To familiarize herself with a user-interface of a software system, a user needs practice. With practice, a user's think time gradually decreases—the novice to expert transition. We propose a queueing model that accounts for this transition in analyzing the performance of a distributed software system. We solve the model using deterministic simulation. Our model captures system performance in terms of system response time. We use the model to demonstrate how users— who are at various experience levels in the novice to expert continuum—may affect the system response time.

Simulated standardized patients (SSP) have emerged as close to a gold standard for measuring the quality of clinical care. This method resolves problems of patient mix across healthcare providers and allows care to be benchmarked against preexisting standards. Nevertheless, SSPs are not real patients. How, then, should data from SSPs be considered relative to clinical observations with real patients in a given health system? Here, we reject the proposition that SSPs are direct substitutes for real patients and that the validity of SSP studies therefore relies on their ability to imitate real patients. Instead, we argue that the success of the SSP methodology lies in its counterfactual manipulations of the possibilities available to real careseekers - especially those paths not taken up by them - through which real responses can be elicited from real providers. Using results from a unique pilot study where SSPs returned to providers for follow-ups when asked, we demonstrate that the SSP method works well to elicit responses from the provider through conditional manipulations of SSP behavior. At the same time, observational methods are better suited to understand what choices real people make, and how these can affect the direction of diagnosis and treatment. A combination of SSP and observational methods can thus help parse out how quality of care emerges for the patient as a shared history between care-seeking individuals and care providers.

Background

The initiation of anti-tuberculosis treatment (ATT) based on results of WHO-approved microbiological diagnostics is an important marker of quality tuberculosis (TB) care. Evidence suggests that other diagnostic processes leading to treatment initiation may be preferred in high TB incidence settings. This study examines whether private providers start anti-TB therapy on the basis of chest radiography (CXR) and clinical examinations.

Methods

This study uses the standardized patient (SP) methodology to generate accurate and unbiased estimates of private sector, primary care provider practice when a patient presents a standardized TB case scenario with an abnormal CXR. Using multivariate log-binomial and linear regressions with standard errors clustered at the provider level, we analyzed 795 SP visits conducted over three data collection waves from 2014 to 2020 in two Indian cities. Data were inverse-probability-weighted based on the study sampling strategy, resulting in city-wave-representative results.

Findings

Amongst SPs who presented to a provider with an abnormal CXR, 25% (95% CI: 21-28%) visits resulted in ideal management, defined as the provider prescribing a microbiological test and not offering a concurrent prescription for a corticosteroid or antibiotic (including anti-TB medications). In contrast, 23% (95% CI: 19-26%) of 795 visits were prescribed anti-TB medications. Of 795 visits, 13% (95% CI: 10-16%) resulted in anti-TB treatment prescriptions/dispensation and an order for confirmatory microbiological testing.

Interpretation

One in five SPs presenting with abnormal CXR were prescribed ATT by private providers. This study contributes novel insights to empiric treatment prevalence based on CXR abnormality. Further work is needed to understand how providers make trade-offs between existing diagnostic practices, new technologies, profits, clinical outcomes, and the market dynamics with laboratories.

Funding

This study was funded by the Bill & Melinda Gates Foundation (grant OPP1091843), and the Knowledge for Change Program at The World Bank.

