bluuebunny/crossref_metadata_2025 huggingface dataset:
GH mutant (R77C) in a pedigree presenting with the delay of growth and pubertal development: structural analysis of the mutant and evaluation of the biological activity
Authors: Petkovic Vibor , Thevis Mario , Lochmatter Didier , Besson Amélie , Eblé Andrée , Flück Christa E , Mullis Primus E
Published: September 2007

A heterozygous missense mutation in the GH-1 gene converting codon 77 from arginine (R) to cysteine (C), which was previously reported to have some GH antagonistic effect, was identified in a Syrian family. The index patient, a boy, was referred for assessment of his short stature (−2.5 SDS) at the age of 6 years. His mother and grandfather were also carrying the same mutation, but did not differ in adult height from the other unaffected family members. Hormonal examination in all affected subjects revealed increased basal GH, low IGF-I concentrations, and subnormal IGF-I response in generation test leading to the diagnosis of partial GH insensitivity. However, GH receptor gene (GHR) sequencing demonstrated no abnormalities. As other family members carrying the GH-R77C form showed similar alterations at the hormonal level, but presented with normal final height, no GH therapy was given to the boy, but he was followed through his pubertal development which was delayed. At the age of 20 years he reached his final height, which was normal within his parental target height. Functional characterization of the GH-R77C, assessed through activation of Jak2/Stat5 pathway, revealed no differences in the bioactivity between wild-type-GH (wt-GH) and GH-R77C. Detailed structural analysis indicated that the structure of GH-R77C, in terms of disulfide bond formation, is almost identical to that of the wt-GH despite the introduced mutation (Cys77). Previous studies from our group demonstrated a reduced capability of GH-R77C to induce GHR/GH-binding protein (GHBP) gene transcription rate when compared with wt-GH. Therefore, reduced GHR/GHBP expression might well be the possible cause for the partial GH insensitivity found in our patients. In addition, this group of patients deserve further attention because they could represent a distinct clinical entity underlining that an altered GH peptide may also have a direct impact on GHR/GHBP gene expression causing partial GH insensitivity. This might be responsible for the delay of growth and pubertal development. Finally, we clearly demonstrate that GH-R77C is not invariably associated with short stature, but that great care needs to be taken in ascribing growth failure to various heterozygous mutations affecting the GH–IGF axis and that careful functional studies are mandatory.
Preventing Stroke Among Children With Sickle Cell Anemia: An Analysis of Strategies That Involve Transcranial Doppler Testing and Chronic Transfusion
Authors: Mazumdar Maitreyi , Heeney Matthew M. , Sox Colin M. , Lieu Tracy A.
Published: September 2007

BACKGROUND. Transcranial Doppler ultrasonography can identify children with sickle cell anemia who are at elevated risk of stroke and may benefit from chronic transfusions. Uncertainty about the risk/benefit trade-offs of chronic transfusion has led some clinicians to decide not to offer transcranial Doppler ultrasonography screening.

OBJECTIVES. Our goals were to (1) compare the projected benefits and risks of 6 primary stroke-prevention strategies, (2) estimate the optimal frequency of screening, and (3) identify key assumptions that influence the risk/benefit relationship.

METHODS. We designed a decision model to compare 6 primary stroke-prevention strategies: (1) annual transcranial Doppler ultrasonography screening until age 16 with children at high risk of stroke receiving monthly transfusion for life; (2) annual transcranial Doppler ultrasonography until age 16 with transfusions until age 18; (3) biannual transcranial Doppler ultrasonography until age 16 with transfusions until age 18; (4) annual transcranial Doppler ultrasonography until age 10 with transfusion until age 18; (5) 1-time screening at age 2 with transfusion until age 18; and (6) no intervention. Assumptions were derived from the published literature.

RESULTS. For a hypothetical cohort of 2-year-old children, the optimal strategy was transcranial Doppler ultrasonography screening annually until age 10 with children at high risk receiving monthly transfusions until age 18. The optimal strategy would prevent 32% of strokes predicted to occur without intervention. The optimal strategy led to benefits similar to more intensive screening and transfusion strategies but resulted in fewer adverse events. All the intervention strategies resulted in net losses in life expectancy, because the projected mortality averted by stroke prevention was outweighed by the projected increase in mortality from transfusion. Results were sensitive to adherence rates to iron-chelation therapy.

CONCLUSIONS. The optimal stroke-prevention strategy was projected to be annual transcranial Doppler ultrasonography screening until age 10 with transfusion for children at high risk until age 18. Better adherence to chelation therapy would improve life expectancy in all intervention strategies.
Cutis marmorata telangiectatica congenita – case report
Authors: Flach Edina , Kellermayer Richárd , Ertl Tibor , Vida Gabriella , Sárkány Ilona , Funke Simone , Gyarmati Judit
Published: September 2007

A cutis marmorata teleangiectatica congenita ritka, általában veleszületett, generalizált vagy lokális cutan érfejlődési rendellenesség, amit jellegzetes tünetek alapján diagnosztizálnak (a bőr tartós márványozottsága, teleangiectasia, phlebectasia, esetleg ulceratio, atrophia), és amely hajlamot mutat klinikai javulásra. Az irodalom eddig közel 300 betegről számolt be. A szerzők jelen dolgozatukban bemutatnak egy esetet, amelyben a klinikai tünetek (a skalpon tág vénák, kétoldali bőrulceratio, testszerte márványozott bőr, a mellkason teleangiectasia) alapján cutis marmorata teleangiectatica congenitát diagnosztizáltak, egyéb társuló rendellenesség nélkül. Az eset kapcsán a szerzők az irodalmat is áttekintik.
Heme-iron in the human body
Authors: Balla József , Balla György , Lakatos Béla , Jeney Viktória , Szentmihályi Klára
Published: September 2007

