Abstract The malignant transformation of giant cell tumor (GCT) of bone is a relatively rare event. Most cases are ‘secondary’ tumors, usually arising in lesions that have been treated previously ...with radiotherapy. Less commonly, secondary malignancy occurs in GCTs that have been treated surgically. The growth of ‘primary’ malignant GCTs has also been reported, but with much lower frequency. In both primary and secondary malignant GCTs, osteosarcomatous transformation is the most frequent histological type seen however malignant fibrous histiocytoma and fibrosarcoma may also develop. Currently, there are no proven radiological or pathological features that can reliably be used to predict malignant transformation in GCT of bone. We discuss the case of a primary malignant GCT with intratumoral calcification. This radiographic finding may herald the presence of osteosarcoma.
Pseudomonas savastanoi pv. savastanoi was identified as the cause of galling on olives (Olea europaea), cv Barnea in South Australia in May 2003 from a property at Greenfields asymptotically =10 km ...north of Adelaide. The bacterium was recovered from galls on 2-year-old olive trees (cv. Barnea) showing symptoms consistent with those attributed to olive knot. Following a targeted survey of cv. Barnea, further infections were located on 2 to 5-year-old trees in four other plantings in South Australia. This is the first record of olive knot in Australia.PUBLICATION ABSTRACT
The exotic Asiatic Citrus Psyllid, Diaphorina citri, would pose a significant threat to the Australian citrus industry and Australia's unique (and often rare or threatened), native biodiversity were ...it to become established due to its ability to vector the debilitating bacterial disease huanglongbing. It is not known if Australia's six indigenous Citrus spp. and other Rutaceae are potential hosts for D. citri, or whether the psyllid could transmit the disease to them. We also do not know whether native psyllids, some of whose host plant relationships are yet to be established, could also harbour and transmit the disease. We examine the consequences of D. citri in Australia to native Rutaceae and psyllids. The situation is further compounded by climate change which will impact the likely establishment and spread of the psyllid. Predictive modelling suggests southern locations would be more suitable for the successful development of the psyllid but that a shortened period when plants are available for feeding would actually result in a reduction in overall potential population. Research priorities for determining the degree of risk posed by the introduction and establishment of D. citri are outlined, including the potential impact of climate change.
Properties of whey and egg white protein foams Pernell, C.W.; Foegeding, E.A.; Luck, P.J. ...
Colloids and surfaces. A, Physicochemical and engineering aspects,
05/2002, Letnik:
204, Številka:
1
Journal Article
Recenzirano
Foams made of varying concentrations (2–20% w/v protein) of egg white and whey protein isolate were compared by measuring rheological and microstructural properties. Egg white proteins formed foams ...with higher yield stress (
τ) at lower protein concentrations and less whipping time than whey protein isolate foams. The model of Princen and Kiss J. Coll. Interf. Sci. 128 (1989) 176 predicts a relationship among
τ, surface tension (
σ), phase volume (
φ), and bubble size (
R
32). This was supported by
τ increasing with
φ, and the relationship between
τ and
φ
1/3 becoming more linear as protein concentration increased. However, egg white foams had yield stress values as much as 100 Pa greater than whey protein foams, despite having similar phase volumes, bubble size, and lower surface tensions. The experimentally determined factors,
Y(
φ), for egg white and whey protein isolate foams were within the range determined by Princen and Kiss J. Coll. Interf. Sci. 128 (1989) 176 for concentrated emulsions. Egg white foams were different in that the values for
Y(
φ) increased at lower phase volumes than for whey protein isolate foams or concentrated emulsions. These results suggest that specific proteins contribute to foam
τ by some means in addition to altering surface properties.
We investigate a mean-field model of interacting synapses on a directed neural network. Our interest lies in the slow adaptive dynamics of synapses, which are driven by the fast dynamics of the ...neurons they connect. Cooperation is modelled from the usual Hebbian perspective, while competition is modelled by an original polarity-driven rule. The emergence of a critical manifold culminating in a tricritical point is crucially dependent on the presence of synaptic competition. This leads to a universal \(1/t\) power-law relaxation of the mean synaptic strength along the critical manifold and an equally universal \(1/\sqrt{t}\) relaxation at the tricritical point, to be contrasted with the exponential relaxation that is otherwise generic. In turn, this leads to the natural emergence of long- and short-term memory from different parts of parameter space in a synaptic network, which is the most novel and important result of our present investigations.
Abstract
Background
An emerging model posits that perceptual inference deficits could lead to distorted internal models of the world, which could then explain the existence of abnormal beliefs or ...delusions experienced by people with schizophrenia(PSZ). Here, we used motion perception tasks to explore how construction of internal models of the environment are utilized unconsciously and automatically in uncertain circumstances to predict and disambiguate perceptual inputs and guide decisions in schizophrenia.
