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In the classical framework, a random walk on a group is a Markov chain with independent and identically distributed increments. In some sense, random walks are time and space homogeneous. This paper is devoted to a class of inhomogeneous random walks on
$\mathbb{Z}^d$
termed ‘Markov additive processes’ (also known as Markov random walks, random walks with internal degrees of freedom, or semi-Markov processes). In this model, the increments of the walk are still independent but their distributions are dictated by a Markov chain, termed the internal Markov chain. While this model is largely studied in the literature, most of the results involve internal Markov chains whose operator is quasi-compact. This paper extends two results for more general internal operators: a local limit theorem and a sufficient criterion for their transience. These results are thereafter applied to a new family of models of drifted random walks on the lattice
$\mathbb{Z}^d$
.
Let X be a compact metric space and let $f: X\!\rightarrow \! X$ be a homeomorphism on X. We show that if f is both pointwise recurrent and expansive, then the dynamical system $(X, f)$ is topologically conjugate to a subshift of some symbolic system. Moreover, if f is pointwise positively recurrent, then the subshift is semisimple; a counterexample is given to show the necessity of positive recurrence to ensure the semisimplicity.
Despite its introduction into the diagnostic nomenclature over four decades ago, there remain large knowledge gaps about disordered gambling. The primary aims of the present study were to document the long-term course, childhood precursors, and adult life outcomes associated with disordered gambling.
Methods
Participants enrolled in the population-representative Dunedin Study were prospectively followed from birth through age 45. Disordered gambling was assessed six times from age 18; composite measures of childhood social class, general intelligence, and low self-control were based on assessments obtained from birth through age 15; adult socioeconomic, financial, and legal outcomes were obtained through age 45. Lifetime disordered gambling was predicted from the three childhood precursors and the adult outcomes were predicted from lifetime disordered gambling.
Results
Past-year disordered gambling usually occurred at only a single time point and recurrence was relatively uncommon. Lower childhood social class, general intelligence, and self-control significantly predicted lifetime disordered gambling in adulthood. In turn, lifetime disordered gambling in adulthood significantly predicted occupational, educational, and financial problems in adulthood (ds = 0.23–0.41). These associations were markedly reduced and sometimes rendered nonsignificant after adjusting for childhood precursors (ds = 0.04–0.32).
Conclusions
Socioeconomic, financial, and legal outcomes in adulthood are not merely consequences of disordered gambling, but also are predicted from childhood precursors. Deflecting the trajectories of young people at risk for developing disordered gambling may help to ameliorate not just the development of later disordered gambling, but also other associated adverse outcomes.
Treatment non-response and recurrence are the main sources of disease burden in major depressive disorder (MDD). However, little is known about its neurobiological mechanism concerning the brain network changes accompanying pharmacotherapy. The present study investigated the changes in the intrinsic brain networks during 6-month antidepressant treatment phase associated with the treatment response and recurrence in MDD.
Methods
Resting-state functional magnetic resonance imaging was acquired from untreated patients with MDD and healthy controls at baseline. The patients' depressive symptoms were monitored by using the Hamilton Rating Scale for Depression (HAMD). After 6 months of antidepressant treatment, patients were re-scanned and followed up every 6 months over 2 years. Traditional statistical analysis as well as machine learning approaches were conducted to investigate the longitudinal changes in macro-scale resting-state functional network connectivity (rsFNC) strength and micro-scale resting-state functional connectivity (rsFC) associated with long-term treatment outcome in MDD.
Results
Repeated measures of the general linear model demonstrated a significant difference in the default mode network (DMN) rsFNC change before and after the 6-month antidepressant treatment between remitters and non-remitters. The difference in the rsFNC change over the 6-month antidepressant treatment between recurring and stable MDD was also specific to DMN. Machine learning analysis results revealed that only the DMN rsFC change successfully distinguished non-remitters from the remitters at 6 months and recurring from stable MDD during the 2-year follow-up.
Conclusion
Our findings demonstrated that the intrinsic DMN connectivity could be a unique and important target for treatment and recurrence prevention in MDD.
