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Bioelectromagnetics Jan 2013This article is the presentation I gave at the D'Arsonval Award Ceremony on June 14, 2011 at the Bioelectromagnetics Society Annual Meeting in Halifax, Nova Scotia. It... (Review)
Review
This article is the presentation I gave at the D'Arsonval Award Ceremony on June 14, 2011 at the Bioelectromagnetics Society Annual Meeting in Halifax, Nova Scotia. It summarizes my research activities in acoustic and electromagnetic millimeter waves over the past 47 years. My earliest research involved acoustic millimeter waves, with a special interest in diagnostic ultrasound imaging and its safety. For the last 21 years my research expanded to include electromagnetic millimeter waves, with a special interest in the mechanisms underlying millimeter wave therapy. Millimeter wave therapy has been widely used in the former Soviet Union with great reported success for many diseases, but is virtually unknown to Western physicians. I and the very capable members of my laboratory were able to demonstrate that the local exposure of skin to low intensity millimeter waves caused the release of endogenous opioids, and the transport of these agents by blood flow to all parts of the body resulted in pain relief and other beneficial effects.
Topics: Acoustics; Animals; Humans; Radio Waves; Radiofrequency Therapy; Ultrasonics
PubMed: 22926874
DOI: 10.1002/bem.21750 -
Current Biology : CB Jun 2017Plankton comprises unicellular plants - phytoplankton - and generally small (millimetres or less) animals - zooplankton - that are adrift on the currents. Phytoplankton...
Plankton comprises unicellular plants - phytoplankton - and generally small (millimetres or less) animals - zooplankton - that are adrift on the currents. Phytoplankton are responsible for about 45% of global annual primary production and are grazed by zooplankton, which in turn are suitably sized food items for predators including commercially important fish and great whales. Plankton are vital components of marine and freshwater water-column ecosystems. They also make major contributions to global biogeochemical cycling, and ameliorate atmospheric accumulation of carbon dioxide by 'pumping' carbon to the deep sea. The integrity of these roles is under threat from climate-related physiological impacts on individual organisms and on the wide-scale distribution of plankton communities.
Topics: Animals; Climate; Fishes; Food Chain; Fresh Water; Plankton; Plants; Seawater; Whales
PubMed: 28586683
DOI: 10.1016/j.cub.2017.02.045 -
The New England Journal of Medicine Jul 2018Platelet counts of less than 150,000 per cubic millimeter during uncomplicated pregnancies are described as gestational thrombocytopenia if no alternative cause is...
BACKGROUND
Platelet counts of less than 150,000 per cubic millimeter during uncomplicated pregnancies are described as gestational thrombocytopenia if no alternative cause is identified. Platelet counts may be even lower in women with pregnancy-related complications. However, the occurrence and severity of thrombocytopenia throughout pregnancy are not defined.
METHODS
We evaluated platelet counts throughout pregnancy in women who delivered at Oklahoma University Medical Center between 2011 and 2014. These platelet counts were compared with those of nonpregnant women who were included in the National Health and Nutrition Examination Survey from 1999 through 2012.
RESULTS
Among the 15,723 deliveries that occurred during the study period, 7351 women had sufficient data for our analyses. Of these women, 4568 had uncomplicated pregnancies, 2586 had pregnancy-related complications, and 197 had preexisting disorders associated with thrombocytopenia. Among the women who had uncomplicated pregnancies, the mean platelet count in the first trimester (mean gestation, 8.7 weeks) was 251,000 per cubic millimeter, which was lower than the mean platelet count in the 8885 nonpregnant women (273,000 per cubic millimeter) (P<0.001). At the time of delivery, 9.9% of the women with uncomplicated pregnancies had a platelet count below 150,000 per cubic millimeter. During the course of the uncomplicated pregnancies and deliveries, only 45 women (1.0%) had a platelet count below 100,000 per cubic millimeter. Among the 12 women with uncomplicated pregnancies who had a platelet count below 80,000 per cubic millimeter, only 5 (0.1%, among whom the range of platelet counts was 62,000 to 78,000 per cubic millimeter; median, 65,000) were identified by medical record review as having no alternative cause for the thrombocytopenia. Platelet counts of less than 150,000 per cubic millimeter at the time of delivery were more common among women who had pregnancy-related complications than among women who had uncomplicated pregnancies (11.9% vs. 9.9%, P=0.01). Throughout their pregnancies and deliveries, 59 women (2.3%) with pregnancy-related complications had a platelet count below 100,000 per cubic millimeter, and 31 (1.2%) had a platelet count below 80,000 per cubic millimeter.
