Body Shadowing Research Articles

A low overhead tree-based energy-efficient routing scheme for multi-hop wireless body area networks

Reliability and energy efficiency are key performance metrics for meeting the requirements of long-term and continuous health monitoring in Wireless Body Area Networks (WBANs). In this paper, we explore energy-efficient routing mechanisms for WBANs. We first present experimental results showing that wireless link quality changes rapidly in WBANs due to body shadowing, and a fixed transmission power results in either wasted energy or low reliability. Moreover, in multi-hop WBANs, as various vital signs are collected from sensors on different body parts, the traffic load among sensor nodes could be severely unbalanced, leading to uneven energy consumption. In this paper, we propose a scheme, we term the tree-based energy-efficient routing scheme (EERS), with low overhead to jointly address adaptive power control and routing in multi-hop WBANs. The proposed scheme can establish an energy-efficient end-to-end path as well as adaptively choose transmission power for sensor nodes. We conduct extensive experiments on a MicaZ WBAN testbed to compare the performance of EERS with the Collection Tree Protocol (CTP) in terms of packet reception ratio (PRR), collection delay, energy consumption, and energy balancing. Experimental results show that EERS outperforms CTP in terms of reliability, delay and energy consumption. In particular, EERS exhibits a mean delay 30% lower than the mean delay of CTP and an energy consumption 10% lower than CTP, while achieving at least 0.95 PRR.

Algorithm for Removing Thick Clouds in TM Image Based on Spectral and Geometric Information

A new cloud removal algorithm based on spectral and geometric information is proposed for generating cloud free and cloud-shadow free mosaic image from multi-temporal TM images.At first,single image and multi-temporal images of thick cloud and cloud-shadow multi-spectral detection models are built based on TM spectral characteristics analysis.Secondly,cloud is detected according to spectral characteristics,and then a technique is applied based on coupled geometrical relationship between the cloud and its shadow by using sun azimuth angle,sun elevation angle and statistical distance between cloud and its shadow so as to automatically predict the approximate location of cloud-shadow.After that,erosion filtering and dilation filtering are used sequentially in the cloud and cloud-shadow fraction image to eliminate the small bits and generate the exact zones contaminated by cloud and cloud-shadow.At last,the cloud and cloud-shadow zones of the target image are replaced by the same-location cloud-free zones on reference images whose spectral information is matched with the target image by the linear regression method.The results show that this algorithm is capable of eliminating the cloud influence from TM image significantly.Moreover,it can effectively eliminate the influence of water body and hill shadow on cloud-shadow.This method can therefore support producing cloud removal images in a quick,simple and applicable way.

NIMASTEP: a software to modelize, study, and analyze the dynamics of various small objects orbiting specific bodies

NIMASTEP is a dedicated numerical software developed by us, which allows one to integrate the osculating motion (using cartesian coordinates) in a Newtonian approach of an object considered as a point-mass orbiting a homogeneous central body that rotates with a constant rate around its axis of smallest inertia. The code can be applied to objects such as particles, artificial or natural satellites or space debris. The central body can be either any terrestrial planet of the solar system, any dwarf-planet, or even an asteroid. In addition, very many perturbations can be taken into account, such as the combined third-body attraction of the Sun, the Moon, or the planets, the direct solar radiation pressure (with the central body shadow), the non-homogeneous gravitational field caused by the non-sphericity of the central body, and even some thrust forces. The simulations were performed using different integration algorithms. Two additional tools were integrated in the software package; the indicator of chaos MEGNO and the frequency analysis NAFF. NIMASTEP is designed in a flexible modular style and allows one to (de)select very many options without compromising the performance. It also allows one to easily add other possibilities of use. The code has been validated through several tests such as comparisons with numerical integrations made with other softwares or with semi-analytical and analytical studies. The various possibilities of NIMASTEP are described and explained and some tests of astrophysical interest are presented. At present, the code is proprietary but it will be released for use by the community in the near future. Information for contacting its authors and (in the near future) for obtaining the software are available on the web site http://www.fundp.ac.be/en/research/projects/page_view/10278201/

The problem of single-beam probing of an unknown medium

We propose an algorithm for determining the shadows of unknown bodies inside an arbitrary medium probed by radiation only in one direction. We demonstrate a successful performance of the algorithm in the case that on a direct visualization (a photograph) the bodies under consideration are indistinguishable. We study the problem of overlapping the shadows of some objects by others and conclude that this circumstance can improve or worsen the quality of reconstruction depending on the radiation characteristics of the medium. The presented results of numerical experiments show good agreement between theoretical and computational methods.

