the salt-sensitive model. These data suggest that angiotensin II via angiotensin type 1 receptor activation contributes to organ damage in nitric oxide–deficient salt-independent hypertension but is protective in salt-induced hypertension. These data further suggest that (1) renal injury may evolve independently of blood pressure and (2) the effectiveness of an antihypertensive agent in ameliorating renal injury may depend on the etiology of the hypertension.
An Adjoint Analysis of the Meridional Overturning Circulation in an Ocean Model
Authors: Bugnion Véronique , Hill Chris , Stone Peter H.
Published: August 2006

Using the adjoint of a fully three-dimensional primitive equation ocean model in an idealized geometry, spatial variations in the sensitivity to surface boundary forcing of the meridional overturning circulation’s strength are studied. Steady-state sensitivities to diapycnal mixing, wind stress, freshwater, and heat forcing are examined. Three different, commonly used, boundary-forcing scenarios are studied, both with and without wind forcing. Almost identical circulation is achieved in each scenario, but the sensitivity patterns show major (quantitative and qualitative) differences. Sensitivities to surface forcing and diapycnal mixing are substantially larger under mixed boundary conditions, in which fluxes of freshwater and heat are supplemented by a temperature relaxation term or under flux boundary conditions, in which climatological fluxes alone drive the circulation, than under restoring boundary conditions. The sensitivity pattern to diapycnal mixing, which peaks in the Tropics is similar both with and without wind forcing. Wind does, however, increase the sensitivity to diapycnal mixing in the regions of Ekman upwelling and decreases it in the regions of Ekman downwelling. Wind stress in the Southern Oceans plays a crucial role in restoring boundary conditions, but the effect is largely absent under mixed or flux boundary conditions. The results highlight how critical a careful formulation of the surface forcing terms is to ensuring a proper response to changes in forcing in ocean models.
A Decade of Ground–Air Temperature Tracking at Emigrant Pass Observatory, Utah
Authors: Bartlett Marshall G. , Chapman David S. , Harris Robert N.
Published: August 2006

Observations of air and ground temperatures collected between 1993 and 2004 from Emigrant Pass Geothermal Climate Observatory in northwestern Utah are analyzed to understand the relationship between these two quantities. The influence of surface air temperature (SAT), incident solar radiation, and snow cover on surface ground temperature (SGT) variations are explored. SAT variations explain 94% of the variance in SGT. Incident solar radiation is the primary variable governing the remaining variance misfit and is significantly more important during summer months than winter months. A linear relationship between the ground–air temperature difference (ΔTsgt-sat) and solar radiation exists with a trend of 1.21 K/(100 W m−2); solar radiation accounts for 1.3% of the variance in SGT. The effects of incident solar radiation also account for the 2.47-K average offset in ΔTsgt-sat. During the winter, snow cover plays a role in governing SGT variability, but exerts only a minor influence on the annual tracking of ground and air temperatures at the site, accounting for 0.5% of the variance in SGT. These observations of the tracking of SGT and SAT confirm that borehole temperature changes mimic changes in SAT at frequencies appropriate for climatic reconstructions.
The European Summer of 2003: Sensitivity to Soil Water Initial Conditions
Authors: Ferranti Laura , Viterbo Pedro
Published: August 2006

The European summer of 2003 is used as a case study to analyze the land surface role in augmenting the local temperature anomalies. Using the European Centre for Medium-Range Weather Forecasts (ECMWF) analysis and the 40-yr ECMWF Re-Analysis (ERA-40) climate, it is shown that in the months preceding the extreme summer events, positive anomalies in the surface shortwave radiation and a large precipitation deficit indicated an impending dry summer in early June. The use of soil water analysis values as possible predictors for drought is currently limited by the systematic attenuation of its seasonal cycle. Several numerical simulations with the ECMWF atmospheric model have been used to explore the atmospheric model sensitivity to the initial soil water conditions. The atmospheric response to large initial perturbations in the root zone extends up to month 2 and is nonlinear, and larger for drier regimes. Perturbations to the whole soil depth increase the amplitude of the atmospheric anomaly and extend its duration up to 3 months. The response of large initial dry soil anomalies greatly exceeds the impact of the ocean boundary forcing. Results from numerical simulations indicate the possible benefit of using perturbations in the initial soil water conditions, commensurate with soil moisture uncertainties, in the generation of the seasonal forecast ensembles.
The NCEP Climate Forecast System
Authors: Saha S. , Nadiga S. , Thiaw C. , Wang J. , Wang W. , Zhang Q. , Van den Dool H. M. , Pan H.-L. , Moorthi S. , Behringer D. , Stokes D. , Peña M. , Lord S. , White G. , Ebisuzaki W. , Peng P. , Xie P.
Published: August 2006

