http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : Schneiderman, Justin (검색결과 2 건)
- 무료
- 기관 내 무료
- 유료
-
-
SQUIDs in biomagnetism: a roadmap towards improved healthcare
Kö,rber, Rainer,Storm, Jan-Hendrik,Seton, Hugh,Mä,kelä,, Jyrki P,Paetau, Ritva,Parkkonen, Lauri,Pfeiffer, Christoph,Riaz, Bushra,Schneiderman, Justin F,Dong, Hui,Hwang, Seong-min,You, Lixi IOP 2016 Superconductor science & technology Vol.29 No.11
<P>Globally, the demand for improved health care delivery while managing escalating costs is a major challenge. Measuring the biomagnetic fields that emanate from the human brain already impacts the treatment of epilepsy, brain tumours and other brain disorders. This roadmap explores how superconducting technologies are poised to impact health care. Biomagnetism is the study of magnetic fields of biological origin. Biomagnetic fields are typically very weak, often in the femtotesla range, making their measurement challenging. The earliest <I>in vivo</I> human measurements were made with room-temperature coils. In 1963, Baule and McFee (1963 <I>Am</I>. <I>Heart J</I>. <A HREF='http://dx.doi.org/10.1016/0002-8703(63)90075-9'> <B>55</B> 95−6</A>) reported the magnetic field produced by electric currents in the heart (‘magnetocardiography’), and in 1968, Cohen (1968 <I>Science</I> <A HREF='http://dx.doi.org/10.1126/science.161.3843.784'> <B>161</B> 784−6</A>) described the magnetic field generated by alpha-rhythm currents in the brain (‘magnetoencephalography’). Subsequently, in 1970, Cohen <I>et al</I> (1970 <I>Appl. Phys. Lett.</I> <A HREF='http://dx.doi.org/10.1063/1.1653195'> <B>16</B> 278–80</A>) reported the recording of a magnetocardiogram using a Superconducting QUantum Interference Device (SQUID). Just two years later, in 1972, Cohen (1972 <I>Science</I> <A HREF='http://dx.doi.org/10.1126/science.175.4022.664'> <B>175</B> 664–6</A>) described the use of a SQUID in magnetoencephalography. These last two papers set the scene for applications of SQUIDs in biomagnetism, the subject of this roadmap.</P> <P>The SQUID is a combination of two fundamental properties of superconductors. The first is flux quantization—the fact that the magnetic flux Φ in a closed superconducting loop is quantized in units of the magnetic flux quantum, Φ<SUB>0</SUB> ≡ <I>h</I>/2<I>e</I>, ≈ 2.07 × 10<SUP>−15</SUP> Tm<SUP>2</SUP> (Deaver and Fairbank 1961 <I>Phys. Rev. Lett.</I> <A HREF='http://dx.doi.org/10.1103/PhysRevLett.7.43'> <B>7</B> 43–6</A>, Doll R and Näbauer M 1961 <I>Phys. Rev. Lett.</I> <A HREF='http://dx.doi.org/10.1103/PhysRevLett.7.51'> <B>7</B> 51–2</A>). Here, <I>h</I> is the Planck constant and <I>e</I> the elementary charge. The second property is the Josephson effect, predicted in 1962 by Josephson (1962 <I>Phys. Lett.</I> <A HREF='http://dx.doi.org/10.1016/0031-9163(62)91369-0'> <B>1</B> 251–3</A>) and observed by Anderson and Rowell (1963 <I>Phys. Rev. Lett.</I> <A HREF='http://dx.doi.org/10.1103/PhysRevLett.10.230'> <B>10</B> 230–2</A>) in 1963. The Josephson junction consists of two weakly coupled superconductors separated by a tunnel barrier or other weak link. A tiny electric current is able to flow between the superconductors as a supercurrent, without developing a voltage across them. At currents above the ‘critical current’ (maximum supercurrent), however, a voltage is developed. In 1964, Jaklevic <I>et al</I> (1964 <I>Phys. Rev. Lett.</I> <A HREF='http://dx.doi.org/10.1103/PhysRevLett.12.159'> <B>12</B> 159–60</A>) observed quantum interference between two Josephson junctions connected in series on a superconducting loop, giving birth to the dc SQUID. The essential property of the SQUID is that a steady increase in the magnetic flux threading the loop causes the critical current to oscillate with a period of one flux quantum. In today’s SQUIDs, using conventional semiconductor readout electronics, one can typically detect a change in Φ corresponding to 10<SUP>−6</SUP> Φ<SUB>0</SUB> in one second. Although early practical SQUIDs were usually made from bulk superconductors, for example, niobium or Pb-Sn solder blobs, today’s devices are invariably made from thin superconducting films patterned with photolithography or even electron lithography. An extensive descri
연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