This chapter describes cancer from a chronological perspective to increase understanding, even if cancer does not necessarily follow a ´predictable´ course. The cancer stages: diagnosis, treatment and recovery have characteristics of their own and different reactions expected from children and young people along these stages. Early intervention with children and families can prevent long term sequels. More knowledge and rigorous research is needed to understand the impact of cancer over time and how to support children and families which experience fear of recurrence.
This paper provides a full classification of the dynamics for continuous-time Markov chains (CTMCs) on the nonnegative integers with polynomial transition rate functions and without arbitrary large backward jumps. Such stochastic processes are abundant in applications, in particular in biology. More precisely, for CTMCs of bounded jumps, we provide necessary and sufficient conditions in terms of calculable parameters for explosivity, recurrence versus transience, positive recurrence versus null recurrence, certain absorption, and implosivity. Simple sufficient conditions for exponential ergodicity of stationary distributions and quasi-stationary distributions as well as existence and nonexistence of moments of hitting times are also obtained. Similar simple sufficient conditions for the aforementioned dynamics together with their opposite dynamics are established for CTMCs with unbounded forward jumps. Finally, we apply our results to stochastic reaction networks, an extended class of branching processes, a general bursty single-cell stochastic gene expression model, and population processes, none of which are birth–death processes. The approach is based on a mixture of Lyapunov–Foster-type results, the classical semimartingale approach, and estimates of stationary measures.
Anxiety disorders are very common and burdensome mental illnesses worldwide, characterized by exagerated feelings of worry and fear. These disorders are highly comorbid with other conditions.
Objectives
The aim of our study is to explore the physical and psychiatric comorbidities and their clinical correlates. The second objective is to identify the predictors of recurrence of anxiety disorders.
Methods
Our study concerned 436 outpatients who met DSM-V diagnostic criteria for anxiety disorders and were followed in the Department of Psychiatry of Monastir (Tunisia) between 1998 and 2017. Selective mutism and seperation anxiety were excluded for lack of cases.
Results
Our results demonstrated that Generalized Anxiety Disorder (GAD) was significantly associated with cardiovascular comorbidity (OR=3.208). Social Anxiety Disorder (SAD) was significantly correlated to avoidant personality disorder (OR=17). Patients with suicide attempts are more likely to have a comorbid personality disorder (OR=11.606). Being married and having a later age of onset are predictors of having comorbid depressive disorder. Furthermore, being married, having an anxiety-anxiety comorbidity and a longer duration of untreated illness (DUI) are predictors of recurrence.
Conclusions
Our study highlights the fact that comorbidities (physical and psychopathological) call for a closer follow up due to the higher risk of recurrence, the higher risk of suicide attempts and the poorer treatment response.
Haloperidol is a first generation, high potency, low cost and widely used antipsychotic. There are inconsistencies in the literature about comparison of effectiveness between long-acting injectable haloperidol (HDLAI) with oral haloperidol (OH), as well as the combined use of both formulations (HDLAI+OH).
Objectives
To verify whether HDLAI reduces the number of emergency visits and hospitalizations when compared to oral OH, or in combination therapy HDLAI+OH.
Methods
Retrospective observational study on a Psychiatric Emergency department, including patients aged 18 to 60 years, both genders, under continuous treatment for at least 5 months with Haloperidol for any psychiatric illness, divided into 3 groups of patients (HDLAI, OH, HDLAI+OH). Dependent variables: visits and admissions. Independent variables: sex and age. Data were checked for normality (Kolmogorov-Smirnov test) and homoscedasticity (Bartlett test). For comparison of average number of visits and hospitalizations of patients Kruskal-Wallis test followed by Dunn’s multiple comparison test was used. It was considered statistically significant if p < 0.05. This study was approved by the Ethics Committee of Maringá State University.
Results
No statistical difference between groups HDLAI and OH was found. The HDLAI+OH group presented higher means of emergency visits and hospitalizations with statistical significance.
Conclusions
It suggests the use of HDLAI can be considered an alternative as effective as oral intake. Prolonged use of associated HDLAI and oral supplementation leads to worst outcomes.