The Climate Forecast System (CFS), the fully coupled ocean–land–atmosphere dynamical seasonal prediction system, which became operational at NCEP in August 2004, is described and evaluated in this paper. The CFS provides important advances in operational seasonal prediction on a number of fronts. For the first time in the history of U.S. operational seasonal prediction, a dynamical modeling system has demonstrated a level of skill in forecasting U.S. surface temperature and precipitation that is comparable to the skill of the statistical methods used by the NCEP Climate Prediction Center (CPC). This represents a significant improvement over the previous dynamical modeling system used at NCEP. Furthermore, the skill provided by the CFS spatially and temporally complements the skill provided by the statistical tools. The availability of a dynamical modeling tool with demonstrated skill should result in overall improvement in the operational seasonal forecasts produced by CPC.

The atmospheric component of the CFS is a lower-resolution version of the Global Forecast System (GFS) that was the operational global weather prediction model at NCEP during 2003. The ocean component is the GFDL Modular Ocean Model version 3 (MOM3). There are several important improvements inherent in the new CFS relative to the previous dynamical forecast system. These include (i) the atmosphere–ocean coupling spans almost all of the globe (as opposed to the tropical Pacific only); (ii) the CFS is a fully coupled modeling system with no flux correction (as opposed to the previous uncoupled “tier-2” system, which employed multiple bias and flux corrections); and (iii) a set of fully coupled retrospective forecasts covering a 24-yr period (1981–2004), with 15 forecasts per calendar month out to nine months into the future, have been produced with the CFS.

These 24 years of fully coupled retrospective forecasts are of paramount importance to the proper calibration (bias correction) of subsequent operational seasonal forecasts. They provide a meaningful a priori estimate of model skill that is critical in determining the utility of the real-time dynamical forecast in the operational framework. The retrospective dataset also provides a wealth of information for researchers to study interactive atmosphere–land–ocean processes.
Attribution of Atmospheric Variations in the 1997–2003 Period to SST Anomalies in the Pacific and Indian Ocean Basins
Authors: Lau Ngar-Cheung , Leetmaa Ants , Nath Mary Jo
Published: August 2006

The individual impacts of sea surface temperature (SST) anomalies in the deep tropical eastern–central Pacific (DTEP) and Indo-western–central Pacific (IWP) on the evolution of the observed global atmospheric circulation during the 1997–2003 period have been investigated using a new general circulation model. Ensemble integrations were conducted with monthly varying SST conditions being prescribed separately in the DTEP sector, the IWP sector, and throughout the World Ocean. During the 1998–2002 subperiod, when prolonged La Niña conditions occurred in DTEP and the SST in IWP was above normal, the simulated midlatitude atmospheric responses to SST forcing in the DTEP and IWP sectors reinforced each other. The anomalous geopotential height ridges at 200 mb in the extratropics of both hemispheres exhibited a distinct zonal symmetry. This circulation change was accompanied by extensive dry and warm anomalies in many regions, including North America. During the 1997–98 and 2002–03 El Niño events, the SST conditions in both DTEP and IWP were above normal, and considerable cancellations were simulated between the midlatitude responses to the oceanic forcing from these two sectors. The above findings are contrasted with those for the 1953–58 and 1972–77 periods, which were characterized by analogous SST developments in DTEP, but by cold conditions in IWP. It is concluded that a warm anomaly in IWP and a cold anomaly in DTEP constitute the optimal SST configuration for generating zonally elongated ridges in the midlatitudes.

Local diagnoses indicate that the imposed SST anomaly alters the strength of the zonal flow in certain longitudinal sectors, which influences the behavior of synoptic-scale transient eddies farther downstream. The modified eddy momentum transports in the regions of eddy activity in turn feed back on the local mean flow, thus contributing to its zonal elongation. These results are consistent with the inferences drawn from zonal mean analyses, which accentuate the role of the eddy-induced circulation on the meridional plane.
Coupled Model Simulations of the West African Monsoon System: Twentieth- and Twenty-First-Century Simulations
Authors: Cook Kerry H. , Vizy Edward K.
Published: August 2006

The ability of coupled GCMs to correctly simulate the climatology and a prominent mode of variability of the West African monsoon is evaluated, and the results are used to make informed decisions about which models may be producing more reliable projections of future climate in this region. The integrations were made available by the Program for Climate Model Diagnosis and Intercomparison for the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. The evaluation emphasizes the circulation characteristics that support the precipitation climatology, and the physical processes of a “rainfall dipole” variability mode that is often associated with dry conditions in the Sahel when SSTs in the Gulf of Guinea are anomalously warm.

