Electromagnetic Energy Sink

The ideal black body fully absorbs all incident rays, that is, all propagating waves created by arbitrary sources. The known idealized realization of a black body is the perfectly matched layer (PML), widely used in numerical electromagnetics. However, ideal black bodies and PMLs do not interact with evanescent fields existing near any finite-size source, and the energy stored in these fields cannot be harvested. Here we introduce the concept of the ideal conjugate matched layer (CML), which fully absorbs energy of both propagating and evanescent fields of sources acting as an ideal sink for electromagnetic energy. Conjugate matched absorbers have exciting application potentials, as resonant attractors of electromagnetic energy into the absorber volume. We derive the conditions on the constitutive parameters of media which can serve as CML materials, numerically study the performance of planar and cylindrical CML and discuss possible realizations of such materials as metal-dielectric composites.Comment: 17 pages, 15 figure

Electromagnetic energy sink

The ideal black body fully absorbs all incident rays, that is, all propagating waves created by arbitrary sources. A known idealized realization of the black body is the perfectly matched layer (PML), widely used in numerical electromagnetics. However, ideal black bodies and PMLs do not interact with evanescent fields that exists near any finite-size source, and the energy stored in these fields cannot be harvested. Here, we introduce the concept of the ideal conjugate matched layer (CML), which fully absorbs the energy of both propagating and evanescent fields of sources acting as an ideal sink for electromagnetic energy. Conjugate matched absorbers have exciting application potentials, as resonant attractors of electromagnetic energy into the absorber volume. We derive the conditions on the constitutive parameters of media which can serve as CML materials, numerically study the performance of planar and cylindrical CML and discuss possible realizations of such materials as metal-dielectric composite

Moral wrongs, disadvantages, and disability: a critique of critical disability studies

Critical disability studies (CDS) has emerged as an approach to the study of disability over the last decade or so and has sought to present a challenge to the predominantly materialist line found in the more conventional disability studies approaches. In much the same way that the original development of the social model resulted in a necessary correction to the overly individualized accounts of disability that prevailed in much of the interpretive accounts which then dominated medical sociology, so too has CDS challenged the materialist line of disability studies. In this paper we review the ideas behind this development and analyse and critique some of its key ideas. The paper starts with a brief overview of the main theorists and approaches contained within CDS and then moves on to normative issues; namely, to the ethical and political applicability of CDS

Practice of ALARA in the pediatric interventional suite

As interventional procedures have become progressively more sophisticated and lengthy, the potential for high patient radiation dose has increased. Staff exposure arises from patient scatter, so steps to minimize patient dose will in turn reduce operator and staff dose. The practice of ALARA in an interventional radiology (IR) suite, therefore, requires careful attention to technical detail in order to reduce patient dose. The choice of imaging modality should minimize radiation when and where possible. In this paper practical steps are outlined to reduce patient dose. Further details are included that specifically reduce operator exposure. Challenges unique to pediatric intervention are reviewed. Reference is made to experience from modern pediatric interventional suites. Given the potential for high exposures, the practice of ALARA is a team responsibility. Various measures are outlined for consideration when implementing a quality assurance (QA) program for an IR service

Diversity and uniformity in genetic responsibility: moral attitudes of patients, relatives and lay people in Germany and Israel

The professional and institutional responsibility for handling genetic knowledge is well discussed; less attention has been paid to how lay people and particularly people who are affected by genetic diseases perceive and frame such responsibilities. In this exploratory study we qualitatively examine the attitudes of lay people, patients and relatives of patients in Germany and Israel towards genetic testing. These attitudes are further examined in the national context of Germany and Israel, which represent opposite regulatory approaches and bioethical debates concerning genetic testing. Three major themes of responsibility emerged from the inter-group and cross-cultural comparison: self-responsibility, responsibility for kin, and responsibility of society towards its members. National contrast was apparent in the moral reasoning of lay respondents concerning, for example, the right not to know versus the duty to know (self-responsibility) and the moral conflict concerning informing kin versus the moral duty to inform (responsibility for kin). Attitudes of respondents affected by genetic diseases were, however, rather similar in both countries. We conclude by discussing how moral discourses of responsibility are embedded within cultural (national, religious) as well as phenomenological (being affected) narratives, and the role of public engagement in bioethical discourse

