In vitro study of a modified sagittal split osteotomy fixation technique of the mandible: a mechanical test.

This study was performed to evaluate the compressive mechanical strength of rigid internal fixation (RIF) using 1.5-mm L-shaped plates fixed with monocortical screws in sagittal split osteotomy (SSO). Thirty synthetic hemimandibles, which had all undergone a 5-mm advancement, were divided into three groups: three 12-mm bicortical titanium screws were placed in an inverted L pattern in group A; one straight 2.0-mm system spaced titanium plate fixed with four 5-mm monocortical screws was used in group B; two 1.5-mm system L-shaped titanium plates, each fixed with four 5-mm monocortical screws, were used in group C. The models were subjected to compressive and progressive mechanical tests with forces applied in the area between the second premolar and first molar to verify resistance in Newtons (N). A displacement speed of 1mm/min was applied, with a maximum 10mm displacement of the distal segment or until disruption of the fixation. The deformity and/or eventual rupture of the plates were evaluated, and consequently their technical stability was determined. The results showed that the modified fixation technique tested in this study on synthetic mandibles resulted in adequate stability and superior mechanical behaviour compared to simulated osteosynthesis with the use of a straight 2.0-mm titanium plate.

Abrupt Climate Change in an Oscillating World.

The notion that small changes can have large consequences in the climate or ecosystems has become popular as the concept of tipping points. Typically, tipping points are thought to arise from a loss of stability of an equilibrium when external conditions are slowly varied. However, this appealingly simple view puts us on the wrong foot for understanding a range of abrupt transitions in the climate or ecosystems because complex environmental systems are never in equilibrium. In particular, they are forced by diurnal variations, the seasons, Milankovitch cycles and internal climate oscillations. Here we show how abrupt and sometimes even irreversible change may be evoked by even small shifts in the amplitude or time scale of such environmental oscillations. By using model simulations and reconciling evidence from previous studies we illustrate how these phenomena can be relevant for ecosystems and elements of the climate system including terrestrial ecosystems, Arctic sea ice and monsoons. Although the systems we address are very different and span a broad range of time scales, the phenomena can be understood in a common framework that can help clarify and unify the interpretation of abrupt shifts in the Earth system.

A thin CdSe shell boosts the electron transfer from CdTe quantum dots to methylene blue.

CdTe core and CdTe/CdSe core/shell quantum dots (QD) are investigated with steady state and time-resolved spectroscopic methods. The coating of the CdTe core with a 0.7 nm thick CdSe shell shifts the lowest exciton absorption band to the red by more than 70 nm making the CdTe/CdSe QD an interesting candidate for application in solar energy conversion. Femtosecond transient absorption measurements are applied to study the photoinduced electron transfer (ET) to the molecular acceptor methylene blue (MB). ET times after single excitation of the QD are determined for different MB : QD ratios. The ET reaction is significantly faster in the case of the MB-CdTe/CdSe QD complexes, indicative of an altered charge distribution in the photoexcited heterostructure with a higher electron density in the CdSe shell. As a result of the efficient absorption of incoming light and the faster ET reaction, the amount of reduced MB in the time resolved experiments is higher for CdTe/CdSe QD compared to CdTe QD.

Early Warning Signals for Regime Transition in the Stable Boundary Layer: A Model Study.

The evening transition is investigated in an idealized model for the nocturnal boundary layer. From earlier studies it is known that the nocturnal boundary layer may manifest itself in two distinct regimes, depending on the ambient synoptic conditions: strong-wind or overcast conditions typically lead to weakly stable, turbulent nights; clear-sky and weak-wind conditions, on the other hand, lead to very stable, weakly turbulent conditions. Previously, the dynamical behaviour near the transition between these regimes was investigated in an idealized setting, relying on Monin-Obukhov (MO) similarity to describe turbulent transport. Here, we investigate a similar set-up, using direct numerical simulation; in contrast to MO-based models, this type of simulation does not need to rely on turbulence closure assumptions. We show that previous predictions are verified, but now independent of turbulence parametrizations. Also, it appears that a regime shift to the very stable state is signaled in advance by specific changes in the dynamics of the turbulent boundary layer. Here, we show how these changes may be used to infer a quantitative estimate of the transition point from the weakly stable boundary layer to the very stable boundary layer. In addition, it is shown that the idealized, nocturnal boundary-layer system shares important similarities with generic non-linear dynamical systems that exhibit critical transitions. Therefore, the presence of other, generic early warning signals is tested as well. Indeed, indications are found that such signals are present in stably stratified turbulent flows.