Performance analysis of wireless body area network in indoor off-body communication

Wireless Body Area Networks (WBANs) are considered to be a new method for short range wireless communication. Channel characteristics of WBAN are different from those of other wireless channels; specifically, when the human body rotates, the WBAN channel between the body surface and the wireless access point is changed via body shadowing. This paper analyzes the characteristics of recently proposed off-body WBAN channels and bit error performances when the human body rotates. In order to avoid inadequate channels and to improve the bit error performances, the receive antenna is attached to the back side, additionally. And the performance for each diversity scheme is evaluated.

Daily distribution of UV-Index in Belo Horizonte (Brazil) and the shadow rule

According to the Shadow Rule (SR), an individual can control the time of exposure to the Sun observing the body's shadow length on a horizontalsurface. Although a simple rule, the SR depends primarily on the ozone column (O3) amount, which can complicate the application of this rule in scenarios of lower O3 amounts like those in the low latitudes of Southern Hemisphere. The SR by itself can be confusing and impractical for application, as the shadow length can be of uneasy grasp and high uncertainty use unless one is equipped with calculator and ruler. Using the daily distribution of erythemal dose rates in Belo Horizonte (BH, 19.92ºS, 43.94ºW, 858 masl, 331 km², Brazil) for a period of 22 months, this work shows that a warning on time for solar exposure can be a safer, more efficient and more practical procedure in terms of creating a culture of casual exposure to the Sun than the use of the SR. For tropical and equatorial Brazilian sites, the diurnal interval for the avoidance of dangerous solar incidence of ultraviolet radiation is that between 2.5 hours after sunrise and 2.5 hours before sunset.

Characterization of the Indoor Multiantenna Body-to-Body Radio Channel

In this paper, we investigate the wideband body-to-body radio channel with multiple antennas at both ends based on a time-domain radio channel measurement campaign. Four single-element transmitters and eight quad-element receivers were mounted on three test people. Both directional and omnidirectional antennas have been investigated. A comparison between electromagnetic antenna simulations and the measurements shows that the multipath environment reduces the body losses effectively. Channel characterizations in terms of path loss, body shadowing, small-scale fading, and spatial correlation have been derived. Small path-loss exponents (< 2.0) are observed in the investigated environments. Considerable power loss due to body blockage makes the body shadowing a prominent factor in the short-range body-to-body communications. Distributed antenna selection diversity is presented to mitigate the body shadowing. A 5-dB diversity gain in the average received power at the mean and 10% outage levels have been identified based on the measurements with two distributed antennas mounted on the transmitter and receiver person and without channel-state information feedback to the transmitter.

S1201-1-3 身体スケール感覚に着目したミニチュア空間体験システムの開発(ヒューマンインターフェース)

The goal of this study is development of "Miniature Space Experience System" which makes an observer feel a sense of standing in a miniature space. For this purpose, we focus on a body shadow to enhance information of his position and change a sense of body scale. Developed system consists of a gantry type camera device which moves in a miniature space and a miniature shadow projection device. And as a result of some experiments utilizing this system, the effectiveness of proposed method was confirmed.

