416 research outputs found

    Performance Analysis of FBMC and CP-OFDM in the Presence of Phase Noise

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    Multi-Carrier (MC) modulation schemes like Or- thogonal Frequency Division Multiplexing (OFDM) are highly sensitive to Phase Noise (PN). In the case of air interfaces operating in higher frequencies, e.g. the range between 6 and 100 GHz frequently called millimeter wave (mmWave), the PN generated by the local oscillators is even more accentuated. Alternative MC systems are being considered for future mmWave wireless communications. In this contribution, we analytically derive expressions for an upper bound for the interference power generated by the PN in OFDM, DFT-Spread-OFDM and Filter Bank Multi-Carrier (FBMC). Then, we evaluate the performance degradation due to that imperfection in terms of coded and uncoded BER

    Definitive Management of Failure After Pyeloplasty

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    Introduction: Failure after pyeloplasty is difficult to manage. We report our experience managing pyeloplasty failures. Methods: We retrospectively reviewed the case log of a single surgeon, from August 1996 to August 2014, to identify all patients undergoing a surgical procedure after failed pyeloplasty. We excluded patients without follow-up exceeding 1 year from initial postpyeloplasty procedure. Failure was defined as a need for additional definitive intervention. Results: Of 247 laparoscopic pyeloplasties, 68 endopyelotomies and 305 simple laparoscopic nephrectomies reviewed, 41 were performed after previous pyeloplasty and had sufficient follow-up. Laparoscopic nephrectomy was performed in nine patients. All three secondary laparoscopic pyeloplasties were successful. Of 29 secondary endopyelotomies, 10 (34%) were successful. Of the 19 failures after secondary endopyelotomy, 12 patients had tertiary pyeloplasty (5 laparoscopic and 7 open surgical), 5 (26%) underwent tertiary endopyelotomy, and 2 (11%) required nephrectomy. Our overall endopyelotomy success rate was 38% (13/34) vs 100% (11/11) for secondary or tertiary pyeloplasty (4 patients lost to follow-up). Median time to failure was 5 months for endopyelotomy. Median follow-up for patients free from intervention was 40.2 months. Conclusions: Secondary pyeloplasty (including both laparoscopic and open surgical approach) is more than twice as successful as endopyelotomy after failed pyeloplasty. Secondary pyeloplasty is an excellent alternative to endopyelotomy in select patients with failure after initial pyeloplasty.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140085/1/end.2015.0837.pd

    Gulbuddin Hekmatyar : Afghanistan's persistent insurgent

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    Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Political Science, 2003."September 2003."Includes bibliographical references.Afghanistan has proved to be one of the most dangerous and unstable political environments in South Asia, if not the world. Against this backdrop, Islamic fundamentalist Gulbuddin Hekmatyar has waged a continuous guerilla war to gain control of the state. Towards this end, he has fought ambitious rivals, every Afghan government, the Soviet Union, and now US forces sent to drive out al Qaeda and destroy the Taliban. This thesis explores Hekmatyar's persistence in such a fluid and violent political landscape, tracing his islamist Hezb-e Islami party's genesis and evolution in the last 30 years. With a rigid Leninist-styled party, Hekmatyar's ability to draw from religious, ethno-regional, and socioeconomic support, as well as foreign aid, has provided him the means to survive and flourish during Afghanistan's enduring devastationby Michael A. Faerber.S.M

    Nonlinear Digital Self-Interference Cancellation with Reduced Complexity for Full Duplex Systems

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    Full duplex transmission is currently viewed as an important technology component for the future 5G and beyond mobile broadband technology. In order to realize its promised theoretical gain, sufficient cancellation of the self-interference must be achieved. The focus throughout this work will be on the digital cancellation, which main target is to cancel the residual self-interference resulting from the insufficient analog cancellation due to hardware imperfections, along with non-linearities existing in the transmitter chain. A novel pre-transmission transformation based on the Cholesky decomposition is presented, that aims at enhancing the digital cancellation performance. A digital cancellation based on the transversal recursive least squares with the exploitation of the dichotomous coordinate descent algorithm to lower the computational complexity is presented. The analysis was extended to include the existence of a received signal of interest, while simultaneously canceling the self-interference signal. By means of numerical simulations, a performance evaluation was carried out and results showed that the level of residual interference after the digital canceler reaches the simulated noise floor power level

    High-throughput genomic technology in research and clinical management of breast cancer. Plasma-based proteomics in early detection and therapy

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    Abstract Protein-based breast cancer biomarkers are a promising resource for breast cancer detection at the earliest and most treatable stages of the disease. Plasma is well suited to proteomic-based methods of biomarker discovery because it is easily obtained, is routinely used in the diagnosis of many diseases, and has a rich proteome. However, due to the vast dynamic range in protein concentration and the often uncertain tissue and cellular origin of plasma proteins, proteomic analysis of plasma requires special consideration compared with tissue and cultured cells. This review briefly touches on the search for plasma-based protein biomarkers for the early detection and treatment of breast cancer. Outlin

    Urologic laparoscopy with a new blunt-tipped trocar: Safe, rapid access without the use of fascial sutures

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    Fifteen patients underwent successful laparoscopic procedures where a new blunt-tipped trocar was used both to gain initial access to and to insufflate the abdominal cavity. The use of this new trocar obviates the need for the use of the Veress needle and appears to be both time-saving and possibly safer. Unlike the Hasson-type trocar, the blunt trocar technique does not require the use of fascial sutures for prevention of air leaks.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31560/1/0000487.pd

    Symptomatic Subcapsular and Perinephric Hematoma Following Ureteroscopic Lithotripsy for Renal Calculi

