282 research outputs found
On the role of feedback in network coding
No full textThesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student submitted PDF version of thesis.Includes bibliographical references (p. 143-149).Network coding has emerged as a new approach to operating communication networks, with a promise of improved efficiency in the form of higher throughput, especially in lossy conditions. In order to realize this promise in practice, the interfacing of network coding with existing network protocols must be understood well. Most current protocols make use of feedback in the form of acknowledgments (ACKs) for reliability, rate control and/or delay control. In this work, we propose a way to incorporate network coding within such a feedback-based framework, and study the various benefits of using feedback in a network coded system. More specifically, we propose a mechanism that provides a clean interface between network coding and TCP with only minor changes to the protocol stack, thereby allowing incremental deployment. In our scheme, the source transmits random linear combinations of packets currently in the TCP congestion window. At the heart of our scheme is a new interpretation of ACKs - the receiver acknowledges every degree of freedom (i.e., a linear combination that reveals one unit of new information) even if it does not reveal an original packet immediately. Such ACKs enable a TCP-compatible sliding-window implementation of network coding. Thus, with feedback, network coding can be performed in a completely online manner, without the need for batches or generations. Our scheme has the nice feature that packet losses on the link can be essentially masked from the congestion control algorithm by adding enough redundancy in the encoding process.(cont.) This results in a novel and effective approach for congestion control over networks involving lossy links such as wireless links. Our scheme also allows intermediate nodes to perform re-encoding of the data packets. This in turn leads to a natural way of running TCP flows over networks that use multipath opportunistic routing along with network coding. We use the new type of ACKs to develop queue management algorithms for coded networks, which allow the queue size at nodes to track the true backlog in information with respect to the destination. We also propose feedback-based adaptive coding techniques that are aimed at reducing the decoding delay at the receivers. Different notions of decoding delay are considered, including an order-sensitive notion which assumes that packets are useful only when delivered in order. We study the asymptotic behavior of the expected queue size and delay, in the limit of heavy traffic.by Jay Kumar Sundararajan.Ph.D
Predicting Legal Systems: an Artificial Neural Network Approach With Statistical Analysis for Comparative Study of Civil Law and Common Law Countries
No full textThis study compares countries with common law with countries with civil law systems and investigates the possibility of predicting legal systems using artificial neural networks (ANNs). The OLS model, ANOVA, ANN, and Tensor Flow are used in the research to analyze the data. The goal is to find out how board characteristics and country legislative frameworks affect how European corporations disclose their social performance. The performance of a hidden layer with five nodes is best, according to the ANN model. The model\u27s accuracy throughout testing and validation is 0.750. The confusion matrix shows that, of the four observations in the test set, three were correctly categorized as "Civil law" and one was incorrectly categorized as "Common law."
To evaluate the model\u27s efficacy, evaluation metrics are computed. The model\u27s accuracy is 0.750, which represents a prediction success rate of 75%. For the "Civil law" class, the recall (true positive rate) is 1.0, indicating that all "Civil law" cases are correctly identified. Metrics for the "Common law" class, however, are not available due to the scant amount of data that is available. The prevalence of countries with common law and civil law systems is compared in the ANOVA analysis. As shown by the computed F-value of 0.482, there is less variance inside each legal system than there is between the two. There is no statistically significant difference in frequency between the two legal systems, according to the p-value of 0.495. Overall, the research\u27s conclusions imply that social performance disclosure between countries with common law and civil law systems differs only slightly. The neural network model\u27s network weights provide insight into the importance of different features in prediction
A Unified Theory of Intrachannel Nonlinearity in Pseudolinear Transmission
No full textThe material of this chapter originates from a visit of the author the AT&T Laboratory in Red Bank, NJ in
the summer of 2000. During that visit, the author was exposed to some experimental work on transmission
using short pulses, which spread very rapidly upon propagation and for this reason were dubbed by Jay
Wiesenfeld into “Tedons” from “to ted” which, according to Merriam-Webster’s Collegiate Dictionary,
means “to spread or turn from the swath and scatter (as new-mown grass) for drying.” Tedons minimize
the effects of nonlinearity by a quick spread, unlike solitons that instead resist to nonlinearity by balancing
nonlinearity with dispersion, so that their shape does not change. He teamed up with Carl Clausen and
Mark Shtaif and developed a perturbative theory, whose results were presented in a series of three papers
1, 2, 3]. The details of that theory and of its derivations were, however, never published in the open
literature. The presentation of these details, together with some later improvements, is the purpose of this
chapter
The impact of social isolation due to the COVID-19 pandemic on patients with dementia and caregivers
No full textSupplementary Material: To view supplementary material for this article, please visit https://doi.org/10.1017/neu.2022.12.Copyright © The Author(s) and Scandinavian College of Neuropsychopharmacology 2022. Objective:
Social distancing to limit COVID-19 transmission has led to extensive lifestyle changes, including for people with dementia (PWD). The aim of this study, therefore, was to assess the impact of lockdown on the mental health of PWD and their carers.