A vas minden élő organizmus számára nélkülözhetetlen, ugyanakkor a fölöslegben lévő aktív vas veszélyes, hiszen szabad gyökök képződését katalizálhatja. Ezért a vas abszorpciója szigorúan szabályozott folyamat, melynek eredménye a vasvesztés és a vasfelvétel egyensúlya. Azokban az országokban, ahol az étkezéssel a hemvas bevitele jelentős, a szervezet vastartalmának nagy része hemből származik. A táplálékkal bevitt hemet a vékonybél enterocyta sejtjei intakt formában receptormediált módon abszorbeálják, majd hem-oxigenáz katalizálta reakcióban degradálják, így a vas transzferrinhez kötve hagyja el az enterocytát. A hem számos protein prosztetikus csoportja, így minden sejtünk szintetizálja. Mennyiségét tekintve a legjelentősebb hemprotein a hemoglobin, mely a vörösvértestekben az oxigén transzportját végzi. A vörösvértestek hemolízise során szabaddá váló hemoglobin specifikusan vagy aspecifikusan plazmaproteinekhez kötődik, és receptormediált úton felvételre kerül, majd degradálódik. A hemoglobinmolekula szerkezeti felépítése megnehezíti, de teljes mértékben nem akadályozza meg a hemoglobin (ferro) oxidációját methemoglobinná (ferri). A reakcióban szuperoxidgyök-anion is képződik, mely további szabad gyökös reakciókaszkádokat indít el. A képződött methemoglobin a hemet nem köti olyan szorosan, mint a hemoglobin, így az oxidáció következménye szabad hem képződése. A hem a plazmaprotein hemopexinhez kötődik, és receptormediált úton a sejtek által felvételre kerül, majd a hem-oxigenázok által katalizált reakcióban degradálódik. A hem ezenkívül a plazma lipoproteinjeihez, valamint az endothelium lipidmembránjához is kapcsolódhat, aminek következtében az LDL oxidálódik, illetve az endothelium oxidatív stresszre érzékenyebbé válik. A jelen összefoglaló célja a hemmel kapcsolatos folyamatok áttekintése.
The undesirable psychological adverse effects of screening
Authors: Döbrőssy Bence , Kovács Attila , Budai András , Cornides Ágnes , Döbrőssy Lajos
Published: September 2007

A szűrővizsgálat elutasításának okai között szerepelnek a szűrés nemkívánatos lélektani mellékhatásai. Ennek lehetséges okai három csoportba sorolhatók: 1.
Általános
okok, mint például az egészségügyi szolgáltatások igénybevételét meghatározó emberi magatartás. Különösen azoknak a szolgáltatásoknak az elutasítása gyakori, amelyek nem a jelenben is kínzó tünetek és panaszok orvoslását célozzák, hanem a jövőben majd esetleg fellépő betegségek megelőzését szolgálják; ilyen „jövőre irányuló” szolgáltatás a szűrővizsgálat is. 2. A
rákbetegségnek a közfelfogásban rögzült negatív képe
és a gyógyíthatóságát illető kételyek. Szóba jönnek továbbá 3. a
szűrővizsgálat szubjektív megtapasztalásával közvetlenül összefüggő okok.
A szolgáltatóknak törekedniük kell az okok kiküszöbölésére: a) a különböző korú, társadalmi helyzetű és műveltségi szintű rétegekhez szóló
egészségnevelés
feladata, hogy kialakítsa a betegségmegelőzés szükségességét elfogadó magatartást, és változtasson az embereknek a rákkal szemben eltúlzottan negatív, a vereséget előre elkönyvelő szemléletén; b) a szűrővizsgálatot szolgáltató szakemberek kötelessége, hogy minden tőlük telhetőt megtegyenek a szűrővizsgálattól visszatartó tényezők mérséklése érdekében. Ennek módja a jó munkaszervezés és a szakmai munka minőségének optimalizálása, valamint a jó kommunikáció: a szűrővizsgálat előtti, alatti és utáni felvilágosítás, információszolgáltatás és tanácsadás.
„Précurseur de toute la musique française moderne“? Die Rezeption Franz Liszts als Komponist in Frankreich zwischen 1844 und 1925
Authors: Kremer Joachim
Published: September 2007

Franz Liszts Wahrnehmung in Frankreich als Komponist setzte ab 1869 ein und erweiterte das bis dahin gewohnte Bild vom Pianisten. Liszts Orchesterwerke wurden zunächst im Lichte der Bewertung der Neudeutschen Schule gesehen, und auch die Kontroversen um die Programmmusik und das dahinterstehende Problemfeld ‚Klassizismus vs. Romantik‘ schufen erschwerte Rezeptionsbedingungen. Behindert wurde die Wahrnehmung zudem durch die selektive und verzögerte Aufführung der Werke. Bis zum aufwändig gefeierten
Centenaire
im Jahre 1911 war Liszt somit der ‚geborene‘ Vorläufer. Der Versuch einer Rehabilitierung kam angesichts der selektiven Wahrnehmung auf der einen und der rasanten Musikentwicklung nach 1900 auf der anderen Seite — zu denken ist an Ravel oder Strawinsky — sehr spät.
Scherzo and the unheimlich: the construct of genre and feeling in the long 19th century
Authors: Péteri Lóránt
Published: September 2007

