alaa ahmed | Religion in American History Blog (original) (raw)

Papers by alaa ahmed

International Journal of Computer Applications, 2011

Abstract Since K-means is widely used for general clustering, its performance is a critical point... more Abstract Since K-means is widely used for general clustering, its performance is a critical point. This performance depends highly on initial cluster centers since it may converge to numerous local minima. In this paper a proposed initialization method to select initial ...

Clinical Chemistry

We evaluated the utility of neopterin and quinolinic acid (QUIN) as surrogate measures of disease... more We evaluated the utility of neopterin and quinolinic acid (QUIN) as surrogate measures of disease activity in juvenile idiopathic inflammatory myopathies (IIMs). Plasma and first morning void urine samples were measured for neopterin and QUIN using commercial ELISA, HPLC, or gas chromatography-mass spectrometry in 45 juvenile IIM patients and 79 healthy controls. Myositis disease activity assessments were obtained. Plasma and urine neopterin and QUIN concentrations were increased in juvenile IIM patients compared with healthy controls (P <0.017). Urine neopterin and QUIN highly correlated with each other (r(s) = 0.73; P <0.0001). Urine neopterin and QUIN correlated moderately with myositis disease activity assessments, including physician and parent global activity assessments, muscle strength testing, functional assessments (Childhood Myositis Assessment Scale, Childhood Health Assessment Questionnaire), skin global activity, and edema on magnetic resonance imaging (r(s) = 0....

Journal of neurophysiology, 2007

We hypothesize that the CNS detects a loss of balance by comparing outputs predicted by a nominal... more We hypothesize that the CNS detects a loss of balance by comparing outputs predicted by a nominal, forward internal model with actual sensory outputs. When the resulting control error signal reaches an anomalously large value, this control error anomaly (CEA) signals a loss of balance and precedes any observable compensatory response. To test this hypothesis, a multi-input, multi-output internal model of a standing forward reach task was developed that incorporated on-line model identification and a Gaussian failure detection algorithm. Eleven healthy young women were then asked to stand and reach forward to a target positioned from 95 to 125% of their maximum reach distance. Kinematic and kinetic data were recorded at 100 Hz unilaterally from the upper body, leg, and foot. Evidence of successful CEA detection was a compensatory step between 100 ms and 2 s later. The results show that use of a threshold, set at 3 SD from the mean, on error in the control of leg segment acceleration ...

PeerJ, 2014

Physiological and emotional states can affect our decision-making processes, even when these stat... more Physiological and emotional states can affect our decision-making processes, even when these states are seemingly insignificant to the decision at hand. We examined whether posture and postural threat affect decisions in a non-related economic domain. Healthy young adults made a series of choices between economic lotteries in various conditions, including changes in body posture (sitting vs. standing) and changes in elevation (ground level vs. atop a 0.8-meter-high platform). We compared three metrics between conditions to assess changes in risk-sensitivity: frequency of risky choices, and parameter fits of both utility and probability weighting parameters using cumulative prospect theory. We also measured skin conductance level to evaluate physiological response to the postural threat. Our results demonstrate that body posture does not significantly affect decision making. Secondly, despite increased skin conductance level, economic risk-sensitivity was unaffected by increased thre...

Journal of Neurophysiology, 2014

Recent findings have demonstrated that reward feedback alone can drive motor learning. 25

The Journal of Pediatrics, 2009

Objective-We studied children with myositis to characterize their metabolic abnormalities and ris... more Objective-We studied children with myositis to characterize their metabolic abnormalities and risk factors for future cardiovascular disease.

Gait & Posture, 2004

Given that a physical definition for a loss of balance (LOB) is lacking, the hypothesis was teste... more Given that a physical definition for a loss of balance (LOB) is lacking, the hypothesis was tested that a LOB is actually a loss of effective control, as evidenced by a control error signal anomaly (CEA). A model-reference adaptive controller and failure-detection algorithm were used to represent central nervous system decision-making based on input and output signals obtained during a challenging whole-body planar balancing task. Control error was defined as the residual generated when the actual system output is compared with the predicted output of the simple first-order polynomial system model. A CEA was hypothesized to occur when the model-generated control error signal exceeded three standard deviations (3 ) beyond the mean calculated across a 2-s trailing window. The primary hypothesis tested was that a CEA is indeed observable in 20 healthy young adults (ten women) performing the following experiment. Seated subjects were asked to balance a high-backed chair for as long as possible over its rear legs. Each subject performed ten trials. The ground reaction force under the dominant foot, which constituted the sole input to the system, was measured using a two-axis load cell. Angular acceleration of the chair represented the one degree-of-freedom system output. The results showed that the 3 algorithm detected a CEA in 94% of 197 trials. A secondary hypothesis was supported in that a CEA was followed in 93% of the trials by an observable compensatory response, occurring at least 100 ms later, and an average of 479 ms, later. Longer reaction times were associated with low velocities at CEA, and vice versa. It is noteworthy that this method of detecting CEA does not rely on an external positional or angular reference, or knowledge of the location of the system's center of mass.