Methods:
Forty-five carers of PWD completed a telephone interview during the baseline assessment of the SOLITUDE study to gather information on life conditions and changes in symptoms of PWD during lockdown. Associations between changes in symptoms of PWD and carers’ concerns and mental health were investigated.
Results:
About 44% of carers experienced anxiety and irritability and reported changes in behavioural and cognitive symptoms in PWD. These changes were associated with worse carers’ mental health and concerns about faster disease progression (χ2 = 13.542, p < 0.001).
Conclusion:
COVID-19-related social isolation has had a negative impact on patients’ and carers’ mental health. Potential long-term neurocognitive consequences require further investigation.This research received no specific grant from any funding agency, commercial or not-for-profit sectors
An Examination of the Globalisation of Authorship in Publishing in 20 Leading Marketing Journals
No full textPurpose of this paper is to examine the global contribution of academics to marketing literature between 1999 and 2003, based on an examination of the location of academics institution of employment, as reported in published works. The data is used to evaluate the global dispersion of publishing.\ud
Design/approach. The paper uses the method of content analysis where the authorship of all articles in 20 leading marketing journals between 1999 and 2003 is examined. An empirical examination of performance was undertaken across geographic regions. There was also an examination of whether the quality of journal affected regional performance.\ud
Findings. The research found that there is a significant "bias" of authorship within the 20 journals examined, with the majority of works published by academics at institutions in North America. There is some variation in regional performance based on the type of journal examined. Limitations. There was no attempt to empirically examine why differences might exist. The study only focused on a sample of 20 English language journals over 5 years. These journals have been included in studies that list the leading marketing journal for US and European academics. Practical Implications. The research suggests that there may in fact be regional differences in publishing behaviour. It is unclear if these differences relate to variations in the "objectives" of institutions within each country or other factors, such as the North American publish-or-perish mentality. The research posits that a marketing knowledge may be unnecessarily restricted, if there is a bias against non-North American perspectives. Originality. While there have been other works examining research performance of institutions, there has been limited examination in marketing on the nation in which authors work and none have used a broad cross-section of journals. This work takes a global "snapshot" of national research performance within marketing
Translating Research to Policy: Setting Provider Payment Rates for Strategic Purchasing under India's National Publicly Financed Health Insurance Scheme
No full textBackground
In 2018, the Government of India launched Ayushman Bharat Pradhan Mantri-Jan Aarogya Yojana (AB PM-JAY), a large tax-funded health insurance scheme. In this paper, we present findings of the Costing of Health Services in India (CHSI) study, describe the process of use of cost evidence for price-setting under AB PM-JAY, and estimate its fiscal impact.
Methods
Reference costs were generated from the first phase of CHSI study, which sampled 11 tertiary public hospitals from 11 Indian states. Cost for Health Benefit Packages (HBPs) was estimated using mixed (top-down and bottom-up) micro-costing methods. The process adopted for price-setting under AB PM-JAY was observed. The cost of each HBP was compared with AB PM-JAY prices before and after the revision, and the budgetary impact of this revision in prices was estimated.
Findings
Following the CHSI study evidence and price consultations, 61% of AB PM-JAY HBP prices were increased while 18% saw a decline in the prices. In absolute terms, the mean increase in HBP price was ₹14,000 (₹450–₹1,65,000) and a mean decline of ₹6,356 (₹200–₹74,500) was observed. Nearly 42% of the total HBPs, in 2018, had a price that was less than 50% of the true cost, which declined to 20% in 2019. The evidence-informed revision of HBP prices is estimated to have a minimal fiscal impact (0.7%) on the AB PM-JAY claims pay-out.
