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Biomedical subjects

S A Freeman

Publications and source records attributed to S A Freeman.

11 recordsLinked to original sources
PubMed2006

An investigation of three physical parameters of PTO entanglements.

The PTO driveline is the most common means of transferring power from a tractor to towed machinery and stationary equipment. While equipment manufacturers install shielding to protect operators and bystanders from coming in contact with operating PTO components (particularly around the knuckle), entanglement is still a cause of some of the most catastrophic agricultural work-related injuries. This study investigated the influence of material type, material length, and angle of material introduction on entanglements with a spinning PTO shaft knuckle. These variables were tested using a laboratory PTO apparatus where 165 entanglements were recorded during the 720 trials conducted. The results indicate that lighter materials, such as cotton thread, have a significantly higher probability of becoming entangled than heavier materials, such as leather bootlaces. Materials that were longer (i.e., extend further below the midline of the PTO knuckle) have higher probabilities of becoming entangled than do shorter materials. The horizontal path that the material traveled across the centerline of the PTO shaft impacted the probability of entanglement. When the angle of intersection of the horizontal path of travel relative to the centerline of the PTO shaft is 90 degrees, or close to 90 degrees, a higher probability of entanglement occurs. All 165 entanglements occurred on the downward rotational side of the PTO knuckle regardless of which side the horizontal path of travel started from. The results of this study provide the first look at understanding the physical phenomena associated with the initial stages of PTO entanglements and set the stage for future research.

Accidents, Occupational↗
PubMed2003

Assessment of Iowa farmers' perceptions about auger safety.

A survey of Iowa farmers was conducted to assess the farmers' perceptions and beliefs regarding auger safety and how these perceptions are put into practice. A questionnaire was designed to obtain information on the following auger-related topics: recognition of safe practices and appropriate shielding, personal practices and behaviors, risk perception, and personal beliefs. A random sample of 400 Iowa farmers (arrayed by county) was selected to be representative of Iowa farms. The response to the mailed survey was 23%. Some returned surveys were eliminated because the respondent was retired or did not own/operate augers, resulting in 57 usable questionnaires. Survey responses indicate that the majority of Iowa farmers who participated in this study can correctly identify appropriate shielding for auger intake that meet or exceed ASAE standards. Survey responses suggest that it is common practice in Iowa for youth (age 13 to 19) to operate augers. Iowa farmers in this study perceive the most important contributing factors to auger-related injuries to be operating an auger without shielding, failure to pay attention on the job, moving augers in a raised position, and using hand or feet to redirect the flow of grain. Survey results also indicate that carelessness is perceived to be the leading cause of auger-related injuries, and that auger related injuries can be avoided by having respect for the equipment, being careful, and using common sense. The results also show that the Iowa farmers who participated in this study commonly perform auger-related practices (e.g., moving an auger in a raised position) that they identify as being unsafe.

Accidents, Occupational↗
PubMed2000

Assessment of the condition of Iowa augers, auger-related injuries, and farmers' perceptions about auger-related injuries.

This study provides an insight into auger-related injuries, Iowa farmers' perceptions of auger-related injuries and the condition of augers used in Iowa agriculture. Specific auger-related injury data (437 records) from the Iowa Department of Public Health (IDPH) was examined and interpreted. The most likely body part injured was the finger and 11:00 A.M., 3:00 P.M., and 5:00 P.M. were the times of the day with the highest number of injuries reported. In addition, a survey was administered to 400 farmers to ascertain their awareness of auger-related injuries and to determine the condition of their augers. Farmers' perceptions of what body part is most likely to be injured by an auger and the level of severity expected from those injuries coincided with injury records from 1993 to 1997. A total 34% of the primary and secondary augers reported were unshielded or without guarding. This assessment provides insight for development of intervention countermeasures to reduce auger-related injuries.

Adult↗
PubMed1999

Comparing primary and secondary generalized anxiety disorder in a long-term naturalistic study of anxiety disorders.

