Flip-flop Phenomenon Research Articles

Flow around a circular cylinder with slit

Characteristics of flow around a modified circular cylinder are experimentally investigated in the present study. The experimental campaign was performed in a wind tunnel at the Reynolds number of Re=2.67×104, based on the cylinder diameter D and the incoming airflow speed. The cylindrical test model is modified with a slit parallel to the incoming airflow to create a flow communicating channel between the windward and leeward stagnation points. The slit width S changes from 0.05D to 0.15D with an increment of 0.025D. Pressure distributions on the cylinder surface were measured to estimate the aerodynamic forces acting on the test model and a particle image velocimetry (PIV) system was employed to quantify the wake flow patterns of the natural and modified cylindrical test models. Experiment results reveal that a slit contributes to reducing the drag and suppressing the fluctuating amplitude of the dynamic wind loads acting on the test model. The changing trend in drag reduction and lift suppression with the increase of slit width are also discussed based on the surface pressure and PIV measurement results. The PIV measurement results demonstrate clearly that the slit generates a self-issuing jet into the cylinder wake and the passive jet is effective in manipulating the wake vortex shedding process from the circular cylinder. As the jet vortices being shifted downstream, they help to detach the shear layers rolled up from both sides of the circular cylinder. Because of this dynamic interaction process, the antisymmetric pattern of the wake vortex shedding from a natural cylinder is found to be converted to a bistable mode flow behind the slotted cylinders. As a result, the dimensionless vortex shedding frequency is observed to be switched to a very low level and a flip-flop phenomenon is found. A linear stability analysis is then performed to suggest that the intrinsic nature of the cylinder wake flow is greatly modified with the implementation of a slit.

HIGH-SPEED BULLET EJECTIONS DURING THE AGB-TO-PLANETARY NEBULA TRANSITION: HST OBSERVATIONS OF THE CARBON STAR, V HYDRAE

ABSTRACT The well-studied carbon star, V Hya, showing evidence for high-speed, collimated outflows and dense equatorial structures, is a key object in the study of the poorly understood transition of AGB stars into aspherical planetary nebulae. Using the Space Telescope Imaging Spectrograph instrument on board the Hubble Space Telescope, we have obtained high spatial-resolution long-slit optical spectra of V Hya that show high-velocity emission in [S ii] and [Fe ii] lines. Our data set, spanning three epochs spaced apart by a year during each of two periods (in 2002–2004 and 2011–2013), shows that V Hya ejects high-speed (∼200–250 ) bullets once every ∼8.5 years. The ejection axis flip–flops around a roughly eastern direction, both in and perpendicular to the sky-plane, and the radial velocities of the ejecta also vary in concert between low and high values. We propose a model in which the bullet ejection is associated with the periastron passage of a binary companion in an eccentric orbit around V Hya with an orbital period of ∼8.5 years. The flip–flop phenomenon is likely the result of collimated ejection from an accretion disk (produced by gravitational capture of material from the primary) that is warped and precessing, and/or that has a magnetic field that is misaligned with that of the companion or the primary star. We show how a previously observed 17 year period in V Hya’s light-cycle can also be explained in our model. Additionally, we describe how the model proposed here can be extended to account for multipolar nebulae.

Impact of patient age on the iodine/FDG "flip-flop" phenomenon in lung metastasis from thyroid cancer.