Increased Expression of PS1 Is Sufficient to Elevate the Level and Activity of γ-Secretase In Vivo

Increase in the generation and deposition of amyloid-β (Aβ) plays a central role in the development of Alzheimer's Disease (AD). Elevation of the activity of γ-secretase, a key enzyme required for the generation for Aβ, can thus be a potential risk factor in AD. However, it is not known whether γ-secretase can be upregulated in vivo. While in vitro studies showed that expression of all four components of γ-secretase (Nicastrin, Presenilin, Pen-2 and Aph-1) are required for upregulation of γ-secretase, it remains to be established as to whether this is true in vivo. To investigate whether overexpressing a single component of the γ-secretase complex is sufficient to elevate its level and activity in the brain, we analyzed transgenic mice expressing either wild type or familial AD (fAD) associated mutant PS1. In contrast to cell culture studies, overexpression of either wild type or mutant PS1 is sufficient to increase levels of Nicastrin and Pen-2, and elevate the level of active γ-secretase complex, enzymatic activity of γ-secretase and the deposition of Aβ in brains of mice. Importantly, γ-secretase comprised of mutant PS1 is less active than that of wild type PS1-containing γ-secretase; however, γ-secretase comprised of mutant PS1 cleaves at the Aβ42 site of APP-CTFs more efficiently than at the Aβ40 site, resulting in greater accumulation of Aβ deposits in the brain. Our data suggest that whereas fAD-linked PS1 mutants cause early onset disease, upregulation of PS1/γ-secretase activity may be a risk factor for late onset sporadic AD

Extensive innate immune gene activation accompanies brain aging, increasing vulnerability to cognitive decline and neurodegeneration: a microarray study

BACKGROUND: This study undertakes a systematic and comprehensive analysis of brain gene expression profiles of immune/inflammation-related genes in aging and Alzheimer’s disease (AD). METHODS: In a well-powered microarray study of young (20 to 59 years), aged (60 to 99 years), and AD (74 to 95 years) cases, gene responses were assessed in the hippocampus, entorhinal cortex, superior frontal gyrus, and post-central gyrus. RESULTS: Several novel concepts emerge. First, immune/inflammation-related genes showed major changes in gene expression over the course of cognitively normal aging, with the extent of gene response far greater in aging than in AD. Of the 759 immune-related probesets interrogated on the microarray, approximately 40% were significantly altered in the SFG, PCG and HC with increasing age, with the majority upregulated (64 to 86%). In contrast, far fewer immune/inflammation genes were significantly changed in the transition to AD (approximately 6% of immune-related probesets), with gene responses primarily restricted to the SFG and HC. Second, relatively few significant changes in immune/inflammation genes were detected in the EC either in aging or AD, although many genes in the EC showed similar trends in responses as in the other brain regions. Third, immune/inflammation genes undergo gender-specific patterns of response in aging and AD, with the most pronounced differences emerging in aging. Finally, there was widespread upregulation of genes reflecting activation of microglia and perivascular macrophages in the aging brain, coupled with a downregulation of select factors (TOLLIP, fractalkine) that when present curtail microglial/macrophage activation. Notably, essentially all pathways of the innate immune system were upregulated in aging, including numerous complement components, genes involved in toll-like receptor signaling and inflammasome signaling, as well as genes coding for immunoglobulin (Fc) receptors and human leukocyte antigens I and II. CONCLUSIONS: Unexpectedly, the extent of innate immune gene upregulation in AD was modest relative to the robust response apparent in the aged brain, consistent with the emerging idea of a critical involvement of inflammation in the earliest stages, perhaps even in the preclinical stage, of AD. Ultimately, our data suggest that an important strategy to maintain cognitive health and resilience involves reducing chronic innate immune activation that should be initiated in late midlife

