Correlated forward-backward dissociation and neutron spectra as a luminosity monitor in heavy ion colliders

Detection in zero degree calorimeters of the correlated forward-backward Coulomb or nuclear dissociation of two colliding nuclei is presented as a practical luminosity monitor in heavy ion colliders. Complementary predictions are given for total correlated Coulomb plus nuclear dissociation and for correlated forward-backward single neutrons from the giant dipole peak.Comment: 16 pages, latex, revtex source, four postscript figure

Size dependent conduction characteristics of catalyst-multi-walled carbon nanotube junction

Multi-walled carbon nanotubes (MWCNTs) grown by chemical vapor deposition retain the residual catalyst particles from which the growth occurred, which are considered a detriment to MWCNTs’ performance, especially electrical conductivity. The first direct measurements have been made of the electrical transport through the catalyst cap into the MWCNT using nanoscale 2-point-probe to determine the effects of the catalyst particle’s size and the diameter ratio with its associated MWCNT on the electrical transport through the catalyst cap as compared to the inherent conductivity of the MWCNT. The MWCNT diameter is independent of the catalyst size, but the ratio of the catalyst cap diameter to MWCNT diameter (DC/DNT) determines the conduction mechanism. Where DC/DNT is greater than 1 the resulting I–V curve is near ohmic, and the conduction through the catalyst (RC+NT) approaches that of the MWCNT (RNT); however, when the DC/DNT   > RNT. The experimental results are discussed in relation to current crowding at the interface between catalyst and nanotube due to an increased electric field

Physical limitations on quantum nonlocality in the detection of gamma photons emitted from positron/electron annihilation

Recent experimental measurements of the time interval between detection of the two photons emitted in positron/electron annihilation have indicated that collapse of the spatial part of the photon's wavefunction, due to detection of the other photon, does not occur. Although quantum nonlocality actually occurs in photons produced through parametric down-conversion, the recent experiments give strong evidence against measurement-induced instantaneous spatial-localization of high-energy gamma photons. A new quantum-mechanical analysis of the EPR problem is presented which may help to explain the observed differences between photons produced through parametric down-conversion and photons produced through positron/electron annihilation. The results are found to concur with the recent experiments involving gamma photons.Comment: accepted for publication, Phys. Rev.

Modes of ocean variability in the tropical Pacific as derived from Geosat altimetry

Satellite-derived (Geosat altimetry) sea surface height anomalies for the period November 1986 to September 1989 were investigated in order to extract the dominant modes of climate variability in the tropical Pacific. We applied the technique of principal oscillation patterns and computed associated wind stress patterns for each mode. Four modes were identified. The first mode has a time scale of about 3 months and can be identified with the first baroclinic equatorial Kelvin wave mode, which is excited by intraseasonal wind variations over the western equatorial Pacific. The second mode has a time scale of about 6 months and describes the semiannual cycle in the tropical Pacific sea level. Equatorial wave dynamics appears to be crucial for this mode also. The third mode is the annual cycle which shows evidence of off-equatorial Rossby wave propagation. The fourth mode is associated with the El Niño/Southern Oscillation (ENSO) phenomenon. The ENSO mode is found to be consistent with the “delayed action oscillator” scenario

Analysis of motion parameter variations for rotorcraft flight simulators

No standard guidelines currently exist for tuning rotorcraft flight simulation motion platforms. This often leads to systems that are poorly utilized. This paper presents results from a study to determine the influence of parameter variations in two rotorcraft research simulators. Investigations were conducted using three Mission Task Elements (MTEs), and both subjective and objective analysis is used to determine the suitability of motion settings. Motion settings are compared with recommended Objective Motion Cueing Test (OMCT) boundaries for fixed-wing aircraft. Results show differences in the fidelity of motion settings, and recommendations specifically for rotorcraft simulation are presented

Extrinsic And Intrinsic Motivators Of Customer Participation In Compliance Dependent Services