Natural infection with the influenza virus is believed to generate cross-protective immunity across both types and subtypes. However, less is known about the persistence of this immunity and thus the susceptibility of individuals to repeat infection. We used 13 years (2005–2017) of surveillance data from Queensland, Australia, to describe the incidence and distribution of repeat influenza infections. Consecutive infections that occurred within 14 days of prior infection were considered a mixed infection; those that occurred more than 14 days later were considered separate (repeat) infections. Kaplan-Meier plots were used to investigate the probability of reinfection over time and the Prentice, Williams and Peterson extension of the Cox proportional hazards model was used to assess the association of age and gender with reinfection. Among the 188 392 notifications received during 2005–2017, 6165 were consecutively notified for the same individual (3.3% of notifications), and 2958 were mixed infections (1.6%). Overall, the probability of reinfection was low: the cumulative incidence was <1% after one year, 4.6% after five years, and 9.6% after ten years. The majority of consecutive infections were the result of two type A infections (43%) and were most common among females (adjusted hazard ratio (aHR): 1.15, 95% confidence interval (CI) 1.09–1.21), children aged less than 5 years (relative to adults aged 18–64 years aHR: 1.58, 95% CI 1.47–1.70) and older adults aged at least 65 years (aHR: 1.35; 95% CI 1.24–1.47). Our study suggests consecutive infections are possible but rare. These findings have implications for our understanding of population immunity to influenza.
Do genetic risk profiles for drug use disorder (DUD), major depression (MD), and attention-deficit hyperactivity disorder (ADHD) differ substantially as a function of sex, age at onset (AAO), recurrence, mode of ascertainment, and treatment?
Methods
Family genetic risk scores (FGRS) for MD, anxiety disorders, bipolar disorder, schizophrenia, alcohol use disorder, DUD, ADHD, and autism-spectrum disorder were calculated from 1st–5th degree relatives in the Swedish population born 1932–1995 (n = 5 829 952). Profiles of these FGRS were obtained and compared across various subgroups of DUD, MD, and ADHD cases.
Results
Differences in FGRS profiles for DUD, MD, and ADHD by sex were modest, but they varied substantially by AAO, recurrence, ascertainment, and treatment with scores typically higher in cases with greater severity (e.g. early AAO, high recurrence, ascertainment in high intensity clinical settings, and treatment). However, severity was not always related to purer genetic profiles, as genetic risk for many disorders often increased together. However, some results, such as by mode of ascertainment from different Swedish registries, produced qualitative differences in FGRS profiles.
Conclusions
Differences in FGRS profiles for DUD, MD, and ADHD varied substantially by AAO, recurrence, ascertainment, and treatment. Replication of psychiatric studies, particularly those examining genetic factors, may be difficult unless cases are matched not only by diagnosis but by important clinical characteristics. Genetic correlations between psychiatric disorders could arise through one disorder impacting on the patterns of ascertainment for the other, rather than from the direct effects of shared genetic liabilities.
Cholesteatoma is a benign but destructive epithelial lesion in the middle ear and/or mastoid. It is hard to translate data from previous research to daily clinical practice. In this study, factors influencing recurrence rates in daily clinical practice were identified.
Method
The study included 67 patients who were treated for a cholesteatoma with combined approach tympanoplasty. The average follow-up time was 35 months.
Results
The recurrence rate was 23.3 per cent in adults and 45.5 per cent in children. Predictors of recurrence were younger age and a low tegmen. A cholesteatoma in a child and the simultaneous presence of a low tegmen led to recurrence in 82.8 per cent of the patients.
Conclusion
Patients – especially children – with a low tegmen have an increased risk of recurrence. It is recommended that ENT surgeons be aware of recurrence in children, particularly in the case of a low tegmen.
This retrospective study was undertaken to assess the outcome of the medical and/or surgical management of patients presenting with clinical features of arytenoid granuloma.
Methods
The records of 53 males and 9 females were reviewed for predisposing factors, types of treatment received and recurrence following the treatment.
Results
Most of the patients (48 out of 62, 77.4 per cent) were treated conservatively with medical management and voice therapy, which resulted in complete resolution of arytenoid granuloma in over two-thirds of the patients treated (32 out of 48, 66.6 per cent). Overall, 28 patients (out of 62, 45.1 per cent) required surgery (14 failed medical treatment cases and 14 surgery as first-line treatment cases). Of these, five patients (out of 28, 17.9 per cent) had recurrence, and were managed with revision surgery and concurrent local injection of Botox.