Interpretation
Evidence-informed price-setting helped to reduce wide disparities in cost and price, as well as aligning incentives towards broader health system goals. Such strategic purchasing and price-setting requires the creation of systems of generating evidence on the cost of health services. Further research is recommended to develop a cost-function to study changes in cost with variations in time, region, prices, skill-mix and other factors
Self-healing hydrogel coatings for improving the biocompatibility of brain implants
No full textCortical implants are an important component of a variety of novel therapeutic technologies, such as brain-computer interfaces for prosthetic control and sensory restoration devices. However, the widespread use of these devices is limited by the brain’s endogenous foreign body response (FBR) to cortical implants, which involves inflammation and scar tissue formation. FBR is exacerbated by three major factors: reactive chemical pathways such as cytokine gradients, mechanical mismatch between the stiff implant and soft brain tissue, and micromotion at the implant-tissue interface caused by pulsation of brain tissue due to respiration and circulation. This project focused on developing and analyzing hydrogel coatings that attenuate these factors. We worked with three different hydrogel systems—a polyelectrolyte gel, a guest-host gel, and a self-assembling peptide gel—and used mechanical and bio-functional strategies to optimize them for performance as implant coatings. The coatings are designed to closely match the mechanical properties of brain tissue to address mechanical mismatch. They contain physical, non-covalent bonds within their polymer networks that can dissociate and reform to absorb the kinetic energy generated by micromotion, preventing it from perturbing brain tissue. The self-assembling peptide gel contains a cytokine sequestration motif that aims to reduce the activation of inflammatory recruitment agents, addressing the chemical causes of FBR. As part of this project, we developed a custom open-source device to simulate micromotion between an implant and surrounding tissue. We use the device, as well as other methods such as cytotoxicity assays and rheological analysis, to characterize the hydrogels and compare the effectiveness of various modifications. We developed versions of the hydrogels adapted for use as implant coatings that outperformed covalent hydrogel PEGDA at reducing micromotion at the implant interface. Our work with the self-assembling peptide gel focused on molecular dynamics simulation of the cytokine sequestration motif’s assembly with the cytokine CCL2 in order to develop an improved peptide motif that maximized CCL2 affinity. We demonstrated that the new motif outperforms the original motif at sequestering CCL2. Overall, this work represents advancement in development of FBR-reducing implant coatings, as well as in the techniques used to evaluate their efficacy.Ph.D.Includes bibliographical reference
The Dystopian Novels in the First Half of the 20th Century: A Comparative Study of 1984 (George Orwell), Brave New World (Aldous Huxley) and Anthem (Ayn Rand)
No full textNot availabl
A prospective study of dynamic treatment of fracture phalanx and metacarpals of the hand with Kirschner-wire fixation/external fixator and finger splint: Daycare management (30 cases)
No full textIntroduction: Fractures of the phalanx and metacarpals are some of the most frequently encountered orthopedics injuries and constitute between 14-28% of all visits to emergency department which comprises 46% of the hand fracture and out of that mostly involved are the proximal phalanx and metacarpal neck fracture are most common and then the middle and distal phalanx and the base of metacarpal. The commonest complication with surgical treatment were stiff painful joints due to prolonged immobilization at fracture sites. This prospective study was undertaken to evaluate the functional outcome after surgical stabilization of metacarpal and phalanx fracture on day care basis. Materials And Methods: In our study we treated 30 patients who came to our hospital by fixation either with K wire or external fixation or hybrid fixation under local anaesthesia depending on the type of fracture between 2013 to 2014 with the average age 28 years with the youngest being 18 years and the oldest being 41 years with transverse, spiral, oblique closed fracture, grade 1 compound fracture, intraarticular, extraarticular, comminuted and non comminuted fracture of phalanx and metacarpals.These were day care treatment. Patient was allowed to begin his daily routine work from post operative day l. During this course the operated site was protected with splinting. Results: Clinical Outcomes were assessed as Excellent, Good, Satisfactory and Poor. Radiological assessment was done by taking x-ray to check radiological union.There were 24 cases had excellent outcome, 5 cases had good outcome and only 1 case had satisfactory outcome which occurred due to mal-union. There were 3 cases of pin-tract infection which subsided with oral antibiotics, and 3 cases of malunion. Conclusion: This was a day care procedure, patient were admitted, treated and discharged on the same day & encouraged to begin mobilization of the joints of hands from day 1
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