The assignment problem in distributed computing

This dissertation focuses on the problem of assigning the modules of a program to the processors in a distributed system with the goal of minimizing the overall cost of running the program. The cost depends on the execution times of the modules on the processors and on the cost of communication between modules. This module allocation problem arises in a variety of situations where one is interested in making optimum use of available computer resources. The general module allocation problem is intractable; however it becomes polynomially-solvable when the communication graph is restricted. In this dissertation, we restrict our attention to k-trees;As the first problem, we study parametric module allocation on partial k-trees. We allow the costs, both execution and communication, to vary linearly as functions of a real parameter t. We show that if the number of processors is fixed, the sequence of optimum assignments that are obtained, as t varies from zero to infinity, can be constructed in polynomial time. As an auxiliary result, we develop a linear-time algorithm to find a separator in a k-tree. We discuss the implications of our results for parametric versions of the weighted vertex cover, independent set, and 0-1 quadratic programming problems on partial k-trees;Next, we consider two variants of the assignment problem. The first problem is to find a minimum-cost assignment when one of the processors has a limited memory. The second is to find an assignment that minimizes the maximum processor load. We present exact dynamic programming algorithms for both problems, which lead to approximation schemes for the case where the communication graph is a partial k-tree. Faster algorithms are presented for trees with uniform costs. In contrast to these results, we show that, for arbitrary graphs, no fully polynomial time approximation schemes exist unless P = NP. Both dynamic programming algorithms have been implemented. The implementation details and our experimental results are presented

Intracellular delivery of nanomaterials for sub-cellular imaging and tracking of biomolecules.

Nanomaterials have many intriguing applications in biology and medicine. Unique properties such as enhanced electrical properties, increased chemical reactivity and resistance to degradation, novel optical properties and comparable size to that of biological systems have led to their use in various biomedical applications. The most important applications of nanomaterials for medicine are in drug delivery and imaging. This research focuses on utilizing the biocompatibility of single walled Carbon nanotubes (SWCNTs) and optical properties colloidal quantum dots (QDs) for cellular drug delivery and imaging of biomolecules. The first part of this research deals with single walled carbon nanotubes which are excellent candidates for targeted drug delivery applications due their unique structural and functional properties. However, prior to their use in therapeutics, their biocompatibility needs to be thoroughly investigated. The objectives of this research were to establish the biocompatibility of SWCNTs and demonstrate their use as drug delivery carriers into cells. Blood, a living tissue, is chosen as the biological system as it contains various cells which can potentially interact with SWCNTs during the delivery mechanism. The interactions of these cells in the blood (specifically white blood cells or leukocytes) with the SWCNTs provide vital information regarding the immune response of the host to the nanotubes. This research investigates the immune response of white blood cells due to SWCNTs via (a) direct interaction - presence of nanotubes in the blood and, (b) indirect interaction - presentation of nanotubes by antigen-presenting-cells to white blood cells. These two interactions recreate the innate and adaptive immune responses occurring in the body to any foreign substance. SWCNTs are functionalized with single stranded DNA (ss-DNA), which serves as a dispersant of nanotubes as well as a backbone for further attachment of other biomolecules of interest. Confocal microscopy and flow cytometric studies are performed to characterize the interactions. Results from this acute immune response study demonstrate the biocompatibility of SWCNTs in whole blood and also confirm the cellular delivery of single stranded DNA. The second part of the research is on colloidal quantum dots (QDs): nanometer sized semiconductor crystals typically between 1 run to 20 nm in diameter. In addition to being size comparable with many biological systems, and having large surface area for multiple biomolecules attachment, they possess high resistance to chemical and photo degradation, tunable emission based on size and composition which makes them excellent candidates for cellular delivery and imaging. The main objectives of this research was to demonstrate the use of QDs for cellular imaging as well as targeted biomolecule delivery by conjugating the QDs with an antibody to a functional protein and delivery into live cells. Conventional techniques deliver QDs as aggregates, however, a major challenge in the use of QDs for cellular imaging and biomolecule delivery is achieving freely dispersed QDs inside the cells. In this research, a new technique to deliver monodispersed QDs inside live cells was developed. The approach combines osmosis driven fluid transport into cells achieved by creating hypotonic environment and reversible permeabilization using low concentrations of cell permeabilization agents like Saponin. The results confirm that highly efficient endocytosis-free intracellular delivery of QDs can be accomplished using this method. Confocal microscopy is used to image the QDs inside the cells and flow cytometry is used for quantifying the fluorescence. To demonstrate targeted delivery, QDs are conjugated to the antibody of a protein: the nuclear transcriptional factor, NFkB (Nuclear Factor kappa-light chain-enhancer of activated B cells) using EDC/sulfo NHS chemistry methods. NFkB is a family of proteins with 5 different subunits and is involved in a variety of biological processes such as immune and inflammatory responses and cellular developmental processes. In unstimulated cells, NFkB is inactive in cytoplasm and translocates to the nucleus upon stimulation using bacterial products, viruses, radiation, and the like. QDs fluorescence could be used to monitor NFKB activity over extended periods of time in live cells