The psychological concept of the uncanny
(“das Unheimliche”)
has been established in studies by E. Jentsch (1906) and S. Freud (1919). On the grounds of cultural and textual references, which can be found in these studies, one might regard the uncanny as a discourse construct contained in various literary, evaluative, and visual texts stretching from the late 18th century to the First World War. In my paper, I wish to discuss the assumption that the scherzo genre, commonly seen as founded on Haydn’s opus 33 string quartets and coming to a first fruition in various Beethoven cycles shows a particular propensity to act as the musical vehicle for an uncanny quality. The closer scrutiny of two “programmatic” scherzi (those are the 3rd movement of Mahler’s 2nd Symphony and
L’Apprenti sorcier
by Dukas) might shed light on the advantages of a genre-oriented approach when musical meaning is concerned.
Franz Liszts Briefe an Emilie Merian-Genast aus den Beständen des Goethe- und Schiller-Archivs, Weimar Teil 1
Authors: Hamburger Klára
Published: September 2007

Aus den größtenteils unveröffentlichten Briefen Franz Liszts entfaltet sich eine sympathische Frauengestalt. Die aus einer angesehenen Weimarer Theaterfamilie stammende Mezzosopranistin Emilie Genast, eine hochmusikalische Lied- und Oratoriumsängerin, um 22 Jahre jünger als er, wurde ihm zur idealen Muse, indem sie die Lisztschen Lieder und Psalmen, die Titelrolle der
Legende von der Heiligen Elisabeth
beseelt und erfolgreich vortrug. Die Musikgeschichte hat ihr auch das Entstehen neuer Lisztscher Gesänge zu verdanken. Intim gestaltete sich das persönliche Verhältnis der beiden in der vielleicht schwersten Zeit des Vielgeprobten: nachdem die Fürstin Wittgenstein im Mai 1860 nach Rom gereist war. Der Künstler, nahe fünfzig, wußte nicht, wann und wohin er zu reisen hatte, wie er seine Laufbahn fortsetzen würde, einzig, das seines Bleibens in Weimar nicht war — bis er endlich im Herbst 1861 nach Rom kam. 1863 heiratete Emilie Dr. Merian in Basel. Von dieser Zeit an vertiefte und veredelte sich ihre Sympathie zu einer gegenseitigen, respektvollen, bis an des Meisters Lebensende dauernden Künstlerfreundschaft.
„Dem Fürsten meinen Respekt!“ Neue Perspektiven zu David Poppers Löwenberger Jahren 1862 bis 1868
Authors: Birkin-Feichtinger Ingeborg
Published: September 2007

David Popper wurde auf Empfehlung von Hans von Bülow als Nachfolger von Theodor Oswald in die Hofkapelle des Fürsten Friedrich Wilhelm Konstantin von Hohenzollern-Hechingen zu Löwenberg in Schlesien ab Herbst 1862 aufgenommen. In dem Kapellmeister Max Seifriz fand er einen Förderer und Freund. Beginn seiner Konzerttätigkeit, die ihn ausgehend von seiner Heimatstadt Prag in viele deutsche Städte führte, z. B. Leipzig, Breslau, Berlin, Karlsruhe, Meiningen, Stuttgart, nach Wien, London und in die Schweiz. Im Dezember 1867 begannen die Verhandlungen mit Wien. Ab Oktober 1868 wurde Popper erster Violoncellist und Solospieler im Orchester des k. k. Hofoperntheaters in Wien.
Seeing Cells: Teaching the Visual/Verbal Rhetoric of Biology
Authors: Dinolfo John , Heifferon Barbara , Temesvari Lesly A.
Published: September 2007

This pilot study obtained baseline information on verbal and visual rhetorics to teach microscopy techniques to college biology majors. We presented cell images to students in cell biology and biology writing classes and then asked them to identify textual, verbal, and visual cues that support microscopy learning. Survey responses suggest that these students recognized some of the rhetorical strategies used and conflated others, revealing intriguing questions for further research in undergraduate microscopy education.
Multimodal Analysis: An Integrative Approach for Scientific Visualizing on the Web
Authors: Maier Carmen Daniela , Kampf Constance , Kastberg Peter
Published: September 2007

The Multimodal approach offers technical communicators and science writers an analytical tool to synthesize the meaning made in the connections across communicative modes. This multimodal synthesis can help technical communicators better exploit the meaning-making potential of multimodal combinations and understand the needs of future generations shaped by their increasingly developed multimodal literacy.
Drawing to Learn Science: Legacies of Agassiz
Authors: Lerner Neal
Published: September 2007

The use of visual representation to learn science can be traced to Louis Agassiz, Harvard Professor of Zoology, in the mid-19th century. In Agassiz's approach, students were to study nature through carefully observing, drawing and then thinking about what the observations might add up to. However, implementation of Agassiz's student-centered approach has struggled with the conflict between science as a form of developing “mental discipline” in which mastery of scientific facts is the goal and science learning as a socially situated activity with an emphasis on the process of learning, not merely its products. Present-day attempts to have students draw to learn science often succumb to these same conflicts, limiting their full realization.
Amplifiers, Optical
Authors: Mukai Takaaki
Published: August 2007