Based on the quality of their twentieth-century simulations over West Africa in summer, three GCMs are chosen for analysis of the twenty-first century integrations under various assumptions about future greenhouse gas increases. Each of these models behaves differently in the twenty-first-century simulations. One model simulates severe drying across the Sahel in the later part of the twenty-first century, while another projects quite wet conditions throughout the twenty-first century. In the third model, warming in the Gulf of Guinea leads to more modest drying in the Sahel due to a doubling of the number of anomalously dry years by the end of the century. An evaluation of the physical processes that cause these climate changes, in the context of the understanding about how the system works in the twentieth century, suggests that the third model provides the most reasonable projection of the twenty-first-century climate.
Storm Tracks and Climate Change
Authors: Bengtsson Lennart , Hodges Kevin I. , Roeckner Erich
Published: August 2006

Extratropical and tropical transient storm tracks are investigated from the perspective of feature tracking in the ECHAM5 coupled climate model for the current and a future climate scenario. The atmosphere-only part of the model, forced by observed boundary conditions, produces results that agree well with analyses from the 40-yr ECMWF Re-Analysis (ERA-40), including the distribution of storms as a function of maximum intensity. This provides the authors with confidence in the use of the model for the climate change experiments. The statistical distribution of storm intensities is virtually preserved under climate change using the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) A1B scenario until the end of this century. There are no indications in this study of more intense storms in the future climate, either in the Tropics or extratropics, but rather a minor reduction in the number of weaker storms. However, significant changes occur on a regional basis in the location and intensity of storm tracks. There is a clear poleward shift in the Southern Hemisphere with consequences of reduced precipitation for several areas, including southern Australia. Changes in the Northern Hemisphere are less distinct, but there are also indications of a poleward shift, a weakening of the Mediterranean storm track, and a strengthening of the storm track north of the British Isles. The tropical storm tracks undergo considerable changes including a weakening in the Atlantic sector and a strengthening and equatorward shift in the eastern Pacific. It is suggested that some of the changes, in particular the tropical ones, are due to an SST warming maximum in the eastern Pacific. The shift in the extratropical storm tracks is shown to be associated with changes in the zonal SST gradient in particular for the Southern Hemisphere.
Recent Climatology, Variability, and Trends in Global Surface Humidity
Authors: Dai Aiguo
Published: August 2006

In situ observations of surface air and dewpoint temperatures and air pressure from over 15 000 weather stations and from ships are used to calculate surface specific (q) and relative (RH) humidity over the globe (60°S–75°N) from December 1975 to spring 2005. Seasonal and interannual variations and linear trends are analyzed in relation to observed surface temperature (T) changes and simulated changes by a coupled climate model [namely the Parallel Climate Model (PCM)] with realistic forcing. It is found that spatial patterns of long-term mean q are largely controlled by climatological surface temperature, with the largest q of 17–19 g kg−1 in the Tropics and large seasonal variations over northern mid- and high-latitude land. Surface RH has relatively small spatial and interannual variations, with a mean value of 75%–80% over most oceans in all seasons and 70%–80% over most land areas except for deserts and high terrain, where RH is 30%–60%. Nighttime mean RH is 2%–15% higher than daytime RH over most land areas because of large diurnal temperature variations. The leading EOFs in both q and RH depict long-term trends, while the second EOF of q is related to the El Niño–Southern Oscillation (ENSO). During 1976–2004, global changes in surface RH are small (within 0.6% for absolute values), although decreasing trends of −0.11% ∼ −0.22% decade−1 for global oceans are statistically significant. Large RH increases (0.5%–2.0% decade−1) occurred over the central and eastern United States, India, and western China, resulting from large q increases coupled with moderate warming and increases in low clouds over these regions during 1976–2004. Statistically very significant increasing trends are found in global and Northern Hemispheric q and T. From 1976 to 2004, annual q (T) increased by 0.06 g kg−1 (0.16°C) decade−1 globally and 0.08 g kg−1 (0.20°C) decade−1 in the Northern Hemisphere, while the Southern Hemispheric q trend is positive but statistically insignificant. Over land, the q and T trends are larger at night than during the day. The largest percentage increases in surface q (∼1.5% to 6.0% decade−1) occurred over Eurasia where large warming (∼0.2° to 0.7°C decade−1) was observed. The q and T trends are found in all seasons over much of Eurasia (largest in boreal winter) and the Atlantic Ocean. Significant correlation between annual q and T is found over most oceans (r = 0.6–0.9) and most of Eurasia (r = 0.4–0.8), whereas it is insignificant over subtropical land areas. RH–T correlation is weak over most of the globe but is negative over many arid areas. The q–T anomaly relationship is approximately linear so that surface q over the globe, global land, and ocean increases by ∼4.9%, 4.3%, and 5.7% per 1°C warming, respectively, values that are close to those suggested by the Clausius–Clapeyron equation with a constant RH. The recent q and T trends and the q–T relationship are broadly captured by the PCM; however, the model overestimates volcanic cooling and the trends in the Southern Hemisphere.
How Well Do We Understand and Evaluate Climate Change Feedback Processes?
Authors: Bony Sandrine , Colman Robert , Kattsov Vladimir M. , Allan Richard P. , Bretherton Christopher S. , Dufresne Jean-Louis , Hall Alex , Hallegatte Stephane , Holland Marika M. , Ingram William , Randall David A. , Soden Brian J. , Tselioudis George , Webb Mark J.
Published: August 2006

