bluuebunny/crossref_metadata_2025 huggingface dataset:
First-principles study of high-pressure phonon dispersions of wurtzite, zinc-blende, and rocksalt AlN
Authors: Saib S. , Bouarissa N. , Rodríguez-Hernández P. , Muñoz A.
Published: January 2008

We present ab initio calculations of the phonon dispersions and density of states for wurtzite, zinc-blende, and rocksalt AlN under hydrostatic pressure using density functional perturbation theory. The calculations predict the full phonon dispersions throughout the Brillouin zone. Our results regarding zone-center modes for wurtzite and zinc-blende structures show generally good agreement with Raman measurements and previous theoretical data. For rocksalt structure, the present results are predictions. The different behavior of the lattice vibration properties under pressure in the three phases being studied here is discussed. The pressure coefficients and mode Grüneisen parameters are determined from the pressure dependence of vibration modes.
Spatially resolved photoluminescence mapping of single CdS nanosheets
Authors: Rho H. , Lee K.-Y. , Hoang T. B. , Titova L. V. , Mishra A. , Smith L. M. , Jackson H. E. , Yarrison-Rice J. M. , Choi Y.-J. , Choi K. J. , Park J.-G.
Published: January 2008

We have utilized spatially resolved low temperature photoluminescence to probe the electronic states and structural symmetries of individual single crystalline CdS nanosheets. Spatially resolved photoluminescence imaging of a single CdS nanosheet reveals a distinctive spectral variation across the nanosheet. We observe A-like exciton states which emit most strongly near the outer edges of the 5μm wide nanosheet, while B-like exciton states emit most strongly along the center region of the 30μm long axis of the nanosheet.
Extraction enhancement in organic light emitting devices by using metallic nanowire arrays
Authors: Hsu Shen-Yu , Lee Ming-Chang , Lee Kuang-Li , Wei Pei-Kuen
Published: January 2008

The extraction efficiency of organic light emitting devices is enhanced by depositing metallic nanowires on the glass surface and indium tin oxide (ITO) anode. For the aluminum tris-(8-hydroxyquinoline) (Alq3) based devices, a 100nm-width and 450nm-period gold nanowire array increases light extraction up to 46% from glass substrate and 80% from the organic layer. Such metallic nanowire arrays double the brightness with small absorption, only 10% lower than ITO glass. In addition, colors of the devices can be selected by the period of nanowire array. We demonstrated blue to red light emission by using single Alq3-based device.
Enhanced dielectric response of ZrO2 upon Ti doping and introduction of O vacancies
Authors: Dutta Gargi , Hembram K. P. S. S. , Rao G. Mohan , Waghmare Umesh V.
Published: January 2008

We determine the electronic properties and dielectric response of zirconia (ZrO2) with oxygen vacancies (O vacancies) and Ti doping using first-principles density functional theory calculations based on pseudopotentials and a plane wave basis. We find significantly enhanced static dielectric response in zirconia with Ti doping and introduction of oxygen vacancies. Softening of phonon modes are responsible for the enhanced dielectric response of doped samples compared to pure zirconia.
Near infrared quantum cascade detector in GaN∕AlGaN∕AlN heterostructures
Authors: Vardi A. , Bahir G. , Guillot F. , Bougerol C. , Monroy E. , Schacham S. E. , Tchernycheva M. , Julien F. H.
Published: January 2008

A quantum cascade detector in the GaN/AlGaN/AlN material system was implemented. The design takes advantage of the large internal field existing in the nitrides in order to generate the essential saw tooth energy level structure. The device operates in the near IR spectral range with a room temperature responsivity at λ=1.7μm of 10mA∕W (1000V∕W) at zero bias. The spectroscopic measurements are in good agreement with simulations.
High pressure phase transitions and compressibilities of Er2Zr2O7 and Ho2Zr2O7
Authors: Zhang F. X. , Lang M. , Becker U. , Ewing R. C. , Lian J.
Published: January 2008

Phase stability and compressibility of rare earth zirconates with the defect-fluorite structure were investigated by in situ synchrotron x-ray diffraction. A sluggish defect-fluorite to a cotunnitelike phase transformation occurred at pressures of ∼22 and ∼30GPa for Er2Zr2O7 and Ho2Zr2O7, respectively. Enhanced compressibility was found for the high pressure phase as a result of increasing cation coordination number and cation-anion bond length.
Cascade single-chip phosphor-free white light-emitting diodes
Authors: Guo X. , Shen G. D. , Guan B. L. , Gu X. L. , Wu D. , Li Y. B.
Published: January 2008

In order to resolve the problems existing in the conventional phosphor-converted light-emitting-diodes (LEDs) and red-green-blue LEDs, the cascade single-chip phosphor-free white LED was proposed with GaAs∕GaN heterojunction direct wafer bonding. Corresponding to the color-matching calculation, the white LED demonstrated the CIE chromaticity coordinates of about (0.3, 0.3) at 20mA, which was very close to the ideal white light position (1∕3, 1∕3) on the chromaticity diagram. The fabrication and the electrical and optical performances of such white LEDs were described.
Personal Memories of Pauli
Authors: Weisskopf Victor F.
Published: January 2008