A Measurement-Based Fading Model for Wireless Personal Area Networks

Personal area networks (PANs) are wireless communications systems with high data rates but small coverage area. PAN propagation channels differ from the well-explored propagation channels of wide-area networks due to several reasons: (i) the distances are typically very small, (ii) the antenna arrangements can be quite different, and (iii) the influence from human presence in the environment is different. The current paper presents results of a channel measurement campaign, where measurements are conducted over distances of 1-10 m using several multi-antenna devices, combined to create different PAN scenarios. For each measured Tx-Rx separation, channel realizations are obtained by small spatial movements of the antenna devices, and by rotating the persons holding the devices. From the results, we draw two main conclusions: (i) The small scale amplitude statistics, analyzed as the variations over a small sampling area and frequency subchannels, cannot be described in a satisfactory way using only the Rayleigh or Ricean distribution, rather a mixed distribution, the generalized gamma distribution, is more suitable; (ii) it is advantageous to distinguish between two types of large-scale fading: body shadowing (due to the orientation of the person holding the device) and shadowing due to surrounding objects (lateral movement). We also define and parameterize a complete statistical model for all fading.

Neovascular membrane over the ciliary body as a potential complication of transscleral diode laser cyclophotocoagulation

Neovascular membrane over the ciliary body as a potential complication of transscleral diode laser cyclophotocoagulation

Hudson River School

Hudson River School:On Asher B. Durand's "Early Morning at Cold Spring" (1850) Marie-Ovide Gina Dorcely (bio) A swish of ribbon holds the curtain Asters creep along the green carpet In the foreground: a spotted cow In its red, brown, orange, cream resplendence, A question: How did you arrive, here, on the body's shadow: Were you a whisper sent to plumb these fields— Come to melt our mettle? No matter, In this land of fiddles and cloudhoppers, One arrives to make a poetry of distinction. Here, all are found under the cloth Live or die in the aerie of fallen leaves. Marie-Ovide Gina Dorcely Marie-Ovide Gina Dorcely is a poet, translator, and nonfiction prose writer. She has received awards for her writing from the Cave Canem Foundation and the Breadloaf Writers Conferences. Her work has appeared in Ploughshares, Caribbean Writer, and The Portable Lower East Side. She was born in Haiti. Copyright © 2007 Charles H. Rowell

Long-lasting capture of tactile attention by body shadows

Four experiments addressed the role of cast shadows of the body in orienting tactile spatial attention to the body itself. We used a modified spatial-cueing paradigm to examine whether viewing of the cast shadow of a hand can elicit spatial shifts of tactile attention to that very same hand. Participants performed a speeded tactile-discrimination task (thumb versus index finger, regardless of touched hand), while viewing the shadow of either the touched or untouched hand cast in front of them by a lateral light-source. The hand casting the shadow changed either between blocks (expt 1) or unpredictably within each block (expts 2-4). In experiments 1 and 2 tactile targets were preceded by central non-informative visual cues delivered near the shadow of the index finger and thumb. Despite the fact that cast shadows were always task-irrelevant and non-predictive of which hand was stimulated, tactile discrimination was consistently faster at the hand casting the shadow than at the other hand. This effect was not modulated by the duration of cue-target asynchrony, nor did it depend on whether the visual cue was present or not (expt 3). In addition, it was still reliable when vision of the hands was precluded, whereas it became inconsistent when the cast shadow of the hand was replaced by the cast shadow of an object (expt 4). Our results suggest that body shadows can induce a long-lasting capture of tactile attention for stimuli at the body itself.

3726 立体的ディスプレイへの映像と影の提示システムの開発(S69 ヒューマンインタフェース)

3726 立体的ディスプレイへの映像と影の提示システムの開発(S69 ヒューマンインタフェース)

Binding personal and extrapersonal space through body shadows.

Shadows in visual scenes can have profound effects on visual perception. Here we have found that visual distracters distant from the body interfere with human spatial discrimination of tactile targets at a hand, particularly when the shadow of the stimulated hand stretches toward them in extrapersonal space. These findings suggest that shadows cast by a person's own body parts can bridge the gap between personal and extrapersonal space.