Processes in the climate system that can either amplify or dampen the climate response to an external perturbation are referred to as climate feedbacks. Climate sensitivity estimates depend critically on radiative feedbacks associated with water vapor, lapse rate, clouds, snow, and sea ice, and global estimates of these feedbacks differ among general circulation models. By reviewing recent observational, numerical, and theoretical studies, this paper shows that there has been progress since the Third Assessment Report of the Intergovernmental Panel on Climate Change in (i) the understanding of the physical mechanisms involved in these feedbacks, (ii) the interpretation of intermodel differences in global estimates of these feedbacks, and (iii) the development of methodologies of evaluation of these feedbacks (or of some components) using observations. This suggests that continuing developments in climate feedback research will progressively help make it possible to constrain the GCMs’ range of climate feedbacks and climate sensitivity through an ensemble of diagnostics based on physical understanding and observations.
An Adjoint Analysis of the Meridional Overturning Circulation in a Hybrid Coupled Model
Authors: Bugnion Véronique , Hill Chris , Stone Peter H.
Published: August 2006

Multicentury sensitivities in a realistic geometry global ocean general circulation model are analyzed using an adjoint technique. This paper takes advantage of the adjoint model’s ability to generate maps of the sensitivity of a diagnostic (i.e., the meridional overturning’s strength) to all model parameters. This property of adjoints is used to review several theories, which have been elaborated to explain the strength of the North Atlantic’s meridional overturning. This paper demonstrates the profound impact of boundary conditions in permitting or suppressing mechanisms within a realistic model of the contemporary ocean circulation. For example, the so-called Drake Passage Effect in which wind stress in the Southern Ocean acts as the main driver of the overturning’s strength, is shown to be an artifact of boundary conditions that restore the ocean’s surface temperature and salinity toward prescribed climatologies. Advective transports from the Indian and Pacific basins play an important role in setting the strength of the overturning circulation under “mixed” boundary conditions, in which a flux of freshwater is specified at the ocean’s surface.

The most “realistic” regime couples an atmospheric energy and moisture balance model to the ocean. In this configuration, inspection of the global maps of sensitivity to wind stress and diapycnal mixing suggests a significant role for near-surface Ekman processes in the Tropics. Buoyancy also plays an important role in setting the overturning’s strength, through direct thermal forcing near the sites of convection, or through the advection of salinity anomalies in the Atlantic basin.
The Role of Context in Learning to Teach Writing
Authors: Pardo Laura S.
Published: August 2006

The yearlong qualitative study this article describes explores how three beginning elementary teachers in urban schools struggled with policy, students, and their own commitment of learning to teach writing to their students. Findings indicate that beginning teachers learned to teach writing by drawing on a variety of knowledge sources, that beginning teachers' writing instruction was heavily influenced by various aspects of their individual teaching contexts, and that because these various aspects of teaching context often conflicted with each other, creating tensions for the beginning teacher, learning to teach writing was strongly shaped by how each teacher learned to manage the various conflicting aspects of her individual teaching context. Implications for teacher education emerged and include focusing on writing pedagogy, examining teaching contexts and decision making within various settings, and using case studies to examine how experienced teachers work successfully within a variety of teaching contexts.
Investigating Early Career Urban Teachers' Perspectives on and Experiences in Professional Development
Authors: Anderson Lauren , Olsen Brad
Published: August 2006