We older disciples of the great Wolfgang Pauli remember with pleasure and nostalgia the prewar years when we had the privilege to work with him. It was one of the most interesting, stimulating and productive periods in physics. At the same time, however, Europe saw events that were among the most terrible and depraved actions of man against man. The coincidence in the history of humankind of the greatest achievements and the worst evils has always impressed and depressed me deeply. As Dickens said: “It was the best of times, it was the worst of times.”
The Physics of Dance
Authors: Laws Kenneth
Published: January 2008

Most dance enthusiasts—dancers, teachers and spectators—consider dance to be a purely aesthetic performing art, involving human body movement performed to music. They recognize that the challenge for the dancer is to communicate the visual images intended by the choreographer and the dancer. Many also realize that part of the enjoyment of dance depends on recognizing the difficulty of performing these movements well—making physically challenging steps appear smooth and graceful. Few, however, take the further step of analyzing the physics of these movements to understand the difficulties facing the performer. Why are certain movements particularly difficult? Some movements appear to violate fundamental physical principles. How does a dancer create such illusions? How do dancers use physical principles of motion to their advantage, rather than fight against them?
Wallace Clement Sabine and Acoustics
Authors: Beranek Leo L.
Published: January 2008

Wallace Clement Sabine was the world's first and most celebrated acoustical scientist. He received his graduate training in the physics department at Harvard University and remained on Harvard's faculty until his death, in 1919. His reputation is based not only on his contributions to acoustics, but also on his teaching and administrative contributions to the physics curricula at Harvard and his services to the US during World War I.
Ultra-High-Current Electron Induction Accelerators
Authors: Kapetanakos Chris A. , Sprangle Phillip
Published: January 2008

To probe deeper into the subnuclear structure of matter, physicists over the last 50 years have developed a remarkably sophisticated technology of high-energy accelerators. By design, these accelerators have operated at relatively low currents, primarily to avoid complications due to electric fields generated by the charged-particle beams themselves. Machines such as the linear accelerator at Stanford University (SLAC) produce electron beams with energies as high as 32 GeV and peak currents of about 120 milliamps. Although of fairly low current, these devices have proven extremely successful in high-energy physics experiments, where one can irradiate a target over an extended period of time to get a statistically significant number of collisional events.
Opportunities in Physics and Major Research Facilities
Authors: Hebel L. Charles
Published: January 2008

Few human endeavors have been as fruitful—intellectually, technologically and culturally—as the study of physics. Recent discoveries and future prospects are the subjects of two current evaluations. The 1984 Research Briefing on Selected Opportunities in Physics (PHYSICS TODAY, January, page 20) has been prepared by a panel headed by Hans Frauenfelder and Mildred Dresselhaus for the Office of Science and Technology Policy and the National Science Foundation. Also, the Physics Survey Committee, headed by William Brinkman, is completing its report for the National Research Council. As observed in the 1984 Research Briefing:
Neutron Scattering from Polymers
Authors: Stein Richard S. , Han Charles C.
Published: January 2008

Some years ago, one of our mentors expressed the desire to “color polymer molecules red” so that one could follow them in a solid and see how they arrange themselves and how they move among similar or different molecules. As we will see in this article, the excitement today over the application of small-angle neutron scattering to the study of polymers lies in the possibility of fulfilling his wish to understand the conformation and dynamics of polymer molecules.
Bohr's First Theories of the Atom
Authors: Heilbron John L.
Published: January 2008

When confronted with a case in which an accepted theory appears to fail, the physicist, like anyone else, has a choice of strategies. The most obvious, which is also that recommended by armchair methodologists, is to invent an entirely new theory; an example might be Johannes Kepler's system of planetary motions. The most likely strategy, because it involves the least reconstruction, is to seek the slightest departure from received ideas that will save the phenomena; an example is John Couch Adams's supposition of the existence of a distant planet to account for irregularities in the motions of Uranus. In both of the examples the strategies worked: Kepler's system, transformed by Newton, became the basis of the world of classical physics; Adams's calculations, and those of his French contemporary Urbain J. J. Leverrier, led to the discovery of Neptune.
Niels Bohr as Fund Raiser
Authors: Aaserud Finn
Published: January 2008

Nuclear physics came of age as a discipline in the 1930s. In 1932, the “miraculous year” of nuclear physics, physicists discovered two new particles, the neutron and the positron, developed revolutionary particle-accelerator equipment and split nuclei for the first time by manmade machines. The study of the nucleus soon developed into an independent field, becoming the central area of research in theoretical physics. During the mid-1930s, Niels Bohr's Institute for Theoretical Physics at the University of Copenhagen experienced a successful transition to the new field of investigation, consolidating its position as an international Mecca for theoretical physics research. In early 1936 Bohr proposed his revolutionary compound-nucleus model, and in late 1938 the Bohr institute's cyclotron, a major device for provoking nuclear reactions, was the first such apparatus to go into operation in Europe. Since then, Bohr's institute has been an international leader in theoretical nuclear physics research.
Functional deficit of T regulatory cells in Fulani, an ethnic group with low susceptibility to
Plasmodium falciparum
malaria
Authors: Torcia Maria G. , Santarlasci Veronica , Cosmi Lorenzo , Clemente AnnMaria , Maggi Laura , Mangano Valentina D. , Verra Federica , Bancone Germana , Nebie Issa , Sirima Bienvenu Sodiomon , Liotta Francesco , Frosali Francesca , Angeli Roberta , Severini Carlo , Sannella Anna R. , Bonini Paolo , Lucibello Maria , Maggi Enrico , Garaci Enrico , Coluzzi Mario , Cozzolino Federico , Annunziato Francesco , Romagnani Sergio , Modiano David
Published: January 2008

