bluuebunny/crossref_metadata_2025 huggingface dataset:
Some Properties and Identities of Bernoulli and Euler Polynomials Associated with p‐adic Integral on ℤp
Authors: Kim D. S. , Kim T. , Dolgy D. V. , Lee S. H. , Rim S.-H.
Published: April 2012

We investigate some properties and identities of Bernoulli and Euler polynomials. Further, we give some formulae on Bernoulli and Euler polynomials by using p‐adic integral on ℤp.
Estimate of the Arctic Convective Boundary Layer Height from Lidar Observations: A Case Study
Authors: Di Liberto L. , Angelini F. , Pietroni I. , Cairo F. , Di Donfrancesco G. , Viola A. , Argentini S. , Fierli F. , Gobbi G. , Maturilli M. , Neuber R. , Snels M.
Published: April 2012

A new automated small size lidar system (microlidar or MULID) has been developed and employed to perform aerosol measurements since March 2010 at Ny Ålesund (78.9°N,11.9°E), Svalbard. The lidar observations have been used to estimate the PBL height by using the gradient method based on abrupt changes in the vertical aerosol profile and monitor its temporal evolution. The scope of the present study is to compare several approaches to estimate the PBL height, by using lidar observations, meteorological measurements by radio soundings, and a zero-order one-dimensional model based on a parameterization of the turbulent kinetic energy budget within the mixing layer, under the assumptions of horizontal homogeneity, and neglecting radiation and latent heat effects. A case study is presented here for a convective PBL, observed in June 2010 in order to verify whether the Gradient Method can be applied to lidar measurements in the Arctic region to obtain the PBL height. The results obtained are in good agreement with the PBL height estimated by the analysis of thermodynamic measurements obtained from radio sounding and with the model.
The Endoscopic Management of Pain in Chronic Pancreatitis
Authors: Goodman Adam J. , Gress Frank G.
Published: April 2012

Pain resulting from chronic pancreatitis is often debilitating and difficult to manage. Many approaches have been used to treat these patients, including narcotic analgesia, antidepressants, pancreatic enzymes, octreotide, denervation procedures, such as celiac plexus block, and various palliative, decompression, or drainage procedures. Many of these procedures can be performed endoscopically, while others require a more invasive, surgical approach. The effectiveness of these therapies is not only highly variable but also often controversial. This review will discuss the endoscopic options for pain management in patients with chronic pancreatitis and their utility in treating this difficult disease.
Correlation between Wear Resistance and Lifetime of Electrical Contacts
Authors: Song Jian , Koch Christian , Wang Liangliang
Published: April 2012

Electrical contacts are usually plated in order to prevent corrosion. Platings of detachable electrical contacts experience wear because of the motion between contacts. Once the protecting platings have been worn out, electrical contacts will fail rapidly due to corrosion or fretting corrosion. Therefore the wear resistance of the platings is a very important parameter for the long lifetime of electrical contacts. Many measures which improve the wear resistance can diminish the conductivity of the platings. Due to the fact that platings of electrical contacts must have both a high wear resistance and a high electrical conductivity, the manufacturing of high performance platings of electrical contacts poses a great challenge. Our study shows firstly the correlation between the wear resistance of platings and lifetime of electrical contacts and then the measures, which improve the wear resistance without impairing the electrical performance of the contacts.
Metric-Based Cooperative Routing in Multihop Ad Hoc Networks
Authors: He Xin , Li Frank Y.
Published: April 2012

Cooperative communication fully leverages the broadcast nature of wireless channels and exploits time/spatial diversity in a distributed manner, thereby achieving significant improvements in system capacity and transmission reliability. Cooperative diversity has been well studied from the physical layer perspective. Thereafter, cooperative MAC design has also drawn much attention recently. However, very little work has addressed cooperation at the routing layer. In this paper, we propose a simple yet efficient scheme for cooperative routing by using cooperative metrics including packet delivery ratio, throughput, and energy consumption efficiency. To make a routing decision based on our scheme, a node needs to first determine whether cooperation on each link is necessary or not, and if necessary, select the optimal cooperative scheme as well as the optimal relay. To do so, we calculate and compare cooperative routing metric values for each potential relay for each different cooperative MAC scheme (C-ARQ and CoopMAC in this study), and further choose the best value and compare it with the noncooperative link metric. Using the final optimal metric value instead of the traditional metric value at the routing layer, new optimal paths are set up in multihop ad hoc networks, by taking into account the cooperative benefits from the MAC layer. The network performance of the cooperative routing solution is demonstrated using a simple network topology.
A Heuristic Scheduling Algorithm for Minimizing Makespan and Idle Time in a Nagare Cell
Authors: Muthukumaran M. , Muthu S.
Published: April 2012

