Biomedical subjects

R J Watts

Publications and source records attributed to R J Watts.

At least 19 recordsLinked to original sources

PubMed2006

Observation of a strongly nested Fermi surface in the shape-memory alloy Ni0.62Al0.38.

The Fermi surface topology of the shape-memory alloy Ni0.62Al0.38 has been determined using Compton scattering. A large area of this Fermi surface can be made to nest with other areas by translation through a vector of approximately 0.18[1,1,0](2pi/a), which corresponds to the wave vector associated with martensitic precursor phenomena such as phonon softening and diffuse streaking in electron diffraction patterns. This observation is compelling evidence that these phenomena are driven by the enhanced electron-lattice coupling due to the Fermi surface nesting.

Journal Article↗

PubMed2004

Direct observation of the multisheet Fermi surface in the strongly correlated transition metal compound ZrZn2.

The existence of flat areas of a Fermi surface (FS), predicted by electronic structure calculations and used in models of both magnetically mediated and phonon-mediated Fulde-Ferrell-Larkin-Ovchinnikov superconducting states, is reported in the paramagnetic phase of the ferromagnetic superconductor ZrZn2 using positron annihilation. The strongly mass-renormalized FS sheet, dominating the Fermi level density of states, is seen for the first time. The delocalization of the magnetization is studied using measured and calculated magnetic Compton profiles.

Journal Article↗

PubMed2002

Engagement in activities revealing the body and psychosocial adjustment in adults with a trans-tibial prosthesis.

The purpose of this study was to examine the effects of the appearance of a prosthesis on social behaviour, social discomfort and psychological well-being in eleven amputees taking delivery of a prosthesis with a silicone cover. Two new scales were developed: the 'Engagement in everyday activities involving revealing the body' (EEARB); and the 'Discomfort-Engagement in everyday activities involving revealing the body' (Discomfort-EEARB) scales. The psychometric properties of these scales were determined using a sample of 101 able-bodied adults. The Hospital Anxiety and Depression Scale and the Rosenberg Self-Esteem Scale were also used to measure psychological well-being in the amputee sample. The EEARB and Discomfort-EEARB proved to have good reliability and validity. Comparison of amputees' scores prior to receiving the silicone cosmesis with those of the able-bodied adults revealed significant behavioural limitations and social discomfort, associated with low self-esteem, anxiety and depression. There was a significant increase in amputees' scores three months afier taking delivery of their prosthesis, indicating that amputees reported engaging in more activities which involved revealing their body, and that they would feel more comfortable in situations which involved revealing the body. As the amputee sample available was small and self-selected, it is not possible to generalise these findings to the amputee population as a whole. However, since there is little previous research investigating the effects of the appearance of the prosthesis, these findings demonstrate the need for further research in this area.

Activities of Daily Living↗

PubMed2001

Evidence for simultaneous abiotic-biotic oxidations in a microbial-Fenton's system.

The conditions that support the simultaneous activity of hydroxyl radicals (OH.) and heterotrophic aerobic bacterial metabolism were investigated using two probe compounds: (1) tetrachloroethene (PCE) for the detection of OH. generated by an iron-nitrilotriacetic acid (Fe-NTA) catalyzed Fenton-like reaction and (2) oxalate (OA) for the detection of heterotrophic metabolism of Xanthobacter flavus. In the absence of the bacterium in the quasi-steady-state Fenton's system, only PCE oxidation was observed; conversely, only OA assimilation was found in non-Fenton's systems containing X. flavus. In combined Fenton's-microbial systems, loss of both probes was observed. PCE oxidation increased and heterotrophic assimilation of OA declined as a function of an increase in the quasi-steady-state H2O2 concentration. Central composite rotatable experimental designs were used to determine the conditions that provide maximum simultaneous abiotic-biotic oxidations, which were achieved with a biomass level of 10(9) CFU/mL, 4.5 mM H2O2, and 2.5 mM Fe-NTA. These results demonstrate that heterotrophic bacterial metabolism can occur in the presence of hydroxyl radicals. Such simultaneous abiotic-biotic oxidations may exist when H2O2 is injected into the subsurface as a microbial oxygen source or as a source of chemical oxidants. In addition, hybrid abiotic-biotic systems could be used for the treatment of waters containing biorefractory organic contaminants present in recycle water, cooling water, or industrial waste streams.