Conclusion
Anti-reflux medication and voice therapy are effective first-line management options. Pre- and post-surgery adjuvant treatment improves the results of surgery. Local injection of Botox was successful in the treatment of failed surgical cases.
The incidence of thyroid carcinoma has been increasing worldwide and surgery is the primary treatment. Central compartment dissection of the neck is a very delicate procedure given the risks of recurrent laryngeal nerve injury and hypoparathyroidism.
Methods
This paper gives a detailed description of this surgical technique in a patient affected by papillary carcinoma of the thyroid gland, supported by highly representative iconographic materials from a tertiary department.
Results
A stepwise description is provided, along with high-quality pictures and specific tips and tricks. Although neck dissection is a well-codified procedure, the fine details of this surgical technique are not currently available and are still the prerogative of the expert surgeon.
Conclusion
The central neck compartment contains several vulnerable structures; damage to these structures would affect patients’ lives, possibly permanently. Anatomical knowledge and standardisation are needed for all surgeons, particularly new surgeons (such as residents) who cannot rely simply on experience.
Sinonasal inverted papillomas are challenging benign tumours of the nasal cavity because of their high recurrence rates and the lifetime malignant transformation risk of 10 per cent as well as their locally aggressive behaviour. This study aimed to describe treatment strategies for inverted papillomas with intracranial or intraorbital involvement.
Method
This was a prospective case series study of 18 patients with inverted papilloma with intracranial or intraorbital involvement. Patient demographic data, imaging, pathology, surgical technique and recurrences were recorded prospectively over a period of seven years.
Results
A total of 83 per cent of the patients in this study had been previously operated on, consisting of 8 cases with intracranial involvement, 1 case with intraorbital involvement and 9 with both. During follow up with a medium of 37 months (range, 13–115 months) there were two recurrences.
Conclusion
It was postulated that intracranial or intraorbital involvement observed in this series was the result of multiple revisions. However, using accurate imaging protocols and the pedicle-oriented approach for tumour excision, complete tumour removal was achieved in most cases with minimal post-operative complications.
This study evaluated the post-operative indications for sinonasal topical steroid treatment using a corticosteroid (steroid)-eluting, sinus-bioabsorbable device and its effects in patients with eosinophilic chronic rhinosinusitis.
Method
Post-operative courses were investigated in two groups: group A with patients who underwent sinonasal topical steroid treatment, and group B with control patients who did not.
Results
Group A was significantly younger than group B (p < 0.01), and the pre-operative computed tomography score was significantly higher in group A than in group B (p < 0.05). In the post-operative stage, the nasal symptoms questionnaire component of olfactory loss and the post-operative endoscopic appearance score were significantly worse in group A than in group B (p < 0.01).
Conclusion
These data suggest that younger age, more severe rhinosinusitis and post-operative olfactory loss led to the need for sinonasal topical steroid treatment to prevent relapsing inflammation after functional endoscopic sinus surgery in patients with eosinophilic chronic rhinosinusitis.
Anxiety disorders frequently recur in clinical populations, but the risk of recurrence of anxiety disorders is largely unknown in the general population. In this study, recurrence of anxiety and its predictors were studied in a large cohort of the adult general population.
Methods
Baseline, 3-year and 6-year follow-up data were derived from the Netherlands Mental Health Survey and Incidence Study-2 (NEMESIS-2). Respondents (N = 468) who had been in remission for at least a year prior to baseline were included. Recurrence was assessed at 3 and 6 years after baseline, using the Composite International Diagnostic Interview version 3.0. Cumulative recurrence rates were estimated using the number of years since remission of the last anxiety disorder. Furthermore, Cox regression analyses were conducted to investigate predictors of recurrence, using a broad range of putative predictors.
Results
The estimated cumulative recurrence rate was 2.1% at 1 year, 6.6% at 5 years, 10.6% at 10 years, and 16.2% at 20 years. Univariate regression analyses predicted a shorter time to recurrence for several variables, of which younger age at interview, parental psychopathology, neuroticism and a current depressive disorder remained significant in the, age and gender-adjusted, multivariable regression analysis.
