150 research outputs found

    The Giza Pyramids: A History of Wireless Electricity Transmission Validated by Today’s Science

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    This paper conducts a review to a recent theory that was introduced by Christopher Dunn in 1998 and 2010. This theory suggests that the ancient Egyptians had the technology to generate and wirelessly transmit electrical energy using the Great Pyramids of Giza. Also, the paper makes a comparison between the principle of this old technology to what is being developed in the present time to achieve wireless and efficient transmission of the electric energy

    The Effect of the Milling Vial Shape on the In-Situ Consolidation of a Nanocrystalline Al-Li-GNPs Nanocomposite Synthesized by Room Temperature Ball-Milling

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    Several studies investigating the ball-milling of ductile face-centered cubic metals have reported a so-called in-situ consolidation phenomenon where the milled powder is also consolidated during the milling process. Thus, instead of refined powders or agglomerated particles, the formation of spherical bulk particles of the milled material is reported using a combination of cryomilling and room temperature milling processes. In this study, we studied the effect of the milling vial shape on the in-situ consolidation of a graphene nanoplatelets (GNPs) reinforced aluminum-lithium (Al-Li) matrix nanocomposite for the first time. An in-situ consolidated nanometric Al-Li-GNPs nanocomposite with an average grain size of 48 nm and high hardness of 1.48 GPa was attained after only 8 h of room-temperature milling. The results presented suggest that dense nanostructured composites can be prepared by in-situ consolidation during a one-step milling process and subsequently investigated in order to analyze their mechanical behavior. This allows for the intrinsic mechanical behavior of the synthesized material to be examined without the interference of subsequent high-temperature consolidation processes, thus avoiding unwanted structural changes such as grain growth and second phase formations.This research was funded by the Qatar National Research Fund (a member of the Qatar Foundation), grant number NPRP11S-1203-170056. The statements made herein are solely the responsibility of the authors

    Autonomic Dysfunction Predicts Early Cardiac Affection in Patients with Systemic Sclerosis

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    Objective: To detect the early preclinical alterations in cardiac autonomic control as well as altered cardiac function in systemic sclerosis (SSc) patients and their relevance to the clinical features of the disease using noninvasive methods. Methods: 30 SSc patients and 15 healthy controls matched for age and sex underwent clinical examination, serological analysis, and echocardiographic assessment including Doppler flow imaging to evaluate cardiac function, and 24-hour Holter monitoring analyzed for arrhythmia and heart rate variability (HRV) in the time and frequency domains. Results: The trans-mitral Doppler of early to atrial wave (E/A) ratio was reversed in five patients (16.6%) and the tricuspid E/A ratio was reversed in 10 patients (33.3%). Holter analysis for SSc patients revealed an increased prevalence of premature ventricular contractions (PVC) $ 10/h (P = 0.02), supra-ventricular tachycardias (SVTs) (P = 0.2), and total PVC count (P = 0.0000). Highly significant (P = 0.000) impairment in all HRV parameters was demonstrated in the SSc patients. Total skin thickness score (TSS), Raynaud’s phenomenon and anti-scleroderma 70 (anti-SCL70) showed significant positive correlations with all arrhythmia parameters, while showing a significant negative correlation with the impaired ventricular diastolic function and various HRV parameters. No correlation was found between arrhythmia and HRV parameters and disease duration, disease type, or presence of anti-centromere antibodies. Conclusion: Low heart rate variability, increased TSS and the presence of anti-SCL70 are correlated with preclinical cardiac involvement in SSc patients and may predict the likelihood of malignant arrhythmia and sudden cardiac death. Therefore, noninvasive HRV evaluation before clinical cardiac involvement in these patients might be beneficial when added to the clinical and laboratory assessments in detecting high-risk patients, and may allow for implementation of preventive measures and initiation of appropriate therapy early in the course of the disease

    Review: The effect of different nanofiller materials on the thermoelectric behavior of bismuth telluride