Previous interethnic comparative studies on the susceptibility to malaria performed in West Africa showed that Fulani are more resistant to
Plasmodium falciparum
malaria than are sympatric ethnic groups. This lower susceptibility is not associated to classic malaria-resistance genes, and the analysis of the immune response to
P. falciparum
sporozoite and blood stage antigens, as well as non-malaria antigens, revealed higher immune reactivity in Fulani. In the present study we compared the expression profile of a panel of genes involved in immune response in peripheral blood mononuclear cells (PBMC) from Fulani and sympatric Mossi from Burkina Faso. An increased expression of T helper 1 (TH1)-related genes (IL-18, IFNγ, and TBX21) and TH2-related genes (IL-4 and GATA3) and a reduced expression of genes distinctive of T regulatory activity (CTLA4 and FOXP3) were observed in Fulani. Microarray analysis on RNA from CD4
+
CD25
+
(T regulatory) cells, performed with a panel of cDNA probes specific for 96 genes involved in immune modulation, indicated obvious differences between the two ethnic groups with 23% of genes, including TGFβ, TGFβRs, CTLA4, and FOXP3, less expressed in Fulani compared with Mossi and European donors not exposed to malaria. As further indications of a low T regulatory cell activity, Fulani showed lower serum levels of TGFβ and higher concentrations of the proinflammatory chemokines CXCL10 and CCL22 compared with Mossi; moreover, the proliferative response of Fulani to malaria antigens was not affected by the depletion of CD25
+
regulatory cells whereas that of Mossi was significantly increased. The results suggest that the higher resistance to malaria of the Fulani could derive from a functional deficit of T regulatory cells.
‘Communication is everything I think.’ Parenting a child who needs Augmentative and Alternative Communication (AAC)
Authors: Marshall Julie , Goldbart Juliet
Published: January 2008

Background: Anecdotal and research evidence suggests that professionals may not fully understand the perspectives of families of children who need or use Augmentative and Alternative Communication (AAC). This may impact on the provision of appropriate services.

Aims: The aim was to explore the lived experience of parents of children in Britain who used AAC, with particular emphasis on the ways in which children's need for and use of AAC impacts on family life and communication.

Methods & Procedures: The parents/carers of 11 children aged 3–10 years, who lived in Britain and who were in the early stages of using AAC, were recruited to take part in the study. Individual semi‐structured interviews were carried out in order to access rich descriptions of parents' experiences and views about having children who need to use AAC. The interviews were recorded, transcribed verbatim and analysed thematically to generate thematic networks.

Outcomes & Results: Analysis revealed three thematic networks. The three Global Themes represented by the networks were concerned with the following areas: the child's communication and interaction; wider societal issues; and parents' views and experiences. Each Global Theme contained lower order Organizational Themes and these in turn were comprised of Basic Themes. Parents shared many common concerns, but the data also revealed some diversity of views. The themes and sub‐themes are described with illustrative and representative quotes.

Conclusions: These parents are experts on their children and may also be experts on AAC. Many factors impact on parents and the level and type of involvement they have with their children and their upbringing. Speech and language therapists need to acknowledge parents' knowledge and expertise regarding their children. They need to recognize that there are parent, child, family and external factors which impact on parents' ability and willingness to be involved in speech and language therapist provision, and that these factors are not static over time. The use of ethnographic interviewing techniques should be considered a valuable aspect of speech and language therapist intervention.
Adjacent positioning of cellular structures enabled by a Cdc42 GTPase-activating protein–mediated zone of inhibition
Authors: Tong Zongtian , Gao Xiang-Dong , Howell Audrey S. , Bose Indrani , Lew Daniel J. , Bi Erfei
Published: December 2007

Cells of the budding yeast Saccharomyces cerevisiae are born carrying localized transmembrane landmark proteins that guide the subsequent establishment of a polarity axis and hence polarized growth to form a bud in the next cell cycle. In haploid cells, the relevant landmark proteins are concentrated at the site of the preceding cell division, to which they recruit Cdc24, the guanine nucleotide exchange factor for the conserved polarity regulator Cdc42. However, instead of polarizing at the division site, the new polarity axis is directed next to but not overlapping that site. Here, we show that the Cdc42 guanosine triphosphatase–activating protein (GAP) Rga1 establishes an exclusion zone at the division site that blocks subsequent polarization within that site. In the absence of localized Rga1 GAP activity, new buds do in fact form within the old division site. Thus, Cdc42 activators and GAPs establish concentric zones of action such that polarization is directed to occur adjacent to but not within the previous cell division site.
Random Drift and the Omniscient Viewpoint
Authors: Millstein Roberta L.
Published: January 2008

