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Walker JF, Jansen RK, Zanis MJ, Emery NC. Sources of inversion variation in the small single copy (SSC) region of chloroplast genomes. AMERICAN JOURNAL OF BOTANY 2015; 102:1751-2. [PMID: 26546126 DOI: 10.3732/ajb.1500299] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 09/29/2015] [Indexed: 05/02/2023]
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Walker JF, Zanis MJ, Emery NC. Correction to "Comparative analysis of complete chloroplast genome sequence and inversion variation in Lasthenia burkei (Madieae, Asteraceae)". AMERICAN JOURNAL OF BOTANY 2015; 102:1008. [PMID: 26101424 DOI: 10.3732/ajb.1500990] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
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Linton AL, Richmond JM, Walker JF, Sibbald WJ. Proteinuria and renal pathology in generalized sepsis. CONTRIBUTIONS TO NEPHROLOGY 2015; 42:118-22. [PMID: 6398190 DOI: 10.1159/000409970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Walker JF, Zanis MJ, Emery NC. Comparative analysis of complete chloroplast genome sequence and inversion variation in Lasthenia burkei (Madieae, Asteraceae). AMERICAN JOURNAL OF BOTANY 2014; 101:722-9. [PMID: 24699541 DOI: 10.3732/ajb.1400049] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
PREMISE OF THE STUDY Complete chloroplast genome studies can help resolve relationships among large, complex plant lineages such as Asteraceae. We present the first whole plastome from the Madieae tribe and compare its sequence variation to other chloroplast genomes in Asteraceae. METHODS We used high throughput sequencing to obtain the Lasthenia burkei chloroplast genome. We compared sequence structure and rates of molecular evolution in the small single copy (SSC), large single copy (LSC), and inverted repeat (IR) regions to those for eight Asteraceae accessions and one Solanaceae accession. KEY RESULTS The chloroplast sequence of L. burkei is 150 746 bp and contains 81 unique protein coding genes and 4 coding ribosomal RNA sequences. We identified three major inversions in the L. burkei chloroplast, all of which have been found in other Asteraceae lineages, and a previously unreported inversion in Lactuca sativa. Regions flanking inversions contained tRNA sequences, but did not have particularly high G + C content. Substitution rates varied among the SSC, LSC, and IR regions, and rates of evolution within each region varied among species. Some observed differences in rates of molecular evolution may be explained by the relative proportion of coding to noncoding sequence within regions. CONCLUSIONS Rates of molecular evolution vary substantially within and among chloroplast genomes, and major inversion events may be promoted by the presence of tRNAs. Collectively, these results provide insight into different mechanisms that may promote intramolecular recombination and the inversion of large genomic regions in the plastome.
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Stoehr AM, Walker JF, Monteiro A. Spalt expression and the development of melanic color patterns in pierid butterflies. EvoDevo 2013; 4:6. [PMID: 23419038 PMCID: PMC3610209 DOI: 10.1186/2041-9139-4-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2012] [Accepted: 12/04/2012] [Indexed: 03/06/2023] Open
Abstract
Background Little is currently known about wing pattern development in the butterfly family Pieridae, which consists mostly of black melanized elements on white or yellow/orange backgrounds. A single transcription factor, Spalt (Sal), has been previously associated with the development of some pattern elements in Pieris rapae, but it is unclear to what extent Sal is associated with patterns in other pierid species. Results We use immunohistochemistry targeting Sal proteins across several pierids and show that Sal is associated with dense patches of melanization across species but is not associated with vein-melanization or diffuse melanization on the wing. In addition, Sal is expressed along cross-veins and wing compartment midlines that do not develop melanization. Male and female P. rapae spots are sexually dimorphic in size and this dimorphism is also present in the domains of Sal expression. Finally, by disrupting cells positioned in the center of the anterior black spots of P. rapae, before and during the time of Sal expression, spot size was reduced. Conclusions Our results suggest, but do not conclusively show, that pierid spots may develop in a manner similar to that of nymphalid eyespots, that is, containing a group of signaling cells at the center of the pattern responsible for the differentiation of the complete spot, and that spots and eyespots share at least one signal-response gene in common, the transcription factor Sal. We propose that focal differentiation and focal signaling mechanisms evolved prior to the split of the nymphalid and pierid lineages.