Käänteisen synteettisen apertuurin tutkan signaalinkäsittely ja liikekompensaatio

Synteettisen apertuurin tutkalla voidaan muodostaa korkearesoluutioisia kaksi- tai kolmiulotteisia tutkakuvia tutkittavista kohteista ja kohdealueista. Korkea resoluutio tutkan ja kohdealueen keskipisteen yhdistävän suoran suuntaisessa etäisyydessä saavutetaan käyttämällä lähetettävälle radioalueen signaalille laajaa taajuuskaistaa. Toinen, etäisyyssuuntaa vastaan kohtisuorassa oleva ulottuvuus tutkakuvaan saadaan kohteen ja tutkan välistä kulma-asentoa muuttavan suhteellisen liikkeen avulla. Tämä kulma-asennon muutos aiheuttaa vastaanotettuun signaaliin Doppler-siirtymiä, joita voidaan hyödyntää sivusuuntaisen erottelukyvyn muodostamiseen. Tämä tutkielma keskittyy yksipaikkaisen käänteisen synteettisen apertuurin tutkan signaalinkäsittelyyn. Tällöin tutkan ja kohteen välinen suhteellinen liike on ideaalisessa tapauksessa kohteen tasaista pyörimisliikettä. Perinteiset etäisyys-Doppler- ja polar-format-prosessointimenetelmät perustuvat Fourier-muunnokseen ja tiettyihin approksimaatioihin. Tutkielmassa esitetään matemaattisesti optimaalinen prosessointimenetelmä, joka ei sisällä approksimaatioita. Tässä käänteiskuvausmenetelmässä tutkakuvan prosessointi suoritetaan erikseen jokaiselle kuvapisteelle korreloimalla kuvapisteestä muodostettua pisteleviämisfunktiota tutkan vastaanottaman signaalin kanssa. Pisteleviämisfunktiolla tarkoitetaan ideaalisen pistemäisen sirottajan vastetta kuvaa muodostavalle systeemille. Kaikissa prosessointimenetelmissä kohteen tuntematon ja epäideaalinen liiketila heikentää tai voi jopa tehdä mahdottomaksi onnistuneen tutkakuvan muodostamisen. Erityisesti käänteiskuvausmenetelmässä on jokaisen kuvapisteen etäisyys tutkasta ajan funktiona tunnettava eksplisiittisesti. Tuntematon liiketila aiheuttaa vastaanotettuun signaaliin vaihemuutoksia, jotka on korjattava ennen kuvan muodostamista liikekompensaation avulla. Tutkielmassa simuloidaan taajuusaskellettua tutkasignaalia, jonka avulla voidaan toteuttaa käänteiskuvausmenetelmä ja tutkia tälle prosessointimenetelmälle sopivia liikekompensaatiomenetelmiä. Rotaatioakselin tarkan sijainnin määrittämiseen käytetään tuloskuvan kontrastin maksimointia. Kontrastiksi määritellään tuloskuvan amplitudien keskihajonnan ja keskiarvon suhde. Käänteiskuvausmenetelmän kanssa yhteensopiviksi liikekompensaatiomenetelmiksi todetaan maksimikorrelaatiomenetelmä ja dominoivia sirottajia hyödyntävät menetelmät. Toteutettujen liikekompensaatiomenetelmien tarkoituksena on muokata vastaanotettu signaali sellaiseen muotoon, että kohteella on ainoastaan tasaista pyörimisliikettä liikekompensaation jälkeen. Jatkotutkimuksen aiheeksi ehdotetaan liikekompensaation yhdistämistä käänteiskuvausmenetelmän prosessointiin