Validation of a new spectrometer for noninvasive measurement of cardiac output

Acetylene is a blood-soluble gas and for many years its uptake rate during rebreathing tests has been used to calculate the flow rate of blood through the lungs (normally equal to cardiac output) as well as the volume of lung tissue. A new, portable, noninvasive instrument for cardiac output determination using the acetylene uptake method is described. The analyzer relies on nondispersive IR absorption spectroscopy as its principle of operation and is configured for extractive (side-stream) sampling. The instrument affords exceptionally fast (30 ms, 10%–90%, 90%–10%, at 500 mL min–1 flow rates), interference-free, simultaneous measurement of acetylene, sulfur hexafluoride (an insoluble reference gas used in the cardiac output calculation), and carbon dioxide (to determine alveolar ventilation), with good (typically ±2% full-scale) signal-to-noise ratios. Comparison tests with a mass spectrometer using serially diluted calibration gas samples gave excellent (R2>0.99) correlation for all three gases, validating the IR system's linearity and accuracy. A similar level of agreement between the devices also was observed during human subject C2H2 uptake tests (at rest and under incremental levels of exercise), with the instruments sampling a common extracted gas stream. Cardiac output measurements by both instruments were statistically equivalent from rest to 90% of maximal oxygen consumption; the physiological validity of the measurements was confirmed by the expected linear relationship between cardiac output and oxygen consumption, with both the slope and intercept in the published range. These results indicate that the portable, low-cost, rugged prototype analyzer discussed here is suitable for measuring cardiac output noninvasively in a point-of-care setting

Doctoral advising, research productivity and the academic balancing act: insights from Michael A. Hitt, Edwin A. Locke, Fred Luthans, Lyman W. Porter, and Anne Tsui

Achieving academic success requires diligence among all concerned – doctoral students, academic advisors, and institutions. This paper presents interviews of five outstanding scholars who have dedicated their lives to research productivity, academic advising, and scholarly service. The work/life balance and output they achieved is the result of purposeful planning, tenacity, and passion for the field and students. The paper first introduces the topic of academic success, then initial thoughts from the authors are presented. Brief biographies of the scholars are shared to demonstrate academic contributions. Interviews are presented as direct quotes from participants, with collective insights offered after each specific question

Aging and aerobic fitness affect the contribution of noradrenergic sympathetic nerves to the rapid cutaneous vasodilator response to local heating

Sedentary aging results in a diminished rapid cutaneous vasodilator response to local heating. We investigated whether this diminished response was due to altered contributions of noradrenergic sympathetic nerves; assessing 1) the age-related decline and, 2) the effect of aerobic fitness. We measured skin blood flow (SkBF)(laser-Doppler flowmetry) in young (24±1 yr) and older (64±1 yr) endurance-trained and sedentary men (n=7 per group) at baseline and during 35 min of local skin heating to 42 °C at three forearm sites: 1) untreated; 2) bretylium tosylate (BT), preventing neurotransmitter release from noradrenergic sympathetic nerves; and 3) yohimbine and propranolol (YP), antagonising α- and β-adrenergic receptors. SkBF was converted to cutaneous vascular conductance (CVC) (SkBF/mean arterial pressure) and normalized to maximal CVC (%CVCmax) achieved by skin heating to 44 °C. Pharmacological agents were administered using microdialysis. In the young trained, the rapid vasodilator response was reduced at the BT and YP sites (P0.05) but treatment with BT did (P>0.05). Neither BT nor YP treatments affected the rapid vasodilator response in the older sedentary group (P>0.05). These data suggest that the age-related reduction in the rapid vasodilator response is due to an impairment of sympathetic-dependent mechanisms, which can be partly attenuated with habitual aerobic exercise. Rapid vasodilation involves noradrenergic neurotransmitters in young trained men, and non-adrenergic sympathetic cotransmitters (e.g., neuropeptide Y) in young sedentary and older trained men, possibly as a compensatory mechanism. Finally, in older sedentary men, the rapid vasodilation appears not to involve the sympathetic system

Artificial photosynthesis: semiconductor photocatalytic fixation of CO_2 to afford higher organic compounds