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Klasson KT, Taylor PA, Walker JF, Jones SA, Cummins RL, Richardson SA. Modification of a Centrifugal Separator for In-Well Oil-Water Separation. SEP SCI TECHNOL 2011. [DOI: 10.1081/ss-200042503] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Stewart KE, Cianfrini LR, Walker JF. Stress, social support and housing are related to health status among HIV-positive persons in the deep south of the United States. AIDS Care 2010; 17:350-8. [PMID: 15832883 DOI: 10.1080/09540120412331299780] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Self-report health status measures are consistently associated with medical outcomes and are cost-effective. Studies using such measures find that those who live in rural areas or have limited access to support experience poorer health status and poorer outcomes. A survey addressing these issues was administered to 401 HIV-positive persons throughout Alabama. Hierarchical regression models examined the relation of housing stability, stress, substance use and other variables to physical (PCS) and mental (MCS) health status. The sample was 34% female and 66% African-American. Most were receiving antiretroviral medications, and nearly 20% were in unstable housing. Age showed a significant negative relationship to health status. CD4 cell count (p < 0.01) was positively associated with PCS; perceived general stress (p < 0.02) and housing stability (p < 0.04) were negatively associated. The model accounted for 14% of the variance in PCS (p < 0.001). For MCS, general stress (p < 0.001) was negatively associated and substance use tended towards a negative association (p < 0.075). Social support (p < 0.02) was positively associated with MCS. The model accounted for nearly 31% of the MCS variance (p < 0.001). Health status among HIV-positive persons may be improved by assessing and addressing social issues such as social isolation, life stressors and housing.
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Zhang JW, Walker JF, Guardiola J, Yu J. Pulmonary sensory and reflex responses in the mouse. J Appl Physiol (1985) 2006; 101:986-92. [PMID: 16675617 DOI: 10.1152/japplphysiol.00161.2006] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mouse model research is proliferating because of its readiness for genetic manipulation. Little is known about pulmonary vagal afferents in mice, however. The purpose of this study was to determine whether their pulmonary afferents are similar to those in large animals. Single-unit activity was recorded in the cervical vagus nerve of anesthetized, open-chest, and mechanically ventilated mice. We evaluated airway sensory activity in 153 single units; 141 were mechanosensitive, with 134 inflation receptors and 7 deflation receptors. The remaining 12 receptors were chemosensitive and mechanically insensitive, showing low basal firing frequency and behaving like C-fiber or high-threshold Adelta-receptors. In separate studies, phrenic activity was recorded as an index of respiratory drive to assess pulmonary reflexes. Lung inflation produced a typical Hering-Breuer reflex, and intravenous injection of phenylbiguanide produced the typical chemoreflex resulting in apnea, bradycardia, and hypotension. These reflexes were blocked by bilateral vagotomy. We conclude that mice possess a similar set of airway sensors and pulmonary reflexes as typically found in larger animals.
