Photon contribution to the “super-hard” pomeron

It is shown that direct photons provide a leading twist mechanism for diffractive jet production in which the jets carry away all of the momentum lost by the proton. Two-photon processes are thus expected to asymptotically dominate “super-hard” pomeron events in ep collisions. We report the expected rates from these events for recent ZEUS and H1 data cuts. We also estimate the direct photon contribution to the “super-hard” pomeron events observed by the CERN UA8 group for collisions. It is again argued that direct photons are the leading mechanism for these events. We find that direct photons are an appreciable fraction of the events seen by UA8.     

K–K excitations on as “primary” superfields

We show that the K–K spectrum of IIB string on is described by “twisted chiral” superfields, naturally described in “harmonic superspace”, obtained by taking suitable gauge singlets polynomials of the D3-brane boundary superconformal field theory.To each p-order polynomial is associated a massive K–K short representation with states. The quadratic polynomial corresponds to the “supercurrent multiplet” describing the “massless” bulk graviton multiplet.     

On “diagonal” Bianchi cosmologies

A list of the possible “diagonal” Bianchi cosmologies is given, with a proof that it is complete.     

Deformed “commutative” Chern–Simons’ system

Noncommutative Chern–Simons’ system is non-perturbatively investigated at a full deformed level. A deformed “commutative” phase space is found by a non-canonical change between two sets of deformed variables of noncommutative space. It is explored that in the “commutative” phase space all calculations are similar to the case in commutative space. Spectra of its energy and angular momentum of the Chern–Simons’ system are obtained at the full deformed level. The noncommutative–commutative correspondence is clearly showed. Formalism for the general dynamical system is briefly presented. Some subtle points are clarified.     

Novel comprehension of “common path” principle

The idea of “common path” has been widely applied in optical instrument design for 30 years and even today. But the meaning of “common path” has not yet been explained clearly and sometimes confusion has been created. In this paper an “adaptive principle” is proposed and recommended on optical instrument system. It suggests that the designer not only arranges the measurement system to obtain measurement signal but also sets a channel to give prediction of noise or disturbance in real time or short term. Such a recommendation is based on the recent studies on nonlinear dynamics and atmospheric disturbance by means of experiments as well as theoretical analysis.     

Schlieren “PIV” for turbulent flows

The possibility of using commercial PIV equipment combined with schlieren optics to measure the velocity fields of turbulent flows is explored. Given a sufficiently high Reynolds number and adequate refractive flow differences, turbulent eddies can serve as the PIV “particles” in a schlieren image or shadowgram. The PIV software analyzes motion between consecutive schlieren or shadowgraph frames to obtain velocity fields. Velocimetry examples of an axisymmetric sonic helium jet in air and a 2D turbulent boundary layer at Mach 3 are shown. Due to optical path integration, axisymmetric flows require the inverse Abel transform to extract center-plane velocity data. Conditions for optimum schlieren sensitivity are examined. In its present embodiment, “schlieren PIV” is not useful for laminar flows nor for fully 3D flows. Otherwise it functions much like standard PIV under conditions where individual particles are not resolved and velocimetry is instead based on correlation of the motion of turbulent structures. “Schlieren PIV” shows significant promise for general refractive turbulent flow velocimetry if its integrative nature can be overcome through sharp-focusing optics.     

Completeness of “good” Bethe ansatz solutions of a quantum-group-invariant Heisenberg model

The sl_q(2) quantum-group-invariant Heisenberg model with open boundary conditions is investigated by means of the Bethe ansatz. As is well known, quantum groups for q equal to a root of unity possess a finite number of “good” representations with non-zero q-dimension and “bad” ones with vanishing q-dimension. Correspondingly, the state space of an invariant Heisenberg chain decomposes into “good” and “bad” states. A “good” state may be described by a path of only “good” representations. It is shown that the “good” states are given by all “good” Bethe ansatz solutions with roots restricted to the first periodicity strip, i.e. only positive-parity strings (in the language of Takahashi) are allowed. Applying Bethe's string-counting technique completeness of the “good” Bethe states is proven, i.e. the same number of states is found as the number of all restricted paths on the sl_q(2) Bratteli diagram. It is the first time that a “completeness” proof for an anisotropic quantum-invariant reduced Heisenberg model is performed.     