Radioiodine therapy is an effective treatment for lung metastasis from thyroid cancer. However, cases of lung metastasis without iodine uptake are often encountered. In such cases, FDG accumulation in lung lesions is often observed. There is a reverse relationship between iodine and FDG accumulation in thyroid cancer lesions, the so-called "flip-flop" phenomenon. The aim of this study was to assess the relationship between patient age and the occurrence of the flip-flop phenomenon. Eighty-six patients who underwent radioiodine therapy for lung metastasis were studied retrospectively (age 17-73years; median 60years; males:females 22:64). We compared the clinical data and imaging findings (size and FDG uptake of lung nodules) between patients with (n=44) and without (n=42) iodine uptake in lung metastasis. Significantly more young patients showed iodine accumulation in lung metastasis than old patients (p=0.0025). Lung metastases with larger size or greater FDG uptake showed no iodine uptake more frequently with significant difference (p=0.015 and <0.001, respectively). Among patients with FDG uptake in the lung metastasis, 57.1% of young patients (<60years) and 24.3% of the old patients (≥60years) showed iodine uptake (p=0.0029). Higher patient age and lung nodules with large size or FDG accumulation are negative factors for iodine accumulation in lung metastases from thyroid cancer. In addition, our results show that young patients have a greater likelihood of iodine uptake even when FDG accumulates in lung metastasis, in contrast to old patients.

Comparative pharmacokinetics of ceftiofur hydrochloride and ceftiofur sodium after administration to water buffalo (Bubalus bubalis)

OBJECTIVE To evaluate pharmacokinetics and bioavailability after administration of ceftiofur hydrochloride and ceftiofur sodium to water buffalo (Bubalus bubalis). ANIMALS 5 healthy adult water buffalo (3 males and 2 nonlactating females). PROCEDURES All animals received a dose (2.2 mg/kg) of 3 ceftiofur products (2 commercially available suspensions of ceftiofur hydrochloride [CEF1 and CEF2, IM] and ceftiofur sodium [CEF3, IV]). Blood samples were collected for up to 196 hours. Concentrations of ceftiofur in plasma were determined by use of high-performance liquid chromatography, and pharmacokinetic parameters were calculated on the basis of noncompartmental methods. RESULTS Most of the pharmacokinetic parameters, except for bioavailability and the area under the concentration-time curve extrapolated to infinity, were significantly different between the 2 products administered IM. Mean ± SD bioavailability of CEF1 and CEF2 was 89.57 ± 32.84% and 86.28 ± 11.49%, respectively, which indicated good absorption of both products. In addition, there was a longer drug residence time for CEF1 than for CEF2. Data analysis for CEF1 revealed a flip-flop phenomenon. CONCLUSIONS AND CLINICAL RELEVANCE In this study, there was good absorption of CEF1, and CEF1 had a longer drug residence time in vivo than did CEF2. On the basis of pharmacokinetic parameters and the in vitro antimicrobial susceptibility, a dosage regimen of 2.2 mg/kg administered at 48- and 36-hour intervals for CEF1 and CEF2, respectively, could be an appropriate choice for the treatment of buffalo with infectious diseases.

Interaction between charged nanoparticles and vesicles: coarse-grained molecular dynamics simulations.

An enhanced understanding of the interactions between charged nanoparticles (CNPs) and a curved vesicle membrane may have important implications for the design of nanocarrier agents and drug delivery systems. In this work, coarse-grained molecular dynamics (CGMD) simulations of the CNPs with vesicles were performed to evaluate the effects of hydrophobicity, surface charge density and distribution on the curved vesicle membrane. The simulations reveal that there exist four distinct modes (insertion, repulsion, adhesion, and penetration) in the CNP-vesicle interaction. In contrast to previous studies on a planar membrane, the interactions of CNPs and a curved vesicle membrane show some novel properties. CNPs with low surface charge density (or neutral ones) can penetrate into the interior of the vesicle membrane more easily because of the increased membrane tension. The asymmetry between two leaflets of the membrane induces different interaction strengths of the negatively CNPs with the outer and inner leaflets. After penetration, the negatively CNPs prefer to stay close to the inner leaflet inside the vesicle where CNPs have stronger interactions with their surroundings. In the present work, we analyze the detailed mechanism of CNP's spontaneous penetration into vesicles, which is rarely mentioned in previous simulations. Moreover, we found that the negatively CNPs with the same surface charge density but different distribution result in different modes: the homogeneous mode is more likely to adsorb on the vesicle surface while the inhomogeneous mode tends to be more penetrable. In addition, the flip-flop phenomenon of the lipid membrane and the exchanging of water in or out of the vesicle were observed during penetration. Our results demonstrate that the electrostatic effect plays an essential role in the interaction between CNPs and vesicles. These findings suggest a way of controlling the CNP-vesicle interaction by coupling the hydrophobic properties, surface charge density and distribution of CNPs to enhance the probability of CNP's penetration into vesicles.

