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Biomedical subjects

T Jacobson

Publications and source records attributed to T Jacobson.

At least 19 recordsLinked to original sources
PubMed2004

New limits on Planck scale Lorentz violation in QED.

Constraints on possible Lorentz symmetry violation (LV) of order E/M(Planck) for electrons and photons in the framework of effective field theory (EFT) are discussed. Using (i) the report of polarized MeV emission from GRB021206 and (ii) the absence of vacuum Cerenkov radiation from synchrotron electrons in the Crab Nebula, we improve previous bounds by 10(-10) and 10(-2), respectively. We also show that the LV parameters for positrons and electrons are different, discuss electron helicity decay, and investigate how prior constraints are modified by the relations between LV parameters implied by EFT.

Journal Article↗
PubMed2003

A strong astrophysical constraint on the violation of special relativity by quantum gravity.

Special relativity asserts that physical phenomena appear the same to all unaccelerated observers. This is called Lorentz symmetry and relates long wavelengths to short ones: if the symmetry is exact it implies that space-time must look the same at all length scales. Several approaches to quantum gravity, however, suggest that there may be a microscopic structure of space-time that leads to a violation of Lorentz symmetry. This might arise because of the discreteness or non-commutivity of space-time, or through the action of extra dimensions. Here we determine a very strong constraint on a type of Lorentz violation that produces a maximum electron speed less than the speed of light. We use the observation of 100-MeV synchrotron radiation from the Crab nebula to improve the previous limit by a factor of 40 million, ruling out this type of Lorentz violation, and thereby providing an important constraint on theories of quantum gravity.

Journal Article↗
PubMed2001

Volatile anesthetics give a false-positive reading in chemical agent monitors in the "H" mode.

Chemical agent monitors (CAMs) are routinely used by the armed forces and emergency response teams of many countries for the detection of the vesicant sulfur mustard (HD) and the G series of organophosphate nerve agents. Ambient operating room isoflurane levels were found to produce strong positive signals in the "H" mode when the CAM was used to monitor the efficacy of decontamination procedures during routine surgical procedures on HD-poisoned animals requiring up to 8 hours of general anesthesia. Subsequent testing showed that isoflurane, as well as desflurane, sevoflurane, halothane and methoxyflurane, produce two ionization peaks in the CAM response. One of these peaks is interpreted by the CAM processing software as HD, resulting in a CAM "H" mode bar response. No interference was encountered with isoflurane, desflurane, and sevoflurane when the CAM was set to the "G" mode, although extremely high (nonclinical) concentrations of halothane and methoxyflurane yielded a weakly positive bar response. These findings have potentially serious ramifications for the medical management of patients resulting from terrorist, military, or chemical agent decommissioning activity when concomitant chemical injuries are also possible.

Anesthetics↗
PubMed1998

Effects of milk or water on lunch intake in preschool children.

In Sweden, milk and milk products are important sources of daily energy intake but the role of milk with preschool lunch meals has been debated frequently and water is often alternatively given today. We studied the effects of milk or water on lunch energy intake. Water or milk alternatively was served in a controlled, within-subject design on 12 occasions to 36 children aged 4-6 years, and energy intake was analysed at an individual level in three typical preschool lunches with a varying degree of preference among the children. When milk was given with the meals, a mean additional energy intake of 17% (p<0.0001) was found. The pattern was similar among boys and girls and irrespective of the lunch dish served. However, for the least preferred dish (fish with potatoes) milk helped to increase the energy intake by 26%. Physical activity measured as MET units (energy expenditure/body weight), atmosphere at the table as registered by a three-graded scale, and meal duration did not differ with meals or milk/water. Milk with preschool lunch meals seems to be a significant source of energy to achieve nutritional goals for this group of children.

Animals↗
PubMed1998

Testing the Uniform Needs Assessment Instrument for hospital discharge planning with older adults.