Free Radical Biology and Medicine, 2003

To assess novel liquid chromatography/mass spectrometric methods for measuring oxidative damage t... more To assess novel liquid chromatography/mass spectrometric methods for measuring oxidative damage to nucleic acids and lipids, we compared urinary excretion of 8-hydroxy-2Ј-deoxyguanosine (8-OHdG), 5-hydroxymethyl-2Ј-deoxyuridine (5-OHmU), and 8-hydroxyguanosine (8-OxoG), and an isoprostane, 8-iso-prostaglandin F 2 ␣ (IsopF 2 ␣) in 234 healthy men (n ϭ 113) and women (n ϭ 121), 80 current smokers, 96 never-smokers), and 58 ex-smokers (no tobacco use for 3 years). The 8-OHdG and 8-OxoG did not differ significantly by group; 5-OHmU was higher in smokers, compared with ex-(p Ͻ .003) and never-(p Ͻ .0001) smokers and in ex-vs. never-smokers (p ϭ .014) at, respectively, 13.5 Ϯ 0.7, 11.3 Ϯ 1.0, and 8.7 Ϯ 0.3 g/g creatinine. IsopF 2 ␣ was higher in smokers, compared with ex-(p ϭ .007) and never-smokers (p Ͻ .0001) and in ex-vs. never-smokers (p ϭ .002) at, respectively, 1.1 Ϯ 0.10; 0.74 Ϯ 0.07, and 0.51 Ϯ 0.04 g/g creatinine. There were significant correlations among all three nucleic acid adducts and between IsopF 2 ␣ and both 5-OHmU and 8-OHdG. Many smokers and ex-smokers had high levels of either 5-OHmU excretion or IsopF 2 ␣ excretion, but not both. We conclude that 5-OHmU and IsopF 2 ␣ are more discriminating of oxidative stress from tobacco smoke than the other two compounds measured. Whether characteristic patterns of excretion of these indicators forecast differential disease risk should be explored in future research.

Current Biology, 2008

To manipulate an object skillfully, the brain must learn its dynamics, specifying the mapping bet... more To manipulate an object skillfully, the brain must learn its dynamics, specifying the mapping between applied force and motion. A fundamental issue in sensorimotor control is whether such dynamics are represented in an extrinsic frame of reference tied to the object or an intrinsic frame of reference linked to the arm. Although previous studies have suggested that objects are represented in arm-centered coordinates , all of these studies have used objects with unusual and complex dynamics. Thus, it is not known how objects with natural dynamics are represented. Here we show that objects with simple (or familiar) dynamics and those with complex (or unfamiliar) dynamics are represented in object-and arm-centered coordinates, respectively. We also show that objects with simple dynamics are represented with an intermediate coordinate frame when vision of the object is removed. These results indicate that object dynamics can be flexibly represented in different coordinate frames by the brain. We suggest that with experience, the representation of the dynamics of a manipulated object may shift from a coordinate frame tied to the arm toward one that is linked to the object. The additional complexity required to represent dynamics in object-centered coordinates would be economical for familiar objects because such a representation allows object use regardless of the orientation of the object in hand.

Clinical Biomechanics, 2005

Background. Most falls are attributed to a loss of balance without a quantitative definition of t... more Background. Most falls are attributed to a loss of balance without a quantitative definition of the term. It has been proposed that a loss of balance is detectable as an unusually large (anomalous) value of the system control error. The hypotheses were tested that age will not affect the detection of control error anomaly, or prediction of the associated compensatory response, in a challenging balancing task.

Natural Immunity, 1998

The aim of this study was to determine whether treatment of patients with immune thrombocytopenic... more The aim of this study was to determine whether treatment of patients with immune thrombocytopenic purpura (ITP) with intravenous immunoglobulin (IVIg) is associated with a modification in the antiplatelet glycoprotein (GP) antibodies (Abs). Fourteen patients with ITP (11 females and 3 males, mean age 36.6 years, range 18-72) received one to four IVIg treatment courses. The preparation used was ISIVEN that was given in a dose of 2 g/kg body weight in a 5-day schedule and in monthly intervals. Levels of IgG, IgM and IgA isotypes of Abs to GPs IIb/IIIa and Ib/IX were measured before the treatment, and before and after each treatment course. Two patients did not respond to IVIg, 6 had a temporary response, 5 had a sustained response and 1 patient responded well to the treatment but was lost to follow-up. The patients had a high prevalence of serum Abs directed against GPs IIb/IIIa and Ib/IX before the treatment, and the mean IgG isotype levels of both Abs increased after each treatment course, and decreased again before the following course began. Whenever high Ab levels of either isotype (&amp;gt; 10 U/ml) were detected before the treatment, they were significantly decreased before the last treatment course. The elevated levels of IgG Abs to IIb/IIIa and Ib/IX after every course are probably a result of displacement of these Abs from Fc receptors by the IVIg, rather than of exogenous infusion of these Abs contained within the IVIg, whereas the decrease in high Ab levels after a few treatment courses results from the immunomodulatory effects of IVIg: suppression of Ab formation, and the presence of anti-idiotypes.