Carbon dioxide is an appealing renewable feedstock for industrial chemical processes. This does not mean, however, that all chemical processes using CO_2 are environmentally-friendly. Perspectives on the sustainability of CO_2 utilization and artificial photosynthesis are provided. The discussions focus on the photocatalytic production of C_x (x ≥ 2) compounds, where all the carbon in the products is derived from CO_2. This area of research, while promising, has received far less attention than analogous systems leading to C_1 products

Pathways of Understanding: the Interactions of Humanity and Global Environmental Change

How humans, interacting within social systems, affect and are affected by global change is explored. Recognizing the impact human activities have on the environment and responding to the need to document the interactions among human activities, the Consortium for International Earth Science Information Network (CIESIN) commissioned a group of 12 scientists to develop a framework illustrating the key human systems that contribute to global change. This framework, called the Social Process Diagram, will help natural and social scientists, educators, resource managers and policy makers envision and analyze how human systems interact among themselves and with the natural system. The Social Process Diagram consists of the following blocks that constitute the Diagram's structural framework: (1) fund of knowledge and experience; (2) preferences and expectations; (3) factors of production and technology; (4) population and social structure; (5) economic systems; (6) political systems and institutions; and (7) global scale environmental processes. To demonstrate potential ways the Diagram can be used, this document includes 3 hypothetical scenarios of global change issues: global warming and sea level rise; the environmental impact of human population migration; and energy and the environment. These scenarios demonstrate the Diagram's usefulness for visualizing specific processes that might be studied to evaluate a particular global change issues. The scenario also shows that interesting and unanticipated questions may emerge as links are explored between categories on the Diagram

Adoptive transfer of cytomegalovirus-specific CTL to stem cell transplant patients after selection by HLA–peptide tetramers

Stem cell transplantation is used widely in the management of a range of diseases of the hemopoietic system. Patients are immunosuppressed profoundly in the early posttransplant period, and reactivation of cytomegalovirus (CMV) remains a significant cause of morbidity and mortality. Adoptive transfer of donor-derived CMV-specific CD8(+) T cell clones has been shown to reduce the rate of viral reactivation; however, the complexity of this approach severely limits its clinical application. We have purified CMV-specific CD8(+) T cells from the blood of stem cell transplant donors using staining with HLA-peptide tetramers followed by selection with magnetic beads. CMV-specific CD8(+) cells were infused directly into nine patients within 4 h of selection. Median cell dosage was 8.6 x 10(3)/kg with a purity of 98% of all T cells. CMV-specific CD8(+) T cells became detectable in all patients within 10 d of infusion, and TCR clonotype analysis showed persistence of infused cells in two patients studied. CMV viremia was reduced in every case and eight patients cleared the infection, including one patient who had a prolonged history of CMV infection that was refractory to antiviral therapy. This novel approach to adoptive transfer has considerable potential for antigen-specific T cell therapy

Visible Region Photooxidation on TiO_2 with a Chromophore−Catalyst Molecular Assembly

Nanocrystalline films of TiO_2 derivatized by adsorption of polypyridyl complexes of RuII have provided a basis for a family of solution photoelectrochemical devices. At the molecular level, a key feature in these devices is irreversible photoinjection into the TiO_2 conduction band following metal-to-ligand charge-transfer (MLCT) excitation giving Ru^(III). Reduction of Ru^(III) by I^- followed by I_3^- reduction at the anode completes the cell. It should be possible to exploit this basic scheme for the photoproduction of high-energy chemicals, and we report preliminary results on such an example based on an adsorbed chromophore−oxidant molecular assembly

Visible Region Photooxidation on TiO_2 with a Chromophore−Catalyst Molecular Assembly

Nanocrystalline films of TiO_2 derivatized by adsorption of polypyridyl complexes of RuII have provided a basis for a family of solution photoelectrochemical devices. At the molecular level, a key feature in these devices is irreversible photoinjection into the TiO_2 conduction band following metal-to-ligand charge-transfer (MLCT) excitation giving Ru^(III). Reduction of Ru^(III) by I^- followed by I_3^- reduction at the anode completes the cell. It should be possible to exploit this basic scheme for the photoproduction of high-energy chemicals, and we report preliminary results on such an example based on an adsorbed chromophore−oxidant molecular assembly