Transition phenomena in diffusive motions due to the change of memory effects

2019 ◽  
Vol 34 (01) ◽  
pp. 2050013
Author(s):  
Dongmi Kim ◽  
Hyun-Joo Kim

In the anomalous diffusions, the transition phenomena from superdiffusion (or subdiffusion) to normal diffusion have been found in several experiments and studied by stochastic models. In this study, we found the diffusion transition which occurs twice in a stochastic process, first from superdiffusion to subdiffusion, and then from subdiffusion to normal diffusion by using the nonstationary Markovian replication process with the memory of the previous step exponentially decaying with time. In the early stage, when the walker strongly follows the previous step, superdiffusive behaviors occur, while in the intermediate stage in which the memory effect decays exponentially, the motion of the walker shows subdiffusive behaviors. Eventually, as the memory effect almost disappears, the motion reduces to normal diffusion. We also found that the Hurst exponent in the intermediate subdiffusive region becomes smaller when the change of the memory effect is more abrupt.

2021 ◽  
Vol 49 (5) ◽  
pp. 030006052110106
Author(s):  
Hoda Salah Darwish ◽  
Mohamed Yasser Habash ◽  
Waleed Yasser Habash

Objective To analyze computed tomography (CT) features of symptomatic patients with coronavirus disease 2019 (COVID-19). Methods Ninety-five symptomatic patients with COVID-19 confirmed by reverse-transcription polymerase chain reaction from 1 May to 14 July 2020 were retrospectively enrolled. Follow-up CT findings and their distributions were analyzed and compared from symptom onset to late-stage disease. Results Among all patients, 15.8% had unilateral lung disease and 84.2% had bilateral disease with slight right lower lobe predilection (47.4%). Regarding lesion density, 49.4% of patients had pure ground glass opacity (GGO) and 50.5% had GGO with consolidation. Typical early-stage patterns were bilateral lesions in 73.6% of patients, diffuse lesions (41.0%), and GGO (65.2%). Pleural effusion occurred in 13.6% and mediastinal lymphadenopathy in 11.5%. During intermediate-stage disease, 47.4% of patients showed GGO as the disease progressed; however, consolidation was the predominant finding (52.6%). Conclusion COVID-19 pneumonia manifested on lung CT scans with bilateral, peripheral, and right lower lobe predominance and was characterized by diffuse bilateral GGO progressing to or coexisting with consolidation within 1 to 3 weeks. The most frequent CT lesion in the early, intermediate, and late phases was GGO. Consolidation appeared in the intermediate phase and gradually increased, ending with reticular and lung fibrosis-like patterns.


Author(s):  
P. E. Gibbs ◽  
G. W. Bryan

The development of male characters, notably a penis and a vas deferens, on the female (the phenomenon of ‘imposex’) of the dog-whelk, Nucella lapillus, is described. Three stages are recognized: an ‘early’ stage involving the formation of a vas deferens and a small penis, an ‘intermediate’ stage characterized by the enlargement of the female penis to a size approaching that of the male and a ‘late’ stage during which the female opening (vulva) is occluded by overgrowth of vas deferens tissue. This blockage of the pallial oviduct prevents the release of egg capsules and renders the female sterile. The extent and cause of such reproductive failure is evident from the high incidence of females containing aborted capsules in declining populations close to sources of tributyltin (TBT) contamination. These same populations comprise fewer females than expected and it would appear that the accumulation of aborted capsules within the pallial oviduct eventually causes the premature death of the female.


1998 ◽  
Vol 11 (3) ◽  
pp. 411-423 ◽  
Author(s):  
Jewgeni H. Dshalalow

In this paper we introduce and study functionals of the intensities of random measures modulated by a stochastic process ξ, which occur in applications to stochastic models and telecommunications. Modulation of a random measure by ξ is specified for marked Cox measures. Particular cases of modulation by ξ as semi-Markov and semiregenerative processes enabled us to obtain explicit formulas for the named intensities. Examples in queueing (systems with state dependent parameters, Little's and Campbell's formulas) demonstrate the use of the results.