Pattern Recognition in Pharmacokinetic Data Analysis.

Pattern recognition is a key element in pharmacokinetic data analyses when first selecting a model to be regressed to data. We call this process going from data to insight and it is an important aspect of exploratory data analysis (EDA). But there are very few formal ways or strategies that scientists typically use when the experiment has been done and data collected. This report deals with identifying the properties of a kinetic model by dissecting the pattern that concentration-time data reveal. Pattern recognition is a pivotal activity when modeling kinetic data, because a rigorous strategy is essential for dissecting the determinants behind concentration-time courses. First, we extend a commonly used relationship for calculation of the number of potential model parameters by simultaneously utilizing all concentration-time courses. Then, a set of points to consider are proposed that specifically addresses exploratory data analyses, number of phases in the concentration-time course, baseline behavior, time delays, peak shifts with increasing doses, flip-flop phenomena, saturation, and other potential nonlinearities that an experienced eye catches in the data. Finally, we set up a series of equations related to the patterns. In other words, we look at what causes the shapes that make up the concentration-time course and propose a strategy to construct a model. By practicing pattern recognition, one can significantly improve the quality and timeliness of data analysis and model building. A consequence of this is a better understanding of the complete concentration-time profile.

Simultaneous Characterization of Intravenous and Oral Pharmacokinetics of Lychnopholide in Rats by Transit Compartment Model.

The pharmacokinetic properties of a new molecular entity are important aspects in evaluating the viability of the compound as a pharmacological agent. The sesquiterpene lactone lychnopholide exhibits important biological activities. The objective of this study was to characterize the pharmacokinetics of lychnopholide after intravenous administration of 1.65 mg/kg (n = 5) and oral administration of 3.3 mg/kg (n = 3) lychnopholide in rats (0.2 ± 0.02 kg in weight) through nonlinear mixed effects modeling and non-compartmental pharmacokinetic analysis. A highly sensitive analytical method was used to quantify the plasma lychnopholide concentrations in rats. Plasma protein binding of this compound was over 99 % as determined by a filtration method. A two-compartment body model plus three transit compartments to characterize the absorption process best described the disposition of lychnopholide after both routes of administration. The oral bioavailability was approximately 68 %. The clearance was 0.131 l/min and intercompartmental clearance was 0.171 l/min; steady-state volume of distribution was 4.83 l. The mean transit time for the absorption process was 9.15 minutes. No flip-flop phenomenon was observed after oral administration. The pharmacokinetic properties are favorable for further development of lychnopholide as a potential oral pharmacological agent.

Chromospheric activity and rotational modulation of the RS Canum Venaticorum binary V711 Tauri during 1998–2004

We present long-term high-resolution spectroscopic observations of the very active RS Canum Venaticorum-type star V711 Tau, obtained during several observing runs from 1998 to 2004, and study its chromospheric activity. Using the spectral subtraction technique, several optical chromospheric activity indicators [including the He I D-3, Na I D-1, D-2, H alpha and Ca II infrared triplet (IRT) lines] formed at different atmospheric heights are analysed. Strong chromospheric emission supports earlier results that indicate that V711 Tau is a very active system. Two large optical flares were detected during our observations. The results suggest that the main part of chromospheric emission is attributed to the primary star of the system. The secondary also presents weak emission but is less active. The ratios of EW8542/EW8498 indicate that Ca II IRT emission arises predominantly from plage-like regions. We have found rotational modulation of chromospheric activity in the H alpha and Ca II IRT lines, which suggests the presence of the chromospheric active longitudes over the surface of V711 Tau. Two active longitudes separated by about 180 degrees were observed to dominate the activity, and the so-called flip-flop phenomenon was seen during our observations. Moreover, the chromospheric activity level shows a long-term variation that gradually increases from a deep minimum near the year 2002. A close spatial connection of photospheric spots and chromospheric active regions in both short and long timescales was found for V711 Tau.