A Lie Bracket solution of the optimal thrust magnitude on a singulararc in atmospheric flight

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76114/1/AIAA-1992-4345-144.pd

PHARMACOKINETIC INVESTIGATION OF REMOGLIFLOZIN IN RAT PLASMA SAMPLES BY HIGH-THROUGHPUT HPLC-MS-MS

Objective: Remogliflozin (REMO), a selective inhibitor of the renal sodium-dependent glucose transporter 2 channel, which could increase urine glucose excretion and lower plasma glucose in humans. To establish a simple, sensitive and completely validated HPLC-MS-MS approach for the analysis of Remogliflozin in rat plasma samples. Methods: The method was developed after simple step protein precipitation by acetonitrile and Empagliflozin (EMPA) was used as internal standard. Separation was done on an CORTECS C18, 90 Å, 2.7 µm, 4.6 mm X 150 mm with an isocratic mobile phase consisting of 0.1% Formic acid: acetonitrile (20:80%, v/v) and pumped at a flow stream of 0.8 ml/min at ambient temperature. Results: The approach developed showed fine calibration curve in the quantity range of 5-1000 pg/ml with correlation coefficient (r2) of ≥ 0.9997 and the intra-run accuracy and precision was 99.91 to 109.07% and 0.17 to 1.34, inter-run accuracy and precision was 99.8 to 101.54 and 0.17 to 1.66 according to FDA guidelines. Conclusion: The newly designed and validated approach was simple, fast and applied effectively for single-dose oral pharmacokinetic investigation in Wistar male rats for the quantification of REMO in biological matrix

Tailoring 3D single-walled carbon nanotubes anchored to indium tin oxide for natural cellular uptake and intracellular sensing.

The ability to monitor intracellular events in real time is paramount to advancing fundamental biological and clinical science. We present the first demonstration of a direct interface of vertically aligned single-walled carbon nanotubes (VASWCNTs) with eukaryotic cells, RAW 264.7 mouse macrophage cell line. The cells were cultured on indium tin oxide with VASWCNTs. VASWCNTs entered the cells naturally without application of any external force and were shown to sense the intracellular presence of a redox active moiety, methylene blue. The technology developed provides an alluring platform to enable electrochemical study of an intracellular environment

Nanotechnology and the Treatment of HIV Infection

Suboptimal adherence, toxicity, drug resistance and viral reservoirs make the lifelong treatment of HIV infection challenging. The emerging field of nanotechnology may play an important role in addressing these challenges by creating drugs that possess pharmacological advantages arising out of unique phenomena that occur at the “nano” scale. At these dimensions, particles have physicochemical properties that are distinct from those of bulk materials or single molecules or atoms. In this review, basic concepts and terms in nanotechnology are defined, and examples are provided of how nanopharmaceuticals such as nanocrystals, nanocapsules, nanoparticles, solid lipid nanoparticles, nanocarriers, micelles, liposomes and dendrimers have been investigated as potential anti-HIV therapies. Such drugs may, for example, be used to optimize the pharmacological characteristics of known antiretrovirals, deliver anti-HIV nucleic acids into infected cells or achieve targeted delivery of antivirals to the immune system, brain or latent reservoirs. Also, nanopharmaceuticals themselves may possess anti-HIV activity. However several hurdles remain, including toxicity, unwanted biological interactions and the difficulty and cost of large-scale synthesis of nanopharmaceuticals

"Exploring Environmental Factors in Neurosurgical and Ophthalmology Operating Rooms to Mitigate Surgical Site Infections: An Observation Study."