Alexander Rosenberg (1994) claims that the omniscient viewpoint of the evolutionary process would have no need for the concept of random drift. However, his argument fails to take into account all of the processes which are considered to be instances of random drift. A consideration of these processes shows that random drift is not eliminable even given a position of omniscience. Furthermore, Rosenberg must take these processes into account in order to support his claims that evolution is deterministic and that evolutionary biology is an instrumental science.
Heroic Antireductionism and Genetics: A Tale of One Science
Authors: Vance Russell E.
Published: January 2008

In this paper I provide a novel argument against the claim that classical genetics is being reduced to molecular genetics. Specifically, I demonstrate that reductionists must subscribe to the unargued and problematic thesis that molecular genetics is ‘independent’ of classical genetics. I also argue that several standard antireductionist positions can be faulted for unnecessarily conceding the Independence Thesis to the reductionists. In place of a ‘tale of two sciences’, I offer a ‘heroic’ stance that denies classical genetics is being reduced, yet sees classical and molecular genetics as fundamentally unified.
Gauge Invariance, Cauchy Problem, Indeterminism, and Symmetry Breaking
Authors: Liu Chuang
Published: January 2008

The concepts in the title refer to properties of physical theories (which are given, in this paper, a model-theoretic formulation and appropriate idealizations) and this paper investigates their nature and relations. The first three concepts, especially gauge invariance and indeterminism, have been widely discussed in connection to spacetime theories and the hole argument. Since the gauge invariance principle is at the crux of the issue, this paper aims at clarifying the nature of gauge invariance (either in general or as general covariance). I first explore the following chain of relations: gauge invariance => the conservation laws => the Cauchy problem => indeterminism. Then I discuss gauge invariance in light of our understanding of the above relations and the possibility of spontaneous symmetry breaking.
Understanding Bias in Scientific Practice
Authors: Shaffer Nancy E.
Published: January 2008

Methodological objectivism is a conception of bias which obscures the contingent and limited nature of methodological principles behind the guise of fixed a priori standards. I suggest as an alternative a more flexible view of the operation of bias which I call the attribution model. The attribution model makes explicit the working principles of both parties to an actual charge of bias. It enables those involved to identify the issues in dispute between them, and is the basis for an approach to handling charges of bias within the process of discussion and negotiation which characterizes normal scientific decision-making.
Points East and West: Acupuncture and Comparative Philosophy of Science
Authors: Allchin Douglas
Published: January 2008

Acupuncture, the traditional Chinese practice of needling to alleviate pain, offers a striking case where scientific accounts in two cultures, East and West, diverge sharply. Yet the Chinese comfortably embrace the apparent ontological incommensurability. Their pragmatic posture resonates with the New Experimentalism in the West—but with some provocative differences. The development of acupuncture in China (and not in the West) further suggests general research strategies in the context of discovery. My analysis also exemplifies how one might fruitfully pursue a comparative philosophy of science that explores how other cultures investigate and validate their conclusions about the natural world.
Evidence and Association: Epistemic Confusion in Toxic Tort Law
Authors: Parascandola Mark
Published: January 2008

Attempts at quantification turn up in many areas within the modern courtroom, but nowhere more than in the realm of toxic tort law. Evidence, in these cases, is routinely presented in statistical form. The vagueness inherent in phrases such as ‘balance of probabilities’ and ‘more likely than not’ is reinterpreted to correspond to precise mathematical values. Standing alone these developments would not be a cause for great concern. But in practice courts and commentators have routinely mixed up incompatible quantities, leading to grave injustice. I argue that these confusions result from an unjustified assumption of universal causal determinism.
Completeness and Indeterministic Causation
Authors: Devito Scott
Published: January 2008

In The Chances of Explanation, Paul Humphreys presents a metaphysical analysis of causation. In this paper, I argue that this analysis is flawed. Humphreys' model of Causality incorporates three completeness requirements. I show that these completeness requirements, when applied in the world, force us to take causally irrelevant factors to be causally relevant. On this basis, I argue that Humphreys' analysis should be rejected.
Mental Models in Data Interpretation
Authors: Chinn Clark A. , Brewer William F.
Published: January 2008

This paper presents a cognitive account of the process of evaluating scientific data. Our account assumes that when individuals evaluate data, they construct a mental model of a data-interpretation package, in which the data and theoretical interpretations of the data are integrated. We propose that individuals attempt to discount data by seeking alternative explanations for events within the mental model; data-interpretation packages are accepted when the individual cannot find alternative accounts for these events. Our analysis indicates that there are many levels at which data-interpretation packages can be accepted or denied.
When Several Bayesians Agree that There will be no Reasoning to a Foregone Conclusion
Authors: Kadane Joseph B. , Schervish Mark J. , Seidenfeld Teddy
Published: January 2008