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    Objective: Ureteroscopic lithotripsy (URSL) is believed to be associated with less risk of symptomatic renal hematoma than extracorporeal shockwave lithotripsy (SWL) and percutaneous nephrolithotomy (PCNL). We sought to document the rate of and risk factors for this rare complication following URSL for renal calculi. Methods: With Institutional Review Board approval, we reviewed 1087 cases of URSL performed between July 2009 and October 2012 for four surgeons. We identified cases for renal calculi complicated by symptomatic ?hematoma? by searching electronic medical records of patients undergoing URSL with a web-based search tool and cross-referencing with a departmental quality improvement database for postoperative complications. Chi-squared tests were used to assess risk factors. Results: Among 877 renal units exposed to URSL for renal calculi, 4 were complicated by symptomatic subcapsular hematomas (SH) and 3 by symptomatic perinephric hematomas (PH), yielding a 0.5% and 0.3% rate for each complication, respectively. Pain was the primary presenting symptom. Almost all cases presented within 24 to 48 hours postop. Two PH patients required postoperative blood transfusion. Four patients (two SH, two PH) were hospitalized for observation. Ureteral sheaths were used in two cases (one PH and one SH). There was no association with age, diabetes, body mass index (BMI), or operative duration (p-values all>0.05). However, hematoma did correlate with female gender, preoperative hypertension, preoperative ureteral stenting, intraoperative ureteral sheath use, and postoperative ureteral stenting (all p-values<0.0001). Conclusions: While symptomatic hematoma is a complication of URSL, the rate of such outcome (0.8%) is far less than that reported by prior series with SWL and PCNL. This may partially be attributable to collection biases, where subclinical cases are not imaged, or anchoring biases, where clinicians attribute symptoms to another possible etiology. This outcome can be morbid, but can often be conservatively managed with observation.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140379/1/end.2014.0176.pd

    A Search for In-Situ Field OB Star Formation in the Small Magellanic Cloud

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    Whether any OB stars form in isolation is a question central to theories of massive star formation. To address this, we search for tiny, sparse clusters around 210 field OB stars from the Runaways and Isolated O-Type Star Spectroscopic Survey of the SMC (RIOTS4), using friends-of-friends (FOF) and nearest neighbors (NN) algorithms. We also stack the target fields to evaluate the presence of an aggregate density enhancement. Using several statistical tests, we compare these observations with three random-field datasets, and we also compare the known runaways to non-runaways. We find that the local environments of non-runaways show higher aggregate central densities than for runaways, implying the presence of some "tips-of-iceberg" (TIB) clusters. We find that the frequency of these tiny clusters is low, 45%\sim 4-5\% of our sample. This fraction is much lower than some previous estimates, but is consistent with field OB stars being almost entirely runaway and walkaway stars. The lack of TIB clusters implies that such objects either evaporate on short timescales, or do not form, implying a higher cluster lower-mass limit and consistent with a relationship between maximum stellar mass (mmaxm_{\rm max}) and the mass of the cluster (MclM_{\rm cl}). On the other hand, we also cannot rule out that some OB stars may form in highly isolated conditions. Our results set strong constraints on the formation of massive stars in relative isolation.Comment: 24 pages, 13 figures, Accepted to Ap

    Consistency of Hemoglobin A1c Testing and Cardiovascular Outcomes in Medicare Patients With Diabetes

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    Background: Annual hemoglobin A1c testing is recommended for patients with diabetes mellitus. However, it is unknown how consistently patients with diabetes mellitus receive hemoglobin A1c testing over time, or whether testing consistency is associated with adverse cardiovascular outcomes. Methods and Results: We identified 1 574 415 Medicare patients (2002–2012) with diabetes mellitus over the age of 65. We followed each patient for a minimum of 3 years to determine their consistency in hemoglobin A1C testing, using 3 categories: low (testing in 0 or 1 of 3 years), medium (testing in 2 of 3 years), and high (testing in all 3 years). In unweighted and inverse propensity‐weighted cohorts, we examined associations between testing consistency and major adverse cardiovascular events, defined as death, myocardial infarction, stroke, amputation, or the need for leg revascularization. Overall, 70.2% of patients received high‐consistency testing, 17.6% of patients received medium‐consistency testing, and 12.2% of patients received low‐consistency testing. When compared to high‐consistency testing, low‐consistency testing was associated with a higher risk of adverse cardiovascular events or death in unweighted analyses (hazard ratio [HR]=1.21; 95% CI, 1.20–1.23; P\u3c0.001), inverse propensity‐weighted analyses (HR=1.16; 95% CI, 1.15–1.17; P\u3c0.001), and weighted analyses limited to patients who had at least 4 physician visits annually (HR=1.15; 95% CI, 1.15–1.16; P\u3c0.001). Less‐consistent testing was associated with worse results for each cardiovascular outcome and in analyses using all years as the exposure. Conclusions: Consistent annual hemoglobin A1c testing is associated with fewer adverse cardiovascular outcomes in this observational cohort of Medicare patients of diabetes mellitus

    Development and Pilot Feasibility Study of a Health Information Technology Tool to Calculate Mortality Risk for Patients with Asymptomatic Carotid Stenosis: The Carotid Risk Assessment Tool (CARAT)

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    Patients with no history of stroke but with stenosis of the carotid arteries can reduce the risk of future stroke with surgery or stenting. At present, a physicians’ ability to recommend optimal treatments based on an individual’s risk profile requires estimating the likelihood that a patient will have a poor peri-operative outcomes and the likelihood that the patient will survive long enough to gain benefit from the procedure. We describe the development of the CArotid Risk Assessment Tool (CARAT) into a 2-year mortality risk calculator within the electronic medical record, integrating the tool into the clinical workflow, training the clinical team to use the tool, and assessing the feasibility and acceptability of the tool in one clinic setting
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