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    This review paper summarizes and discusses the effect of nanosized fillers on bismuth telluride nanocomposites for thermoelectric applications. Classified into various dimensions based on electron confinement in space, the nanofiller effect on the figure-of-merit value is studied. By combining experimental data with theoretical models, the mechanisms for enhancing the thermoelectric properties were proposed. The outcomes of this review paper suggest that doped bismuth telluride composites (doped with selenium for n-type or antinomy for p-type) offer better thermoelectric properties compared to undoped composites. Moreover, improvements in undoped bismuth telluride composites are exclusive for the n-type only. The figure-of-merit value for bismuth telluride composites is less than two, where the 2D nanofillers show optimum ZT improvements. Nevertheless, the inconsistency of reported data in the thermoelectric area is a problem that must be addressed to have more control over the precision of the reported results for a better understanding of the concepts in this field.This work was supported by Grant no. NPRP10–0206–170366 from Qatar National Research Fund (a member of the Qatar Foundation). The statements made herein are solely the responsibility of the authors. Open access publication of this article was funded by the Qatar National Library

    Non-Invasive Data Acquisition and IoT Solution for Human Vital Signs Monitoring: Applications, Limitations and Future Prospects

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    The rapid development of technology has brought about a revolution in healthcare stimulating a wide range of smart and autonomous applications in homes, clinics, surgeries and hospitals. Smart healthcare opens the opportunity for a qualitative advance in the relations between healthcare providers and end-users for the provision of healthcare such as enabling doctors to diagnose remotely while optimizing the accuracy of the diagnosis and maximizing the benefits of treatment by enabling close patient monitoring. This paper presents a comprehensive review of non-invasive vital data acquisition and the Internet of Things in healthcare informatics and thus reports the challenges in healthcare informatics and suggests future work that would lead to solutions to address the open challenges in IoT and non-invasive vital data acquisition. In particular, the conducted review has revealed that there has been a daunting challenge in the development of multi-frequency vital IoT systems, and addressing this issue will help enable the vital IoT node to be reachable by the broker in multiple area ranges. Furthermore, the utilization of multi-camera systems has proven its high potential to increase the accuracy of vital data acquisition, but the implementation of such systems has not been fully developed with unfilled gaps to be bridged. Moreover, the application of deep learning to the real-time analysis of vital data on the node/edge side will enable optimal, instant offline decision making. Finally, the synergistic integration of reliable power management and energy harvesting systems into non-invasive data acquisition has been omitted so far, and the successful implementation of such systems will lead to a smart, robust, sustainable and self-powered healthcare system

    Validity of the Shahin Mixed Depression Scale: A Self-Rated Instrument Designed to Measure the Non-DSM Mixed Features in Depression

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    Background: The DSM5-defined mixed features in depression do not include psychomotor agitation, irritability or distractibility because they are considered overlapping symptoms. A growing number of modern psychiatrists have expressed dissatisfaction with this and proposed alternative sets of mixed symptoms that are much more common and clinically relevant. Among such alternative criteria were those proposed by Koukopoulos. He utilized the research diagnostic criteria of agitated depression (RDC-A) as a mixed depression subtype, and validated another form of mixed depression, the Koukopoulos criteria for mixed depression (K-DMX). Purpose: This study provides psychometric validation for the first self-rated scale designed to measure the most common mixed symptoms in depression as proposed by Koukopoulos. Patients and methods: We conducted a multicenter cross-sectional study of 170 patients with unipolar depression. They completed the Shahin Mixed Depression Scale (SMDS) and underwent expert interviews as a gold standard reference. SMDS' psychometric properties were assessed, including Cronbach's alpha, factor analysis, sensitivity, specificity, predictive value and accuracy. Results: We found significant association and agreement between mixity according to SMDS and the gold standard (K-DMX and RDC-A according to expert interview) with good internal consistency (Cronbach's alpha=0.87), high sensitivity (=91.4%), specificity (=98.0%), positive predictive value (=96.9%), negative predictive value (= 94.2%) and accuracy (=95.2%). Factor analysis identified one factor for psychomotor agitation and another for mixity without psychomotor agitation. Conclusion: SMDS was a reliable and valid instrument for assessing the frequently encountered and clinically relevant mixed features in depression