Initial operation of a newly developed multichord motional Stark effect diagnostic in KSTAR.

A photo-elastic modulator based 25-chord motional Stark effect (MSE) diagnostic has been successfully developed and commissioned in Korea Superconducting Tokamak Advanced Research. The diagnostic measures the radial magnetic pitch angle profile of the Stark splitting of a D-alpha line at 656.1 nm by the electric field associated with the neutral deuterium heating beam. A tangential view of the neutral beam provides a good spatial resolution of 1-3 cm for covering the major radius from 1.74 m to 2.28 m, and the time resolution is achieved at 10 ms. An in-vessel calibration before the vacuum closing as well as an in situ calibration during the tokamak operation was performed by means of specially designed polarized lighting sources. In this work, we present the final design of the installed MSE diagnostic and the first results of the commissioning.

Kinds versus continua: a review of psychometric approaches to uncover the structure of psychiatric constructs.

The question of whether psychopathology constructs are discrete kinds or continuous dimensions represents an important issue in clinical psychology and psychiatry. The present paper reviews psychometric modelling approaches that can be used to investigate this question through the application of statistical models. The relation between constructs and indicator variables in models with categorical and continuous latent variables is discussed, as are techniques specifically designed to address the distinction between latent categories as opposed to continua (taxometrics). In addition, we examine latent variable models that allow latent structures to have both continuous and categorical characteristics, such as factor mixture models and grade-of-membership models. Finally, we discuss recent alternative approaches based on network analysis and dynamical systems theory, which entail that the structure of constructs may be continuous for some individuals but categorical for others. Our evaluation of the psychometric literature shows that the kinds-continua distinction is considerably more subtle than is often presupposed in research; in particular, the hypotheses of kinds and continua are not mutually exclusive or exhaustive. We discuss opportunities to go beyond current research on the issue by using dynamical systems models, intra-individual time series and experimental manipulations.

A high etendue spectrometer suitable for core charge eXchange recombination spectroscopy on ITER.

A feasibility study for the use of core charge exchange recombination spectroscopy on ITER has shown that accurate measurements on the helium ash require a spectrometer with a high etendue of 1mm(2)sr to comply with the measurement requirements [S. Tugarinov et al., Rev. Sci. Instrum. 74, 2075 (2003)]. To this purpose such an instrument has been developed consisting of three separate wavelength channels (to measure simultaneously He/Be, C/Ne, and H/D/T together with the Doppler shifted direct emission of the diagnostic neutral beam, the beam emission (BES) signal), combining high dispersion (0.02 nm/pixel), sufficient resolution (0.2 nm), high efficiency (55%), and extended wavelength range (14 nm) at high etendue. The combined measurement of the BES along the same sightline within a third wavelength range provides the possibility for in situ calibration of the charge eXchange recombination spectroscopy signals. In addition, the option is included to use the same instrument for measurements of the fast fluctuations of the beam emission intensity up to 2 MHz, with the aim to study MHD activity.

Real-time MSE measurements for current profile control on KSTAR.

To step up from current day fusion experiments to power producing fusion reactors, it is necessary to control long pulse, burning plasmas. Stability and confinement properties of tokamak fusion reactors are determined by the current or q profile. In order to control the q profile, it is necessary to measure it in real-time. A real-time motional Stark effect diagnostic is being developed at Korean Superconducting Tokamak for Advanced Research for this purpose. This paper focuses on 3 topics important for real-time measurements: minimize the use of ad hoc parameters, minimize external influences and a robust and fast analysis algorithm. Specifically, we have looked into extracting the retardance of the photo-elastic modulators from the signal itself, minimizing the influence of overlapping beam spectra by optimizing the optical filter design and a multi-channel, multiharmonic phase locking algorithm.

Early warning of climate tipping points from critical slowing down: comparing methods to improve robustness.

We address whether robust early warning signals can, in principle, be provided before a climate tipping point is reached, focusing on methods that seek to detect critical slowing down as a precursor of bifurcation. As a test bed, six previously analysed datasets are reconsidered, three palaeoclimate records approaching abrupt transitions at the end of the last ice age and three models of varying complexity forced through a collapse of the Atlantic thermohaline circulation. Approaches based on examining the lag-1 autocorrelation function or on detrended fluctuation analysis are applied together and compared. The effects of aggregating the data, detrending method, sliding window length and filtering bandwidth are examined. Robust indicators of critical slowing down are found prior to the abrupt warming event at the end of the Younger Dryas, but the indicators are less clear prior to the Bølling-Allerød warming, or glacial termination in Antarctica. Early warnings of thermohaline circulation collapse can be masked by inter-annual variability driven by atmospheric dynamics. However, rapidly decaying modes can be successfully filtered out by using a long bandwidth or by aggregating data. The two methods have complementary strengths and weaknesses and we recommend applying them together to improve the robustness of early warnings.