Adopting a focused factory is a powerful approach for today manufacturing enterprise. This paper introduces the basic manufacturing concept for a struggling manufacturer with limited conventional resources, providing an alternative solution to cell scheduling by implementing the technique of Nagare cell. Nagare cell is a Japanese concept with more objectives than cellular manufacturing system. It is a combination of manual and semiautomatic machine layout as cells, which gives maximum output flexibility for all kind of low-to-medium- and medium-to-high- volume productions. The solution adopted is to create a dedicated group of conventional machines, all but one of which are already available on the shop floor. This paper focuses on the development of heuristic scheduling algorithm in step-by-step method. The algorithm states that the summation of processing time of all products on each machine is calculated first and then the sum of processing time is sorted by the shortest processing time rule to get the assignment schedule. Based on the assignment schedule Nagare cell layout is arranged for processing the product. In addition, this algorithm provides steps to determine the product ready time, machine idle time, and product idle time. And also the Gantt chart, the experimental analysis, and the comparative results are illustrated with five ([Formula: see text] to [Formula: see text]) scheduling problems. Finally, the objective of minimizing makespan and idle time with greater customer satisfaction is studied through.
Multimodel GCM-RCM Ensemble-Based Projections of Temperature and Precipitation over West Africa for the Early 21st Century
Authors: Diallo I. , Sylla M. B. , Giorgi F. , Gaye A. T. , Camara M.
Published: April 2012

Reliable climate change scenarios are critical for West Africa, whose economy relies mostly on agriculture and, in this regard, multimodel ensembles are believed to provide the most robust climate change information. Toward this end, we analyze and intercompare the performance of a set of four regional climate models (RCMs) driven by two global climate models (GCMs) (for a total of 4 different GCM-RCM pairs) in simulating present day and future climate over West Africa. The results show that the individual RCM members as well as their ensemble employing the same driving fields exhibit different biases and show mixed results in terms of outperforming the GCM simulation of seasonal temperature and precipitation, indicating a substantial sensitivity of RCMs to regional and local processes. These biases are reduced and GCM simulations improved upon by averaging all four RCM simulations, suggesting that multi-model RCM ensembles based on different driving GCMs help to compensate systematic errors from both the nested and the driving models. This confirms the importance of the multi-model approach for improving robustness of climate change projections. Illustrative examples of such ensemble reveal that the western Sahel undergoes substantial drying in future climate projections mostly due to a decrease in peak monsoon rainfall.
Diet and Nutrition in
Circulation
and the
Circulation
Subspecialty Journals
Authors:   The Editors
Published: April 2012

The following articles are being highlighted as part of
Circulation's
Topic Review series. This series will summarize the most important manuscripts, as selected by the editors, published in
Circulation
and the
Circulation
subspecialty journals. The studies included in this article represent the articles related to diet and nutrition that were published in
Circulation
and the
Circulation
subspecialty journals in 2010 and 2011.
Spectral Analysis of Tropical Atmospheric Dynamical Variables Using a Linear Shallow-Water Modal Decomposition
Authors: Gehne Maria , Kleeman Richard
Published: April 2012

Space–time spectral analysis has been used frequently in studying observational evidence of convectively coupled equatorial waves. Here 23 yr of brightness temperature Tb data and dynamical reanalysis data are analyzed by an appropriate projection onto the meridional basis functions of the β-plane linear shallow-water equations. Evidence of peaks in power along linear equatorial mode dispersion curves in Tb, zonal and meridional wind, divergence, and geopotential spectra are presented.

Another feature of all space–time spectra considered is the redness in frequency, zonal wavenumber, and meridional mode number. It is found that spectral peaks in the dynamical variable spectra are largely consistent with linear shallow-water waves, but peaks related to barotropic waves and extratropical storm track activity are also apparent. The convectively coupled wave signals are seen to be confined to the first few meridional basis functions, suggesting a filtering method to reduce noise for these signals. This result also has implications for future modeling and theoretical work. A comparison of the results herein for two different reanalysis products shows only minor differences, adding confidence in the robustness of the results presented. This work implies that any comprehensive theory of tropical convection should explain the ubiquity of moist linear waves as well as the spectral redness with respect to all temporal and horizontal scales.
A Comparison of the Transition of Equatorial Waves between Two Types of ENSO Events in a Multilevel Model
Authors: Chen Guanghua
Published: April 2012

The differences in the transitions of equatorial mixed Rossby–gravity (MRG) waves to off-equatorial tropical depression (TD)-type disturbances during ENSO events are investigated with a global baroclinic anomaly model. The model reproduces reasonably the perturbation evolution within realistic three-dimensional summer mean states corresponding to El Niño (EN) and La Niña (LN) years. Based on wave structure and energetics diagnosis, the results indicate that, following the longitudinal shift of the favorable environmental fields, the wave characteristics are altered accordingly. In the presence of a circulation–convection feedback, the wave train exhibits more rapid growth, a more eastern location of transition, and a more northward-shifting component during EN years than during LN years. The convective heating acts as a leading energy source to supply the wave growth and the increase in eddy kinetic energy is directly attributed to barotropic conversion in the monsoon region.