Author(s):  
Luboš Střelec

This article deals with one of the important parts of applying chaos theory to financial and capital markets – namely searching for long memory effects in time series of financial instruments. Source data are daily closing prices of Central Europe stock market indices – Bratislava stock index (SAX), Budapest stock index (BUX), Prague stock index (PX) and Vienna stock index (ATX) – in the period from January 1998 to September 2007. For analysed data R/S analysis is used to calculate the Hurst exponent. On the basis of the Hurst exponent is characterized formation and behaviour of analysed financial time series. Computed Hurst exponent is also statistical compared with his expected value signalling independent process. It is also operated with 5-day returns (i.e. weekly returns) for the purposes of comparison and identification nonperiodic cycles.


2004 ◽  
Vol 92 (4) ◽  
pp. 2520-2529 ◽  
Author(s):  
Yoriko Takikawa ◽  
Reiko Kawagoe ◽  
Okihide Hikosaka

Dopamine (DA) neurons respond to sensory stimuli that predict reward. To understand how DA neurons acquire such ability, we trained monkeys on a one-direction-rewarded version of memory-guided saccade task (1DR) only when we recorded from single DA neurons. In 1DR, position-reward mapping was changed across blocks of trials. In the early stage of training of 1DR, DA neurons responded to reward delivery; in the later stages, they responded predominantly to the visual cue that predicted reward or no reward (reward predictor) differentially. We found that such a shift of activity from reward to reward predictor also occurred within a block of trials after position-reward mapping was altered. A main effect of long-term training was to accelerate the within-block reward-to-predictor shift of DA neuronal responses. The within-block shift appeared first in the intermediate stage, but was slow, and DA neurons often responded to the cue that indicated reward in the preceding block. In the advanced stage, the reward-to-predictor shift occurred quickly such that the DA neurons' responses to visual cues faithfully matched the current position-reward mapping. Changes in the DA neuronal responses co-varied with the reward-predictive differentiation of saccade latency both in short-term (within-block) and long-term adaptation. DA neurons' response to the fixation point also underwent long-term changes until it occurred predominantly in the first trial within a block. This might trigger a switch between the learned sets. These results suggest that midbrain DA neurons play an essential role in adapting oculomotor behavior to frequent switches in position-reward mapping.


Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 101-101 ◽  
Author(s):  
Michal Sieniawski ◽  
Thorsten Reineke ◽  
Andreas Josting ◽  
Volker Diehl ◽  
Andreas Engert

Abstract Purpose: We performed semen and hormone analysis before and after treatment to investigate the influence of disease and therapy on the fertility status of male patients with Hodgkin lymphoma (HL). Patients & Methods: Patients (pts) with first diagnosis of HL without previous chemotherapy or radiotherapy who were enrolled into trials of German Hodgkin Study Group (GHSG) between 1988 and 2003 were analyzed. 202 pts were evaluated prior to treatment and 112 pts were evaluated after treatment. Results: The median age in the pre-treatment evaluation group were 26 years and 27 years in the post-treatment evaluation group. In pre-treatment evaluation group 51% of pts were advance stage of disease, 31% in intermediate stage and 11% in early stage. In the post-treatment evaluation group 45% of pts were in intermediate stage of disease, 44% in advanced stage and 11% in early stage. Before treatment 20% (40/202) of pts had normozoospermia and 80% (162/202) had dyspermia. After treatment, 64% (72/112) of pts had azoospermia, 30% (33/112) other dyspermia and 6% (7/112), the differences are significant (p<0.001). Azoospermia was observed in 67% (62/93) of pts treated with combined modality, in 90% (9/10) of those treated with chemotherapy alone and in 11% (1/9) of those treated with radiotherapy alone (p<0.001). Azoospermia was more frequent after BEACOPP then after COPP/ABVD - 85% (34/40) vs. 63% (37/59) (p<0.001). There was no difference between patients treated with 8 cycles of BEACOPP escalated (n=15) and those treated with 8 cycles BEACOPP baseline (n=21); with 93% and vs. 86% (p>0.05). The median time of onset of spermatogenesis was 27 months. During the first year after the treatment the onset of spermatogenesis was found in 18% of pts, during the second year in 23%, during the third year in 35% and in 35% after the third year. In univariate risk factors analysis, we found exttranodal involvement, risk groups, treatment with chemotherapy and BEACOPP being significantly predictive for asevere damage of fertility, none of these factors was significant in multivariate analysis. In the contrast to the pre-treatment analysis, most of the pts (79%) showed abnormal FSH-levels (p<0.001). LH and testosterone were normal in most of patients; these results were similar to pre-treatment levels (p>0.005). There was the relationship between the post-therapeutic FSH level and sperm count; in the group with normal FSH levels, 23% of pts showed azoospermia and in the group with abnormal FSH level 78% of pts were azoospermic (p<0.001). The correlation between sperm count and LH and testosterone level was not so pronounced. Conclusion: The majority of patients with HL were azoospermic after treatment, but recovery of spermatogenesis was observed depending on the treatment received. The FSH level appears to be helpful in diagnosis of the fertility status.