This study explores the potential differences in comorbidity and course between primary generalized anxiety disorder (GAD), which develops before other anxiety disorders, and secondary GAD. As part of the Harvard/Brown Anxiety Research Project (HARP), a naturalistic, long-term, longitudinal study of 711 subjects from a variety of clinic settings with DSM III-R defined anxiety disorders, 210 subjects with GAD were identified. Of these, 78 (37%) had primary GAD, and 84 (40%) had secondary GAD; of the remainder, 28 (13%) had no other anxiety disorder and 20 (10%) developed GAD within a month of another anxiety disorder and were excluded from the analysis. All subjects were comorbid for at least one other anxiety disorder. Primary GAD subjects were more likely to be in episode at intake (90% vs. 77%, P = .04) and less likely than secondary GAD subjects to have current or past agoraphobia without panic disorder (3% vs. 11%, P = .04), social phobia (19% v. 52%, P = .001), simple phobia (14% v. 30%, P = .02), or post traumatic stress disorder (5% vs. 20%, P = .01). Subjects with primary GAD were also less likely to have current or past alcohol use disorders (17% vs. 37%, P = .004) or major depressive disorder (60% vs. 76%, P = .03). There were no significant differences in either treatment approaches or remission rates for primary compared to secondary GAD. Whether GAD first occurs before or after another anxiety disorder, it is similar in terms of prevalence, treatment, and course. The only significant differences between primary and secondary GAD lie in the rates of comorbidity of both other anxiety disorders and non-anxiety disorders, including major depression and substance abuse. These results support the concept of GAD as a valid, separate and distinct entity, whether it occurs primarily or secondarily.

Adolescent↗
PubMed1997

Expression of murine interleukin 11 and its receptor alpha-chain in adult and embryonic tissues.

Interleukin 11 (IL-11) is a multifunctional cytokine that has diverse effects on blood cells and their precursors and on a number of cell types outside of the hematopoietic system. The cDNAs encoding murine IL-11 and its receptor alpha-chain (IL-11R alpha) have recently been isolated. We have used the RNase protection assay to examine the expression of murine IL-11 and IL-11R alpha in a range of adult mouse tissues, in embryos, and during development of embryonic stem (ES) cells into cystic embryoid bodies in vitro. The testis showed a high level of IL-11 gene expression while a much lower level of expression was detected in the lung, stomach, small intestine, and large intestine. Expression of IL-11 was not detected between day 10.5 and day 18.5 post coitum of embryonic development or in differentiating ES cells in vitro. In contrast, the IL-11R alpha was found to be expressed in all adult tissues examined, during embryonic development, and in totipotent and differentiating ES cells.

Animals↗
PubMed1996

The Dtk receptor tyrosine kinase, which binds protein S, is expressed during hematopoiesis.

Dtk (Tyro 3/Sky/Rse/Brt/Tif) belongs to a recently recognized subfamily of receptor tyrosine kinases that also includes Ufo (Axl/Ark) and Mer (Eyk). Ligands for Dtk and Ufo have been identified as protein S and the related molecule Gas6, respectively. This study examined expression of Dtk during ontogeny of the hematopoietic system and compared the pattern of expression with that of Ufo. Both receptors were abundantly expressed in differentiating embryonic stem cells, yolk sac blood islands, para-aortic splanchnopleural mesoderm, fractionated AA4+ fetal liver cells, and fetal thymus from day 14 until birth. Although Ufo was expressed at moderate levels in adult bone marrow, expression of Dtk in this tissue was barely detectable. In adult bone marrow subpopulations fractionated using counterflow centrifugal elutriation, immunomagnetic bead selection for lineage-depletion and FACS sorting for c-kit expression, very low levels of Dtk and/or Ufo were detected in some cell fractions. These results suggest that Dtk and Ufo are likely to be involved in the regulation of hematopoiesis, particularly during the embryonic stages of blood cell development.

Animals↗
PubMed1994

Theory of electroporation of planar bilayer membranes: predictions of the aqueous area, change in capacitance, and pore-pore separation.