Biodegradation, Environmental↗

PubMed2001

Comparison of mineral and soluble iron Fenton's catalysts for the treatment of trichloroethylene.

Contaminant degradation, stoichiometry, and role of hydroxyl radicals (OH*) in four Fenton's systems were investigated using trichloroethylene (TCE) as a model contaminant. A standard Fenton's system, a modified soluble iron system with a pulse input of hydrogen peroxide, and two modified mineral-catalyzed systems (pH 3 and 7) were studied. In the standard Fenton's system, which had the most efficient reaction stoichiometry, 78% of the TCE was degraded; however, chloride analysis indicated that no more than two of the three chlorines were displaced per TCE molecule degraded. Although the modified soluble iron system was characterized by 91% TCE degradation, chloride analysis also indicated that no more than two of the chlorines were lost from the TCE. In the goethite system of pH 3, > 99% of the TCE was degraded. Near-complete release of chloride suggested that the TCE may have been mineralized. Only 22% degradation of TCE was achieved in the pH 7 goethite system. and there was minimal release of chloride. The mineral-catalyzed reactions exhibited the least efficient reaction stoichiometry of the four systems. Experiments using hydroxyl radical scavengers showed that the standard Fenton's system degraded TCE entirely by hydroxyl radical mechanisms, while approximately 10-15% of the degradation achieved in the modified soluble iron and goethite-catalyzed systems at pH 3 was mediated by non-hydroxyl radical mechanisms. In the goethite system at pH 7, only non-hydroxyl radical mechanisms were found. The goethite-catalyzed system at pH 3 effectively degraded the parent compound and may have the potential to mineralize contaminants when used for in situ soil and groundwater remediation and ex situ waste stream treatment in packed-bed reactors.

Biodegradation, Environmental↗

PubMed2000

A foundation for the risk-based treatment of gasoline-contaminated soils using modified Fenton's reactions.

The relative oxidation of representative aromatic and aliphatic hydrocarbons found in gasoline was evaluated to provide the foundation for risk-based treatment of petroleum-contaminated soils and groundwater using modified Fenton's reagent (catalyzed hydrogen peroxide). Aromatic components of gasoline are considered more hazardous than the aliphatic fractions due to their higher mobility in the subsurface and their higher acute and chronic toxicities. Benzene, toluene, and mixed xylenes (BTX) were selected as aromatic compounds representative of unleaded gasoline, while nonane, decane, and dodecane (NDD) were used as model aliphatic compounds. The effects of hydrogen peroxide (H(2)O(2)) concentration, iron catalyst concentration, and pH on the degree of treatment of the model compounds were investigated using central composite rotatable experimental designs. Oxidation of the aromatic compounds required less iron and less H(2)O(2) than did oxidation of the aliphatic compounds, while proceeding more effectively at near-neutral pH. Greater than 95% of the BTX was treated at near-neutral pH using 2. 5% H(2)O(2) and 12.5 mM iron (III), while only 37% nonane, 7% decane, and 1% dodecane oxidation was achieved under the same conditions. The results show that the more toxic and mobile aromatic fraction was more effectively oxidized using less H(2)O(2) and more economical conditions, including near-neutral pH, compared to the aliphatic fraction. A process design based on treating only the aromatic fraction of petroleum may provide significantly lower costs when using modified Fenton's reagent for the treatment of contaminated soils and groundwater.

Gasoline↗

PubMed2000

Acute and chronic toxicity of the herbicide benzofenap (Taipan 300) to Chironomus tepperi Skuse (Diptera: Chironomidae) and Isidorella newcombi (Adams and Angas) (Gastropoda: Planorbidae).