An overview of optical amplifiers, which are used for direct amplification of optical signals, is presented. The article includes the physics and device performance of practical optical amplifiers, such as semiconductor optical amplifiers, rare‐earth ion‐doped fiber amplifiers, fiber Raman amplifiers and fiber Brillouin amplifiers. System applications of optical amplifiers are also reviewed.
Color Vision
Authors: Webster Michael A.
Published: August 2007

Color provides important cues to both the nature and location of objects in our environment. Normal human color vision is trichromatic because it depends on sampling the light spectrum with three classes of cone photoreceptor maximally sensitive to short, medium, or long wavelengths. Most forms of color‐blindness are genetic and result from losses or alterations of the cone photopigments. Postreceptoral neurons sum the cone signals to form luminance‐sensitive channels and contrast them to form color‐opponent channels. Color opponency is suggested by both physiology and color appearance, though higher stages of color coding in the visual system remain unclear. Perceived color is strongly affected by adaptation to colors viewed previously and by induction from surrounding colors. These processes help normalize the response to color and contribute to color constancy for objects viewed in different lighting.
Colorimetry
Authors: Stockman Andrew
Published: August 2007

Colorimetry is concerned with the measurement and numerical specification of the color of visual stimuli. Color depends on the underlying biology of the human visual system, and in the first instance on the spectral properties of the three types of light‐sensitive cone photoreceptors in the eye. Color and color matches are trichromatic, meaning they can be specified by three variables that are linearly related to the outputs of the three cone types. The primary aim of colorimetry is to be able to specify those variables for lights of any spectral composition.
Diodes, Light‐emitting
Authors: Gardner Nathan F. , George Craford M. , Steranka Frank M.
Published: August 2007

A light‐emitting diode (LED) is a semiconductor device that emits monochromatic ultraviolet, visible, or infrared electromagnetic radiation when an electric current is passed through it. The semiconductor material is a compound or alloy of elements from columns III and V of the periodic table. Light‐emitting diodes are compact, mechanically rugged, energy efficient, are of low voltage, and have long operating lifetimes. For colored lighting applications, the efficiency of LEDs far exceeds that of filtered incandescent sources and they are becoming the dominant technology. LEDs are widely used as indicator lights, for backlighting small displays in electronic equipment, in exterior and interior lighting of automobiles, in large‐area full‐color displays, and for data communication. LEDs will be used for general white‐light illumination purposes to the extent that the energy efficiency improves and higher‐power, higher‐flux devices become available.
Image Processing of Optical Data
Authors: Petrou Maria
Published: August 2007

Image processing is concerned with the processing of digital images for the purpose of image enhancement, image restoration, image compression, and feature salienation so that the processed image can be viewed by a higher‐level computer vision module. These objectives are achieved by using linear and nonlinear methods. From the mathematical point of view, a digital image is a two‐dimensional array of numbers; so the linear methods used are based on linear algebra. The nonlinear methods used are various types of thresholding as well as methods based on statistics and probability.
Laser Isotope Separation
Authors: Letokhov Vladilen , Ryabov Evgeny
Published: August 2007

This paper gives in a concise form, an idea of the principles of various laser isotope separation methods, the current status of studies in this field, and industrial applications of laser isotope separation techniques.
Laser Physics
Authors: Zayhowski John J. , Kelley Paul L.
Published: August 2007

This article concerns the physics of lasers, including population inversion, pumping processes, stimulated emission, and resonators. Important laser characteristics such as narrow spectral linewidth, high spatial collimation, and ultrashort pulses are discussed. A review is given of several types of laser media, laser dynamics, and modes of laser operation. Methods for control of laser output and practical considerations in laser design are considered. Finally, there is a discussion of nonlinear optical techniques for frequency conversion of laser radiation.
Lasers, Dye
Authors: Duarte Francisco J. , Foster David R.
Published: August 2007

Dye lasers are inherently tunable, and powerful, sources of narrow‐linewidth radiation. This means that dye lasers can change the emission color continuously while emitting radiation of extremely high spectral purity. In addition, these tunable lasers can be configured to yield extremely short pulses in the femtosecond regime. As such, dye lasers have found a wide variety of applications in fundamental physics, spectroscopy, medicine, and the military. In this article, basic aspects of dye‐laser operation are examined and explained. These include a discussion of the excitation process, via classical rate equations, the origin of tunability, and the theory of dispersion that explains the achievement of very narrow laser linewidths. Although most of the article deals with traditional liquid dye lasers, a section is devoted to newly developed solid‐state dye lasers. Important applications, such as laser isotope separation and laser cooling are also discussed.
Lasers, Free‐electron
Authors: Pellegrini Claudio , Reiche Sven
Published: August 2007

Free‐electron lasers are radiation sources, based on the coherent emission of synchrotron radiation of relativistic electrons within an undulator or wiggler. The resonant radiation wavelength depends on the electron beam energy and can be tuned over the entire spectrum from micrometer to X‐ray radiation. The emission level of free‐electron lasers is several orders of magnitude larger than the emission level of spontaneous synchrotron radiation, because the interaction between the electron beam and the radiation field modulates the beam current with the periodicity of the resonant radiation wavelength. The high brightness and the spectral range of this kind of radiation source allows studying physical and chemical processes on a femtosecond scale with angstrom resolution.
Lasers, Gas
Authors: Eden J. Gary , Eichler Jürgen
Published: August 2007