As the first point of care for many healthcare seekers, private pharmacies play an important role in tuberculosis (TB) care. However, previous studies in India have showed that private pharmacies commonly dispense symptomatic treatments and broad-spectrum antibiotics over-the-counter (OTC), rather than referring patients for TB testing. Such inappropriate management by pharmacies can delaye TB diagnosis. We assessed medical advice and OTC drug dispensing practices of pharmacists for standardized patients presenting with classic symptoms of pulmonary TB (case 1) and for those with sputum smear positive pulmonary TB (case 2), and examined how practices have changed over time in an urban Indian site. We examined how and whether private pharmacies improved practices for TB in 2019 compared to a baseline study conducted in 2015 in the city of Patna, using the same survey sampling techniques and study staff. The proportion of patient-pharmacist interactions that resulted in correct or ideal management, as well as the proportion of interactions resulting in antibiotic, quinolone, and corticosteroid are presented, with standard errors clustered at the provider level. To assess the difference in case management and the use of drugs across the two cases by round, a difference in difference (DiD) model was employed. A total of 936 SP interactions were completed over both rounds of survey. Our results indicate that across both rounds of data collection, 331 of 936 (35%; 95% CI: 32-38%) of interactions were correctly managed. At baseline, 215 of 500 (43%; 95% CI: 39-47%) of interactions were correctly managed whereas 116 of 436 (27%; 95% CI: 23-31%) were correctly managed in the second round of data collection. Ideal management, where in addition to a referral, patients were not prescribed any potentially harmful medications, was seen in 275 of 936 (29%; 95% CI: 27-32%) of interactions overall, with 194 of 500 (39%; 95% CI: 35-43%) of interactions at baseline and 81 of 436 (19%; 95% CI: 15-22%) in round 2. No private pharmacy dispensed anti-TB medications without a prescription. On average, the difference in correct case management between case 1 vs. case 2 dropped by 20 percent points from baseline to the second round of data collection. Similarly, ideal case management decreased by 26 percentage points between rounds. This is in contrast with the dispensation of medicines, which had the opposite effect between rounds; the difference in dispensation of quinolones between case 1 and case 2 increased by 14 percentage points, as did corticosteroids by 9 percentage points, antibiotics by 25 percentage points and medicines generally by 30 percentage points. Our standardised patient study provides valuable insights into how private pharmacies in an Indian city changed their management of patients with TB symptoms or with confirmed TB over a 5-year period. We saw that overall, private pharmacy performance has weakened over time. However, no OTC dispensation of anti-TB medications occurred in either survey round. As the first point of contact for many care seekers, continued and sustained efforts to engage with Indian private pharmacies should be prioritized.

The sites of cardiac excitation-contraction (E-C) coupling are composed of sarcoplasmic reticulum (SR)-localized calcium release channels, known as ryanodine receptors (RyRs), coupled to voltage-gated L-type calcium channels (LTCCs) on the sarcolemma in junctional membrane micro- domains termed "couplons". Mounting evidence suggests that the dysregulation of calcium fluxes within these domains is critical in the pathogenesis of heart failure. Despite their essential role in the maintenance of normal myocardial excitation and contractility, our quantitative understanding of couplons is greatly limited due to the formidable technical challenge of imaging and exploring the structure-function relationship of the E-C coupling site. In the work presented here, I developed novel two- and three-dimensional approaches for in-resin, correlated super-resolution fluorescent light microscopy (LM) and electron microscopy (EM) to quantify the distribution of key E-C coupling molecules and reveal their association with membranous organelles in mammalian cardiomyocytes. The imaging of resin-embedded sections with stochastic optical reconstruction microscopy (STORM) was immediately followed by ultrastructural mapping using scanning or transmission EM. Three-dimensional EM data were reconstructed with both array and EM tomography. Correlated imaging using STORM and scanning EM across multiple cells revealed that while most RyRs were mapped within couplons, 21.0 ± 4.5% (n=6) of RyRs were non- junctional. LTCCs were found in couplons, and most NCXs were confined to the non-junctional subdomain of the sarcolemma. The exact localizations of junctional and non- junctional RyRs were further elucidated using correlated STORM and EM tomography, confirming that RyR signals colocalized with "feet" structures visible in couplons at the EM level. Interestingly, a significant population of non-junctional RyRs was found at the inter-membrane junctions between the network SR and the outer membrane of mitochondria. This technique was further applied to study the ultrastructural remodeling and associated RyR reorganization in genetically engineered junctophilin 2 knockout mice, a disease model which mimics abnormal E-C coupling observed in heart failure. The approach presented in this dissertation has facilitated the expansion of our understanding of ion-channel organization in the cardiomyocyte E-C coupling pathway and will pave the way for detailed models of the molecular mechanisms that lead to reduced myocardial contractility in heart failure