Despite their interconnectedness, teacher education, teacher development, and teacher retention are often treated as discrete domains of inquiry. This article and the research on which it reports resist such compartmentalization and instead focus on relationships between teachers' pasts, presents, and futures. In particular, this qualitative study of 15 specialized teacher education program graduates examines urban teachers' perspectives on and experiences in professional development. Specific attention is paid to the role of professional development—in conjunction with other forces, including preservice preparation and workplace conditions—in shaping teachers' attitudes about their work and their professional futures. Findings illuminate four kinds of complexity underlying teachers' early career needs that are discussed and used to generate suggestions for how universities might better support teacher education program graduates to build rewarding and effective long-term careers in education.
How Well Do 1st-Year Teachers Teach
Authors: Good Thomas L. , McCaslin Mary , Tsang Henry Y. , Zhang Jizhi , Wiley Caroline R. H. , Bozack Amanda Rabidue , Hester Waverely
Published: August 2006

The authors present a program of research on the teaching practices of 1st-year teachers that has evolved within a partnership between and among a university and area school districts. The research links observed 1st-year teaching practices with school level (elementary, middle, high school) and type of teacher preparation (traditional bachelor's degree or nontraditional master's degree or postbaccalaureate certification). This study was conducted during 3 consecutive years, and results suggest that 1st-year teachers, as a group, performed adequately. School-level analyses reveal higher quality classroom management practices at the elementary level. Type of preparation analyses reveal higher quality management practices among teachers who attended traditional programs. The potential interaction between school level and type of preparation was not definitive but suggests further research is needed on the match between type of preparation and school level as expressed in quality of teaching practices.
Educating Managers for Post-bureaucracy
Authors: Hendry John
Published: August 2006

The dominant conception of the manager is of a morally neutral technician engaged in a world of purely rational problem solving. This is the conception advanced by business schools, by management consultants and, in large measure, by managers themselves. It is also that of the critical sociology of management, in which managers are cast as morally disabled technical problem solvers not because they choose to be so but because, in the bureaucratic business corporation, they have no choice. In both its mainstream and its critical forms, this conception of management is closely tied to the rationalizing characteristics of bureaucratic organization, but what of management in post-bureaucracy? This article explores the role of the business manager in the flexible network organizations that are characteristic of early 21st-century business, and their implications for management education.
Breaking from the Weight of the Eternal Present
Authors: Fournier Valérie
Published: August 2006

This article reflects on an attempt to encourage students to imagine alternative forms of organizing, and on the ultimate failure of this pedagogical experiment. It explores students’ reluctance to take organizational difference seriously in terms symptomatic of a broader inertia in social sciences that severs ‘difference’ from the realm of possibility, reducing difference to degrees of capitalist practices and the future to an extension of the present. Drawing on the work of Gibson-Graham, it argues that making alternative organizing conceivable requires challenging the capitalocentric reading of the economy, and developing a vocabulary of economic differences. It suggests that to address the common charge that alternatives will not be able to withstand the ‘tide of history’, we also need to work on conceptions of time and history that open the future to the possibility of difference. It draws on Foucault’s genealogy to ‘break history’ and insert points of rupture at which ‘new beginnings’ can be imagined.
Reconciling Hierarchy and Democracy
Authors: Clarke Martin , Butcher David
Published: August 2006

Pluralistic organizations are often argued to have become an indisputable reality for senior managers. In consequence, the role of hierarchy has come under close scrutiny. How can organizations balance the need for congruence, provided through hierarchy, with the need for greater organizational democracy? As yet, the potential for management education and learning to impact on this debate, at either an organizational or a societal level, has been largely unfulfilled. This article argues that the aspirational values of liberal adult educationalists have a significant contribution to make to the management of contemporary organizations. It positions these values alongside the business requisites that shape organizations and examine the motivations of senior managers to apply these ideas in practice. The concept of voluntarism, derived from the field of political philosophy, is proposed as an alternative organizational binding mechanism that alters the rationale for the role of hierarchy. The implications for senior executives and management educational-ists are considered.
Applying a Synergistic Learning Approach in Entrepreneurship Education
Authors: Collins Lorna A. , Smith Alison J. , Hannon Paul. D.
Published: August 2006