Methods
We used a random dot kinematogram algorithm developed by Roitman & Shadlen (2002). In the first experiment (PSZ,N=47, Controls,N=38), we used 4 (20–100%) motion coherence levels and 2 motion durations (500 and 1000 ms). On each trial, direction of motion was selected randomly from 0.1 - 360°. Second, to test perceptual inference when motion direction changes, we implemented a similar task (PSZ, N=44, Controls=36) using 2 coherence levels (35% and 100%) in which, midway through the trials, motion direction changed by 90°. In both tasks, participants were to report the direction perceived at the end of the trial (the changed direction for the second task) using a mouse to align a bar onto the perceived direction of motion. Performance was quantified as the angular difference between the true direction and the reported direction. We quantified response errors using a three-component mixture model, assuming that participants’ direction reports were a combination of 1) correct perception of motion direction with some precision, 2) random guesses, and 3) opposite direction perception of the true motion direction. Further, we derived response bias estimates based on (i) influence of the prior trial when the current trial was of low coherence and (ii) initial motion direction (in the motion change experiment).
Results
We observed that in both tasks, precision estimates decreased with reducing coherence, and more so in PSZ, and guess rate estimates were higher in PSZ across all coherence levels. Importantly, we found that when the current trial was of a lower coherence level than the prior trial, the perceived motion direction in PSZ was influenced by the prior trial motion direction, as evidenced by a significantly greater response bias towards the prior than in controls. Further, in PSZ, this response bias correlated with mean precision estimates across low coherence trials. In the changed motion estimation task, we observed a similar pattern, whereby PSZ manifested lower precision estimates, and more so on low coherence trials, and this was associated with response bias towards initial motion direction. Interestingly, in PSZ, response bias measures (towards the prior) were associated with the preoccupation and conviction dimensions on the Peters Delusions Inventory, while precision measures were associated with visual hallucinations.
Discussion
These results suggest that, in situations of uncertainty (in this case, low coherence trials), PSZ are more influenced by prior expectation and sensory evidence from the previous trial to discriminate new perceptual inputs and to guide decisions. These data also provide further evidence for the theoretical link between positive symptoms such as hallucinations and delusions and aberrant perceptual inference.
We consider the quantum centipede made of \(N\) fermionic quantum walkers on the one-dimensional lattice interacting by means of the simplest of all hard-bound constraints: the distance between two ...consecutive fermions is either one or two lattice spacings. This composite quantum walker spreads ballistically, just as the simple quantum walk. However, because of the interactions between the internal degrees of freedom, the distribution of its center-of-mass velocity displays numerous ballistic fronts in the long-time limit, corresponding to singularities in the empirical velocity distribution. The spectrum of the centipede and the corresponding group velocities are analyzed by direct means for the first few values of \(N\). Some analytical results are obtained for arbitrary \(N\) by exploiting an exact mapping of the problem onto a free-fermion system. We thus derive the maximal velocity describing the ballistic spreading of the two extremal fronts of the centipede wavefunction, including its non-trivial value in the large-\(N\) limit.
Amiodarone: clinical trials Naccarelli, G V; Wolbrette, D L; Patel, H M ...
Current opinion in cardiology
15, Številka:
1
Journal Article
Recenzirano
Amiodarone is an antiarrhythmic agent commonly used in the treatment of supraventricular and ventricular tachyarrhythmias. This article reviews the results and clinical implications of primary and ...secondary prevention trials in which amiodarone was used in one of the treatment arms. Key post-myocardial infarction primary prevention trials include the European Myocardial Infarct Amiodarone Trial (EMIAT) and the Canadian Amiodarone Myocardial Infarction Trial (CAMIAT), both of which demonstrated that amiodarone reduced arrhythmic but not overall mortality. In congestive heart failure patients, amiodarone was studied as a primary prevention strategy in two pivotal trials: Grupo de Estudio de la Sobrevida en la Insuficiencia Cardiac en Argentina (GESICA) and Amiodarone in Patients With Congestive Heart Failure and Asymptomatic Ventricular Arrhythmia (CHF-STAT). Amiodarone was associated with a neutral overall survival and a trend toward improved survival in nonischemic cardiomyopathy patients in CHF/STAT and improved survival in GESICA. In post-myocardial infarction patients with nonsustained ventricular tachycardia and a depressed ejection fraction, the Multicenter Automatic Defibrillator Implantation Trial (MADIT) demonstrated that implantable cardioverter-defibrillators (ICD) statistically improved survival compared to the antiarrhythmic drug arm, most of whose patients were taking amiodarone. In patients with histories of sustained ventricular tachycardia or ventricular fibrillation, the Cardiac Arrest Study in Seattle: Conventional Versus Amiodarone Drug Evaluation (CASCADE) trial demonstrated that empiric amiodarone lowered arrhythmic recurrence rates compared to other drugs guided by serial Holter or electrophysiologic studies. However, arrhythmic death rates were high in both treatment arms of the study. Several secondary prevention trials, including the Antiarrhythmics Versus Implantable Defibrillators Study (AVID), the Canadian Implantable Defibrillator Study (CIDS), and the Cardiac Arrest Study Hamburg (CASH), have demonstrated the superiority of ICD therapy compared to empiric amiodarone in improving overall survival. Based on the above findings, amiodarone is safe to use in post-myocardial infarction and congestive heart failure patients that need antiarrhythmic therapy. Although amiodarone is effective in treating malignant arrhythmias, high-risk patients should be considered for an ICD as frontline therapy.
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