2010 ◽  
Vol 06 (01) ◽  
pp. 65
Author(s):  
Riccardo Lencioni ◽  

The treatment of hepatocellular carcinoma (HCC) is rapidly evolving as loco-regional and systemic therapies continue to improve. Image-guided radiofrequency (RF) ablation is established as the treatment of choice for patients with early-stage HCC when transplantation or resection are precluded. Recent refinements to technique have substantially increased the ability of RF ablation to achieve sustained complete response of target tumours in properly selected patients, and new alternate thermal and non-thermal methods for local tumour treatment are currently under investigation. Transarterial chemo-embolisation (TACE) is the standard of care for patients with multinodular disease at the intermediate stage. The introduction of drug-eluting beads, which enhance drug delivery to the tumour and reduce systemic exposure, appears to improve anticancer activity and the safety profile of TACE compared with conventional regimens. Despite these advances, the long-term outcomes of patients treated with loco-regional therapies remain unsatisfactory because of the high rate of tumour recurrence. The introduction of molecular-targeted therapies that inhibit tumour proliferation and angiogenesis has opened new prospects in this regard. Clinical trials focused on combining interventional treatment with systemically active drugs are ongoing. The outcomes of such studies are eagerly awaited, as they have the potential to revolutionise the treatment of HCC.


2019 ◽  
Vol 37 (15_suppl) ◽  
pp. e14544-e14544
Author(s):  
Joanne Evans ◽  
Caroline Ward ◽  
Madhava Pai ◽  
Rohini Sharma

e14544 Background: Transarterial chemo-embolization (TACE) is the standard of care for patients with intermediate stage hepatocellular carcinoma (HCC) with adequate synthetic function, and as bridging treatment in early stage disease. Survival outcomes are heterogeneous, and improved biomarkers are needed for detection of early relapse. Current practice relies on monitoring of alpha-foetoprotein (AFP) and serial imaging. Circulating cell-free DNA (cfDNA) is a compelling emergent biomarker. Here, we describe the first study of cfDNA as prognostic biomarker in HCC following TACE. Methods: 34 patients treated with TACE (2012-2018) who had full demographic information and longitudinal stored plasma available were identified. Samples were retrieved and cfDNA extracted using the QIAamp Circulating Nucleic Acid Kit. cfDNA yields were quantified by high-sensitivity Qubit analysis. Results: 74% of patients were male, 66% had Childs Pugh A disease, and 56% of patients secreted AFP ( > 10ng/mL). Aetiologies of liver diseases were varied: viral hepatitis (44%), alcoholic or non-alcoholic steatohepatitis/cirrhosis (29%), hereditary or auto-immune (12%), and unexplained (15%). 79% of patients saw a fall in cfDNA titre following TACE. Where no reduction was seen, patients had a poorer median overall survival than those who did: 20 months (range 5.13 – 66.7 months) compared to 37 months (9.9 – 79.3 months). Of note, 44% of patients were AFP non-secretors. Here, cfDNA had a clear advantage in disease monitoring, with mean cfDNA titres in this group falling post treatment: from 1605.1 (range 185.9 – 6830) ng/mL to 693.7 (range undetectable - 2300) ng/mL and rising again with subsequent progression (mean of 1329.2 - range 616 – 3341 - ng/mL). Conclusions: These findings support a cost-effective monitoring role for plasma cfDNA analysis following treatment with TACE, with an added advantage in AFP non-secretors. Prospective validation is suggested to fully assess clinical utility.


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