The secret of velvety skin

Asperity scattering adds a 'surface lobe' to the usual diffuse, backscatter, and specular lobes of rough surfaces. Although rarely acknowledged, it is an important effect in many materials that are covered with a thin layer of sparse scatterers, such as dust or hairs. In common cases where single scattering predominates, asperity scattering adds important contributions to the structure of the occluding contour and the edge of the body shadow. This is because the bidirectional reflectance distribution function (BRDF) is inversely proportional to the cosines of both the illumination and viewing angles. The BRDF is generally low (and typically negligible) except when either the illuminating rays or visual directions graze the surface. Because asperity scattering selectively influences the edges in the image of an object, it has (as judged by photometric magnitudes) a disproportionally large effect on (human) visual appreciation. We identify it as a neglected but often decisive visual cue in the rendering of human skin. Its effect is to make smooth cheeks look 'velvety' or 'peachy', that is to say, soft (the appearances of both velvet and peachy skin are dominated by asperity scattering). This is a most important aesthetic and emotional factor that is lacking in Lambertian (looks merely dullish and paper-like), 'skin-type' BRDF (looks like glossy plastic), or even translucent (looks 'hard', vitreous) types of rendering.

On the duration of the total eclipse of a satellite of a body

This paper solves the problem of the duration of the total eclipse of a satellite of a body, provided that (a) the body is spherical in shape and the mass distribution inside the body is spherically symmetrical; (b) the satellite is a very small object; (c) the satellite's, orbit around a body is circular and the satellite can pass through the centre of its shadow; (d) a source of light is the source of the conical body's shadow (umbra) and it does not change its apparent position in the sky; (e) there are no perturbations on the satellite's orbit. The solution presented represents the general discussion of the problem based on utilization of some parts of the theory of contraction mappings.

The Karma of Sparrows, Bedbugs, and Body Shadows: Chapters from a Memoir

Karma consists of passionate but often amusing stories about myself and many intellectuals, farmers, workers, and officials, filtered through my own sensibility as a modern Chinese man now living in the West. The readers will see how ordinary Chinese lived, eventually survived, or perished, in those turbulent years, and what physical and spiritual forces led them to perform unimaginable deeds. Chinese values, customs, and traditions are explained and contrasted to those of western society. Karma is a forthcoming book.

体重増加不良で発見された食道異物症例

A child with mental retardation, who could not report to subjective symptoms, came to our institute because of failure to gain weight. A foreign body shadow of a safety-pin was found accidentally in his chest with a plain X-ray.This patient was a 16-month-old male, and the foreign body shadow of an open safety-pin was found at the first cervical constriction of the esophagus. The sharp end of the safety pin was upwards.He was admitted to emergency, and we attempted to remove the safety-pin by direct esophagoscopy under general anesthesia. However, the pin was buried in the wall of the esophagus, and we gave up because of the danger involved. The next day we performed an incision of the neck and removed the safety-pin.

Shadows of convex bodies

It is proved that if C C is a convex body in R n {\mathbb {R}^n} then C C has an affine image C ~ \tilde C (of nonzero volume) so that if P P is any 1 1 -codimensional orthogonal projection, \[ | P C ~ | ≥ | C ~ | ( n − 1 ) / n . |P\tilde C| \geq \,|\tilde C{|^{(n - 1)\,/\,n}}. \] It is also shown that there is a pathological body, K K , all of whose orthogonal projections have volume about n \sqrt n times as large as | K | ( n − 1 ) / n |K{|^{(n - 1)\,/\,n}} .

安全ピン気管支異物の一症例

A 21-month-old male has complained of fever and cough for two weeks. Dec. 2, 1989, because of suspection of pneumonia, X-ray examination was done. The radiograph revealed a foreign body shadow of a safety-pin and pneumonia in the left bronchus. It was not obvious when he had aspirated the safety-pin. In January 11, 1990, providing thracotomy and extracorporeal circulation in advance, the foreign body was removed in three pieces with ventiration bronchoscope through a tracheostoma. The safety-pin was 26×6 mm in size and has been eroded. No sever postoperative complication was observed. He was discharged 4 weeks after the operation. One hundred and ninety four cases of foreign bodies in the air way were treated in our department during past 32 years. Male to female ratio in our cases was about 2.2: 1. One hundred and twenty six cases of these foreign bodies were peanuts. This is the first case of safety-pin in our department.