Treatment of pacemaker-induced superior vena cava syndrome by balloon angioplasty and stenting.

Superior vena cava (SVC) syndrome is a rare but serious complication after pacemaker implantation. This report describes three cases of SVC syndrome treated with venoplasty and venous stenting, with an average follow-up of 30.7 (±3.1) months. These cases illustrate that the definitive diagnosis, and the extent and location of venous obstruction, can only be determined by venography.

Creation of a gilded trap by the high economic value of the Maine lobster fishery.

Unsustainable fishing simplifies food chains and, as with aquaculture, can result in reliance on a few economically valuable species. This lack of diversity may increase risks of ecological and economic disruptions. Centuries of intense fishing have extirpated most apex predators in the Gulf of Maine (United States and Canada), effectively creating an American lobster (Homarus americanus) monoculture. Over the past 20 years, the economic diversity of marine resources harvested in Maine has declined by almost 70%. Today, over 80% of the value of Maine's fish and seafood landings is from highly abundant lobsters. Inflation-corrected income from lobsters in Maine has steadily increased by nearly 400% since 1985. Fisheries managers, policy makers, and fishers view this as a success. However, such lucrative monocultures increase the social and ecological consequences of future declines in lobsters. In southern New England, disease and stresses related to increases in ocean temperature resulted in more than a 70% decline in lobster abundance, prompting managers to propose closing that fishery. A similar collapse in Maine could fundamentally disrupt the social and economic foundation of its coast. We suggest the current success of Maine's lobster fishery is a gilded trap. Gilded traps are a type of social trap in which collective actions resulting from economically attractive opportunities outweigh concerns over associated social and ecological risks or consequences. Large financial gain creates a strong reinforcing feedback that deepens the trap. Avoiding or escaping gilded traps requires managing for increased biological and economic diversity. This is difficult to do prior to a crisis while financial incentives for maintaining the status quo are large. The long-term challenge is to shift fisheries management away from single species toward integrated social-ecological approaches that diversify local ecosystems, societies, and economies.

Peak longitudinal strain delay is superior to TDI in the selection of patients for resynchronisation therapy.

BACKGROUND: Mechanical dyssynchrony has proven to be superior to QRS duration in predicting response to cardiac resynchronisation therapy (CRT). Whether time to peak longitudinal strain delay between the mid-septum and mid-lateral left ventricular wall better predicts CRT response than tissue Doppler imaging (TDI) is unclear. This study compares the value of the two methods for the assessment of mechanical dyssynchrony and prediction of CRT responders. METHODS: 66 clinical responders and 17 nonresponders to CRT with severe systolic heart failure (LVEF <35%), New York Heart Association classification III or IV and a wide QRS >130 ms with left bundle branch block were evaluated by peak longitudinal strain and TDI. Doppler echocardiograms and electromechanical time delay (EMD) intervals were acquired before and after pacemaker implantation. RESULTS: In all responders EMD measured by peak longitudinal strain was >60 ms before implantation, compared with 76% of the patients measured by TDI. Nonresponders had EMD <60 ms measured by both techniques. Only peak longitudinal strain delay showed shortened values in every responder postimplantation and demonstrated the most significant reduction and could predict responders to CRT. However, EMD measured by TDI did not diminish in 30% of the positive clinical responders. Nonresponders showed worsening of the EMD with peak longitudinal strain, but not with TDI. CONCLUSIONS: Responders to CRT can be excellently predicted if EMD before implantation determined by peak longitudinal strain delay is >60 ms. Peak longitudinal strain delay appears to be superior to TDI to predict the response to CRT. (Neth Heart J 2010;18:574-82.).

Baffle puncture guided by transoesophageal echocardiography in a patient with dextrocardia and Mustard correction.