Sensitivity experiments show that the dynamic effect alone fails to capture the observed wave behaviors although the damped modes also experience a scale contraction and a slight northward migration. The near-surface thermodynamic fields related to sea surface temperature (SST) and low-level specific humidity can play a crucial role in the scale contraction and the propagation characteristics for tropical synoptic waves. The heating feedback scheme combining the actions of SST and low-level moisture can amplify and accelerate the modification of wave characteristics initiated by the dynamic effect, producing a tighter wave structure and steering the wave train toward the warmer and moister ocean.
Season-Dependent Forecast Skill of the Leading Forced Atmospheric Circulation Pattern over the North Pacific and North American Region*
Authors: Jia XiaoJing , Lin Hai , Lee June-Yi , Wang Bin
Published: April 2012

Multimodel ensemble (MME) seasonal forecasts are analyzed to evaluate numerical model performance in predicting the leading forced atmospheric circulation pattern over the extratropical Northern Hemisphere (NH). Results show that the time evolution of the leading tropical Pacific sea surface temperature (SST)-coupled atmospheric pattern (MCA1), which is obtained by applying a maximum covariance analysis (MCA) between 500-hPa geopotential height (Z500) in the extratropical NH and SST in the tropical Pacific Ocean, can be predicted with a significant skill in March–May (MAM), June–August (JJA), and December–February (DJF) one month ahead. However, most models perform poorly in capturing the time variation of MCA1 in September–November (SON) with 1 August initial condition. Two possible reasons for the models’ low skill in SON are identified. First, the models have the most pronounced errors in the mean state of SST and precipitation along the central equatorial Pacific. Because of the link between the divergent circulation forced by tropical heating and the midlatitude atmospheric circulation, errors in the mean state of tropical SST and precipitation may lead to a degradation of midlatitude forecast skill. Second, examination of the potential predictability of the atmosphere, estimated by the ratio of the total variance to the variance of the model forecasts due to internal dynamics, shows that the atmospheric potential predictability over the North Pacific–North American (NPNA) region is the lowest in SON compared to the other three seasons. The low ratio in SON is due to a low variance associated with external forcing and a high variance related to atmospheric internal processes over this area.
Changing the Climate Sensitivity of an Atmospheric General Circulation Model through Cloud Radiative Adjustment
Authors: Sokolov Andrei P. , Monier Erwan
Published: April 2012

Conducting probabilistic climate projections with a particular climate model requires the ability to vary the model’s characteristics, such as its climate sensitivity. In this study, the authors implement and validate a method to change the climate sensitivity of the National Center for Atmospheric Research (NCAR) Community Atmosphere Model, version 3 (CAM3), through cloud radiative adjustment. Results show that the cloud radiative adjustment method does not lead to physically unrealistic changes in the model’s response to an external forcing, such as doubling CO2 concentrations or increasing sulfate aerosol concentrations. Furthermore, this method has some advantages compared to the traditional perturbed physics approach. In particular, the cloud radiative adjustment method can produce any value of climate sensitivity within the wide range of uncertainty based on the observed twentieth century climate change. As a consequence, this method allows Monte Carlo–type probabilistic climate forecasts to be conducted where values of uncertain parameters not only cover the whole uncertainty range, but cover it homogeneously. Unlike the perturbed physics approach that can produce several versions of a model with the same climate sensitivity but with very different regional patterns of change, the cloud radiative adjustment method can only produce one version of the model with a specific climate sensitivity. As such, a limitation of this method is that it cannot cover the full uncertainty in regional patterns of climate change.
Warm Season Response over North America to a Shutdown of the Atlantic Meridional Overturning Circulation and CO2 Increases
Authors: Pu Bing , Vizy Edward K. , Cook Kerry H.
Published: April 2012

Paleo-proxy and modeling evidence suggest that a shutdown of the Atlantic meridional overturning circulation (AMOC) would decrease North Atlantic Ocean sea surface temperatures and have far-reaching climate impacts. The authors use a regional climate model to examine the warm season response over North America to a hypothetical late-twenty-first-century shutdown of the AMOC with increased atmospheric CO2. In the future simulation, precipitation decreases over the western and central United States by up to 40% and over eastern Mexico by up to 50%. Over the eastern United States rainfall generally increases except during July. Variations in the moisture convergence associated with large-scale circulation changes dominate the rainfall variations, while evaporation plays a critical role over the northeastern United States in spring and the north-central United States in summer. During April–June the westward extension of the North Atlantic subtropical high enhances southwesterly moisture fluxes from the Gulf of Mexico into the eastern and south-central United States. Increases in low-level moisture content reduce the stability of the atmosphere. Enhanced southerly winds promote convergence over the eastern United States through the Sverdrup vorticity balance and precipitation increases. In July–August anomalous anticyclonic moisture fluxes associated with an anomalous high over the Gulf of Mexico and eastern Pacific decrease the moisture supply into the United States and Mexico. Over the central United States decreases in evaporation support decreases in low-level moisture content and increases in atmospheric stability. Over the eastern United States the Sverdrup balance weakens in summer and anomalous moisture convergence is mainly located over the East Coast.
Daily, Global, High-Resolution SST and Sea Ice Reanalysis for 1985–2007 Using the OSTIA System
Authors: Roberts-Jones Jonah , Fiedler Emma Kathleen , Martin Matthew James
Published: April 2012