This article reviews the characteristics of gas lasers that are chiefly responsible for their effectiveness as both scientific and industrial tool. The basic principles common to operation of all gas lasers and a few of their general properties are discussed. The lasers are categorized according to the pumping mechanisms: electron‐impact excitation (copper and gold laser, Ar‐ and Kr‐ion lasers), excitation transfer (He–Ne laser, He–Cd laser, CO2laser), reactive collision lasers (excimer laser (ArF, KrF, XeCl, XeF, F2), chemical lasers (HF, COIL)), and other lasers in the far infrared, ultraviolet, and soft X‐ray region. Selected applications of pulsed and continuous gas lasers are presented in material processing, marking and laser evaporation, microlithography, photochemical processing, stereolithography, and medicine.
Lasers, Solid‐state
Authors: Fan Tso Yee
Published: August 2007

An overview of solid‐state lasers, which are lasers using doped, dielectric solids as the gain media, is presented. The article includes information on the history, materials physics, technology, and application of these devices.
Lidar (Laser Radar)
Authors: Argall P. S. , Sica R. J.
Published: August 2007

Lidar is an active remote sensing technique similar in principle to radar, except that it utilizes light rather than radio waves. Lidar finds applications in many areas, including atmospheric and oceanic research, digital mapping, chemical and biological agent detection, speed measurement, and targeting. This chapter describes the principles of lidar and provides examples of the application of lidar in measuring the properties of the Earth's atmosphere.
Luminescence
Authors: Hofmann Detlev M. , Böhm Manfred
Published: August 2007

The article gives an introduction to the widespread phenomenon of light emission from matter under the aspect of the most common stimulation sources, that is, the use of photons for photoluminescence, or electron beams for cathodoluminescence, electric fields in the case of electroluminescence, chemical energy for chemiluminescence, sound waves for sonoluminescence, or thermal energy for the stimulation of the thermoluminescence phenomena. It focuses mostly on the respective principles of the luminescence excitation, rather than an overview of the uncountable applications of the methods in all areas of science, technology, and engineering.
Microscopy
Authors: Hellmuth Thomas
Published: August 2007

Principles, methods, and applications of light microscopy, electron microscopy, and scanning probe microscopy are described and complemented by related techniques such as ultrasound microscopy, field‐emission microscopy and X‐ray microscopy. Advanced methods such as Raman microscopy, low‐energy electron microscopy, and scanning near‐field microscopy representing new trends in the field of microscopy are discussed.
Modulators and Demodulators, Optical
Authors: LiKamWa Patrick , Yao Shi‐Kay , Young Eddie H.
Published: August 2007

Modulation is a means of adding a signal information to an energy carrier used for transmission. Demodulation is the process of extracting the signal information from the carrier. Electromagnetic waves have been used extensively as the carrier for radio and television broadcasting as well as wireless and satellite telephony and data communications. Optical waves are electromagnetic waves that are at the much higher end of the frequency spectrum compared to radio frequencies. Therefore, information can be sent at much higher rates using optical carrier waves than using radio waves. In this chapter, the application and the technology of various optical modulators are described. The various forms of modulation formats and demodulation techniques are also discussed.
Optical Aberrations
Authors: Turner Mary G.
Published: August 2007

A spherical wave front propagating through the optical system, by the time it exits the system, is often no longer perfectly spherical. The departure of any wave front that is exiting the optical system from the ideal spherical reference can be described by an aberration function. The aberration function can be expressed in the form of different polynomials. The optical system that introduces aberrations does not form a stigmatic or ideal image. The distribution of energy at the image surface for different wave front aberrations can be described by ray aberration functions. Wave and ray aberrations are closely related. This article presents the basics optical aberrations, commonly expressed in these two forms.
Optical Computing
Authors: Tanida Jun , Ichioka Yoshiki
Published: August 2007

Optical computing is an area of technology for information processing that utilizes excellent features of light. Beginning with some historical background of this technological field, the concept of optical computing is described with respect to definition, motivation, advantages, targets, and classifications. Then two major categories, analog optical computing and digital optical computing, are used to explain concrete instances of this technology. Analog optical computing includes Fourier image processing, acoustooptical signal processing, optical neural computing, and spatiotemporal information processing. Digital optical computing covers logic gates and circuit constructions, computing paradigms, optical computer architectures, and VLSI photonics. Finally, some comments on potential applications of optical computing are added to suggest effective areas for this technological field.
Optical Materials
Authors: Jellison Gerald E.
Published: August 2007

Transparent optical materials are used in a variety of applications ranging from the very common, such as corrective lenses, to the very sophisticated, such as fiber‐optic communications. As common as these applications are, optical materials possess many interesting and complicating properties, which are often ignored. For example, all optical materials absorb light in some spectral regions, and all materials experience dispersion, where the refractive index is a function of the wavelength of light. In this chapter, the basic physics of light interaction with optical materials is presented, primarily to explain many of these commonly observed phenomena. The emphasis of the chapter is on materials that are transparent in the region from the ultraviolet (down to ∼120 nm) to the mid‐infrared (up to ∼40 microns). Perturbations of the basic optical properties of materials, such as those due to external strain and electric fields, will also be discussed. The properties of several specific optical materials will be discussed with the intent of demonstrating the basic physics and not to present a comprehensive listing of optical data. Thin films (that is, films with thicknesses on the order of the wavelength of light) are also discussed with the intent of understanding the physics of these materials and how they interact with light to produce the desired affects, such as reducing or enhancing the amount of light transmitted through or reflected from an optical device.
Optical Tomography
Authors: Hillman Elizabeth M. C.
Published: August 2007