A large increase in the transmembrane voltage, U(t), of a fluid bilayer membrane is believed to result in the occurrence of temporary aqueous pathways ("pores") across the membrane. The number, size, and evolution dynamics of these pores are expected to be crucial to the transport of water-soluble species ranging from small ions to macromolecules such as proteins and nucleic acids. In this paper we use a transient aqueous pore theory to estimate the fraction of the membrane area, Fw(t), which is temporarily occupied by water-filled pores for short square, exponential, and bipolar square pulses. For short pulses, "reversible electrical breakdown" occurs when the transmembrane voltage reaches about 1 V, and Fw(t) is predicted to rise rapidly, but always to be less than 10(-3). The conductance of a large number of pores causes reversible electrical breakdown and prevents a significantly larger U from being reached. Despite the large dielectric constant of water, for reversible electroporation the associated change in membrane capacitance, delta C, due to the pores is predicted to be small. Moreover, for a flat membrane the minimum value of the mean pore-pore separation is large, about 60 times the minimum pore radius. In flat membranes, pores are predicted to repel, but the opposite is expected for curved cell membranes, allowing the possibility of coalescence in cell membranes. For some moderate values of U, rupture (irreversible electrical breakdown) occurs, as one or more supracritical pores expand to the membrane boundary and the entire membrane area becomes aqueous. In all cases it is found that a quantitative description of electroporation requires that a pore size distribution, rather than a single size pore.

Electric Conductivity↗
PubMed1994

Selection of rural assistive technology using a HyperCard-based knowledge system.

Resources and expertise on selecting assistive technology appropriate for an agricultural work setting are scarce. To meet this need a prototype knowledge system for the selection and documentation of rural assistive technology (BNG DATA) was developed to aid professionals working with farmers, ranchers, and agricultural workers with physical disabilities. The knowledge system consists of a hypertext database of technology examples and a decision support system that helps users identify solution alternatives to meet consumers' needs. End-user acceptance of BNG DATA was determined through field trials and an evaluation questionnaire administered to staff of the U.S. Department of Agriculture's AgrAbility Project. Using a statistical experiment in conjunction with the questionnaire, it was concluded that BNG DATA significantly reduced the time required by end users to find acceptable solution alternatives for consumers and increased the end users' confidence in the solutions they obtained. This manuscript describes the development and testing of BNG DATA, focusing on the selection of appropriate technology.

Agriculture↗
PubMed1993

Characterization of a chelator-resistant proteinase from Thermus strain Rt4A2.

The Thermus isolate Rt4A2 was found to produce an extracellular chelator-resistant proteinase. The proteinase was purified to homogeneity by (NH4)2SO4 precipitation, cation-exchange chromatography, gel-filtration chromatography, and weak anion-exchange chromatography. The Rt4A2 proteinase was found to have properties typical of an alkaline serine proteinase. It had a pH optimum of 9.0 and was specifically inhibited by phenylmethanesulphonyl fluoride. Its isoelectric point was greater than 10.25. Its molecular-mass was 31.6 kDa as determined by SDS/PAGE. N-terminal sequencing has shown it to have high sequence similarity with other serine proteinases from Thermus species. The proteinase hydrolysed a number of substrates including fibrin, casein, haemoglobin, collagen, albumin and the synthetic chromogenic peptide substrate Suc-Ala-Ala-Pro-Phe-NH-Np. The specific activity of the purified proteinase using azocasein as substrate was 313 units/mg. Substrate inhibition was observed above an azocasein concentration of 0.05% (w/v). Esterase activity was directed mainly towards those substrates containing the aliphatic or aromatic residues of alanine, glycine, tryptophan, tyrosine and phenylalanine. Thermostability half-lives of greater than 7 days at 70 degrees C, 43 h at 80 degrees C and 90 min at 90 degrees C were found in the presence of 5 mM CaCl2. At 90 degrees C increasing the CaCl2 concentration 100-fold (0.5 mM to 50 mM) caused a 4.3-fold increase in the half-life of the enzyme from 30 to 130 min. Half-lives of 19.4 min at 100 degrees C and 4.4 min at 105 degrees C were found in the presence of 50 mM CaCl2. The metal chelators EGTA and EDTA reduced the stability at higher temperatures but had no effect on the activity of the proteinase. Activity was not stimulated by common metal activators such as Ca2+, Mg2+ and Zn2+.

Amino Acid Sequence↗
PubMed1978

Custom-fitted appliances for intestinal fistulas.

A method for containing troublesome intestinal stomas or fistulas in open wounds is described. Custom-fitted faceplates are made using alginate materials and vulcanizing silicone rubber at room temperature. Three patients have been presented illustrating the rehabilitation and palliation that can be achieved by collaborative interaction between surgeons, enterostomal therapists, and prosthetic technicians.

Adult↗