Viral Immunology, 1998

The hantavirus is known to cause hemorraghic fever with renal syndrome (HFRS), which is widely sp... more The hantavirus is known to cause hemorraghic fever with renal syndrome (HFRS), which is widely spread in Europe and Asia. Several reports have shown an association of hantavirus antibody titers and the occurrence of renal dysfunction. From these observations, it appears that the virus is widely distributed, and different strains prevail in various areas. In the present work we studied 81 patients with end-stage renal-failure under hemodialysis (HD) treatment, 55 with mild to moderate renal failure, and 50 healthy subjects for the presence of antibodies to Hantaan and Puumala viruses. We found that 12.3% of the hemodialysis patients and 9% of the mild to moderate renal failure patients had elevated IgG anti-body titers to Puumala virus compared with 2% of the controls. IgM antibodies to Puumala virus was principally elevated in patient with chronic renal failure (CRF) not on hemodialysis (14.5%) compared with the hemodialyzed (1.2%) and controls (0%) subjects. Hantaan virus IgG antibodies were detected in 3.7% of the HD patients, 5.5% of the CRF not on HD, and in none of the controls. IgM Hantaan antibodies were found only in the non-HD renal failure patients. None of the sera were found to contain antibodies to phospholipids or single-stranded DNA. These results emphasize the widespread nature of infection with hantaviruses and imply that elaborate testing for these serologies should be performed, especially in patients with unexplained renal failure.

Journal of Hepatology, 2000

Backgrouna;/Aim: Primary sclerosing cholangitis is a chronic cholestatic syndrome with a presumed... more Backgrouna;/Aim: Primary sclerosing cholangitis is a chronic cholestatic syndrome with a presumed autoimmune basis frequently associated with inflammatory bowel disease. The aim of this study was to determine the protile and significance of serum autoantibodies in patients with primary sclerosing cholangitis. Methods: Serum samples taken from 73 untreated patients (32 female and 41 male, median age 45 years) with well-defined primary sclerosing cholangitis, and from 75 healthy age-and sex-matched controls were assayed for 20 different autoantibodies. Results: Of 73 patients, 71 (97%) were positive for at least 1 autoantibody; whereas 59173 patients (81%) were positive for 23 antibodies. Patients with primary sclerosing cholangitis had a significantly greater rate of positivity than controls for antinuclear, anticardiolipin, antineutrophil cytoplasmic, and antithyroperoxidase antibodies as well as rheumatoid factor. The rate

JCR: Journal of Clinical Rheumatology, 1999

Antineutrophil cytoplasmic antibodies (ANCA) are autoantibodies directed against components of ne... more Antineutrophil cytoplasmic antibodies (ANCA) are autoantibodies directed against components of neutrophils and monocytes, and are helpful in identifying different forms of vasculitis. Until the discovery of ANCA, there was no specific laboratory method for the investigation of systemic vasculitis. Many issues regarding ANCA, such as their role in the pathogenesis of vasculitis, sensitivity, specificity, predictive value, and antigen specificity are still unclear. The differential diagnosis of the vasculitic syndromes is often difficult because of the variable presentation, but is important because of the variable outcome.Wegener's granulomatosis, microscopic polyangiitis, and Churg-Strauss syndrome are three vasculidities that commonly are associated with a positive ANCA. The "gold standard" for a precise diagnosis of vasculitis depends on both the clinical and pathologic features. ANCA testing is used to support the clinical and pathologic findings. The ANCA pattern, determined by indirect immunofluorescence, can be either cytoplasmic (C-ANCA), perinuclear (P-ANCA), or atypical perinuclear (X-ANCA). Interpretation of the ANCA pattern can be problematic, and a reactive antinuclear antibody can contribute to the confusion, requiring testing for reactivities to specific autoantigens. Proteinase-3 and myeloperoxidase are the most common autoantigens and are commonly associated with C-ANCA and P-ANCA, respectively. ANCA reactivity to other autoantigens is associated with the X-ANCA pattern.

Journal of Allergy and Clinical Immunology, 1998

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International Journal of Cardiology, 1998

Twenty-nine patients with clinically defined Takayasu arteritis and 26 healthy control volunteers... more Twenty-nine patients with clinically defined Takayasu arteritis and 26 healthy control volunteers were recruited by INSSYS investigators from their clinical practices. Patients with Takayasu arteritis were divided into those with clear-cut clinically active or inactive disease based on Birmingham Vasculitis Activity Scores. Multiple serological tests were performed including ESR, C-reactive protein, tissue factor, von Willebrand factor, thrombomodulin, tissue plasminogen activator, ICAM-1, VCAM-1, E-selectin and PECAM-1. No test was reliably able to distinguish between healthy volunteers and patients with active Takayasu arteritis. At present there is no known serological test which can consistently supplant vascular histopathology in determining the activity of Takayasu arteritis.