The Uniform Needs Assessment Instrument (UNAI) was developed to systematically assess the continuing care needs of high-risk older adults in response to the 1986 Omnibus Budget Reconciliation Act. Based on previous studies, a revised UNAI was tested with 103 hospitalized older adults, comparing usual discharge planning with the UNAI. High interrater reliability was obtained. The UNAI had high (> or = 85%) sensitivity and specificity when comparing needs identification on the UNAI with subjects' reported needs at 10 to 14 days after discharge. Overall, the UNAI was more effective (sensitive and specific).

Aftercare↗
PubMed1997

Stricture and pouchitis after ileal pouch-anal anastomosis.

Ileal pouch-anal anastomosis is a surgical procedure used for the treatment of people with chronic ulcerative colitis and familial adenomatous polyposis. The surgery is intended to preserve anal sphincter function, but it carries a risk for certain complications, including pouchitis and anastomotic stricture. The purpose of this article is to review the clinical manifestations, causes, and treatment of anastomotic stricture and pouchitis after ileal pouch-anal anastomosis.

Anastomosis, Surgical↗
PubMed1996

Standardized ET nursing database: imagine the possibilities.

A national database of the components of ET nursing practice currently does not currently exist. Justification for ET nurse services requires hard data that demonstrate quality and cost-effectiveness of care. Lacking hard data, the value of the services provided by ET nurses remains difficult to quantify. The Nursing Minimum Data Set is the first step in building a nursing database. The purpose of this article is to familiarize ET nurses with the concepts of nursing information systems, the Nursing Minimum Data Set, and classification systems. Implications for ET nursing practice are also presented.

Cost-Benefit Analysis↗
PubMed1995

Modeling unemployment duration in a dependent competing risks framework: identification and estimation.

Three Mixed Proportional Hazard models for estimation of unemployment duration when attrition is present are considered. The virtue of these models is that they take account of dependence between failure times in a multivariate failure time distribution context. However, identification in dependent competing risks models is not straightforward. We show that these models, independently derived, are special cases of a general frailty model. It is also demonstrated that the three models are identified by means of identification of the general model. An empirical example illustrates the approach to model dependent failure times.

Humans↗
PubMed1994

Long-term treatment of hypercholesterolemia with dietary fiber.

PURPOSE: To evaluate the hypocholesterolemic effects of long-term treatment (36 to 51 weeks) with a mixture of dietary fibers (guar gum, pectin, soy, pea, corn bran) administered twice a day. PATIENTS AND METHODS: Fifty-nine subjects with moderate hypercholesterolemia who completed a 15-week, placebo-controlled study with the dietary fiber were treated for an additional 36 weeks with 20 g/day of fiber. Subjects were counseled and monitored on a National Cholesterol Education Program (NCEP) Step-One Diet before starting and during treatment. Analyses of changes in lipoprotein values during the additional 36 weeks of treatment took into account changes in weight, diet, and other variables that might have affected the response to treatment. RESULTS: There were no significant effects on the levels of either triglycerides or high-density lipoprotein cholesterol (HDL-C). Levels of total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) and the LDL/HDL ratio were significantly reduced during treatment. The mean percentage reductions from baseline after 51 weeks of treatment were approximately 5% for TC, 9% for LDL-C, and 11% for the LDL/HDL ratio. Changes were apparent after 3 weeks of treatment, with the maximum reductions occurring by the 15th week of treatment. CONCLUSIONS: For subjects on a Step-One Diet who complied with the treatment regimen, the moderate cholesterol-lowering effects of the fiber persisted throughout the 36-to-51 week treatment period.

Chi-Square Distribution↗
PubMed1994

Sympathomimetic drug abuse masking an endogenous hyperadrenergic state, Graves' disease.

Sympathomimetic drug use or abuse in a thyrotoxic individual can be clinically devastating as a result of enhanced cellular sensitivity to adrenergic stimulation. Thus, it is critical to recognize thyrotoxicosis in a patient with coexistent sympathomimetic drug abuse. This case report describes a patient with Graves' disease and severe hyperadrenergic symptomatology that was thought to result from sympathomimetic drug abuse.

Adolescent↗