ABC-based Forecasting in State Space Models

Approximate Bayesian Computation (ABC) has gained popularity as a method for conducting inference and forecasting in complex models, most notably those which are intractable in some sense. In this paper we use ABC to produce probabilistic forecasts in state space models (SSMs). Whilst ABC-based forecasting in correctly-specified SSMs has been studied, the misspecified case has not been investigated, and it is that case which we emphasize. We invoke recent principles of 'focused' Bayesian prediction, whereby Bayesian updates are driven by a scoring rule that rewards predictive accuracy; the aim being to produce predictives that perform well in that rule, despite misspecification. Two methods are investigated for producing the focused predictions. In a simulation setting, 'coherent' predictions are in evidence for both methods: the predictive constructed via the use of a particular scoring rule predicts best according to that rule. Importantly, both focused methods typically produce more accurate forecasts than an exact, but misspecified, predictive. An empirical application to a truly intractable SSM completes the paper

Predicting response to leuprolide of women with premenstrual dysphoric disorder by daily mood rating dynamics

Approximately 60–70 percent of women with premenstrual dysphoric disorder (PMDD) show symptomatic improvement in response to the GnRH agonist leuprolide acetate, which suppresses ovarian function. However, it has been very difficult to either predict or understand why some women respond, while others do not. We applied several complementary statistical methods to the dynamics of pre-treatment mood rating data to determine possible predictors of response for women with PMDD. We compared responders (n = 33) to nonresponders (n = 12) in clinical trials of leuprolide (three months in duration) as a treatment for PMDD, on the basis of pre-trial daily self-ratings of sadness, anxiety, and irritability. We analyzed both sequential irregularity (approximate entropy, ApEn) and a quantification of spikiness of these series, as well as a composite measure that equally weighted these two statistics. Both ApEn and Spikiness were significantly smaller for responders than nonresponders (P ≤ 0.005); the composite measure was smaller for responders compared with nonresponders (P ≤ 0.002) and discriminated between the subgroups with high sensitivity and specificity. In contrast, mean symptom levels were indistinct between the subgroups. Relatively regular and non-spiky pre-trial dynamics of mood ratings predict a positive response to leuprolide by women with PMDD with high probability, moreover based on typically less than 3 months of daily records. The statistical measures may have broad and direct applicability to behavioral studies for many psychiatric disorders, facilitating both accurate diagnosis and the prediction of response to treatment

An asymptomatic radiolucent lesion in posterior mandible: A case report

Radiolucent mandibular lesions are commonly evident on head and neck imaging and present a diagnostic dilemma for the radiologist. These may represent a broad spectrum of lesions arising from both odontogenic and nonodontogenic structures. Furthermore, few radiolucent lesions are often identified as incidental lesions by the radiologist on imaging performed for different reasons. Location of the lesion, borders, internal structure, and its effect on surrounding structures are the key points to narrow the differential diagnosis. Imaging is essential not only for the diagnosis of lesions, but also to guide therapy and monitor the treatment response. Here is a case report on traumatic bone cyst that presented as an asymptomatic radiolucent lesion in right posterior mandible and was discovered incidentally on routine radiograph. The lesion was diagnosed based on patient′s anamnesis and radiographic examination. This paper aims at discussing the differential diagnosis, various radiological characteristics, and their prediction in prognosis of the lesion

Radiographic manifestations of systemic diseases in jaw bones: A systematic review

Disorders of the endocrine system, bone metabolism and other systemic diseases may have an effect on the form and function of bone and teeth. The dental radiograph provides information which is valuable in the diagnosis of systemic disease. It provides the first clue that leads to an early diagnosis of the disease. Oral radiographic manifestations are not always present in given patient and the degree of expression is highly variable and it may reflect the severity and duration of the systemic disease. Many systemic diseases have oral manifestations. The oral cavity might well be thought of as the window to the body because oral manifestations accompany many systemic diseases. These oral manifestations must be properly recognized if the patient is to receive appropriate diagnosis and referral for treatment. This article highlight the radiographic manifestations of systemic diseases in jaw bones so as to enable the dental practitioner to diagnose the systemic diseases that manifest in the jaw bones for early diagnosis and treatment of the disease

Pleomorphic adenoma of the parotid gland with cystic degeneration: A rare case report

Pleomorphic adenoma, also called benign mixed tumor, is the most common tumor of the salivary glands. Usually they are found as solitary, unilateral, firm and mobile, painless, slow growing masses. Only 10% of them occur in the minor salivary glands and 90% of them occur in the parotid gland. The incidence of parotid tumor is about 2.4 in 100000/year of all neoplasia of head and neck region, the right side being commonly involved and seen more often in males. Management involves surgical resection by superficial or total parotidectomy. This case report illustrates clinical features, imaging characteristics and histopathological features in a case of pleomorphic adenoma

Conventional and digital radiographic methods in the detection of simulated external root resorptions: A comparative study

Objective : To evaluate and compare the efficacy of conventional and digital radiographic methods in the detection of simulated external root resorption cavities and also to evaluate whether the detectability was influenced by resorption cavity sizes. Methods : Thirty-two selected teeth from human dentate mandibles were radiographed in orthoradial, mesioradial and distoradial aspect using conventional film (Insight Kodak F-speed; Eastman Kodak, Rochester, NY) and a digital sensor (Trophy RVG advanced imaging system) with 0.7mm and 1.0mm deep cavities prepared on their vestibular, mesial and distal surfaces at the cervical, middle and apical thirds. Three dental professionals, an endodontist, a radiologist and a general practitioner, evaluated the images twice with a one-week time interval. Results : No statistical significance was seen in the first observation for both conventional and digital radiographic methods in the detection of simulated external root resorptions and for small and medium cavities but statistical difference was noted in the second observation (P< 0.001) for both the methods. Conclusion : Considering the methodology and the overall results, conventional radiographic method (F-speed) performed slightly better than the digital radiographic method in the detection of simulated radiographic method but better consistency was seen with the digital system. Overall size of the resorption cavity had no influence on the performance of both methods and suggests that initial external root resorption lesion is not well-appreciated with both the methods as compared to the advanced lesion

Drug induced neutropenia manifesting as oral ulcerations

As dental practitioners, we often come across oral ulcerations of varied etiology. Among all the causes of oral ulcers, those due to neutropenia are significant. Neutropenia can occur in many systemic conditions and also in patients on long-term therapy of certain drugs like phenytoin. The diagnosis of neutropenia in time leads to early recognition of the cause of this fatal condition. Here, we report a case of a 50-year-old female patient who developed oral ulcerations secondary to phenytoin-induced neutropenia. Early diagnosis of the condition led to discontinuation of the offending drug and significant improvement in her blood picture and also prevented her from falling prey to many other systemic infections that neutropenia can cause