Acute and chronic toxicity tests were conducted on the herbicide benzofenap (Taipan 300) using two Australian freshwater invertebrates. The commercial formulation of benzofenap and a blank formulation containing only the adjuvants of Taipan 300 were tested against final instar larvae of the midge Chironomus tepperi and adults of the aquatic snail Isidorella newcombi. In 24-h acute bioassays the midge larvae did not show significant mortality at a nominal concentration of 1.2 mg/L active ingredient (AI), double the maximum notional concentration expected in rice fields after application of Taipan 300 at the permit rate of 2 L/ha. No significant snail mortality was recorded in acute bioassays (24-h exposure, 48-h recovery) at nominal concentrations up to 76 mg/L AI, which is over 120 times the maximum notional field concentration. In chronic assays, the pupation and emergence of C. tepperi was monitored after a 4-h pulse exposure of final instar larvae to Taipan 300 (nominal concentrations 0.001 to 0.1 mg/L AI) and adjuvant-only (0.1 mg/L equivalent) treatments. No statistically significant effects were observed, although emergence appeared to be delayed by higher benzofenap concentrations and by the adjuvant-only treatment. During snail bioassays, egg and feces production were monitored for 21 days after 24-h exposure to Taipan 300 (nominal concentrations 1.2 mg/L to 60 mg/L AI) and adjuvant-only treatments (60 mg/L equivalent). No significant chronic effects were proven against I. newcombi, despite a decline in egg mass production following exposure to all treatments and a reduction in the total numbers of eggs produced at the highest nominal concentrations tested (60 mg/L AI and adjuvant-only treatments). Similarly, feces production by snail pairs exposed to the majority of treatments declined, but these differences were not statistically significant. It is concluded that Taipan 300 does not represent a significant risk to mature C. tepperi larvae or adult I. newcombi in downstream environments when applied to rice fields at the permit rate of 2 L/ha.

Acetophenones↗

PubMed1999

Hydrogen peroxide decomposition in model subsurface systems.

Rates of hydrogen peroxide decomposition, hydroxyl radical production, and oxygen evolution were investigated in silica sand-goethite slurries using unstabilized and stabilized hydrogen peroxide formulations. The goethite-catalyzed decomposition of unstabilized hydrogen peroxide formulations resulted in more rapid hydrogen peroxide loss and oxygen evolution relative to systems containing a highly stabilized hydrogen peroxide formulation. Systems at neutral pH and those containing higher goethite concentrations were characterized by higher rates of hydrogen peroxide decomposition and by more oxygen evolution. The stabilized hydrogen peroxide formulation showed greater hydroxyl radical production relative to the unstabilized formulations. Furthermore, hydroxyl radical production rates were greater at neutral pH than at the acidic pH regimes. The results suggest that when stabilized hydrogen peroxide is injected into the subsurface during in situ bioremediation, naturally occurring minerals such as goethite may initiate Fenton-like reactions. While these reactions may prove to be toxic to microorganisms, they have the potential to chemically oxidize contaminants in soils and groundwater.

Biodegradation, Environmental↗

PubMed1999

Long-day up-regulation of a GAMYB gene during Lolium temulentum inflorescence formation.

Long-day exposure of the grass Lolium temulentum may regulate flowering via changes in gibberellin (GA) levels. Therefore, we have examined both GA levels and expression of a MYB transcription factor that is specific to the GA signal transduction pathway in monocots. This MYB gene from L. temulentum shows over 90% nucleotide identity with the barley and rice GAMYB genes, and, like them, gibberellic acid (GA3) up-regulates its expression in the seed. Furthermore, cDNAs of both the barley and L. temulentum GAMYB show the same simple patterns of hybridization with digests of L. temulentum genomic DNA. Compared with vegetative shoot apices of L. temulentum, the in situ mRNA expression of LtGAMYB does not change during the earliest steps of "floral" initiation at the apex. However, by 100 h (the double-ridge stage of flowering) its expression increased substantially and was highest in the terminal and lateral spikelet sites. Thereafter, expression declined overall but then increased within stamen primordia. Prior to increased LtGAMYB expression, long-day exposure sufficient to induce flowering led to increased (5- to 20-fold) levels of GA1 and GA4 in the leaf. Thus, increases first in GA level in the leaf followed by increased expression of LtGAMYB in the apex suggest important signaling and/or response roles in flowering.