Background: Surgical site infections (SSIs) are infections that patients can acquire after undergoing surgery in a hospital. These infections are quite common and can pose a significant risk to the patient's health. The operating room (OR) is a sterile space with regulated airflow, humidity, and pressure to ensure a clean environment. OR traffic should be minimized to maintain sterility and reduce SSI risks. Methods: This observational study aimed to understand how operating room staff behavior and environmental factors affect surgical outcomes. The study was conducted for 4 weeks at a teaching hospital and focused on 10 neurosurgical procedures. The research student leading the study observed OR traffic patterns and documented environmental parameters such as temperature, humidity, and pressure. Automated data acquisition was implemented for ophthalmology cases. Results: The study found correlations between particulate sizes and room conditions in an operating room. 0.3μm particulate size had a moderate to strong positive correlation of 0.737, while 1.0μm showed a very weak positive correlation of 0.087. The 5.0μm particulate size had a moderate positive correlation of 0.344, with 11.8% variability attributed to observed operating room traffic. The study also noted mild fluctuations in temperature, humidity, and pressure within the operating room. Conclusion: A prospective research study conducted at a university-affiliated teaching hospital suggests a potential link between the OR environment and the risk of developing surgical site infections (SSIs). However, the study's limitations and small sample size must be considered when interpreting the findings. Future research should address these constraints for accurate results. Understanding the OR environment is crucial in preventing SSIs, improving patient outcomes, and reducing the burden of postoperative complications. Public Health Significance: Surgical site infections (SSIs) are of a significant concern in the healthcare industry, particularly in neurosurgery and ophthalmology. SSIs result in physical discomfort, extended hospital stays, increased healthcare costs, and mortality. By prioritizing prevention of SSIs, healthcare resources can be utilized more efficiently, reducing the economic burden on the healthcare system. Controlling SSIs is crucial for maintaining high standards of patient care, reducing healthcare burden, preventing infections, and fostering a more equitable healthcare system

The assignment problem in distributed computing

This dissertation focuses on the problem of assigning the modules of a program to the processors in a distributed system with the goal of minimizing the overall cost of running the program. The cost depends on the execution times of the modules on the processors and on the cost of communication between modules. This module allocation problem arises in a variety of situations where one is interested in making optimum use of available computer resources. The general module allocation problem is intractable; however it becomes polynomially-solvable when the communication graph is restricted. In this dissertation, we restrict our attention to k-trees;As the first problem, we study parametric module allocation on partial k-trees. We allow the costs, both execution and communication, to vary linearly as functions of a real parameter t. We show that if the number of processors is fixed, the sequence of optimum assignments that are obtained, as t varies from zero to infinity, can be constructed in polynomial time. As an auxiliary result, we develop a linear-time algorithm to find a separator in a k-tree. We discuss the implications of our results for parametric versions of the weighted vertex cover, independent set, and 0-1 quadratic programming problems on partial k-trees;Next, we consider two variants of the assignment problem. The first problem is to find a minimum-cost assignment when one of the processors has a limited memory. The second is to find an assignment that minimizes the maximum processor load. We present exact dynamic programming algorithms for both problems, which lead to approximation schemes for the case where the communication graph is a partial k-tree. Faster algorithms are presented for trees with uniform costs. In contrast to these results, we show that, for arbitrary graphs, no fully polynomial time approximation schemes exist unless P = NP. Both dynamic programming algorithms have been implemented. The implementation details and our experimental results are presented.</p

Optimal thrust magnitude on a singular arc in atmospheric flight.

In optimal control theory, the cases where the second order necessary conditions are trivially satisfied are named the singular cases and the corresponding controls, the singular controls. These are shown to occur quite frequently in a wide variety of practical applications and play an important role. Lie and Poisson brackets can be used to express these singular controls in a very elegant and systematic manner. However, in the literature, Lie bracket solutions are derived only for the simplest cases of a single or multiple inputs appearing linearly in the equations of motion. These come under a category called the totally singular arcs, where all the controls are singular simultaneously. The cases where both singular and non-singular cases occur together, however, are quite common in the literature, especially in trajectory optimization problems. These are called partially singular arcs. This dissertation extends the Lie and Poisson bracket solutions to partially singular arcs of order one. The significance of singular controls in trajectory optimization is illustrated through an example orbital plane change problem. A general trajectory optimization problem in the atmosphere is shown to be partially singular with the thrust magnitude being the singular control and the aerodynamic controls being non-singular. The extended Lie bracket solution is then applied to obtain the thrust magnitude expression on the singular arc. This is shown to be identical to the expression derived by conventional means. It is also shown to be computationally more efficient and to preserve any symmetry properties in the problem. Some interesting sub-cases are studied with the help of the general expression. Further extensions of the Lie bracket solution are suggested for constrained arcs and higher order singular arcs. Vector formulation is used throughout the thesis to make the results concise and independent of the choice of the coordinate system. An example canonical transformation to flight path variables is derived to illustrate how all the results in vector form can be translated in terms of any desired set of variables.Ph.D.Aerospace EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/103116/1/9303785.pdfDescription of 9303785.pdf : Restricted to UM users only