Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
360
result(s) for
"Banks, Daniel"
Sort by:
Anomalous Diffusion of Proteins Due to Molecular Crowding
We have studied the diffusion of tracer proteins in highly concentrated random-coil polymer and globular protein solutions imitating the crowded conditions encountered in cellular environments. Using fluorescence correlation spectroscopy, we measured the anomalous diffusion exponent α characterizing the dependence of the mean-square displacement of the tracer proteins on time, 〈r2(t)〉∼tα. We observed that the diffusion of proteins in dextran solutions with concentrations up to 400g/l is subdiffusive (α<1) even at low obstacle concentration. The anomalous diffusion exponent α decreases continuously with increasing obstacle concentration and molecular weight, but does not depend on buffer ionic strength, and neither does it depend strongly on solution temperature. At very high random-coil polymer concentrations, α reaches a limit value of αl≈3/4, which we take to be the signature of a coupling between the motions of the tracer proteins and the segments of the dextran chains. A similar, although less pronounced, subdiffusive behavior is observed for the diffusion of streptavidin in concentrated globular protein solutions. These observations indicate that protein diffusion in the cell cytoplasm and nucleus should be anomalous as well, with consequences for measurements of solute diffusion coefficients in cells and for the modeling of cellular processes relying on diffusion.
Journal Article
High aspect ratio diamond nanosecond laser machining
Laser processing of diamond has become an important technique for fabricating next generation microelectronic and quantum devices. However, the realization of low taper, high aspect ratio structures in diamond remains a challenge. We demonstrate the effects of pulse energy, pulse number and irradiation profile on the achievable aspect ratio with 532 nm nanosecond laser machining. Strong and gentle ablation regimes were observed using percussion hole drilling of type Ib HPHT diamond. Under percussion hole drilling a maximum aspect ratio of 22:1 was achieved with 10,000 pulses. To reach aspect ratios on average 40:1 and up to 66:1, rotary assisted drilling was employed using > 2 M pulse accumulations. We additionally demonstrate methods of obtaining 0.1° taper angles via ramped pulse energy machining in 10:1 aspect ratio tubes. Finally, effects of laser induced damage are studied using confocal Raman spectroscopy with observation of up to 36% increase in tensile strain following strong laser irradiation. However, we report that upon application of 600 °C heat treatment, induced strain is reduced by up to ~ 50% with considerable homogenization of observed strain.
Journal Article
Inhalational Constrictive Bronchiolitis: The Evolution of our Understanding of this Disease
The case definition of inhalational constrictive bronchiolitis (CB) has changed over the generations. We identify changes in the description of this illness over time associated with different exposures and present the natural history of CB in a case attributed to military burn pit exposure. The initial descriptions of this disease began with nitric acid spills and silage exposures. In these events, there was an acute exposure, typically a short-term resolution of the adverse respiratory events, and then a progression, leading to disability or a respiratory death. The life-saving role of corticosteroid therapy in this situation was recognized. War gas exposures of World War I and then Saddam Hussein’s use of sulfur mustard gas in the Iran-Iraq War followed. More recently the findings associated with
diacetyl
exposure in commercial popcorn workers remained consistent with previously described presentations, but then the clinical presentation in troops returning from deployment to Southwest Asia was very different, yet with the same histologic findings. We recognize unreconciled disparities in the clinical, physiologic, and imaging presentation in those with inhalational bronchiolitis and acknowledge this as perhaps one of the difficult diagnoses in respiratory medicine.
Journal Article
Clinical Aspects of Asbestos-Related Diseases—What Are the Unresolved Topics?
OBJECTIVE:Despite awareness of the health risks associated with asbestos fiber inhalation and the decline in U.S. utilization (about 0.1% of the yearly peak amount), illnesses associated with exposure persist. Those with disease typically describe excessive exposures in the remote past, yet excessive exposures can occur today, most likely related to careless asbestos abatement procedures. The intent is to address unanswered questions associated with asbestos exposure.