CONCLUSIONS
Mean platelet counts decreased during pregnancy in all the women, beginning in the first trimester. In women who have a platelet count of less than 100,000 per cubic millimeter, a cause other than pregnancy or its complications should be considered. (Funded by the National Heart, Lung, and Blood Institute.).
Topics: Adolescent; Adult; Female; Humans; Platelet Count; Pregnancy; Pregnancy Complications; Pregnancy Complications, Hematologic; Reference Values; Thrombocytopenia; Young Adult
PubMed: 29972751
DOI: 10.1056/NEJMoa1802897 -
Proceedings of the National Academy of... Jan 2019Acoustic tweezers use sound radiation forces to manipulate matter without contact. They provide unique characteristics compared with the more established optical...
Acoustic tweezers use sound radiation forces to manipulate matter without contact. They provide unique characteristics compared with the more established optical tweezers, such as higher trapping forces per unit input power and the ability to manipulate objects from the micrometer to the centimeter scale. They also enable the trapping of a wide range of sample materials in various media. A dramatic advancement in optical tweezers was the development of holographic optical tweezers (HOT) which enabled the independent manipulation of multiple particles leading to applications such as the assembly of 3D microstructures and the probing of soft matter. Now, 20 years after the development of HOT, we present the realization of holographic acoustic tweezers (HAT). We experimentally demonstrate a 40-kHz airborne HAT system implemented using two 256-emitter phased arrays and manipulate individually up to 25 millimetric particles simultaneously. We show that the maximum trapping forces are achieved once the emitting array satisfies Nyquist sampling and an emission phase discretization below π/8 radians. When considered on the scale of a wavelength, HAT provides similar manipulation capabilities as HOT while retaining its unique characteristics. The examples shown here suggest the future use of HAT for novel forms of displays in which the objects are made of physical levitating voxels, assembly processes in the micrometer and millimetric scale, as well as positioning and orientation of multiple objects which could lead to biomedical applications.
PubMed: 30559177
DOI: 10.1073/pnas.1813047115 -
EFORT Open Reviews Jun 2019Glenoid exposure should offer frontal access to the glenoid to allow the ancillary tools to be used freely and thus facilitate the good positioning of the glenoid... (Review)
Review
Glenoid exposure should offer frontal access to the glenoid to allow the ancillary tools to be used freely and thus facilitate the good positioning of the glenoid implant.The two classically recognized approaches for shoulder arthroplasty are the deltopectoral and the transdeltoid approach.The axillary nerve is the most important anatomical structure in the glenoid, passing down the anterior part of the subscapularis, the inferior pole of the joint and the deep face of the deltoid muscle.Inferior glenohumeral release is the key step that allows the humerus to be retracted back or downwards thereby exposing the glenoid face on.In difficult and stiff cases, once pectoralis major release, osteophyte resection and posterior capsulectomy have been performed, a compression fracture, produced by using a retractor to push against the upper extremity of the humerus, can provide the extra few millimetres of space required to use the ancillary tools without hindrance. Cite this article: 2019;4 DOI: 10.1302/2058-5241.4.180057.
PubMed: 31312516
DOI: 10.1302/2058-5241.4.180057 -
Heliyon Nov 2022Millimeter wave path loss modeling is essential for reliable system design and accurate link budget calculations. The motivation for this research is that channel... (Review)
Review
Millimeter wave path loss modeling is essential for reliable system design and accurate link budget calculations. The motivation for this research is that channel modeling in 5G millimeter wave propagation in an indoor environment is a current research topic in which capacity differences have been noticed as a result of different models being utilized. Existing models for future millimeter wave propagation must be tested and improved in order to aid link design. The improvements in the path loss models will allow engineers and researchers to budget for 5G wireless networks with better quality in an indoor environment. In this paper, we discuss the survey of indoor environment undertaking for both line of sight (LOS) and non-line of sight (NLOS) scenarios as well as the comparison of path loss performance analysis of the three commonly used models: Close-In (CI) free space reference model, Floating Intercept (FI), and Alpha-Beta-Gamma (ABG) models at some selected frequencies. The review looked at how to determine efficient path loss models which is a major challenge in millimeter wave propagation. The paper also focuses on the measurement work done in millimeter wave research in interior environments. The analysis of path loss and shadow fading in different frequency bands are presented. The researchers whose publications were examined for this study used a range of methodologies to forecast path loss models and propagation parameters of millimeter wave communication channel. This will help design engineers and researchers calculate budgets for a suitable 5G and even forecasted 6G wireless network in an inside environment. Another purpose of this paper is to get a thorough understanding of the best route loss model, especially for interior situations, and to improve it in future research to provide a better line of fit and simplicity among the three fundamental path loss models: CI, ABG, and FI. In both LOS and NLOS scenarios, the study found that the CI free space reference model and the FI path loss models are the best path loss models for indoor millimeter wave propagation. Future research will focus on how to improve the appropriate model for path loss model estimate in both LOS and NLOS situations in an indoor environment with the best line of fit and the easiest implementation.