Flip-flop phenomenon in systemic sclerosis on fluorodeoxyglucose positron emission tomography/computed tomography.

Systemic sclerosis (SSc) is a rare autoimmune disease, which may affect multiple organ systems. Fluorine-18-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) can demonstrate the degree and anatomical extent of involvement in the entire body and coexisting malignancies in connective tissue diseases. We present a case of SSc with an increased 18F-FDG uptake in the cutaneous and subcutaneous tissues even higher than the neighboring skeletal muscles (“flip-flop phenomenon,” that is, an increased 18F-FDG uptake in the skin but a decreased 18F-FDG uptake in the skeletal muscles).

Population pharmacogenetic pharmacokinetic modeling for flip-flop phenomenon of enteric-coated mycophenolate sodium in kidney transplant recipients.

Enteric-coated mycophenolate sodium (EC-MPS) is effective and safe in preventing rejection after transplantation and is mainly transported by ABCs and OATPs and metabolized by UGTs. The genetic polymorphisms affect the inter-individual variation in drug disposition and elimination. The aims of this study were to develop a population pharmacokinetic (PK) model and to evaluate the influence of genetic and clinical factors on the PK of mycophenolic acid (MPA) in Korean renal transplant recipients. Population analysis of EC-MPS was performed using non-linear mixed effects modeling (NONMEM). After clinical and genetic factors were evaluated using a stepwise covariate method, we selected clinically relevant covariates considering covariate effects. The final model was validated by bootstrap and visual predictive check. At last, we performed the model-based simulations in order to explore an optimal dose to achieve target area under the curve (AUC) in hypothetical scenarios. From 166 plasma concentrations (n=34), a time-lagged two-compartment with a flip-flop model best describes the PK of MPA. The covariate analysis identified lower creatinine clearance (CLcr) and SLCO1B1 variant genotype were correlated with lower MPA clearance, on the contrary, UGT1A9 variant had decreased distribution of MPA, contributing to lower absorption. When considering to UGT1A9, SLCO1B1 genotypes, and renal function, the new recommended dose of 540 mg twice daily resulted in a higher success of achieving the target AUC0-12h in the 30-60 mg.h/L. CLcr, UGT1A9 and SLCO1B1 genotypes seem to be promising parameters to predict the pharmacokinetics with flip-flop phenomenon of EC-MPS in transplant recipient having stable renal function. This model on clinical practice may help prevent overexposure and achieve a proper AUC in the Korean population.

Effect of Ambient Pressure Fluctuations on Dual-Bell Transition Behavior

An experimental investigation was conducted to study the effect of ambient pressure fluctuations on the dual-bell transition behavior. Ambient or backpressure fluctuations of different frequencies (1.0, 1.5, and 3 Hz) were artificially introduced inside the high-altitude simulation chamber using three magnetic valves. The dual-bell transition behavior was found to be very sensitive to backpressurefluctuations of magnitude , which triggered a flip-flop phenomenon that was observed to continue as long as the fluctuations prevailed. Increasing the throttling-up rate also did not seem to help much in achieving a stable dual-bell transition within the scope of the present tests. This, too, was not favorable, as it can lead to a delay in transition. These test results suggested that the dual-bell nozzle can present problems in real-flight operation, especially when the launcher experiences the buffeting phase of flight. The solution perhaps lies in increasing the dual-bell stability parameter to a value greater than the magnitude of backpressure fluctuations so as to avoid the nozzle pressure ratio range that will set the dual bell into a nonstop flip-flop mode during buffeting.

Renaissance of (18)F-FDG positron emission tomography in the imaging of pheochromocytoma/paraganglioma.

Renaissance of (18)F-FDG positron emission tomography in the imaging of pheochromocytoma/paraganglioma.