When can a Bayesian investigator select an hypothesis H and design an experiment (or a sequence of experiments) to make certain that, given the experimental outcome(s), the posterior probability of H will be lower than its prior probability? We report an elementary result which establishes sufficient conditions under which this reasoning to a foregone conclusion cannot occur. Through an example, we discuss how this result extends to the perspective of an onlooker who agrees with the investigator about the statistical model for the data but who holds a different prior probability for the statistical parameters of that model. We consider, specifically, one-sided and two-sided statistical hypotheses involving i.i.d. Normal data with conjugate priors. In a concluding section, using an “improper” prior, we illustrate how the preceding results depend upon the assumption that probability is countably additive.
Antirealist Explanations of the Success of Science
Authors: Kukla Andre
Published: January 2008

Scientific realists have argued that the truth(likeness) of our theories provides the only explanation for the success of science. I consider alternative explanations proposed by antirealists. I endorse Leplin’s contention that neither van Fraassen’s Darwinist explanation nor Laudan’s methodological explanation provides the sort of explanatory alternative which is called for in this debate. Fine’s suggestion— that the empirical adequacy of our theories already explains their success—is more promising for antirealists. Leplin claims that this putative explanation collapses into realism on one reading and into vacuity on another reading. But his analysis conflates three doctrines into two, and one of the three avoids both realism and vacuity.
Scientific Realism and the ‘Pessimistic Induction’
Authors: Psillos Stathis
Published: January 2008

Over the last two decades, the debate over scientific realism has been dominated by two arguments that pull in contrary directions: the ‘no miracle’ argument and the ‘pessimistic induction’. The latter suggests that the historical record destroys the realist’s belief in an explanatory connection between truthlikeness and genuine empirical success. This paper analyzes the structure of the ‘pessimistic induction’, presents a move—the divide et impera move—that neutralizes it, and motivates a substantive yet realistic version of scientific realism. This move is also compared with Worrall’s and Kitcher’s recent reactions to the ‘pessimistic induction’.
Ontic Realism and Scientific Explanation
Authors: Bradie Michael
Published: January 2008

Wesley Salmon defends an ontic realism that distinguishes explanatory from descriptive knowledge. Explanatory knowledge makes appeals to (unobservable) theoretical acausal mechanisms. Salmon presents an argument designed both to legitimize attributing truth values to theoretical claims and to justify treating theoretical claims as descriptions. The argument succeeds but only at the price of calling the distinction between explanation and description into question. Even if Salmon’s attempts to distinguish causal mechanisms from other mechanisms are successful, the assumed centrality of the appeal to such mechanisms in providing scientific explanations is left open by Salmon’s account.
Possible Worlds in the Modal Interpretation
Authors: Hemmo Meir
Published: January 2008

An outline for a modal interpretation in terms of possible worlds is presented. The so-called Schmidt histories are taken to correspond to the physically possible worlds. The decoherence function defined in the histories formulation of quantum theory is taken to prescribe a non-classical probability measure over the set of the possible worlds. This is shown to yield dynamics in the form of transition probabilities for occurrent events in each world. The role of the consistency condition is discussed.
Publisher's Announcement
Authors: McGlashan Yasmin
Published: January 2008

Article numbering

Nuclear Fusion has moved from sequential page numbering to an article numbering system, offering important advantages and flexibility by speeding up the publication process. Papers in different issues or sections can be published online as soon as they are ready, without having to wait for a whole issue or section to be allocated page numbers.

The bibliographic citation will change slightly. Articles should be referenced using the six-digit article number in place of a page number, and this number must include any leading zeros. For instance, from this issue:

Li G.Q. et al 2008 Nucl. Fusion
48 015001

Articles will continue to be published on the web in advance of the print edition.
The interaction between plasma rotation, stochastic fields and tearing mode excitation by external perturbation fields
Authors: De Bock M.F.M. , Classen I.G.J. , Busch C. , Jaspers R.J.E. , Koslowski H.R. , Unterberg B.
Published: January 2008

For fusion reactors, based on the principle of magnetic confinement, it is important to avoid so-called magnetic islands or tearing modes. They reduce confinement and can be the cause of major disruptions. One class of magnetic islands is that of the perturbation field driven modes. This perturbation field can, for example, be the intrinsic error field. Theoretical work predicts a strong relationship between plasma rotation and the excitation of perturbation field modes.

Experimentally, the theory on mode excitation and plasma rotation has been confirmed on several tokamaks. In those experiments, however, the control over the plasma rotation velocity and direction, and over the externally applied perturbation field was limited. In this paper experiments are presented that were carried out at the TEXTOR tokamak. Two tangential neutral beam injectors and a set of helical perturbation coils, called the dynamic ergodic divertor (DED), provide control over both the plasma rotation and the external perturbation field in TEXTOR. This made it possible to set up a series of experiments to test the theory on mode excitation and plasma rotation in detail.