    The Influence of Long-Acting Somatostatin Analogs on 68 Ga-DOTATATE Uptake in Patients With Neuroendocrine Tumors

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    Purpose A high SUVmax tumor-to-liver ratio (TLR) of 68Ga-DOTATATE can be used to select patients with neuroendocrine tumors (NETs) for peptide receptor radionuclide therapy (PRRT). In addition, an SUVmax TLR ≥ 8.1 is associated with increased progression-free survival in NET patients treated with somatostatin analogs (SSAs). To avoid a theoretical interaction, several guidelines recommend performing PET/CT just before the monthly administration of long-acting SSAs. We aimed to investigate the effect of SSA on the SUVmax of 68Ga-DOTATATE in patients with NET and to identify independent predictors for high SUVmax TLR. Patients and Methods For this retrospective study, 192 68Ga-DOTATATE PET/CT scans of 165 patients without (n = 115) and with (n = 77) SSA (octreotide or lanreotide) in the 3 months before PET/CT were collected and reviewed. The effect of SSA on SUVmax values was analyzed by a maximum likelihood mixed model. Results Patients with SSA had a significantly higher median SUVmax TLR than patients without SSA (4.7 [IQR], 3.1-7.7) versus 3.2 [IQR, 2.0-5.4]; P < 0.001). Multivariable logistic regression analysis showed that SSA use was an independent predictor for SUVmax TLR ≥ 8.1 (odds ratio, 2.91; 95% confidence interval, 1.26-6.72; P = 0.012). Conclusions Our data suggest that higher SSA concentrations do not have a negative effect on 68Ga-DOTATATE uptake in tumor lesions. In addition, we found that only SSA use was associated with SUVmax TLR ≥ 8.1. Our results are consistent with previously conducted studies and in line with the recently published guideline that suggests that the relatively recent use of SSA does not necessitate any delay in 68Ga-DOTATATE PET/CT imaging

    Experimental and modeling analysis of p-type Bi0.4Sb1.6Te3 and graphene nanocomposites

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    The state-of-the-art Bismuth-Telluride (Bi2Te3) based systems are promising thermoelectric materials for efficient thermoelectric applications. In this study, the effect of graphene nanosheets (GNS) integrity on thermoelectric properties of a p-type Bi0.4Sb1.6Te3 alloy has been studied using high-energy ball milling and SPS sintering techniques. The synthesized pristine Bi0.4Sb1.6Te3 and 0.05wt% GNS/Bi0.4Sb1.6Te3 nanocomposites at different addition times of GNS have exhibited a single-phase and artifact-free bulk nanocrystalline Bi0.4Sb1.6Te3 with nanocrystals size of 17 nm. The TEM analysis confirmed the mechanical exfoliation of graphene filler in 5m nanocomposite into a single-layered nanostructure with an interplanar spacing of 0.343 nm. The prominent Raman features of the monolayered graphene sheet have appeared in the synthesized 5m-GNS/Bi0.4Sb1.6Te3 nanocomposite. This highlighted the crucial rule of graphene addition time on its structure and morphology of the synthesized nanocomposites. The ZT profile of 5m nanocomposite reached 0.801 at 348 K till 398 K. This resulted in 65% of improvements to the pristine Bi0.4Sb1.6Te3 pellet at 323 K. The obtained results were used to simulate a thermoelectric (TE) device module using ANSYS Workbench. The GNS nanocomposites have shown an ultrahigh output power of 95.57 W compared to 89.96 W for the pristine module at ΔT of 150 °C. The GNS addition has increased the output power of pristine Bi0.4Sb1.6Te3 by 7%, leading to comparable TE performance to other simulated Bi2Te3 systems
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