Pharmacokinetic Assessment of Absorptive Interaction of Oral Etoposide and Morphine in Rats

Etoposide and morphine are well known P-glycoprotein (P-gp) substrates. The pharmacokinetic effect of morphine on plasma etoposide concentration after the oral concomitant use of etoposide and morphine in rats was assessed using a population analysis approach. A P-gp substrate quinidine and the anticholinergic drug propantheline were also administered with etoposide to compare with the effects of morphine. Plasma etoposide concentration after oral administration was well described using a linear 2-compartment open model with first-order kinetic absorption from the intestine, although a flip-flop phenomenon was shown. After administration of etoposide with morphine, an increased concentration and extended time at maximum concentration were observed compared with the administration of etoposide alone. However, coadministered quinidine significantly increased the maximum concentration without changing the time of the peak concentration of etoposide. Coadministered propantheline significantly extended the time at maximum concentration, although no changes in the peak concentration of etoposide were observed. These coadministered drugs resulted in different pharmacokinetic parameters of etoposide and acted as a significant covariate. That is, morphine and quinidine significantly increased the bioavailability of etoposide believed to be due to competitive P-gp inhibition in the intestine. In contrast, morphine and propantheline decreased the absorption rate constant and were associated with the suppression of enterokinesis. These results indicate that it is necessary to understand the effects on P-gp as well as have information on other effects on the gastrointestinal tract, such as enterokinesis suppression, and to appropriately assess the pharmacokinetic interactions of the combined oral use of P-gp substrate drugs.

Distant metastatic lesions in patients with differentiated thyroid carcinoma

Summary Aim: Many investigators have reported an inverse relationship between iodine and glucose utilization of differentiated thyroid carcinoma (DTC) according to its degree of differentiation; however, not every DTC is compatible with this phenomenon. This study was conducted to evaluate the clinical implication of iodine and glucose uptake at distant metastatic lesions in DTC patients. Patients, methods: 64 DTC patients (women 47; mean age 49.9 ± 16.4 years) with distant metastasis who underwent post 131I treatment whole-body scan (RxWBS) and FDG PET/CT were included in the study. Radioiodine (RAI) and FDG uptake of metastatic lesions were evaluated. TSH stimulated serum thyroglobulin (s-Tg) were obtained. Results: 53 of 64 patients (82.8%) were RAI(+) group, and 37 patients (57.8%) were FDG(+) group. Patients in the RAI(–) group showed a higher rate of FDG uptake than RAI(+) group (100.0% vs. 49.1%, p = 0.002). Patients in the FDG(–) group showed a higher rate of RAI uptake than FDG(+) group (100.0% vs. 70.3%, p = 0.002). Patients with s-Tg &lt; 100 ng/ml were frequently observed in the FDG(–)/RAI(+) group and the FDG(+)/ RAI(–) group (p = 0.023). And patients with s-Tg ≥ 500 ng/ml were more frequently observed in the FDG(+)/RAI(+) group, compared with the FDG(+)/RAI(–) group (p = 0.036). Reduced disease-specific survival (DSS) was observed in patients with RAI(–) (p = 0.003), FDG(+) (p = 0.006), SUVmax &gt; 3.6 (p&lt;0.001), and s-Tg &gt; 75.8 ng/ml (p = 0.009). In multivariate analysis, only a SUVmax &gt; 3.6 was significantly predictive of DSS (p = 0.006). Conclusion: An inverse relationship between RAI and FDG uptake, flip-flop phenomenon, was observed in patients with metastatic lesions of DTC. Reduced disease-specific survival was observed in patients with FDG(+), RAI(–) in metastatic lesions, or high s-Tg value.