METHODS:The author summarizes clinical information addressing the case definition of asbestosis, the world-wide rate of mesothelioma, and clinical follow-up for those with exposure.
RESULTS:The author describes information relevant to issues which remain unresolved.
CONCLUSION:Perhaps somewhat surprisingly, even though there have been a great number of manuscripts reporting on the health risks of asbestos exposure, there remain unanswered questions regarding the pathogenesis of this disease.
Journal Article
Constrictive Bronchiolitis Attributable to Inhalation of Toxic Agents: Considerations for a Case Definition
OBJECTIVE:We identified cases of constrictive bronchiolitis (CB), an inflammatory injury obliterating the small airways, in adults caused by inhalational exposure to determine an appropriate case definition.
METHODS:We performed a systematic review with meta-analysis for these cases from 1990 to 2017. Publications were included if there was 1) inhalational exposure; 2) respiratory symptoms/signs; 3) pulmonary function test results; and 4) computerized tomographic chest imaging. Many had a lung biopsy.
RESULTS:Two hundred seventy-four articles were retrieved; 22 manuscripts comprising 102 cases were included. Diagnostic criteria from cases associated with military deployment to southwest Asia were statistically different from criteria of other etiologies.
CONCLUSION:In three cases, the scan was consistent with CB, the biopsy nondiagnostic, yet the diagnosis was made. CB associated with military deployment presented with diagnostic features statistically different from features in the other cases.
Journal Article
X-Ray Interaction and the Electronic, Atomic Cross-Sections and Compton Mass-Attenuation Coefficients of Human Blood, Breasts, Eye Lens, Ovaries, and Testis
The Klein–Nishina formula is used to calculate and investigate the electronic cross-section, atomic cross-section, and Compton mass attenuation coefficients for the human blood, breasts, eye lens, ovaries, and testis, using X-rays in the 0.1–20 MeV energy range. The effects of radiation energy, tissue effective charge number, tissue density, and tissue electronic density on these parameters were studied. The results show that the electronic cross-section and atomic cross-section decrease with increasing radiation energy. These parameters are found to be linearly increasing when the density and electron density of a tissue increase. This increase is more rapid with a bigger slope when the electron density increases as compared to the density of each tissue. A complex relationship between these coefficients and the effective charge number Zeff of tissues is observed because Zeff changes with the energy and linear attenuation coefficient of a tissue. The Compton mass attenuation coefficient is found to be dependent on the effective charge number to mass number ratio Zeff/Aeff instead of just the effective charge number. This increase in the Compton mass attenuation coefficient with increasing Zeff/Aeff is rapid for the lower values of Zeff/Aeff. However, for a higher Zeff/Aeff ratio, the increase is very slow and becomes almost constant for X-ray energies above 10 MeV. The calculated parameters are useful in determining radiation dose for the investigated tissues and their response to low and high-energy X-rays. The results and outcomes are also very useful in shielding and protecting tissues from the hazards of radiation. These parameters are also helpful in determining the scattered and optimum doses to improve image quality and treatment options in radiology and radiation therapy to offer the best care.
Journal Article
Investigating Empirical Mode Decomposition in the Parameter Estimation of a Three-Section Winding Model
Parameter estimation represents an important aspect of modeling electromagnetic systems, and a wide range of parameter estimation strategies has been explored in literature. Most parameter estimation methodologies make use of either time-domain or frequency-domain responses as measured from the terminals of the device under test. Very limited research has, however, been conducted into exploring the use of modal decomposition strategies on the time-domain waveforms for parameter estimation applications. In this paper, the use of Empirical Mode Decomposition for estimating the parameters of a three-section lumped parameter transformer model is explored. A novel approach is proposed to define the optimization cost function in terms of the intrinsic modes of simulated time-domain waveforms. The results are compared with results obtained using classical time-domain and frequency-domain approaches. It is shown through an impulse response test that weighting the modes obtained from the Inferred Empirical Mode Decomposition approach presented in this work offers advantages in terms of accurately representing the target model transfer function dynamics and can assist in interpreting the various dynamic modes associated with the target model.
Journal Article