Distributed Hypothesis Testing over a Noisy Channel: Error-Exponents Trade-Off.

A two-terminal distributed binary hypothesis testing problem over a noisy channel is studied. The two terminals, called the observer and the decision maker, each has access to n independent and identically distributed samples, denoted by U and V, respectively. The observer communicates to the decision maker over a discrete memoryless channel, and the decision maker performs a binary hypothesis test on the joint probability distribution of (U,V) based on V and the noisy information received from the observer. The trade-off between the exponents of the type I and type II error probabilities is investigated. Two inner bounds are obtained, one using a separation-based scheme that involves type-based compression and unequal error-protection channel coding, and the other using a joint scheme that incorporates type-based hybrid coding. The separation-based scheme is shown to recover the inner bound obtained by Han and Kobayashi for the special case of a rate-limited noiseless channel, and also the one obtained by the authors previously for a corner point of the trade-off. Finally, we show via an example that the joint scheme achieves a strictly tighter bound than the separation-based scheme for some points of the error-exponents trade-off.

Fibrovascular Polyp of the Cervical Esophagus: A Rare Neoplasm.

Fibrovascular polyps are rare benign epithelial neoplasia of the cervical esophagus. Usually they are large and frequently require a thoracotomy/thoracoscopy. This is a case report of an elderly lady with a large Fibrovascular polyp who had anemia and weight loss due to dysphagia, managed by rendezvous technique.

Protocol to ensure continued pediatric liver transplantation service during the COVID pandemic and the encouraging outcomes.

Coronavirus disease 2019 is a global pandemic, and to deal with the unexpected, enormous burden on healthcare system, liver transplantation (LT) services have been suspended in many centers. Development of robust and successful protocols in preventing the disease among the recipients, donors and healthcare workers would help in re-starting the LT programs. We adapted a protocol at our center, which is predominantly a living donor liver transplant center based in north India, and continued the service as the pandemic unfolded and peaked in India with good results and shared the experience of the same. Between March 24 and June 7, 2020, during the government-enforced public curfew-"lockdown"-7 children received LT. The protocols of infection control were drafted in our team by local customization of published guidelines. The number of pediatric LT done during the lockdown period in 2020 was similar to that done in corresponding pre-COVID period in 2019. The outcomes were of 100% survival, and none of recipients developed COVID. One potential donor was asymptomatic positive for COVID, responded well to conservative treatment, and was later accepted as a donor. LT program during the COVID pandemic can successfully function after putting in place standard protocols for infection control. These can be implemented with minimal extra involvement of healthcare infrastructure, hence without diversion of resources from COVID management. In conclusion, pediatric liver transplantation services can be continued amid COVID-19 pandemic after establishing a properly observed protocol with minimum additional resources.

Living Donor Liver Transplant for Dengue-Related Acute Liver Failure: A Case Report.

Dengue is a common viral infection, especially in tropical countries, and it is a well-known cause of acute liver failure. The effects on the liver range from a mild illness to acute liver failure. Dengue-related acute liver failure has a high mortality rate, and the role of liver transplant in such cases has been less studied, due to the rapid progression and often associated multiorgan dysfunction in severe cases. Here, we report the first living donor liver transplant for an acute liver failure due to dengue. Although liver transplant is not the choice of treatment for sick patients, timely intervention in specific patients may have a role.

Privacy-Aware Distributed Hypothesis Testing.

A distributed binary hypothesis testing (HT) problem involving two parties, a remote observer and a detector, is studied. The remote observer has access to a discrete memoryless source, and communicates its observations to the detector via a rate-limited noiseless channel. The detector observes another discrete memoryless source, and performs a binary hypothesis test on the joint distribution of its own observations with those of the observer. While the goal of the observer is to maximize the type II error exponent of the test for a given type I error probability constraint, it also wants to keep a private part of its observations as oblivious to the detector as possible. Considering both equivocation and average distortion under a causal disclosure assumption as possible measures of privacy, the trade-off between the communication rate from the observer to the detector, the type II error exponent, and privacy is studied. For the general HT problem, we establish single-letter inner bounds on both the rate-error exponent-equivocation and rate-error exponent-distortion trade-offs. Subsequently, single-letter characterizations for both trade-offs are obtained (i) for testing against conditional independence of the observer's observations from those of the detector, given some additional side information at the detector; and (ii) when the communication rate constraint over the channel is zero. Finally, we show by providing a counter-example where the strong converse which holds for distributed HT without a privacy constraint does not hold when a privacy constraint is imposed. This implies that in general, the rate-error exponent-equivocation and rate-error exponent-distortion trade-offs are not independent of the type I error probability constraint.

Small Fenestra Stapedotomy Versus Large Fenestra Stapedectomy in Improving Hearing Ability in Patients with Otosclerosis: Our 10 Years Experience.

The aim of this study was to review the experience with surgical treatment of otosclerosis over the last 10 years at Amrita Institute of Medical Sciences and Research Centre and to compare it with reported outcomes. A total of 125 patients who had reported between January 2008 and June 2018 were selected for the study. The inclusion criteria for the study included the age group 15-60 years, conductive hearing loss with intact tympanic membrane and an air-bone-gap (ABG) of more than 30 dB. The exclusion criteria included patients below 15 years of age and above 60 years of age, patients with chronic otitis media and the cases of revision stapes surgery. Audiological evaluation was conducted prior to the surgery and post operative audiological evaluation was also performed after 1 month to understand the difference in hearing. In all cases the same surgical technique was used, only the dimension of the foot plate removed varied. Statistical analysis was done using Statistical Package for the Social Sciences (SPSS) (version windows base system, SPSS Inc. Chicago IL USA) software. Mean age in years who underwent surgery is 37.8 ± 11.4 and duration of disease in months median 36 months (range 1-120 months). Of the 125 patients (42% males and 58% females), 73 patients underwent large fenestra stapedotomy, and 52 patients underwent small fenestra stapedotomy. There was significant improvement in the following hearing parameters studied (puretone average of air conduction thresholds-PTA, ABG) in both the groups after surgery. There was no significant difference between the small fenestra and large fenestra groups with respect to improvement in PTA and ABG. On comparison of SDS (pre and post surgery) statistically significant difference was noted only in small fenestra group. However, this difference of SDS was not significant in between group comparison (stapedotomy versus stapedectomy). In summary both techniques are safe and effective treatment for conductive hearing loss in otosclerosis patients. There appears to be no deleterious effects of either procedures on hearing function. Similar results can be obtained in experienced hands using either technique. The absence of serious complications makes it reasonable to perform stapes surgery in both ears in patients with bilateral otosclerosis with conductive hearing loss.