Conclusions
Recurrence of anxiety disorders in the general population is common and the risk of recurrence extends over a lengthy period of time. In clinical practice, alertness to recurrence, monitoring of symptoms, and quick access to health care in case of recurrence are needed.
We show that there is a measure-preserving system
$(X,\mathscr {B}, \mu , T)$
together with functions
$F_0, F_1, F_2 \in L^{\infty }(\mu )$
such that the correlation sequence
$C_{F_0, F_1, F_2}(n) = \int _X F_0 \cdot T^n F_1 \cdot T^{2n} F_2 \, d\mu $
is not an approximate integral combination of
$2$
-step nilsequences.
A fundamental question remains unanswered by theorists of civil war—do colonial institutions play a role in creating conditions for insurgency? In contrast to the scholarship on civil wars which tend to focus on proximate causes of rebellion, this book proposes that many insurgencies around the world -- in Colombia, Sri Lanka, Burma, Nigeria -- have origins in deep historical processes. Bringing history back into the study of civil wars can provide a deeper understanding of the roots of some insurgencies. It can also explain the persistence of conflict which theories of civil war that focus on more proximate determinants cannot. I outline the case of the Maoist insurgency in India, which exemplifies how different forms of colonial indirect rule and indirect revenue collection created land and ethnic inequalities that persisted and created the conditions for rebellion. Analysis of this case has lessons for the long-term legacies of historical institutions for insurgency and allows us to address endogeneity and explain recurrence of conflict. I outline several contributions of my theory to the literature on colonial legacies and political violence in South Asia, and describe the mixed methods nested analysis research design in the book.
The book ends by asking if there are any policy implications of my theory based on colonial institutions. A likely criticism of my theory is that the structural conditions created by colonialism are persistent and sticky and cannot be changed by the government. I show there are policy implications, for example, if political parties are really committed to land reforms as in Kerala and Karnataka, they can reverse some of the pernicious effects of indirect rule and indirect land tenure. Another possible critique of my theory is whether it can explain recent violence patterns of the Maoist conflict. The level of Maoist violence has declined since 2013-14, and the number of surrenders by Maoist cadres has increased in recent years, but low-level violence and attacks against security forces continue. The Maoist insurgency falls into the pattern of low-intensity but persistent insurgencies like the Kashmir and northeast insurgencies in India. While my theory based on colonial legacies is supposed to explain only the initial spatial variation of insurgency, and not its expansion and patterns of violence, it allows us to explain persistence and historical recurrence of conflict.
Preliminary evidence suggests beneficial effects of cognitive remediation in depression. An update of the current evidence is needed. The aim was to systematically assess the effectiveness of cognitive remediation in depression on three outcomes.
Methods
The meta-analysis was pre-registered on PROSPERO (CRD42019124316). PubMed, PsycINFO, Embase and Cochrane Library were searched on 2 February 2019 and 8 November 2020 for peer-reviewed published articles. We included randomized and non-randomized clinical trials comparing cognitive remediation to control conditions in adults with primary depression. Random-effects models were used to calculate Hedges' g, and moderators were assessed using mixed-effects subgroup analyses and meta-regression. Main outcome categories were post-treatment depressive symptomatology (DS), cognitive functioning (CF) and daily functioning (DF).
Results
We identified 5221 records and included 21 studies reporting on 24 comparisons, with 438 depressed patients receiving cognitive remediation and 540 patients in a control condition. We found a small effect on DS (g = 0.28, 95% CI 0.09–0.46, I2 40%), a medium effect on CF (g = 0.60, 95% CI 0.37–0.83, I2 44%) and a small effect on DF (g = 0.22, 95% CI 0.06–0.39, I2 3%). There were no significant effects at follow-up. Confounding bias analyses indicated possible overestimation of the DS and DF effects in the original studies.
Conclusions
Cognitive remediation in depression improves CF in the short term. The effects on DS and DF may have been overestimated. Baseline depressive symptom severity should be considered when administering cognitive remediation.