The perturbation field induced by the DED not only excites magnetic islands, it also sets up a layer near the plasma boundary where the magnetic field is stochastic. It will be shown that this stochastic field alters both the rotational response of the plasma on the perturbation field and the threshold for mode excitation. It therefore has to be included in an extended theory on mode excitation.
The role of spectral modulation cues in virtual sound localization
Authors: Qian Jinyu , Eddins David A.
Published: January 2008

Sound localization cues generally include interaural time difference, interaural intensity difference, and spectral cues. The purpose of this study is to investigate the important spectral cues involved in so-called head related transfer functions (HRTFs) using a combination of HRTF analyses and a virtual sound localization (VSL) experiment. Previous psychoacoustical and physiological studies have both suggested the existence of spectral modulation frequency (SMF) channels for analyzing spectral information (e.g., the spectral cues coded in HRTFs). SMFs are in a domain related to the Fourier transform of HRTFs. The relationship between various SMF regions and sound localization was tested here by filtering or enhancing HRTFs in the SMF domain under a series of conditions using a VSL experiment. Present results revealed that azimuth localization was not significantly affected by HRTF manipulation. Applying notch filters between 0.1 and 0.4cycles∕octave or between 0.35 and 0.65cycles∕octave resulted in significantly less accurate elevation responses at low elevations, while spectral enhancement in these two SMF regions did not produce a significant change in sound localization. Likewise, low-pass filtering at 2cycles∕octave did not significantly influence localization accuracy, suggesting that the major cues for sound localization are in the SMF region below 2cycles∕octave.
Three registers in an untrained female singer analyzed by videokymography, strobolaryngoscopy and sound spectrography
Authors: Švec Jan G. , Sundberg Johan , Hertegård Stellan
Published: January 2008

There has been a lack of objective data on the singing voice registers, particularly on the so called “whistle” register, occurring in the top part of the female pitch range, which is accessible only to some singers. This study offers unique strobolaryngoscopic and high-speed (7812.5images∕s) videokymographic data on the vocal fold behavior of an untrained female singer capable of producing three distinct voice qualities, i.e., the chest, head and whistle registers. The sound was documented spectrographically. The transition from chest to head register, accompanied by pitch jumps, occurred around tones B4–C#5 (500–550Hz) and was found to be associated with a slight decrease in arytenoids adduction, resulting in decrease of the closed quotient. The register shifts from head to whistle, also accompanied by pitch jumps, occurred around tones E5-B5 (670–1000Hz) without any noticeable changes in arytenoids adduction. Some evidence was found for the vocal tract influence on this transition. The mechanism of the vocal fold vibration in whistle register was found principally similar to that at lower registers: vibrations along the whole glottal length and vertical phase differences (indicated by sharp lateral peaks in videokymography) were seen on the vocal folds up to the highest tone G6 (1590Hz).
Training English listeners to perceive phonemic length contrasts in Japanese
Authors: Tajima Keiichi , Kato Hiroaki , Rothwell Amanda , Akahane-Yamada Reiko , Munhall Kevin G.
Published: January 2008

The present study investigated the extent to which native English listeners’ perception of Japanese length contrasts can be modified with perceptual training, and how their performance is affected by factors that influence segment duration, which is a primary correlate of Japanese length contrasts. Listeners were trained in a minimal-pair identification paradigm with feedback, using isolated words contrasting in vowel length, produced at a normal speaking rate. Experiment 1 tested listeners using stimuli varying in speaking rate, presentation context (in isolation versus embedded in carrier sentences), and type of length contrast. Experiment 2 examined whether performance varied by the position of the contrast within the word, and by whether the test talkers were professionally trained or not. Results did not show that trained listeners improved overall performance to a greater extent than untrained control participants. Training improved perception of trained contrast types, generalized to nonprofessional talkers’ productions, and improved performance in difficult within-word positions. However, training did not enable listeners to cope with speaking rate variation, and did not generalize to untrained contrast types. These results suggest that perceptual training improves non-native listeners’ perception of Japanese length contrasts only to a limited extent.
Speech recognition with varying numbers and types of competing talkers by normal-hearing, cochlear-implant, and implant simulation subjects
Authors: Cullington Helen E. , Zeng Fan-Gang
Published: January 2008

Cochlear-implant users perform far below normal-hearing subjects in background noise. Speech recognition with varying numbers of competing female, male, and child talkers was evaluated in normal-hearing subjects, cochlear-implant users, and normal-hearing subjects utilizing an eight-channel sine-carrier cochlear-implant simulation. Target sentences were spoken by a male. Normal-hearing subjects obtained considerably better speech reception thresholds than cochlear-implant subjects; the largest discrepancy was 24dB with a female masker. Evaluation of one implant subject with normal hearing in the contralateral ear suggested that this difference is not caused by age-related disparities between the subject groups. Normal-hearing subjects showed a significant advantage with fewer competing talkers, obtaining release from masking with up to three talker maskers. Cochlear-implant and simulation subjects showed little such effect, although there was a substantial difference between the implant and simulation results with talker maskers. All three groups benefited from a voice pitch difference between target and masker, with the female talker providing significantly less masking than the male. Child talkers produced more masking than expected, given their fundamental frequency, syllabic rate, and temporal modulation characteristics. Neither a simulation nor testing in steady-state noise predicts the difficulties cochlear-implant users experience in real-life noisy situations.
Supporting evidence for reverse cochlear traveling waves
Authors: Dong W. , Olson E. S.
Published: January 2008