A sea surface temperature (SST) and sea ice reanalysis has been produced at the Met Office based on the Operational SST and Sea Ice Analysis (OSTIA) system. The OSTIA reanalysis produces daily, high-resolution, global foundation SST and sea ice concentration fields from 1 January 1985 to 31 December 2007. The SST reanalysis uses reprocessed satellite and in situ observations that are assimilated using a multiscale optimal-interpolation-type scheme similar to that used in the near-real-time OSTIA system. Validation of the SST analysis using assimilated in situ observation-minus-background statistics shows that the accuracy of the analysis increases throughout the reanalysis period; the global root-mean-square difference is approximately 0.50 K by 2007. This approach to validation is supported in the recent period by results from comparisons with independent near-surface Argo data against which a global standard deviation error of 0.55 K was calculated. Assessment of the OSTIA reanalysis at high latitudes demonstrates that the SST and sea ice fields are more consistent with one another in the Southern Hemisphere than in the Northern Hemisphere. Comparison of the sea ice extents to those in a similar reanalysis shows OSTIA to have larger extents in the Northern Hemisphere, and the Southern Hemisphere extents are similar. The OSTIA reanalysis SSTs are shown to be regionally comparable with similar reanalyses, with the largest differences occurring at high latitudes in the summer hemisphere. Differences are observed around the ice edge and in regions with high SST gradients. The OSTIA reanalysis provides a valuable high-resolution addition to the satellite period SST data record that makes use of the (Advanced) Along-Track Scanning Radiometer [(A)ATSR] multimission data.
Influence of Advective Accelerations on Estuarine Exchange at a Chesapeake Bay Tributary
Authors: Basdurak Nuvit B. , Valle-Levinson Arnoldo
Published: April 2012

The influence of nonlinear advection on estuarine exchange flow was investigated with observations at the transition between the James River and Chesapeake Bay, Hampton Roads, Virginia. Data were collected under different tidal forcing, wind forcing, and river discharge in 2004 and 2005. The relative contribution of nonlinear advective terms to the along-channel momentum balance had the same order of magnitude as pressure gradient and friction, verifying recent analytical and numerical model results. Both the magnitude and the spatial distribution of nonlinear advection showed fortnightly variability. Nonlinear advection was more influential on along-channel flow at spring tides than at neap tides because of increased tidal velocities, in a cross-sectionally averaged sense. The flow structures induced by each nonlinear advective process were investigated for the first time with observations. The lateral advection term υuy was found to enhance laterally sheared exchange acting along with Coriolis forcing at spring tides and opposing it at neap tides. Vertical advection wuz showed similar spatial distribution as υuy at spring tides but was vertically sheared (landward at middepth and seaward in the rest of the water column) at neaps. Longitudinal advection uux augmented landward flow in the channel.
Influence of Low-Level Thermodynamic Structure on the Downdraft Properties of Simulated Supercells
Authors: Naylor Jason , Askelson Mark A. , Gilmore Matthew S.
Published: April 2012

Idealized simulations using the Weather Research and Forecasting Model (WRF) were performed to examine the role of capping inversions on the near-surface thermodynamic structure of outflow from simulated supercells. Two simulations were performed: one with the traditional noncapped Weisman and Klemp (WK) analytic sounding and the second with a WK sounding modified to contain a capping inversion. Both sounding environments favor splitting storms and a right-moving supercell by 90 min into the simulation. These two supercell simulations evolve in a qualitatively similar fashion, with both storms exhibiting large, quasi-steady updrafts, hook-shaped appendages in the precipitation mixing ratio field, and prominent localized downdrafts.

Results show that the supercell simulated in the capped environment has a surface cold pool with larger values of pseudoequivalent potential temperature (θep) than the cold pool of the supercell produced in the noncapped simulation. Parcels in the surface cold pool of the supercell produced in the capped sounding simulation have a lower origin height than those in the surface cold pool of the supercell produced in the noncapped simulation for all times. Although θep values in the surface cold pool are primarily associated with the origin height of downdraft parcels and the environmental θep at that level, it is shown that nonconservation of θep primarily associated with hydrometeor melting can decrease θep values of downdraft parcels as they descend by several degrees.
Controlling the Computational Modes of the Arbitrarily Structured C Grid
Authors: Weller Hilary
Published: April 2012

The arbitrarily structured C grid, Thuburn–Ringler–Skamarock–Klemp (TRiSK), is being used in the Model for Prediction Across Scales (MPAS) and is being considered by the Met Office for their next dynamical core. However, the hexagonal C grid supports a branch of spurious Rossby modes, which lead to erroneous grid-scale oscillations of potential vorticity (PV). It is shown how these modes can be harmlessly controlled by using upwind-biased interpolation schemes for PV. A number of existing advection schemes for PV are tested, including that used in MPAS, and none are found to give adequate results for all grids and all cases. Therefore a new scheme is proposed; continuous, linear-upwind stabilized transport (CLUST), a blend between centered and linear-upwind with the blend dependent on the flow direction with respect to the cell edge.