Vague concept of “reversible cleavage” in the theory of the surface tension of solids

Numerous derivations of the well-known Shuttleworth equation have been based on the unclear concept of “reversible cleavage” leading to the decisive step in any derivation - equalization of the surface free energy and surface stress. This is the key concept in contemporary surface thermodynamics of solids. But “cleavage” is not a surface process and, in this field, it cannot be a reversible operation. Besides, the “reversible cleavage” has no formal definition in the domain of the surface tension of solids that is an abnormal for any exact science. Consequently, this concept and all its corollaries including the Shuttleworth and generalized Lippmann equations have to be recognized as incorrect.     

Feasibility of “intermittent” active control of combustion instabilities in liquid fueled combustors using a “smart” fuel injector

This paper describes an experimental investigation of the feasibility of an “intermittent” active control approach for suppressing combustion instabilities in liquid fueled combustors. The developed controller employs a “smart” fuel injector that can modify the spray properties in response to changes in combustor operating conditions. This action weakens or breaks up the coupling between the combustion process and combustor acoustic modes oscillations, thus preventing the excitation of large amplitude instabilities. This approach differs significantly from previously proposed active control methods, both in concept and implementation, as it requires only “intermittent” modification of the combustion process by a single control action as opposed to the continuous action required by most other active control methods. The “smart” fuel injector used in this study consisted of a double-staged, air-assisted atomizer in which counter swirling, primary (inner stage) and secondary (outer stage) air streams were supplied to the injector through separate sets of tangentially oriented orifices. Control of the ratio of air mass flow rates supplied to these two stages, by use of a diverter valve, resulted in significant changes in the spray shape and its axial, tangential, and radial velocity components. This variation in spray properties of the “smart” injector was characterized for different values of the inner to outer air flow rate ratio in cold flow tests with a PDPA system. These results were then correlated with the characteristics of the “intermittently” controlled combustor. Measured quantities included the instability amplitudes, axial dependence of the mean and oscillatory heat release amplitudes, and the characteristics of the recirculation zones, which were all shown to depend on the fuel spray properties. The results of this study demonstrate the feasibility of using “smart” fuel injectors with capabilities for varying the combustion process characteristics to reduce the amplitudes of detrimental combustion instabilities in real engines to acceptable levels.     

Nuclear track radiography of “Hot” aerosol particles

Nuclear track radiography was applied to identify aerosol “hot” particles which contain elements of nuclear fuel and fallout after Chernobyl NPP accident. For the determination of the content of transuranium elements in radioactive aerosols the measurement of the -activity of “hot” particles by SSNTD was used in this work, as well as radiography of fission fragments formed as a result of the reactions (n,f) and (γ,f) in the irradiation of aerosol filters by thermal neutrons and high energy gamma quanta. The technique allowed the sizes and alpha-activity of “hot” particles to be determined without extracting them from the filter, as well as the determination of the uranium content and its enrichment by ²³⁵U, ²³⁹Pu and ²⁴¹Pu isotopes. Sensitivity of determination of alpha activity by fission method is 5×10⁻⁶ Bq per particle. The software for the system of image analysis was created. It ensured the identification of track clusters on an optical image of the SSNTD surface obtained through a video camera and the determination of size and activity of “hot” particles.     

A concise proof of the “geometric” construction of inertial manifolds

By employing the standard strong squeezing property, the “geometric” existence proof of Constantin et al. is considerably simplified, and the parallels between this and other methods thereby emphasised.     

Determination of the “optical” thickness and of the filling factor of discontinuous Au films from photometric and ellipsometric measurements

The “optical” thickness of discontinuous Au films is determined from a suitable combination of photometric and ellipsometric measurements. The value of the metal filling factor which can be deduced from a comparison with the “mass” thickness is found to be in good agreement with the value directly obtained from structure studies.     