My dissertation research focuses on the construction of self and identity by Indian immigrant professional and semi-professional women who live and work in the San Francisco Bay Area. I have made an ethnographic study of the manner in which economic mobility and professional achievement remake gender, race, and class relations. The major issues are: What are the selves and identities of professional Indian women? How is continuity of selves and identities accomplished when individuals constantly shuttle between starkly different ethnoscapes of American workplace, Indian immigrant home, and transnational ideoscapes of ethnic belonging and cross-border ties? Indian immigrants in the San Francisco Bay Area have often been defined as a model minority. Indian immigrant women who have achieved entry into the current post-industrial service-related and technology -based economy in the Bay Area value the capital accumulation, status transformation, socio-economic autonomy, and renegotiation of familial gender relations that are made possible by their employment. However, this quintessential American success story conceals the psychic costs of uneasy Americanization, social misrecognition, long drawn out gender battles, and incessant cross-cultural journeys of selves and identities. Americanization increases with the length of residence in the United States and duration of participation in the American labor force. However, despite their concerted attempts at being "American", my subjects continue to be viewed as "Indians", that is, as representatives of a foreign and exotic culture. Essentialization, whether positive or pejorative, causes psychological dissonance. My respondents are called upon to "speak for" Indian culture precisely when they are drifting away from old Indian habits and adopting new American ways. Nostalgia for the "homeland", as well as, "misrecognition" as "Indian" (rather than "Indian American") leads to a partial abandonment of the path to assimilation, and hence, it results in the reproduction of an Indian diasporic identity that is activated as and when needed. Thus, the Indian immigrant home becomes a principal site for the recomposition of Indian culture, and transnational ties to the "home-country" are strengthened. Code-switching back and forth between the performances of their dual American and Indian identities, my subjects have formulated a unique response to the contradictions in the expectations of American society and workplace on one hand, and the Indian immigrant home and community on the other

This dissertation presents techniques to improve the performance of both coherent as well as non-coherent wireless communication systems via optimizing symbol timing, frequency spacing and by making efficient SNR estimations. We show that some of the design choices made in traditional systems are not optimal and demonstrate the gains that may be achieved by making unconventional, but judicious, choices for these parameters. We start in the area of coherent multi-antenna communications where we introduce an offset between the symbol boundaries of the transmitted waveforms from the different antennas and show that this improves performance in comparison to the traditional symbol aligned transmission. For this modified system, we derive various optimal receivers such as maximum likelihood (ML), best linear unbiased estimator (BLUE), minimum mean squared error (MMSE), and zero forcing (ZF) receivers and show that they outperform the equivalent receiver for the system with aligned symbol boundaries. In some system configurations, the performance gain is close to 2dB. The design methodology for a new symbol pulse shape that increases the performance even more is also presented. Next, we extend the study of SNR estimation from the previously published results of a data aided (DA) single antenna system to the non-data aided (NDA) model and also to systems with multiple antennas (MIMO). In both these cases, we have derived the Cramér- Rao lower bound (CRLB) as well as ML estimators that achieve or perform very close to the CRLB. For MIMO systems we define the SNR and then derive the CRLB and the ML estimators for both the DA as well as the NDA data model. We show that previously published results for single antenna systems are a special case of our general solution. The proposed SNR estimation techniques are demonstrated in a patented algorithm to detect the onset of non-linearity in a remote transmitter by dithering the power of transmitted bursts and estimating the difference in the received SNR. For non-coherent systems we show that the performance of multi-tone M-ary frequency shift keying (MT-MFSK) modulation may be significantly improved if, instead of the usual choice of mutually orthogonal tones, non-orthogonal tones are used. In some system configurations, the proposed system can lead to a 4-fold increase in system capacity. The channel capacity, as well as the performance gains of systems using practical receivers such as ML, least squared (LS) error, and compressed sensing (CS) are demonstrated for both flat and frequency selective channels. Many more choices of spectral efficiency are achievable by the non-orthogonal system, thus enabling the system to adapt to changing link SNR and send data at the optimum spectral efficiency. In order to make this practical, we derive the CRLB and ML estimators for SNR estimation for non-orthogonal MT-MFSK in both the DA as well as the NDA data model