A diagnostic of grid-scale oscillations is proposed that gives further discrimination between schemes than using potential enstrophy alone. Indeed, some schemes are found to destroy potential enstrophy while grid-scale oscillations grow.

CLUST performs well on hexagonal-icosahedral grids and unrotated skipped latitude–longitude grids of the sphere for various shallow-water test cases. Despite the computational modes, the hexagonal icosahedral grid performs well since these modes are easy and harmless to filter. As a result, TRiSK appears to perform better than a spectral shallow-water model.
Treating ADHD with Agomelatine
Authors: Niederhofer Helmut
Published: April 2012

Objective: Agomelatine is a relatively new antidepressant, with affinities to MT1 and MT2 (responsible for the circadian rhythm) as well as to 5-HT2C receptors. Since antidepressants have demonstrated some benefit in the treatment of ADH and because of the fact, that ADHD is often associated with sleep disorders, we assumed, that it might be a therapeutic alternative also for ADHD. Method: We proved this assumption in ten ADHD patients in a placebo controlled manner. Results: Agomelatine’s effect was superior to that of placebo, but seems to be less than that of Methylphenidate or placebo. Conclusion: If ADHD therapy with Methylphenidate or Atomoxetine is not indicated e.g. because of adverse side effects and if an ADHD patient suffers from additional sleep disorders, Agomelatine might be a helpful therapeutic alternative.
The distinct category of healthcare associated bloodstream infections
Authors: Lenz Ryan , Leal Jenine R , Church Deirdre L , Gregson Daniel B , Ross Terry , Laupland Kevin B
Published: April 2012

Background

Bloodstream infections (BSI) have been traditionally classified as either community acquired (CA) or hospital acquired (HA) in origin. However, a third category of healthcare-associated (HCA) community onset disease has been increasingly recognized. The objective of this study was to compare and contrast characteristics of HCA-BSI with CA-BSI and HA-BSI.

Methods

All first episodes of BSI occurring among adults admitted to hospitals in a large health region in Canada during 2000-2007 were identified from regional databases. Cases were classified using a series of validated algorithms into one of HA-BSI, HCA-BSI, or CA-BSI and compared on a number of epidemiologic, microbiologic, and outcome characteristics.

Results

A total of 7,712 patients were included; 2,132 (28%) had HA-BSI, 2,492 (32%) HCA-BSI, and 3,088 (40%) had CA-BSI. Patients with CA-BSI were significantly younger and less likely to have co-morbid medical illnesses than patients with HCA-BSI or HA-BSI (p < 0.001). The proportion of cases in males was higher for HA-BSI (60%; p < 0.001 vs. others) as compared to HCA-BSI or CA-BSI (52% and 54%; p = 0.13). The proportion of cases that had a poly-microbial etiology was significantly lower for CA-BSI (5.5%; p < 0.001) compared to both HA and HCA (8.6 vs. 8.3%). The median length of stay following BSI diagnosis 15 days for HA, 9 days for HCA, and 8 days for CA (p < 0.001). Overall the most common species causing bloodstream infection were Escherichia coli, Staphylococcus aureus, and Streptococcus pneumoniae. The distribution and relative rank of importance of these species varied according to classification of acquisition. Twenty eight day all cause case-fatality rates were 26%, 19%, and 10% for HA-BSI, HCA-BSI, and CA-BSI, respectively (p < 0.001).

Conclusion

Healthcare-associated community onset infections are distinctly different from CA and HA infections based on a number of epidemiologic, microbiologic, and outcome characteristics. This study adds further support for the classification of community onset BSI into separate CA and HCA categories.
Hybrid cells derived from breast epithelial cell/breast cancer cell fusion events show a differential RAF-AKT crosstalk
Authors: Özel Cem , Seidel Jeanette , Meyer-Staeckling Sönke , Brandt Burkhard H , Niggemann Bernd , Zänker Kurt S , Dittmar Thomas
Published: April 2012

Background

The biological phenomenon of cell fusion has been linked to several characteristics of tumour progression, including an enhanced metastatogenic capacity and an enhanced drug resistance of hybrid cells. We demonstrated recently that M13SV1-EGFP-Neo breast epithelial cells exhibiting stem cell characteristics spontaneously fused with MDA-MB-435-Hyg breast cancer cells, thereby giving rise to stable M13MDA435 hybrid cells, which are characterised by a unique gene expression profile and migratory behaviour. Here we investigated the involvement of the PLC-β/γ1, PI3K/AKT and RAS-RAF-ERK signal transduction cascades in the EGF and SDF-1α induced migration of two M13MDA435 hybrid cell clones in comparison to their parental cells.