Pharmacokinetics of Pentoxifylline and Its Main Metabolites in Patients With Different Degrees of Heart Failure Following a Single Dose of a Modified‐Release Formulation

Pentoxifylline (PTX) is extensively metabolized in the body, and all its 3 plasma metabolites (M1, M4, M5) are pharmacologically active. The authors evaluated the pharmacokinetics of PTX and its metabolites in 20 patients with chronic heart failure (CHF). Eleven had moderate and 9 severe CHF. The time courses of PTX, M1, M4, and M5 plasma levels were determined after oral administration of a sustained-release 600-mg tablet of PTX, and for each compound, AUC, maximal plasma concentration (C(max)), and time to C(max) (T(peak)) were calculated. Compared with patients with moderate CHF, those with severe CHF showed a significant delay in T(peak) of PTX (3.9 vs 1.6 hours) and M5 (5.6 vs 3.6 hours), a 59% significant increase in M5 AUC, and a 56% nonsignificant increase in PTX AUC. In the whole population, the AUCs of PTX, M4, and M5 were inversely correlated with markers of liver function, whereas the AUCs of M4 and M5 were inversely correlated with the creatinine clearance. In view of the kinetic features of slow-release formulations (flip-flop phenomenon), the delay in T(peak) of PTX in patients with severe CHF compared with moderate CHF should be ascribed to a reduced elimination rate.

Plasma disposition of enrofloxacin following intravenous and intramuscular administration in donkeys

This study was designed to investigate the plasma disposition and systemic availability of enrofloxacin (ENR) following intramuscular and intravenous administrations. Six donkeys (Equus asinus) were used in this study. The...

Glucose Transporter 1 Expression, Tumor Proliferation, and Iodine/Glucose Uptake in Thyroid Cancer With Emphasis on Poorly Differentiated Thyroid Carcinoma

Glucose transporters 1 (GLUT1) facilitates glucose uptake in cancer. An inverse relationship between I-131 and F-18 fluorodeoxyglucose (FDG) uptake in PET/CT ("flip-flop phenomenon") was described for thyroid cancers (TCs) during dedifferentiation. We investigated the relationship among GLUT1 expression, proliferation, iodine concentration, and glucose uptake in different TC types, with emphasis on "poorly differentiated thyroid carcinoma" (PDTC). For immunohistochemistry, 95 thyroid tumors (follicular adenoma, papillary TC, follicular TC, PDTC, and anaplastic TC [ATC]) were investigated for GLUT1 expression and proliferation (Ki-67 index). For PET/CT study, 47 F-18 FDG PET/CT of patients with TC (22 PDTC), 39 corresponding I-124 PET/CT, and glucose and iodine uptake were evaluated. PTC and FTC were summarized under differentiated TC (DTC). Immunohistochemistry: 65% of TC expressed GLUT1. The number of GLUT1-positive TC and GLUT1 expression increased with escalating dedifferentiation/aggressiveness of TC types (P < 0.001). A correlation between proliferation and GLUT1 expression was noted (P < 0.001). PET/CT study: F-18 FDG uptake was measured in 81% of cases. Occurrence of F-18 FDG-avid cases as well as median F-18 FDG maximum standardized uptake values were lowest in DTC, intermediate in PDTC, and highest in ATC. Accordingly, numbers of iodine-avid cases and median I-124 maximum standardized uptake value featured an inverse pattern. Dedifferentiation in TC is accompanied by GLUT1 upregulation and increased proliferation. PDTC was found to be intermediate between DTC and ATC in terms of GLUT1 expression and F-18 FDG or I-124 uptake, suggesting that the flip-flop phenomenon occurs at a dedifferentiation stage in between. Furthermore, the results suggest that F-18 FDG PET/CT is an important imaging modality for ATC and PDTC.