As a result of the cochlea’s nonlinear mechanics, stimulation by two tones results in the generation of distortion products (DPs) at frequencies flanking the primary tones. DPs are measurable in the ear canal as oto-acoustic emissions, and are used to noninvasively explore cochlear mechanics and diagnose hearing loss. Theories of DP emissions generally include both forward and reverse cochlear traveling waves. However, a recent experiment failed to detect the reverse-traveling wave and concluded that the dominant emission path was directly through the fluid as a compression pressure [Ren, 2004, Nat. Neurosc.7, 333–334]. To explore this further, we measured intracochlear DPs simultaneously with emissions over a wide frequency range, both close to and remote from the basilar membrane. Our results support the existence of the reverse-traveling wave: (1) They show spatial variation in DPs that is at odds with a compression pressure. (2) Although they confirm a forward-traveling character of intraocochlear DPs in a broad frequency region of the best frequency, this behavior does not refute the existence of reverse-traveling waves. (3) Finally, the results show that, in cases in which it can be expected, the DP emission is delayed relative to the DP in a way that supports reverse-traveling-wave theory.
Structural health monitoring by extraction of coherent guided waves from diffuse fields
Authors: Sabra Karim G. , Srivastava Ankit , Lanza di Scalea Francesco , Bartoli Ivan , Rizzo Piervincenzo , Conti Stephane
Published: January 2008

Recent theoretical and experimental studies in a wide range of applications have demonstrated that Green’s functions (impulse responses) can be extracted from cross-correlation of diffuse fields using only passive sensors. This letter demonstrates the passive-only reconstruction of coherent Lamb waves (dc–500kHz) in an aluminum plate of thickness comparable to aircraft fuselage and wing panels. It is further shown that the passively reconstructed waves are sensitive to the presence of damage in the plate as it would be expected in a typical “active” guided wave test. This proof-of-principle study suggests the potential for a structural health monitoring method for aircraft panels based on passive ultrasound imaging reconstructed from diffuse fields.
Characterization of a Conserved Rhoptry-Associated Leucine Zipper-Like Protein in the Malaria Parasite
Plasmodium falciparum
Authors: Haase Silvia , Cabrera Ana , Langer Christine , Treeck Moritz , Struck Nicole , Herrmann Susann , Jansen Pascal W. , Bruchhaus Iris , Bachmann Anna , Dias Suzana , Cowman Alan F. , Stunnenberg Hendrik G. , Spielmann Tobias , Gilberger Tim-Wolf
Published: January 2008

One of the key processes in the pathobiology of the malaria parasite is the invasion and subsequent modification of the human erythrocyte. In this complex process, an unknown number of parasite proteins are involved, some of which are leading vaccine candidates. The majority of the proteins that play pivotal roles in invasion are either stored in the apical secretory organelles or located on the surface of the merozoite, the invasive stage of the parasite. Using transcriptional and structural features of these known proteins, we performed a genomewide search that identified 49 hypothetical proteins with a high probability of being located on the surface of the merozoite or in the secretory organelles. Of these candidates, we characterized a novel leucine zipper-like protein in
Plasmodium falciparum
that is conserved in
Plasmodium
spp. This protein is expressed in late blood stages and localizes to the rhoptries of the parasite. We demonstrate that this
Plasmodium
sp.-specific protein has a high degree of conservation within field isolates and that it is refractory to gene knockout attempts and thus might play an important role in invasion.
Reactive Nitrogen Species Contribute to Innate Host Defense againstCampylobacter jejuni
Authors: Iovine Nicole M. , Pursnani Seema , Voldman Alex , Wasserman Gregory , Blaser Martin J. , Weinrauch Yvette
Published: January 2008

Campylobacter jejuni, a gram-negative, invasive organism, is a common cause of food-borne bacterial diarrheal disease. However, the relationship betweenC. jejuniand the innate immune system is not well described. To better characterize host defense againstC. jejuni, we investigated the ability of nitric oxide/reactive nitrogen species to kill two strains ofC. jejuni. C. jejuniviability was measured after exposure to reactive nitrogen species produced biochemically as acidified nitrite and by bone marrow-derived macrophages. We report that acidified nitrite caused a 3-log-increased kill ofC. jejuni(P< 0.05) at doses that did not affect the viability ofSalmonella entericaserovar Typhimurium. Expression ofNOS2, the gene responsible for the production of inducible nitric oxide, was increased >100-fold in murine macrophages after incubation withC. jejuni(P< 0.001). These macrophages effected a 2-log-increased kill ofC. jejuniover 24 h compared to that by NOS2−/−macrophages unable to produce nitric oxide (P< 0.05). These findings suggest that the mammalian host upregulates the production of nitric oxide in response to exposure toC. jejuniand that nitric oxide and reactive nitrogen species comprise part of the innate defense mechanisms that contribute to the resolution ofC. jejuniinfection.
Genotyping of
Chlamydia trachomatis
by Microsphere Suspension Array
Authors: Huang Chung-Ter , Wong Wing-Wai , Li Lan-Hui , Chiang Chien-Chou , Chen Bor-Dong , Li Shu-Ying
Published: January 2008