This article develops our understanding of how entrepreneurship may be enhanced in existing entrepreneurs and developed in nascent entrepreneurs. It describes the authors’ exploration in the design, development and evaluation of a new programme to create opportunities for learning entrepreneurship capacities. A tripartite approach was taken, bringing together nascent entrepreneurs (undergraduate students), existing entrepreneurs and entrepreneurship facilitators. The programme was delivered using a synergistic learning approach and participatory methods in which all participants were co-learners in a collaborative, peer-learning environment. This article describes the action research approach to the exploration of entrepreneurship education androgogy and contributes to the growing body of literature in entrepreneurship education. It provides insights into how entrepreneurship education can be delivered in innovative and effective ways that mirror the ‘real world’ experience of existing and nascent entrepreneurs. It also provides insights into the nature and use of a synergistic learning approach within an entrepreneurship education context.
Developing Absorptive Capacity in Mature Organizations
Authors: Jones Oswald
Published: August 2006

A considerable amount of research into how organizations absorb new knowledge was prompted by the work of Cohen and Levinthal. In a recent literature review Zahra and George identify two distinct elements of absorptive capacity (potential and realized). This article contributes to the study of managerial agency in the absorption of new knowledge and skills. Zahra and George’s model is extended to incorporate key roles associated with knowledge transfer, including gatekeepers, boundary spanners and change agents. Empirical data are drawn from a longitudinal study of a mature manufacturing firm based in North Wales. Change was initiated by the owner in response to the loss of the company’s major customer—the Ministry of Defence. The main change agent was a recently recruited middle manager who used his mass production experience to improve managerial communications and introduce more efficient working practices to the shopfloor.
The Price of Departmental Harmony
Authors: Shoho Alan
Published: August 2006

The purpose of this case is to reflect and share the experiences of one educational leadership department as it underwent a transformation from being a department of individuals to a department of colleagues. The case illustrates that change is slow and difficult. It also demonstrates the importance of faculty fit to a department. Without it, departments of educational leadership are unlikely to model best practices of leadership to their students and community.
A Diamond in the Rough
Authors: Brown Kathleen M. , Schainker Stanley A.
Published: August 2006

A diamond is a chunk of coal that stood up under pressure. Carat’s Organizational and Administrative Leadership (COAL) program is a diamond in the rough—experiencing strong political pressure from multiple sides. As the state’s premiere educational leadership preparation program, expectations are high. While striving to live up to its national ranking and flagship university status, COAL is feeling the heat—to improve and to be unique, cutting-edge, and innovative. This case raises questions regarding strong, persistent leadership; faculty resistance; and the nature of the change process. Force field analysis, a classic approach in change theory, is suggested as one effective decision-making model.
When Bad Departments Happen to Good People
Authors: Dayton John , Shoho Alan
Published: August 2006

This case study examines the lives of some very different educational leadership professors with a common problem: They are miserable in their work. But how could this be? They have secure jobs at a great university, considerable autonomy in their work schedules, an opportunity to study a subject they love, and a chance to work with great students. What is the problem? The problem is that they now find themselves among the ranks of the damned in the Leadership Department From Hell, or at least their local chapter of this ever-growing franchise. This hypothetical case study presents several archetypal characters known to inhabit the most troubled leadership departments in order to examine what can go wrong in a leadership department. This study also presents guiding discussion questions to explore what might be done to make it better—for everyone.
Can This Department Be Saved? The Educational Leadership Department at Bayou State University
Authors: Fossey Richard
Published: August 2006

This case describes the work of two educational leadership professors who have been asked to serve as outsider reviewers of an educational leadership department at a large urban university. The department has a number of problems, and the university’s provost seems intent on closing it. The provost’s view of the department has been shaped in part by Arthur Levine’s Educating School Leaders, which characterized educational leadership programs as having weak faculty, curricular disarray, and low admission requirements. Over the course of several days, the two professors interview the department’s faculty members and review documentary evidence. At the conclusion of their investigation, they disagree about what they should recommend to the provost. One reviewer believes the department should be closed, and the other believes that the department should be saved and its programs strengthened.
Inferring direct regulatory targets from expression and genome location analyses: a comparison of transcription factor deletion and overexpression
Authors: Tang Lin , Liu Xiao , Clarke Neil D
Published: August 2006

Background

Effects on gene expression due to environmental or genetic changes can be easily measured using microarrays. However, indirect effects on expression can be substantial. The indirect effects of a perturbation need to be distinguished from the direct effects if we are to understand the structure and behavior of regulatory networks.