Amino Acid Sequence↗

PubMed1999

Comparative measurements on a series of accelerators by the same vendor.

A series of comparative measurements were conducted during a 12-month period on a series of linear accelerators made by the same vendor. These measurements were conducted during acceptance and commissioning of six Varian model 2100C linear accelerators which had identical beam energies and beam modifiers. Nominal accelerating potentials, scatter measurements, depth doses, beam profiles, wedge and electron beam descriptors are presented. The results show highly similar beam parameters with observed variations being approximately equivalent to the precision of measurement. This similarity implies that a standard data set can be used to validate new commissioning data.

Electrons↗

PubMed1999

Optimization of simultaneous chemical and biological mineralization of perchloroethylene.

Optimization of the simultaneous chemical and biological mineralization of perchloroethylene (PCE) by modified Fenton's reagent and Xanthobacter flavus was investigated by using a central composite rotatable experimental design. Concentrations of PCE, hydrogen peroxide, and ferrous iron and the microbial cell number were set as variables. Percent mineralization of PCE to CO2 was investigated as a response. A second-order, quadratic response surface model was generated and fit the data adequately, with a correlation coefficient of 0.72. Analysis of the results showed that the PCE concentration had no significant effect within the tested boundaries of the model, while the other variables, hydrogen peroxide and iron concentrations and cell number, were significant at alpha = 0.05 for the mineralization of PCE. The 14C radiotracer studies showed that the simultaneous chemical and biological reactions increased the extent of mineralization of PCE by more than 10% over stand-alone Fenton reactions.

Biodegradation, Environmental↗

PubMed1998

Evaluation of a diode detector array for use as a linear accelerator QC device.

A series of tests were conducted to evaluate the accuracy of a diode detector array in measuring flatness and symmetry of x-ray and electron energies, and the ability to determine change in beam energy. The results show the diode detector array accurately measures flatness and symmetry and can accurately measure or detect change in beam energy. The evaluation also demonstrates the utility of using this model detector system in a linear accelerator QC program.

Biophysical Phenomena↗

PubMed1997

Cloning of a rice cDNA encoding a transcription factor homologous to barley GAMyb.

A cDNA clone, OsGAmyb, which encodes a homologue to the barley Myb-like transcription factor, HvGAMyb, was isolated from a rice endosperm cDNA library. The clone was used to show that expression of the OsGAmyb gene in aleurone cells was stimulated by gibberellic acid and the gene product was shown to transactivate an alpha-amylase gene promoter in transient expression analyses.

Amino Acid Sequence↗

PubMed1997

The critical-care nurse practitioner curriculum at the University of Pennsylvania: update and revision.

This paper describes the philosophical, conceptual, and programmatic characteristics of the Adult Critical Care Nurse Practitioner (CCNP) Program, which began at the University of Pennsylvania in 1993. It outlines the rationale and strategies for curriculum revisions during the 3rd year of program implementation. The basic content and sequencing of courses in the program did not change. Curricular revision in theoretical and field work courses consisted of modifying the approach to teaching with emphasis on critical thinking, diagnostic reasoning, and clinical decision making. Finally, it discusses the future challenges for educating CCNPs, with an emphasis on market demands and research challenges.

Adult↗

PubMed1995

Nurse-physician collaboration and decision outcomes in transplant ambulatory care settings.