Optical tomography (OT) is an imaging technique that uses near‐infrared (NIR) and visible light to resolve the internal structure of scattering objects. OT has recently been the focus of much development as a method for imaging living tissue such as the breast and brain. By using NIR light, it is possible to investigate the hemoglobin in bloodin vivo, since hemoglobin is a strong NIR absorber compared to other tissue constituents. Using spectroscopic techniques to extract the oxygenation state of the hemoglobin in tissue can provide information about the functional state of the tissue, allowing detection of tumors, hemorrhages, and other abnormalities. This article introduces the basic concepts of medical OT, giving two detailed examples of instrumental approaches. The physics of light propagation in scattering tissue and the various techniques for tomographic image reconstruction are then detailed, followed by a review of some of the latest novel approaches to OT.
Photoemission and Photoelectron Spectra
Authors: Himpsel Franz J. , Lindau Ingolf
Published: August 2007

Applications of photoelectron spectroscopy and related techniques are reviewed. They include photoelectric yield spectroscopy, absorption spectroscopy from core levels, photoelectron spectroscopy of core‐level shifts (XPS or ESCA), angle‐resolved photoemission and inverse photoemission, EXAFS, and photoelectron diffraction. These techniques provide information about structure, bonding, and electronic states of atoms, molecules, solids, surfaces, and nanostructures. Advances in detectors and light sources, such as high‐resolution multidetection and synchrotron radiation from undulators, are breaking ground for new applications. Among those are element‐resolved microscopy and high‐resolution spectroscopy of the electronic states relevant to magnetism, superconductivity, and transport properties.
Photographic Recording
Authors: Szajewski Richard P.
Published: August 2007

Photographic recording of images encompasses the capture and storage steps of the imaging chain. Currently, both traditional silver halide films and silicon devices allow high‐quality images to be obtained. Factors influencing the sensitivity and quality performance of the imaging materials for recording images are reviewed with examples of applications to specific imaging tasks. The physical mechanisms applicable to imaging materials and design issues for films and sensor arrays involve compromises between high sensitivity and the ability to record sufficient information density for a high‐quality image. Appropriate imaging materials for holographic recording, the infrared region, and X ray are mentioned.
Speckle and Speckle Metrology
Authors: Joenathan Charles , Tiziani Hans J.
Published: August 2007

Speckles are a three‐dimensional self interference pattern formed by a large number of random coherent waves. This results in a granular structure in free space or can be observed to be superposed on the image of the object and sets a fundamental limitation in high‐resolution hologram microscopy and coherent imagery. Essentially, speckles are a randomly coded pattern that carries information about the object surface, and also has the rare distinction of being a nuisance and simultaneously a useful tool for measurement. Emergence of better measurement capabilities, newer recording media, faster computers and interfaces, and software has revitalized speckle metrology and has resulted in many fascinating new developments. Scores of books and review articles cover the myriads of applications and developments, and this chapter is intended to provide a concise and precise account of speckles starting from its infancy to the latest developments such as temporal speckle pattern interferometry or digital holography. Attractiveness of speckle methods lies in their ability to measure: large deformations, displacements with variable sensitivity to in‐plane and out‐of‐plane, displacement derivatives, shape of a three‐dimensional object, surface roughness, and dynamic displacement. Speckle techniques can nowadays be used to measure a wide range of displacement, sensitivities ranging from 0.25 µm to 150 µm for in‐plane and 0.05 to 150 µm for out‐of‐plane displacements and with shearing techniques to over a 1000 µm.
Spectrometers, Ultraviolet and Visible Light
Authors: Hardwick John L.
Published: August 2007

A wide variety of instruments exist for recording the intensity of light as a function of wavelength. In the visible and ultraviolet regions of the spectrum, these include dispersive spectrometers (based on gratings and prisms) and nondispersive spectrometers (usually interferometric in nature). A discussion of the main kinds of visible and ultraviolet spectrometers is given along with their advantages and drawbacks in terms of resolution, accuracy, efficiency, and ease of use. Considerations for choosing the design of an optical spectrometer are outlined, and the main aberrations associated with common optical designs are discussed.
Spectrometers,X‐ray
Authors: Markert Thomas H. , Förster Eckhart
Published: August 2007

X‐ray spectrometers are used in many fields of pure and applied science as well as in industry. They are employed to investigate cosmic and laboratory high‐temperature plasmas where a high spectral resolution in the emission spectra is required. Commercial X‐ray spectrometers register X‐ray fluorescence of a sample under X‐ray irradiation or electron bombardment. In this case, registration of a wide spectral range with moderate resolution is performed to obtain the elemental composition of a sample.

The main experimental parameters of a spectrometer are its resolving power, sensitivity, and breadth of spectral coverage. Dispersive spectrometers that use X‐ray crystal diffraction to widen the incident spectrum have great advantages in spectral resolution. To raise their sensitivity, different X‐ray optics such as grazing incident mirrors, polycapillaries, bent gratings, or bent crystals are implemented. Nondispersive spectrometers that convert the energy of an incident X ray into a number of “particles” (electron–hole pairs, electron–ion pairs, phonons, etc.) have a moderate spectral resolution, good sensitivity, and wide breadth of spectral coverage. Recently developed microcalorimeters need a complex cryogenic system for the detector but have a competitive spectral resolution as dispersive spectrometers.
Optical Networks
Authors: Alferness Rod C. , Kogelnik Herwig , Wood Thomas H.
Published: August 2007