Results

The most direct way to perturb a transcriptional network is to alter transcription factor activity. Here, for the first time, we compare expression changes and genomic binding in a simple regulon under conditions of both low and high transcription factor activity. Specifically, we assessed the effects on expression and binding due to deletion of the yeast LEU3 transcription factor gene and effects due to elevation of Leu3 activity. Leu3 activity was elevated through overexpression and the introduction of a mutation that renders the protein constitutively active. Genes that are bound and/or regulated by Leu3 under one or both conditions were characterized in terms of their functional annotations and their predicted potential to be bound by Leu3. We also assessed the evolutionary conservation of the predicted binding potential using a novel alignment-independent method. Both perturbations yield genes that are likely to be direct targets of Leu3, including most of the classically defined targets. Additional direct targets are identified by each of the methods. However, experimental and computational criteria suggest that most genes whose expression is affected by the Leu3 genotype are unlikely to be regulated by binding of the protein.

Conclusion

Most genes that are differentially expressed by Leu3 are not direct targets despite the exceptional simplicity of the regulon, and the unusually direct nature of the perturbations investigated. These conclusions are reached through computational analyses that support and extend chromatin immunoprecipitation data on the identities of direct targets. These results have implications for the interpretation of expression experiments, especially in cases for which chromatin immunoprecipitation data are unavailable, incomplete, or ambiguous.
The use of percutaneous coronary intervention in black and white veterans with acute myocardial infarction
Authors: Maynard Charles , Sun Haili , Lowy Elliott , Sales Anne E , Fihn Stephan D
Published: August 2006

Background

It is uncertain whether black white differences in the use of percutaneous coronary intervention (PCI) persist in the era of drug eluting stents. The purpose of this study is to determine if black veterans with acute myocardial infarction (AMI) are less likely to receive PCI than their white counterparts.

Methods

This study included 680 black and 3529 white veterans who were admitted to Veterans Health Administration (VHA) medical centers between July 2003 and August 2004. Information for this study was collected as part of the VHA External Peer Review Program for quality monitoring and improvement for a variety of medical conditions and procedures, including AMI. In addition, Department of Veterans Affairs workload files were used to determine PCI utilization after hospital discharge. Standard statistical methods including the Chi-square, 2 sample t-test, and logistic regression with a cluster correction for medical center were used to assess the association between race and the use of PCI ≤ 30 days from admission.

Results

Black patients were younger, more often had diabetes mellitus, renal disease, or dementia and less often had lipid disorders, previous coronary artery bypass surgery, or chronic obstructive pulmonary disease than their white counterparts. Equal proportions of blacks and whites underwent cardiac catheterization ≤ 30 days after admission, but the former were less likely to undergo PCI (32% vs. 40%, p < 0.0001). This difference persisted after multivariate adjustment, although measures of the extent of coronary artery disease were not available.

Conclusion

Given the equivalent use of cardiac catheterization, it is possible that less extensive or minimal coronary artery disease in black patients could account for the observed difference.
Moms in motion: a group-mediated cognitive-behavioral physical activity intervention
Authors: Cramp Anita G , Brawley Lawrence R
Published: August 2006

Background

When examining the prevalence of physical inactivity by gender and age, women over the age of 25 are at an increased risk for sedentary behavior. Childbearing and motherhood have been explored as one possible explanation for this increased risk. Post natal exercise studies to date demonstrate promising physical and psychological outcomes, however few physical activity interventions have been theory-driven and tailored to post natal exercise initiates. The purpose of this study was to compare the effects of a group-mediated cognitive behavioral intervention based upon social-cognitive theory and group dynamics (GMCB) to a standard care postnatal exercise program (SE).

Method

A randomized, two-arm intervention design was used. Fifty-seven post natal women were randomized to one of two conditions: (1) a standard exercise treatment (SE) and (2) a standard exercise treatment plus group-mediated cognitive behavioral intervention (GMCB). Participants in both conditions participated in a four-week intensive phase where participants received standard exercise training. In addition, GMCB participants received self-regulatory behavioral skills training via six group-mediated counseling sessions. Following the intensive phase, participants engaged in a four-week home-based phase of self-structured exercise. Measures of physical activity, barrier efficacy, and proximal outcome expectations were administered and data were analyzed using ANCOVA procedures.