PubMed: 36406713
DOI: 10.1016/j.heliyon.2022.e11581 -
Sensors (Basel, Switzerland) Sep 2020Recent advances in millimeter wave technologies, both in component and system design, in line with important size and cost reductions, have opened up new applications in... (Review)
Review
Recent advances in millimeter wave technologies, both in component and system design, in line with important size and cost reductions, have opened up new applications in ultra-high-speed wireless communications, radar and imaging sensors. The paper presents the evolution of millimeter wave circuit and modules fabrication and characterization technologies in the past decades. Novel planar low-cost fabrication technologies have been successfully developed in this period. In combination with the standard rectangular wave-guide technology, these offer great opportunities for prototyping and testing of future millimeter wave transceivers or front-ends, which integrate antenna arrays, down-converters, modulators, amplifiers, etc., in a compact fixture. The paper uses, as a suggestive example, the evolution of the multi-port interferometric front-ends implementation from millimeter wave bulky components and systems to miniaturized and high-efficient ones. Circuit and system designs are carefully done to avoid (as much as possible) complicated calibration methods or difficult post-processing of baseband data. This requires an increased effort in design and fabrication, but it allows miniaturization, low-power consumption, while keeping very good overall performances. Useful and straightforward laboratory characterization techniques of circuits and systems are described in detail.
PubMed: 32987889
DOI: 10.3390/s20195477 -
Nanomaterials (Basel, Switzerland) Mar 2021Nanomaterials science is becoming the foundation stone of high-frequency applications. The downscaling of electronic devices and components allows shrinking chip's... (Review)
Review
Nanomaterials science is becoming the foundation stone of high-frequency applications. The downscaling of electronic devices and components allows shrinking chip's dimensions at a more-than-Moore rate. Many theoretical limits and manufacturing constraints are yet to be taken into account. A promising path towards nanoelectronics is represented by atomic-scale materials. In this manuscript, we offer a perspective on a specific class of devices, namely switches designed and fabricated using two-dimensional or nanoscale materials, like graphene, molybdenum disulphide, hexagonal boron nitride and ultra-thin oxides for high-frequency applications. An overview is provided about three main types of microwave and millimeter-wave switch: filament memristors, nano-ionic memristors and ferroelectric junctions. The physical principles that govern each switch are presented, together with advantages and disadvantages. In the last part we focus on zirconium-doped hafnium oxide ferroelectrics (HfZrO) tunneling junctions (FTJ), which are likely to boost the research in the domain of atomic-scale materials applied in engineering sciences. Thanks to their Complementary Metal-Oxide Semiconductor (CMOS) compatibility and low-voltage tunability (among other unique physical properties), HfZrO compounds have the potential for large-scale applicability. As a practical case of study, we present a 10 GHz transceiver in which the switches are FTJs, which guarantee excellent isolation and ultra-fast switching time.
PubMed: 33802404
DOI: 10.3390/nano11030625 -
Proceedings. Mathematical, Physical,... Nov 2014The existence of both water and sediment at the bed of ice streams is well documented, but there is a lack of fundamental understanding about the mechanisms of ice,...
The existence of both water and sediment at the bed of ice streams is well documented, but there is a lack of fundamental understanding about the mechanisms of ice, water and sediment interaction. We pose a model to describe subglacial water flow below ice sheets, in the presence of a deformable sediment layer. Water flows in a rough-bedded film; the ice is supported by larger clasts, but there is a millimetric water layer submerging the smaller particles. Partial differential equations describing the water film are derived from a description of the dynamics of ice, water and mobile sediment. We assume that sediment transport is possible, either as fluvial bedload, but more significantly by ice-driven shearing and by internal squeezing. This provides an instability mechanism for rivulet formation; in the model, downstream sediment transport is compensated by lateral squeezing of till towards the incipient streams. We show that the model predicts the formation of shallow, swamp-like streams, with a typical depth of the order of centimetres. The swamps are stable features, typically with a width of the order of tens to hundreds of metres.
PubMed: 25383024
DOI: 10.1098/rspa.2014.0340