With the explosion of capacity demands driven by the Internet, optical networking systems are experiencing tremendous growth and are providing increasingly high transmission capacities. As importantly, with the advent of the optical amplifier and wavelength‐division multiplexing (WDM), optics is playing a larger role in networking and is extending further to the edge of the network. Once limited to long‐haul point‐to‐point systems, the industry is now commercializing multipoint metro WDM ring systems that include software‐controlled optical wavelength add/drop multiplexers and will soon be capable of offering large optical cross connects. These optical network elements, together with network‐management software, will enable rapid provisioning of wavelength services, as well as rapid network restoration. In addition, as the cost of optics is driven down and the demand for bandwidth to businesses and residential customers continues to grow, optical systems are extending out from the network core and metro to access applications. The confluence of a proliferation of broadband service applications and rapidly maturing optical technology are literally driving optical systems into all segments. Increasingly, optics is literally everywhere.
Dendrimer‐Functionalized Iron Oxide Nanoparticles for Specific Targeting and Imaging of Cancer Cells
Authors: Wang S. H. , Shi X. , Van Antwerp M. , Cao Z. , Swanson S. D. , Bi X. , Baker J. R.
Published: August 2007

We demonstrated a unique approach that combines a layer‐by‐layer (LbL) self‐assembly method with dendrimer chemistry to functionalize Fe3O4 nanoparticles (NPs) for specific targeting and imaging of cancer cells. In this approach, positively charged Fe3O4 NPs (8.4 nm in diameter) synthesized by controlled co‐precipitation of FeII and FeIII ions were modified with a bilayer composed of polystyrene sulfonate sodium salt and folic acid (FA)‐ and fluorescein isothiocyanate (FI)‐functionalized poly(amidoamine) dendrimers of generation 5 (G5.NH2‐FI‐FA) through electrostatic LbL assembly, followed by an acetylation reaction to neutralize the remaining surface amine groups of G5 dendrimers. Combined flow cytometry, confocal microscopy, transmission electron microscopy, and magnetic resonance imaging studies show that Fe3O4/PSS/G5.NHAc‐FI‐FA NPs can specifically target cancer cells overexpressing FA receptors. The present approach to functionalizing Fe3O4 NPs opens a new avenue to fabricating various NPs for numerous biological sensing and therapeutic applications.
Photophysical Properties of a Series of Poly(ladder‐type phenylene)s
Authors: Laquai F. , Mishra A. K. , Ribas M. R. , Petrozza A. , Jacob J. , Akcelrud L. , Müllen K. , Friend R. H. , Wegner G.
Published: August 2007

The photophysical properties, i.e., the fluorescence and phosphorescence of a series of blue light‐emitting poly(ladder‐type phenylene)s have been investigated employing continuous‐wave (cw) and time‐resolved photoluminescence (PL) spectroscopy in solid state and dilute solution. The chemically well‐defined polymers vary from two to five bridged phenyl‐rings per monomer unit bearing aryl‐ or alkyl‐substitution at the bridge‐head carbon atoms. It has been found that the fluorescence energy of the polymers and of the corresponding monomers deviates from a simple 1/N dependence, if the number N of bridged‐phenylene rings is increased beyond a certain limit. Time‐resolved fluorescence spectroscopy on thin films showed that apart from the blue fluorescence of the polymers an additional lower energy emission feature exists, which cannot be assigned to keto‐defects and which seems to be an inherent solid state property of this class of materials. Delayed time‐resolved photoluminescence spectroscopy allowed the detection of phosphorescence energies and lifetimes for all investigated polymers. Photoinduced absorption spectroscopy on thin films showed that the triplet‐triplet absorption red‐shifts with increasing monomer length but reaches a constant value for polymers with N ≥ 4. Amplification of light via amplified spontaneous emission (ASE) from thin film slab waveguide structures could be demonstrated for all ladder‐type polymers but the onset threshold value for ASE varies significantly with the polymer structure.
The Electrochemical Behavior and Direct Determination of Tyrosine at a Glassy Carbon Electrode Modified with Poly (9‐Aminoacridine)
Authors: Fang Bin , Liu Hongying , Wang Guangfeng , Zhou Yunyou , Li Maoguo , Yu Yan , Zhang Wei
Published: September 2007

9‐aminoacridine was firstly immobilized on the surface of a glassy carbon electrode to form a poly (9‐aminoacridine) film modified electrode. The results demonstrated that the modified electrode exhibited a high degree of catalytic activity towards the oxidation of tyrosine and can resolve the interference of tryptophan in the determination of tyrosine. Compared with the bare electrode, the peak current had obviously increased, and the peak potential had shifted in a negative direction. Under the optimum conditions, a linear response to tyrosine was observed in the concentration of 1.0×10‐6‐2.8×10‐3 M, with a correlation coefficient of 0.9987, and a detection limit (S/N=3) of 1.0×10‐7 M. The modified electrode has been successfully applied to determine the concentration of tyrosine in composite amino acid injections; and it displays excellent repeatability and high sensitivity. The proposed sensor has promising features such as ease of fabrication, good reproducibility, high stability and low cost. And most of all, it has good selectivity.
Measurements of lower Carbonyls and Hydrocarbons at Ny‐Alesund, Svalbard
Authors: Mabilia Rosanna , Di Palo Vincenzo , Cassardo Claudio , Ciuchini Carla , Pasini Antonello , Possanzini Massimiliano
Published: September 2007