Association between CST3 rs2424577 Polymorphism and Corpulence Related Phenotypes during Lifetime in Populations of European Ancestry

Objective: Cystatin C, a protein coded by CST3 gene, is implicated in adipose tissue biology. Our hypothesis is that common variants in CST3 gene could play a role in the development of corpulence during lifetime. Methods: Two tag SNPs were selected to capture all SNPs in the CST3 region. We first investigated the association of the two tag SNPs individually and combined into haplotypes with corpulence related phenotypes in 4,288 French subjects (BMI = 24.31 ( 3.74 kg/m²). Significant findings were replicated in five independent populations – 790 Danish lean men (BMI = 24.63 ( 2.30 kg/m²), 672 Danish obese men (BMI = 33.23 ( 2.34 kg/m²), 763 Swedish women (BMI = 21.73 ( 2.87 kg/m²), 1,848 Danish lean women (BMI = 22.66 ( 2.85 kg/m²) and 2,061 Danish obese women (BMI = 37.01 ( 3.59 kg/m²). Results: Rs2424577 was associated with BMI in three independent populations – G/G carriers were less corpulent than A/A carriers in the French individuals (p = 0.045) and in the Danish lean men (p = 0.021), and they were more corpulent in the group of Swedish women (p = 0.004). This phenomenon has been described as a flip-flop phenomenon, probably caused by a multilocus effect. Conclusion: CST3 rs2424577 is associated with BMI in a complex fashion. This association is probably caused by the interaction between several functional variants.

Clinical characteristics and treatment of dystonia

Dystonia is defined as a syndrome of sustained muscle contractions, frequently causing twisting and repetitive movements, or abnormal postures. Its diagnosis is based on clinical characteristics. In dystonia, the pattern of abnormal posture or movement tends to be constant during the short term even if its severity fluctuates. This stereotypy often helps differentiate dystonia from psychogenic reaction. Dystonia may appear only during some specific task (task specificity) especially in its early phase, although it often becomes obscure during the long clinical course, resulting in persistent dystonic posture. Sensory trick or geste antagoniste means the change of severity triggered by some sensory input Overflow phenomenon is the activation of muscles unnecessary to a task, hampering purposeful movement. Symptoms tend to be milder in the morning, with large individual variation of its duration (morning benefit). Symptoms of dystonia may abruptly appear or disappear (flip-flop phenomenon). Cocontraction, believed as an essential feature of dystonia, reflects a loss of reciprocal inhibition of muscle activities, causing involuntary simultaneous contractions of agonists and antagonists. "Negative dystonia," still an unaccepted feature of dystonia, is defined as non-paretic loss of central driving of muscle activities necessary to a task. Apraxia of lid opening/closure, paretic form of hand dystonia, dropped head syndrome, camptocormia, Pisa syndrome, cervical dystonia with limited range of head movement, or mandibular dystonia without cocontractions of masticatory muscles, can be explained with this concept at least in a subset of cases. Treatment of dystonia includes medication, botulinum toxin injection, intrathecal baclofen, surgical intervention, acupuncture and other alternative therapies, rehabilitation, and psychotherapy. Oral medication is usually an adjunct to more potent therapeutic options except for some specific indications like dopa-responsive dystonia. Botulinum toxin is usually the treatment of choice for focal dystonia. Deep brain stimulation can be considered for both focal and non-focal phenotypes of dystonia.

Time series photometry and starspot properties

AbstractSystematic efforts of monitoring starspots from the middle of the XXth century, and the results obtained from the datasets, are summarized with special focus on the observations made by automated telescopes. Multicolour photometry shows correlations between colour indices and brightness, indicating spotted regions with different average temperatures originating from spots and faculae. Long-term monitoring of spotted stars reveals variability on different timescales.On the rotational timescale new spot appearances and starspot proper motions are followed from continuous changes of light curves during subsequent rotations. Sudden interchange of the more and less active hemispheres on the stellar surfaces is the so called flip-flop phenomenon. The existence and strength of the differential rotation is seen from the rotational signals of spots being at different stellar latitudes.Long datasets, with only short, annual interruptions, shed light on the nature of stellar activity cycles and multiple cycles. The systematic and/or random changes of the spot cycle lengths are discovered and described using various time-frequency analysis tools. Positions and sizes of spotted regions on stellar surfaces are calculated from photometric data by various softwares. From spot positions derived for decades, active longitudes on the stellar surfaces are found, which, in case of synchronized eclipsing binaries can be well positioned in the orbital frame, with respect to, and affected by, the companion stars.