Results

Analysis of the migratory behaviour by using the three-dimensional collagen matrix migration assay showed that M13SV1-EGFP-Neo cells as well as M13MDA435 hybrid cells, but not the breast cancer cell line, responded to EGF stimulation with an increased locomotory activity. By contrast, SDF-1α solely stimulated the migration of M13SV1-EGFP-Neo cells, whereas the migratory activity of the other cell lines was blocked. Analysis of signal transduction cascades revealed a putative differential RAF-AKT crosstalk in M13MDA435-1 and -3 hybrid cell clones. The PI3K inhibitor Ly294002 effectively blocked the EGF induced migration of M13MDA435-3 hybrid cells, whereas the EGF induced locomotion of M13MDA435-1 hybrid cells was markedly increased. Analysis of RAF-1 S259 phosphorylation, being a major mediator of the negative regulation of RAF-1 by AKT, showed decreased pRAF-1 S259 levels in LY294002 treated M13MDA435-1 hybrid cells. By contrast, pRAF-1 S259 levels remained unaltered in the other cell lines. Inhibition of PI3K/AKT signalling by Ly294002 relieves the AKT mediated phosphorylation of RAF-1, thereby restoring MAPK signalling.

Conclusions

Here we show that hybrid cells could evolve exhibiting a differential active RAF-AKT crosstalk. Because PI3K/AKT signalling has been chosen as a target for anti-cancer therapies our data might point to a possible severe side effect of AKT targeted cancer therapies. Inhibition of PI3K/AKT signalling in RAF-AKT crosstalk positive cancer (hybrid) cells could result in a progression of these cells. Thus, not only the receptor (activation) status, but also the activation of signal transduction molecules should be analysed thoroughly prior to therapy.
Coupling of dielectric mixing models with full-wave ground-penetrating radar signal inversion for sandy-soil-moisture estimation
Authors: Tran Anh Phuong , Ardekani Mohammad Reza Mahmoudzadeh , Lambot Sébastien
Published: April 2012

We coupled dielectric mixing models with a full-wave ground-penetrating-radar (GPR) model to estimate the soil water content by inversion. Two mixing models were taken into account in this study, namely, a power law model and the Wang and Schmugge model. With this combination, we could account for the frequency dependence of the dielectric permittivity and apparent conductivity in the inverse algorithm and directly estimate the soil water content without using an empirical petrophysical formula or a priori knowledge on soil porosity. The approach was validated by a series of experiments with sandy soil in controlled laboratory conditions. The results showed that the performance of our approach is better than the common approach, which assumes a linear dependence of apparent conductivity on frequency and uses Topp’s equation to transform permittivity to water content. GPR data were perfectly reproduced in the time and frequency domains, leading to very accurate water-content estimates with an average absolute error of less than [Formula: see text]. However, the accuracy was reduced as the water content increased. Sensitivity analysis indicated that the Green’s function was most sensitive to the water content and sand-layer thickness but much less so with DC conductivity. The results also revealed that as the frequency increased, although the permittivity was nearly constant, the apparent electrical conductivity and the attenuation increased remarkably, especially for wet sands due to dielectric losses. The successful validation of the proposed approach opens a promising avenue of development to use dielectric mixing models for soil-moisture mapping from GPR measurements.
Training tomorrow’s dentists
Authors: Woolford Mark J , Wilson Nairn HF
Published: April 2012

Dental schools have an immense responsibility.They train dentists and typically other oral healthcare professionals for the future, which for many, if not most, can be 30–40 years hence. Exactly what will be required over this time is impossible to predict, judging by the range and impact of advances seen in recent years.The programme of instruction leading to initial registration is, and will remain, a foundation for life-long professional development rather than an end-point in itself.The need for continuing professional development and the soon to be introduced arrangements for revalidation are fundamental to the best interests of patients, let alone the future of the profession.A simple truth is that the undergraduate programme can never teach a dentist all that needs to be known about the clinical practice of dentistry, especially to a level of ‘competence’. Notwithstanding core knowledge and competencies, many topics are introduced into learning and teaching, leaving the learner to expand and develop their knowledge and understanding, according to circumstances and individual interests and requirements.This is in contrast to previous expectations that, on graduation, a dentist had knowledge and skills fit for a life-time in practice – the principle of ‘fit for independent practice’. How will dental schools continue to change and what, where and how will dental schools teach?What new challenges will this change post to Deans and Heads of schools? Many now believe that it is time to have a complete rethink and fresh approach to undergraduate dental education.
Antimicrobials and dentistry: a rationale for their use
Authors: Martin Michael V
Published: April 2012

Antibiotics in general dentistry are grossly overused often with no rationale for their use and little proven benefit for the patient.This paper discusses specific situations where antimicrobials can be used effectively.
Migration medicine in dentistry: educational challenges for the future?
Authors: Crean St John
Published: April 2012

The patient population of the UK is changing due to the influx of a significant number of international migrants.The impact this will have and is having upon the changing face of our patient base should be viewed as a manifestation of the globalisation process. For those charged with providing healthcare, there remains a need to maintain a contemporary awareness of the additional health challenges this group may pose.The dental profession, as part of that care provision service, faces the same demands.
How should dental students be trained for the future needs of the population?
Authors: Lewis Kevin
Published: April 2012