Measurements of gaseous organic compounds were carried out near Ny‐Alesund, in the Norwegian Arctic, during September 2004. Twenty alkanes, alkenes and aromatic hydrocarbons from ethane to toluene and six aldehydes and ketones from formaldehyde to butanal, were identified and quantified in air samples. Hydrocarbons showed a quite uniform distribution, with ethane being by far the most abundant component (>1 ppb), followed by propane (>0.4 ppb) and butanes (>0.3 ppb), while for unsaturated homologues, except ethene, concentrations never exceeding 0.05 ppb were observed. This distribution confirmed that hydrocarbon depletion during the transport time from Europe into the Arctic was depending upon their atmospheric lifetimes, calculated relatively to the OH reactivity scale. The presence of short lived hydrocarbons could be associated to local sources of anthropogenic and/or biogenic origin. Although the local air photochemistry played a primary role in the production of lower aldehydes in late summer, the observed mixing ratios of formaldehyde (in the 0.25 – 0.50 ppb range) could not be fully explained by known gas‐phase chemistry. In this case additional sources, such as fluxes of formaldehyde from snow pack to the atmosphere and/or local anthropogenic activities, were to be taken into consideration. The possible influences of these sources on HCHO mixing ratios were analysed by means of a backward‐trajectory circulation model.
4‐(N,N‐Diethylamino) Benzaldehyde Thiosemicarbazone in the Spectrophotometric Determination of Palladium
Authors: Parameshwara P. , Karthikeyan J. , Shetty A. Nityananda , Shetty Prakash
Published: September 2007

4‐(N,N‐diethylamino)benzaldehyde thiosemicarbazone(DEABT) is proposed as a sensitive and selective analytical reagent for the spectrophotometric determination of palladium(II). The reagent reacts with palladium (II) in a potassium hydrogen phthalate‐hydrochloric acid buffer of pH 3.0, to form a yellow complex. Beer's law is obeyed in the concentration range up to 3.60 μgmL‐1. The optimum concentration range for minimum photometric error as determined by Ringbom plot method is 0.36‐3.24 μg mL‐1. The yellow Pd(II)‐DEABT complex shows a maximum absorbance at 408 nm, with molar absorptivity of 3.33 × 104 dm3 mol‐1 cm‐1 and Sandell's sensitivity of the complex from Beer's data, for D=0.001, is 0.0032 μg cm‐2. The composition of the Pd(II)‐DEABT complex is found to be 1:2 (M:L). The interference of various cations and anions in the method were studied. The proposed method was successfully used for the determination of Pd(II) in alloys, catalysts, complexes and model mixtures with a fair degree of accuracy.
Numerical simulation of microdroplet formation in coflowing immiscible liquids
Authors: Hua Jinsong , Zhang Baili , Lou Jing
Published: August 2007

Monodisperse microdroplets can be formed when a liquid is injected via a capillary needle nozzle into another immiscible coflowing liquid in a microchannel. Such system has been applied in microfluidic devices to produce monodisperse microdroplets with controllable size. In this article, the drop formation in a coflowing system is simulated numerically using a front tracking/finite volume method to investigate the droplet formation mechanism. This numerical method solves a single set of Navier–Stokes equations for both liquid phases on a fixed Eulerian two‐dimensional cylindrical coordinate mesh to account for the fluid flow dynamics. The front tracking method is applied to track the movement of the interface between the two immiscible liquids as well as the surface tension force. The simulation results demonstrate that the process of droplet formation in the coflowing immiscible liquids can be reasonably predicted. Two droplet generation modes (namely dripping and jetting), which have been observed in experiments, are successfully produced through the numerical simulations under certain flow conditions. Moreover, the effects of the continuous phase flow speed, viscosity, and the interface tension on the droplet size are investigated. The correlation of the nondimensional droplet size (r) with the continuous phase flow parameters such as the Reynolds number (Reo), Weber number (Weo), Capillary number (Cao), and viscosity ratios (μ*) can be obtained as r ∝ Cao−1/2 Reo−1/6 for the dripping mode and as r} ∝ Cao1/3 Weo−1/2 μ*−1/2 for the jetting mode from the current simulations. © 2007 American Institute of Chemical Engineers AIChE J, 2007
Brief communication: New reconstruction of the Taung endocast
Authors: Falk Dean , Clarke Ron
Published: September 2007

Earlier reconstructions of the Taung endocast, from the juvenile type specimen for Australopithecus africanus, were achieved without benefit of the advanced computer technology that is available today and before morphological differences were identified that distinguish endocasts of Paranthropus from those of A. africanus. Here, we reconstruct and measure a relatively complete virtual endocast of Taung and provide a new cranial capacity estimate of 382 cm3 and a projected adult capacity of 406 cm3, which are smaller than previous estimates. Linear measurements and ratios were also obtained from an endocast of Sts 5 and five Paranthropus endocasts and compared with those of Taung. A number of previously unrecognized foramina, processes, and canals are identified in the bony material that adheres to the base of the Taung endocast. The newly reconstructed virtual endocast of Taung displays a number of shape features that sort it more closely with gracile than robust australopithecines, including squared‐off frontal lobes in dorsal view, and the shape of the tips of its temporal poles. The Taung endocast also shares some features with Paranthropus endocasts, while other characteristics such as small temporal lobes may be due to its juvenile status. Just how much of Taung's unique morphology is due to its juvenile status may eventually be clarified by comparing its endocast with those from other juvenile australopithecines such as the 3.3‐million‐year‐old juvenile from Dikika, Ethiopia. Am J Phys Anthropol, 2007. © 2007 Wiley‐Liss, Inc.