OBJECTIVE: This study examined the nature of nurse-physician collaborative practice as reflected in problems presented by transplant patients in telephone contacts with clinical nurse specialists (CNSs). DESIGN: Exploratory descriptive study. SAMPLE/SETTING: The sample consisted of 202 renal and renal-pancreas transplant recipients who telephoned nurses at the outpatient clinic of a tertiary care medical center. METHODS: Over a period of 6 weeks, using a data collection form, nurse specialists recorded the types and frequencies of problems described by transplant patients via telephone interaction and categorized the outcomes of decisions. RESULTS: Of the 437 calls, averaging 2.16 calls per patient, problems were classified as general questions (46%), medication related (32%), and clinical signs and symptoms (22%) such as fever, rejection, colds, and urinary tract infections. Decision outcomes (n = 354) categorized as independent or collaborative for problem resolution were: CNS only (80%), MD only (11%), and collaborative (9%). CONCLUSIONS: Resolution of 80% of patients' problems presented in telephone interactions shows that advanced practice nurses play a pivotal role in the delivery of care to outpatient transplant recipients. Independent decision making on the part of the nurse occurs within the context of ongoing collaboration and communication with physician colleagues.

Adolescent↗

PubMed1994

Critical care clinical nurse specialist in home health care: survey results.

Two surveys were designed and sent to health care providers in the Philadelphia metropolitan area. The purpose of the surveys was to explore whether there was a need for critical care CNSs (CCCNS) in the field of high-tech, complex home care and to determine the characteristics of that role. In addition, the surveys sought to identify the necessary curriculum content a CCCNS graduate program should include to prepare individuals for practice in home care. One survey was sent to home care providers and an amended version to in-hospital personnel identified as responsible for discharge planning. Eighty-three percent of the home care survey respondents and 85% of the in-hospital survey respondents perceived a need for a CCCNS in the high-tech, complex home care field. The identified roles of the CCCNS in home care were similar for both respondent groups. They included consultant to the home care agency, patient-family educator, staff educator, and hospital-to-home coordinator. Some suggestions for curriculum content included courses on technology, discharge planning, health policy, and chronic illness. Although a preliminary exploration, the surveys demonstrated the existence of patients with high-tech, complex home care needs and supported the belief that CCCNSs have a role in their care.

Continuity of Patient Care↗

PubMed1994

The influence of life table corrections for smokers and nonsmokers on the health effects of radon using the BEIR (biological effects of ioniziing radiation) IV method.

The BEIR IV report gives graphs and tables that are used to estimate the risks due to radon (222Rn) and its decay products. The BEIR IV hypothesis predicts that the lifetime risks will depend upon the "normal" incidence of fatal lung cancers for nonsmokers and smokers and the life expectancies of both groups. This paper examines the influence of recent information on these health risks. The factors considered are a) the life tables for both sexes and for those who never smoked, formerly smoked, are currently light smokers, or are currently heavy smokers, and b) the age-dependent fatal lung cancer rates for the same groups of people. In general, the calculations indicate that people who have never smoked would have the same risks as those listed in the BEIR IV report as nonsmokers. For males, those who smoke or formerly smoked would have calculated risks that are greater than people who never smoked; however, for males, the smokers and former smokers considered in this paper have lower calculated risks than the BEIR IV smokers. For females, the heavy smokers examined here would have greater calculated risks than the BEIR IV smokers. The reasons for these differences are presented.

Female↗

PubMed1993

Determining person-years of life lost using the BEIR V method.

A method is given that permits the calculation of the estimated person-years of life lost when groups of males or females are exposed to low linear energy transfer (LET) ionizing radiation. It is felt that this determination is informative in rating risks to populations from radiation exposures. For example, when 1,000,000 females have received an acute 10 mSv, the total number of radiation-induced fatal cancers is 835. The total number of person-years of life lost is 1.4 x 10(4) or an average of about 5 d. However, the 22 who die of leukemia suffer an average of about 34 y. Those who die of other forms of cancer lose an average of 16 y. Some examples have been reported by the U.S. National Academy of Sciences (1990) report. In those cases where the Committee presented results, the method given here is in good agreement.

Age Factors↗