As UK graduates have become the minority of new General Dental Council (GDC) registrants, this is a timely moment to be examining what kind of dental graduate we are producing, and why.This opinion article intentionally challenges some of the central assumptions that the various stakeholders will traditionally make.
Implementing adult learning theory into dental education
Authors: McHarg Jane
Published: April 2012

Examples from undergraduate education are used to illustrate the implementation of adult learning theory. However, the general rules apply to vocational training, postgraduate and continual professional development: empower the learner to take control!.
Implications of the quality agenda for National Health Service primary dental care
Authors: Chestnutt Ivor G
Published: April 2012

A National Health Service that works to prevent ill health and provide care that is personal, effective and safe is a key policy objective.This article considers the implications of this agenda for NHS primary dental care and discusses current thinking on how improvements to the quality of care may be achieved and monitored.
Developing volunteering guidelines and approaches
Authors: Wilson Ian , Gill Amarjit
Published: April 2012

This article summarises the work of Bridge2Aid in creating a UK network to oversee the standards of UK non-governmental organisations and as a resource to those wanting to volunteer.
Is dentistry dangerous?
Authors: Martin Mike V
Published: April 2012

Every mouth contains hundreds of species of bacteria, viruses, fungi and some cases parasites. Dentistry involves working in among these micro-organisms and the possible risk of a transmission of pathogens to operator, staff and patient. What are the risks and are the precautions we take justified?.
Is head and neck cancer infectious? Human papilloma virus in oral and pharyngeal cancer
Authors: Thavaraj Selvam , Stokes Angela , Odell Edward W
Published: April 2012

There has been a growth in publications associating human papilloma virus and head and neck squamous cell carcinoma. The virus has recently been recognised as a causative factor for some head and neck cancers that have a distinct clinical profile of site, age and prognosis. We review the epidemiological trends, mechanism of carcinogenesis, methods of detection, clinical characteristics and discuss the likely future directions of HPVassociated research in head and neck cancer.
Is dentistry worth investing in? An opinion on the views of the financial community
Authors: Stack Shane
Published: April 2012

Shane Stack, a partner at Medical Money Management, independent financial advisors to the medical and dental professions, seeks to explore the question on the minds of most dental students and newly qualified dentists considering a career as a practitioner or owner: is it worth the investment?
Dental stem cells and bone repair
Authors: Platt Christopher I , Crean St John
Published: April 2012

Repair of a periodontal bone defect following surgery or trauma is essential to prevent further bone loss through resorption (Figure 1). Materials currently used for this procedure include autologous bone, deproteinised bovine bone or alloplastic bone substitutes. Although effective at maintaining periodontal architecture, these graft materials can be difficult to implant and may fail to incorporate into host tissue. Dental stem cells are currently being investigated for repair of mandibular bone defects. Recent clinical pilot studies in which autologous dental stem cells have been grafted into mandibular defects have produced encouraging results. This review will discuss current research surrounding the development of dental stem cells for bone augmentation and repair.
e-Den goes from strength to strength
Authors: Brunton Paul
Published: April 2012

With its funding secured and an ever increasing bank of content, e-Den is an invaluable e-learning resource for the profession.
Regulation – public protection not paperwork
Authors: Lockyer Alison
Published: April 2012

The word ‘regulation’ means different things to different people. At its worst, it represents unnecessary red tape, burdensome paperwork and endless form filling. At its best it means driving forward higher standards, protecting the vulnerable and giving people reassurance that all is well.
CQC and GDC: a practitioner’s nightmare? How did we get here?
Authors: Boynton Sue , Henderson Stephen
Published: April 2012

The dental profession is anticipating the arrival of the Care Quality Commission (CQC) which will regulate the delivery of dental services from 1 April 2011. This article reflects upon the perceived failure of the healthcare professions to justify the trust that the public placed in them, and describes the reasons behind how the CQC came to regulate dental practices.
Care Quality Commission: the view from the British Dental Association
Authors: Sanderson Susie
Published: April 2012

Barring a last-minute change of heart by government, Care Quality Commission (CQC) registration will be upon us by the time you read this. The 1 April deadline for registration will have passed and dentists across England will, theoretically at least, be registered. At the time of writing (a few months ahead of the deadline) it’s hard to say how closely theory and reality will be aligned…
Equivalence training for non-EEA dentists: a way forward?
Authors: Walsh Paul
Published: April 2012

In order for a qualified overseas dentist from outside the European Economic Area (EEA) to work in the NHS they must undergo a period of supervised practice and acquire the knowledge equivalent to that of a UK dentist who has completed vocational training (VT). This article outlines how the present system of VT ‘by assessed period’ has developed and is currently functioning. It then proposes a more bespoke system which may meet the needs of many of these overseas dentists more effectively.
What is clinical audit’s purpose: quality assurance or quality improvement?
Authors: Dixon Nancy
Published: April 2012