Research on customer participation has focused primarily on the customer’s participatory role in service creation during the face-to-face service exchange (Bateson 1989; Bowen 1986; Chase 1978; Kelley, Donnelly, and Skinner 1990; Lovelock and Young 1979; and Mills, Chase, and Margulies 1983) however customer involvement often extends beyond the face-to-face exchange.  This is especially the case with compliance dependent services (CDS).  CDS are services that require customer participation with his or her service delivery role while within the service organization and once away from the service facility to ensure goal attainment and customer satisfaction.  Examples of CDS include dental care, weight loss programs, preventive auto maintenance, education, exercise programs, health care programs (diabetes, hypertension), prenatal care, long-term financial planning, debt management programs, and smoking cessation programs. In an early CDS study, Dellande (1999) found motivation to be the most important customer attribute in gaining customer compliance.  In this research we further our understanding of the role of motivation by studying the impact of persuasive provider communication, an extrinsic customer motivator, on intrinsic customer compliance motivation.  One important characteristic of persuasive messages that influences their effectiveness is how they are framed.  Among other factors, effective persuasive messages require comprehension and retention, yielding and behavior in accordance with the message content (McGuire 1966).  Specifically, existing research suggests that behavior is affected by the extent to which messages emphasize the potentially negative consequences of failing to engage in a given behavior relative to a message in which the possible beneficial (i.e., positive) consequences of engaging in that action are emphasized (Roberson and Rogers 1988, Tykocinski et. al, 1994).  We explore this distinction in the dental compliance service context.  We specifically examine how the manner in which written compliance-related communications are framed influences consumers’ intended compliance behaviors

Pressure dependent conduction of individual multi-walled carbon nanotubes: the effect of mechanical distortions

Multi-walled carbon nanotubes (MWCNTs) show an oscillation in electrical resistance (from I–V measurements) during mechanical distortion in which peak separation is inversely correlated with the diameter of the MWCNTs. These results provide the first experimental support of the theoretical prediction that distortion causes Van Hove singularities and Dirac cones in MWCNTs to misalign and cause the opening of the band gap, and suggest that when fabricating contacts for CNTs for device applications, the pressure caused by the contact deposition method must be taken into account for manufacturing devices with consistent properties

Chemical Recycling of Consumer-Grade Black Plastic into Electrically Conductive Carbon Nanotubes

The global plastics crisis has recently focused scientists’ attention on finding technical solutions for the ever-increasing oversupply of plastic waste. Black plastic is one of the greatest contributors to landfill waste, because it cannot be sorted using industrial practices based on optical reflection. However, it can be readily upcycled into carbon nanotubes (CNTs) using a novel liquid injection reactor (LIR) chemical vapor deposition (CVD) method. In this work, CNTs were formed using black and white polystyrene plastics to demonstrate that off-the-shelf materials can be used as feedstock for growth of CNTs. Scanning electron microscopy analysis suggests the CNTs from plastic sources improve diameter distribution homogeneity, with slightly increased diameters compared with control samples. Slight improvements in quality, as determined by Raman spectroscopy of the D and G peaks, suggest that plastics could lead to increased quality of CNTs. A small device was constructed as a demonstrator model to increase impact and public engagement

Increased Electrical Conductivity of Carbon Nanotube Fibers by Thermal and Voltage Annealing

We report the effect of annealing, both electrical and by applied voltage, on the electrical conductivity of fibers spun from carbon nanotubes (CNTs). Commercial CNT fibers were used as part of a larger goal to better understand the factors that go into making a better electrical conductor from CNT fibers. A study of thermal annealing in a vacuum up to 800 °C was performed on smaller fiber sections along with a separate analysis of voltage annealing up to 7 VDC; both exhibited a sweet spot in the process as determined by a combination of a two-point probe measurement with a nanoprobe, resonant Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Scaled-up tests were then performed in order to translate these results into bulk samples inside a tube furnace, with similar results that indicate the potential for an optimized method of achieving a better conductor sample made from CNT fibers. The results also help to determine the surface effects that need to be overcome in order to achieve this