“Alternative medical therapy” use among singers: Prevalence and implications for the medical care of the singer

Singers are extremely conscious of health problems that affect their voices and well-being and often take an active role in seeking care for these problems. They frequently seek treatment from providers or with modalities considered “alternative” to traditional medical care. A survey of singers was completed to elucidate their attitudes and practices regarding “alternative modalities” of medical care. Frequently singers will self-medicate or take advice from people not well versed in the special needs of a professional voice user. They will fail to share this information with the physician when seeking “traditional” medical care. These practices may predispose the singer to suboptimal or even dangerous care. These results are discussed, as well as the implications for the medical physician treating the singer. The possible detrimental pharmacologic effects of “natural therapies” widely used by singers are presented, with special attention to the particular concerns for the professional singer     

“Compensatory falsetto”: Effects on vocal quality

The term “compensatory falsetto”, for the purpose of this investigation, refers to the development of an abnormally high-pitched voice in the presence of laryngeal pathology where more socially acceptable lower pitched voice production is possible. The purpose of this investigation was to compare laryngeal compensations and their effects on objective measures of vocal function during production of compensatory falsetto voice. Eighteen patients with abnormally high-pitched voice in the presence of underlying laryngeal pathology were evaluated in the Department of Otolaryngology at the University of Miami School of Medicine from January 1988 through December 1992 and were diagnosed with “compensatory falsetto”. Vocal fold paralysis (n = 11) was the most common laryngeal pathology. Vibratory characteristics were evaluated through videostrobolaryngoscopic examination. Acoustic and aerodynamic parameters assessed included fundamental frequency, jitter rate, harmonic-to-noise ratio, glottal air flow, and maximum phonation time. Production of a higher-pitched voice appeared to improve glottic closure and decrease the amount of air loss during phonation. A corresponding increase in maximum phonation time and improvement in acoustic characteristics of jitter and harmonic-to-noise ratio was also observed.     

Track detectors in radiation monitoring of the sunken submarine “Komsomolets”

Track method (using the CN and CR-39 detectors, spark couner of tracks as well as selective sorbents for plutonium and uranium) is applied in 1994 and 1995 together with many other methods in radioecological monitoring of water in the region of the sunken nuclear submarine (NS) “Komsomolets”. The detection assembles were installed with the help of the submersibles MIR. The results obtained inside the NS and on its surface as well as near and on the remote buoy station do not contradict the data obtained by other methods confirming the absence of the plutonium leakage outside of the submarine.     

The contribution of aryepiglottic constriction to “ringing” voice quality—A videolaryngoscopic study with acoustic analysis

Fiberscopic video laryngoscopy was performed on five professional singers to determine the presence or absence of aryepiglottic narrowing as a function of voice quality. Each sang “Happy Birthday” and parts of the “Star Spangled Banner” in six different voice qualities: speech, falsetto, sob (a low larynx with a vocal tract expanded by relaxing the middle constrictors), twang, belting, and opera. Several features were found to be common among the subjects and related to specific qualities. Aryepiglottic constriction was present in all singers in twang, belting, and opera qualities. Spectrographic analysis related the constriction to the presence of the “singer's formant.” The presence of this type of constrictive behavior will require further research to ascertain the possible benefits to those for whom a louder voice is essential and to understand the relationship of this constrictive maneuver to the natural closure functions of the larynx.     

“Slow” active control of combustion instabilities by modification of liquid fuel spray properties

This paper describes an experimental investigation of the feasibility of using “slow” active control approaches, which “instantaneously” change liquid fuel spray properties, to suppress combustion instabilities. The objective of this control approach was to break up the feedback between the combustion process heat release and combustor pressure oscillations that drive the instability by changing the characteristics of the combustion process (e.g., the characteristic combustion time). To demonstrate the feasibility of such control, this study used a proprietary fuel injector (Nanomiser^TM), which can vary its fuel spray properties, to investigate the dependence of acoustics–combustion process coupling, i.e., the driving of combustion instabilities, upon the fuel spray properties. This study showed that by changing the spray characteristics it is possible to significantly damp combustion instabilities. Furthermore, using combustion zone chemiluminescence distributions, which were obtained by Abel’s deconvolution synchronized with measured acoustic data, it has been shown that the instabilities were mostly driven midway between the combustor centerline and wall, a short distance downstream from the flame holder, where the mean axial flow velocity is approximately zero in the vortex near the flame holder. The results of this study strongly suggest that a “slow” active control system that employs controllable fuel injectors could be effectively used to prevent the onset of detrimental combustion instabilities.