The identification of
Chlamydia trachomatis
genotypes is important for both the study of molecular epidemiology and infection control. We have developed a microsphere suspension array assay that can identify
C. trachomatis
genotypes rapidly and accurately and also discriminate among multiple genotypes in one clinical specimen.
PHENOSITE: A WEB DATABASE INTEGRATING THE MOUSE PHENOTYPING PLATFORM AND THE EXPERIMENTAL PROCEDURES IN MICE
Authors: MASUYA HIROSHI , YOSHIKAWA SUMI , HEIDA NAOHIKO , TOYODA TETSURO , WAKANA SHIGEHARU , SHIROISHI TOSHIHIKO
Published: December 2007

Recently, a number of collaborative large-scale mouse mutagenesis programs have been launched. These programs aim for a better understanding of the roles of all individual coding genes and the biological systems in which these genes participate. In international efforts to share phenotypic data among facilities/institutes, it is desirable to integrate information obtained from different phenotypic platforms reliably. Since the definitions of specific phenotypes often depend on a tacit understanding of concepts that tends to vary among different facilities, it is necessary to define phenotypes based on the explicit evidence of assay results. We have developed a website termed PhenoSITE (Phenome Semantics Information with Terminology of Experiments: ), in which we are trying to integrate phenotype-related information using an experimental-evidence–based approach. The site's features include (1) a baseline database for our phenotyping platform; (2) an ontology associating international phenotypic definitions with experimental terminologies used in our phenotyping platform; (3) a database for standardized operation procedures of the phenotyping platform; and (4) a database for mouse mutants using data produced from the large-scale mutagenesis program at RIKEN GSC. We have developed two types of integrated viewers to enhance the accessibility to mutant resource information. One viewer depicts a matrix view of the ontology-based classification and chromosomal location of each gene; the other depicts ontology-mediated integration of experimental protocols, baseline data, and mutant information. These approaches rely entirely upon experiment-based evidence, ensuring the reliability of the integrated data from different phenotyping platforms.
BOOK REVIEW: "PRINCIPLES OF QUANTUM COMPUTATION AND QUANTUM INFORMATION, Vol. I: BASIC CONCEPTS, VOL. II: BASIC TOOLS AND SPECIAL TOPICS" BY G. BENENTI, G. CASATI AND G. STRINI
Authors: BERGOU JÁNOS A.
Published: January 2008

This two-volume book is a great addition to the growing number of books devoted to the field. It is very clearly written by classroom professionals, always with the students in mind. The tutorial presentation is supplemented with a number of exercises whose solutions are also given at the end of each volume. The first volume can serve as a textbook for a one semester introductory course in quantum computation and quantum information. The second volume is more technical and brings the reader to the level of the current literature. It is useful for the specialist, can serve as a textbook for a more advanced course, or has its place as a reference book. In summary, I can highly recommend this book to anyone interested in this field.
REPRESENTATION CLASS AND GEOMETRICAL INVARIANTS OF QUANTUM STATES UNDER LOCAL UNITARY TRANSFORMATIONS
Authors: YU ZU-HUAN , LI-JOST XIAN-QING , FEI SHAO-MING
Published: January 2008

We investigate the equivalence of bipartite quantum mixed states under local unitary transformations by introducing representation classes from a geometrical approach. It is shown that two bipartite mixed states are equivalent under local unitary transformations if and only if they have the same representation class. Detailed examples are given on calculating representation classes.
QUANTUM CORRELATIONS IN SUCCESSIVE SPIN MEASUREMENTS
Authors: AHANJ ALI , JOAG PRAMOD S. , GHOSH SIBASISH
Published: January 2008

In this paper, we consider a hidden variable theoretical description of successive measurements of non-commuting spin observables on an input spin-s state. Although these spin observables are non-commuting, they act on different states, and so the joint probabilities for the outputs of successive measurements are well-defined. We show that, in this scenario, hidden variable theory (HVT) leads to Bell-type inequalities for the correlation between the outputs of successive measurements. We account for the maximum violation of these inequalities by quantum correlations (i.e. the correlations of successive measurements on a quantum state) by varying the spin value and the number of successive measurements. Our approach can be used to obtain a measure of the deviation of Quantum Mechanics from the theory obeying realism and time-locality, in terms of the amount of classical information needed to be transferred between successive measurements in order to simulate the above-mentioned correlations in successive measurements.
CLASSICAL AND QUANTUM CONTROL OF A SIMPLE QUANTUM SYSTEM
Authors: XI ZAIRONG , JIN GUANGSHENG
Published: January 2008

A qubit which is prepared in one of two non-orthogonal states and subjected to bit-flipping noise is considered. The objective is to use measurement and feedback control to correct the state of the qubit. Three classical schemes using projective measurements, i.e. discrimination and re-preparation, do nothing and random preparation, have been discussed, and are not optimal with respect to a performance which is quantified by the average fidelity of the corrected state compared to the initial state. In addition, one quantum scheme using a non-projective measurement with an optimum measurement strength achieves the best trade-off between gaining information about the system and disturbing it through measurement back-action. The performance of a quantum control scheme outperforms the classical schemes. Furthermore, no universal corrected scheme is discussed.