Results and discussion

ANCOVA of change scores for frequency, minutes, and volume of physical activity revealed significant treatment effects over the intensive and home-based phases (p's < 0.01). In addition, ANCOVA of change in mean barrier efficacy and proximal outcome expectations at the conclusion of the intensive phase demonstrated that GMCB participants increased their initial level of barrier efficacy and outcome expectations while SE participants decreased (p < 0.05).

Conclusion

While both exercise programs resulted in improvements to exercise participation, the GMCB intervention produced greater improvement in overall physical activity, barrier efficacy and proximal outcome expectations.
The role of thermal niche selection in maintenance of a colour polymorphism in redback salamanders (Plethodon cinereus)
Authors: Petruzzi Erin E , Niewiarowski Peter H , Moore Francisco B-G
Published: August 2006

Background

In eastern North America two common colour morphs exist in most populations of redback salamanders (Plethodon cinereus). Previous studies have indicated that the different morphs may be adapted to different thermal niches and the morphological variation has been linked to standard metabolic rate at 15°C in one population of P. cinereus. It has therefore been hypothesized that a correlated response to selection on metabolic rate across thermal niches maintains the colour polymorphism in P. cinereus. This study tests that hypothesis.

Results

We found that the two colour morphs do sometimes differ in their maintenance metabolic rate (MMR) profiles, but that the pattern is not consistent across populations or seasons. We also found that when MMR profiles differ between morphs those differences do not indicate that distinct niches exist. Field censuses showed that the two colour morphs are sometimes found at different substrate temperatures and that this difference is also dependent on census location and season.

Conclusion

While these morphs sometimes differ in their maintenance energy expenditures, the differences in MMR profile in this study are not consistent with maintenance of the polymorphism via a simple correlated response to selection across multiple niches. When present, differences in MMR profile do not indicate the existence of multiple thermal niches that consistently mirror colour polymorphism. We suggest that while a relationship between colour morph and thermal niche selection appears to exist it is neither simple nor consistent.
Control of annual reproductive cycle in the subtropical house sparrow (Passer domesticus): evidence for conservation of photoperiodic control mechanisms in birds
Authors: Trivedi Amit K , Rani Sangeeta , Kumar Vinod
Published: August 2006

Background

In many birds, day length (=photoperiod) regulates reproductive cycle. The photoperiodic environment varies between different seasons and latitudes. As a consequence, species at different latitudes may have evolved separate photoperiodic strategies or modified them as per their adaptive need. We studied this using house sparrow as a model since it is found worldwide and is widely investigated. In particular, we examined whether photoperiodism in house sparrows (Passer domesticus) at 27°N, 81°E shared features with those exhibited by its conspecifics at high latitudes.

Results

Initial experiment described in the wild and captive conditions the gonad development and molt (only in captives) cycles over a 12-month period. Both male and female sparrows had similar seasonal cycles, linked with annual variations in day length; this suggested that seasonal reproduction in house sparrows was under the photoperiodic control. However, a slower testis and attenuated follicular growth among captives indicated that other (supplementary) factors are also involved in controlling the reproductive cycle. Next experiment examined if sparrows underwent seasonal variations in their response to stimulatory effects of long day lengths. When birds were transferred every month over a period of 1 year to 16 hours light:8 hours darkness (16L:8D) for 17–26 weeks, there was indeed a time-of-year effect on the growth-regression cycle of gonads. The final experiment investigated response of house sparrows to a variety of light-dark (LD) cycles. In the first set, sparrows were exposed for 31 weeks to photoperiods that were close to what they receive in between the period from sunrise to sunset at this latitude: 9L:15D (close to shortest day length in December), 12L:12D (equinox, in March and September) 15L:9D (close to longest day length in June). They underwent testicular growth and regression and molt in 12L and 15L photoperiods, but not in 9L photoperiod. In the second set, sparrows were exposed for 17 weeks to photoperiods with light periods extending to different duration of the daily photosensitivity rhythm (e.g. 2L:22D, 6L:18D, 10L:14D, 14L:10D, 18L:6D and 22L:2D). Interestingly, a slow and small testicular response occurred under 2L and 10L photoperiods; 6L:18D was non-inductive. On the other hand, 14L, 18L and 22L photoperiods produced testicular growth and subsequent regression response as is typical of a long day photostimulation.

Conclusion

Subtropical house sparrows exhibit photoperiodic responses similar to that is reported for its population living at high latitudes. This may suggest the conservation of the photoperiodic control mechanisms in birds evolved over a long period of time, as a physiological strategy in a temporally changing environment ensuring reproduction at the best suited time of the year.