A baffle puncture is a challenging procedure but can be safely done using direct visualization of the region of interest. To our knowledge, however, it has never been performed in a patient with dextrocardia. We present a 62-year-old male with dextrocardia, right isomerism, congenitally corrected transposition of the great arteries, persistent left-sided superior and inferior caval veins, atrial septum defect, and pulmonary valve stenosis. The atrial septum defect was surgically closed with a Teflon patch, a variant Mustard operation was performed, and also a prosthetic tricuspid valve was implanted. The patient developed multiple episodes of atrial tachycardia leading to acute heart failure on many occasions. An electrophysiological study was undertaken in order to create a bi-atrial electro-anatomical map. Owing to the presence of a prosthetic tricuspid valve, the femoral venous access was used and a baffle puncture was performed using continuous monitoring with fluoroscopy and transoesophageal echocardiography (TEE). The baffle puncture was successful and the tachycardia was ablated in the systemic venous atrium. To our knowledge, we present the very first case report demonstrating a successful baffle puncture in a patient with dextrocardia and Mustard correction. Direct imaging using TEE seems to be a very useful tool for guiding the puncture.

[Purulent pericarditis in a patient with knee pain]. / Een purulente pericarditis bij een pijnlijke knie.

A 40-year-old man with pain in his left, swollen knee that persisted for 6 weeks presented with chest pain, dyspnoea and subfebrile temperature. The pain worsened during inspiration and was relieved by sitting up straight. The electrocardiogram showed pericarditis. The patient was treated with high-dose carbasalate calcium. Initially, echocardiography revealed a 2-cm pericardial effusion with no signs of influx inhibition. Blood cultures were positive for Neisseria meningitidis, and treatment was expanded to include antibiotics. Based on a deterioration in patient condition and the tamponade image, pericardiocentesis was performed. Repeated transoesophageal echocardiography showed insufficient drainage of the purulent pericardial effusion. Pericardiectomy was then performed. The patient was doing very well, 3 years after this. If left untreated, the mortality rate for purulent pericarditis approaches 100%. It is therefore important to diagnose at an early stage so that treatment with antibiotics and surgery, which can reduce mortality considerably, can be performed.

Helical structure of unidirectionally shadowed metal replicas of cyanide hydratase from Gloeocercospora sorghi.

The helical filaments of the cyanide hydratase from Gloeocercospora sorghi have been reconstructed in three dimensions from freeze dried, unidirectionally shadowed specimens using iterative real-space helical reconstruction. The average power spectrum of all selected images has three clear reflections on different layer lines. The reconstruction is complicated by the fact that three possible indexing schemes are possible and reconstructions using the starting symmetries based on each of these indexing schemes converge on three-dimensional volumes which appear plausible. Because only one side is visible in shadowed specimens, it is necessary to examine the phases from a single filament by cryo-electron microscopy in order to make an unequivocal assignment of the symmetry. Because of the novel nature of the reconstruction method used here, conventional cryo-EM methods were also used to determine a second reconstruction, allowing us to make comparisons between the two. The filament is shown to have a left-handed one-start helix with D(1) symmetry, 5.46 dimers per turn and a pitch of 7.15nm. The reconstruction suggests the presence of an interaction across the groove not previously seen in nitrilase helical fibres.

Embolization of a huge tricuspid valve vegetation in a patient with intravenous drug abuse and HIV infection with an remarkable recovery.

We describe a patient with bacterial tricuspid valve endocarditis as a result of using intravenous drugs, and HIV infection. The course was complicated by embolisation of this huge vegetation; the follow-up was remarkable. Although this condition is life threatening, it was accompanied by a relatively slight derangement in the haemodynamic and respiratory condition of the patient. We describe the implications of intravenous drug use and HIV infection for the management of this condition.

A giant pseudoaneurysm becoming apparent after cardiac resynchronisation therapy.

A 57-year-old male patient with coronary artery disease developed a pseudoaneurysm after an inferior infarct in 1997. He underwent coronary bypass surgery and resection of the pseudoaneurysm located at the inferior wall. Unfortunately, the pseudoaneurysm recurred due to dehiscence of the patch, necessitating a second surgical intervention. After six years he developed progressive heart failure due to severe left ventricular dysfunction. He was referred to our institution for cardiac resynchronisation therapy (CRT) because of drug refractory heart failure which was associated with a left bundle branch block, ejection fraction of 12%, and a NYHA class IV status. After successful implantation of a biventricular pacemaker, a remarkable clinical recovery was observed. Left ventricular function improved and echocardiography now demonstrated that the pseudoaneurysm at the inferior wall had recurred for the third time. This diagnosis could not be established by preoperative echocardiography.