Clinical audit has become a key activity for healthcare organisations and professionals in England. The clinical audit process is frequently described as a cycle of steps that includes making changes in practice. However, some evidence suggests that clinical audit is not effective in producing improvements in the quality of patient care. The explanation may be that clinicians and managers are seeing clinical audit as a quality assurance process, which implies making small adjustments in practice to conform to standards, rather than as a quality improvement process.
Whole-tooth tissue engineering: lessons from development
Authors: Sloan Alastair J
Published: April 2012

In an era of regenerative medicine, dentistry can be at the forefront due to the restorative procedures dental practitioners currently use. Orthopaedic practice encourages tissue regeneration through guided tissue regeneration and long term programmes of research on dental tissue regeneration have allowed us to develop a mechanistic understanding of the biological processes underpinning the key events during caries-induced natural tissue regeneration. These may be translated into novel therapies, which will improve on the relatively empirical traditional dental restorative approaches. Tissue engineering solutions for dental disease offer exciting and realistic opportunities and recent reports of bio-engineering of tooth structures and dental tissue regeneration have opened the way for exploitation of these technologies. Engineering of a whole ‘bio-tooth’ and its clinical application may be achievable in the longer term while exploitation of the natural reparative ability of the dentine-pulp complex is leading to significant advances in providing more translational solutions to address the effects of dental disease. Stem cells from the dental pulp have been extensively studied as a source for tooth regeneration but the use of stem cells from bone marrow and embryonic stem cells has demonstrated the possibility of generating teeth from non-dental cells by carefully mimicking the mechanisms observed during embryonic development. There are many challenges ahead but by a careful understanding of both the cell and the molecular biology underpinning tooth development, dentine repair, and the role of stem cells in these processes, tissue-engineered teeth could be a choice for replacement of missing teeth.
Training to be a specialist – the prizes and pitfalls
Authors: Dubal Raj
Published: April 2012

Having obtained my Bachelor of Dental Surgery (BDS) in 2001, I was sure that my academic career had come to an end. The first and last thought I remember having as I embarked on vocational training was ‘finally an income and no more exams’. Nothing could have been further from the truth and, having completed my specialist training in fixed and removable prosthodontics, in this article I aim to highlight the journey I travelled, with perils and prizes, and give some insight into the self-funded mono-speciality training pathway for potential applicants.
Challenges of exodontia in an ageing patient
Authors: Renton Tara
Published: April 2012

The World Health Organization’s definition of an aging or elderly patient is (for most developed-world countries) 65 and over. The population of the developed world is getting older and is increasingly dentate. Both trends will increase the likelihood for exodontia. It is generally accepted that any increase in age may have a negative effect on surgical outcomes and thus will impact on the need for exodontia and its complexity.
Dento-legal risks associated with treating the older patient
Authors: Lewis Kevin
Published: April 2012

The older patient can present dento-legal risks of many different kinds, not all of which are immediately apparent. This fact needs to be considered in the context of an ageing population, more members of which are likely to be retaining more of their teeth, later into life and presenting with more complex dental needs. Ensuring that every member of the dental team understands where and why these additional risks might exist is a necessary pre-requisite to being able to take appropriate steps to minimise and manage them. This article suggests ways to identify and deal effectively with some of the risks involved.
Specialist training in special care dentistry
Authors: Kerr Bryan , Boyle Carole
Published: April 2012

Special care dentistry is the most recent dental specialty to be recognised by the General Dental Council. It differs from most dental specialties as it is defined by the patients rather than by specific dental procedures.
The myth of unexplained pain
Authors: de C Williams Amanda C
Published: April 2012

Persistent (chronic) pain is widespread in medical practice and in the population, yet is often hard to explain. To encounter difficulties in explaining pain or finding a physical cause (on which we usually build the explanation) is not the same as determining that there is no physical cause. Such pain is difficult, aversive, hard to treat and inconvenient for all concerned, but it is not unexplained.
Repair of nerves injured during dental and oral surgery procedures
Authors: Smith Keith G
Published: April 2012

There is still some disagreement and confusion about the optimal management of patients who have suffered a nerve injury during a dental or oral surgery procedure. The majority of the nerve injuries are temporary and normal sensation will usually return without any surgical intervention but there are some patients for whom exploration and repair of their injured nerves may be beneficial. The difficulty lies with the assessment of the nerve injury and the decision making as to whether it is likely to be a temporary injury that will fully recover without any intervention or if early surgical intervention should be recommended.
Supervision of orthodontic therapists: what is all of the confusion about?
Authors: Day Christian , Hodge Trevor
Published: April 2012

Since their introduction there has been a lot of discussion and confusion as to the level of supervision that a qualified orthodontic therapist (OT) requires. This has led to lack of clarity within the specialty as to the role of the OT, in particular during periods where the practitioners are absent. In turn, this has unsettled a number of these dental care professionals (DCPs) as they are unsure of their position within their practices and are keen to remain within the General Dental Council (GDC) regulations – although these are not black and white and it is in the grey areas where confusion can lie.