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Yu J, Lin SX, Zhang JW, Walker JF. Pulmonary nociceptors are potentially connected with neuroepithelial bodies. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2006; 580:301-6; discussion 351-9. [PMID: 16683735 DOI: 10.1007/0-387-31311-7_46] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Peters NE, Shanley JB, Aulenbach BT, Webb RM, Campbell DH, Hunt R, Larsen MC, Stallard RF, Troester J, Walker JF. Water and solute mass balance of five small, relatively undisturbed watersheds in the U.S. THE SCIENCE OF THE TOTAL ENVIRONMENT 2006; 358:221-42. [PMID: 15978657 DOI: 10.1016/j.scitotenv.2005.04.044] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2004] [Accepted: 03/25/2005] [Indexed: 05/03/2023]
Abstract
Geochemical mass balances were computed for water years 1992-1997 (October 1991 through September 1997) for the five watersheds of the U.S. Geological Survey Water, Energy, and Biogeochemical Budgets (WEBB) Program to determine the primary regional controls on yields of the major dissolved inorganic solutes. The sites, which vary markedly with respect to climate, geology, physiography, and ecology, are: Allequash Creek, Wisconsin (low-relief, humid continental forest); Andrews Creek, Colorado (cold alpine, taiga/tundra, and subalpine boreal forest); Río Icacos, Puerto Rico (lower montane, wet tropical forest); Panola Mountain, Georgia (humid subtropical piedmont forest); and Sleepers River, Vermont (humid northern hardwood forest). Streamwater output fluxes were determined by constructing empirical multivariate concentration models including discharge and seasonal components. Input fluxes were computed from weekly wet-only or bulk precipitation sampling. Despite uncertainties in input fluxes arising from poorly defined elevation gradients, lack of dry-deposition and occult-deposition measurements, and uncertain sea-salt contributions, the following was concluded: (1) for solutes derived primarily from rock weathering (Ca, Mg, Na, K, and H(4)SiO(4)), net fluxes (outputs in streamflow minus inputs in deposition) varied by two orders of magnitude, which is attributed to a large gradient in rock weathering rates controlled by climate and geologic parent material; (2) the net flux of atmospherically derived solutes (NH(4), NO(3), SO(4), and Cl) was similar among sites, with SO(4) being the most variable and NH(4) and NO(3) generally retained (except for NO(3) at Andrews); and (3) relations among monthly solute fluxes and differences among solute concentration model parameters yielded additional insights into comparative biogeochemical processes at the sites.
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Soukhova G, Wang Y, Ahmed M, Walker JF, Yu J. Bradykinin stimulates respiratory drive by activating pulmonary sympathetic afferents in the rabbit. J Appl Physiol (1985) 2003; 95:241-9. [PMID: 12679361 DOI: 10.1152/japplphysiol.00582.2002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We recently identified a vagally mediated excitatory lung reflex by injecting hypertonic saline into the lung parenchyma (Yu J, Zhang JF, and Fletcher EC. J Appl Physiol 85: 1485-1492, 1998). This reflex increased amplitude and burst rate of phrenic (inspiratory) nerve activity and suppressed external oblique abdominal (expiratory) muscle activity. In the present study, we tested the hypothesis that bradykinin may activate extravagal pathways to stimulate breathing by assessing its reflex effects on respiratory drive. Bradykinin (1 microg/kg in 0.1 ml) was injected into the lung parenchyma of anesthetized, open-chest and artificially ventilated rabbits. In most cases, bradykinin increased phrenic amplitude, phrenic burst rate, and expiratory muscle activity. However, a variety of breathing patterns resulted, ranging from hyperpnea and tachypnea to rapid shallow breathing and apnea. Bradykinin acts like hypertonic saline in producing hyperpnea and tachypnea, yet the two agents clearly differ. Bradykinin produced a higher ratio of phrenic amplitude to inspiratory time and had longer latency than hypertonic saline. Although attenuated, bradykinin-induced respiratory responses persisted after vagotomy. We conclude that bradykinin activates multiple afferent pathways in the lung; portions of its respiratory reflexes are extravagal and arise from sympathetic afferents.
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Walker JF, Kane CJ. Effects of body mass on nicotine-induced thermogenesis and catecholamine release in male smokers. SHENG LI XUE BAO : [ACTA PHYSIOLOGICA SINICA] 2002; 54:405-10. [PMID: 12399821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/27/2023]
Abstract
The aims of this study were to examine the effects of nicotine on resting energy expenditure (REE) and plasma catecholamine release following ad libitum smoking in fasted, middle-aged males; and, to determine if the acute responses in REE and catecholamine release to smoking differ between normal weight (< or = 25 kg/m(2)) and overweight (> 25 kg/m(2)) smoker groups. REE was measured by indirect calorimetry in 32 fasted male smokers prior to, and 30 minutes after, consuming either two 0.16 mg nicotine (low yield) or two 1.74 mg nicotine (high yield) cigarettes. Plasma nicotine and norepinephrine levels were simultaneously measured. There was no thermic effect of nicotine or catecholamine response after smoking low yield cigarettes in both groups, nor after smoking high yield cigarettes in the overweight group. In contrast, REE increased 7.2%, which was accompanied by an increase in plasma norepinephrine release, after smoking high yield cigarettes in the normal weight group. Controlling plasma nicotine level ablated these increases. In conclusion, body mass interacts with the thermic effect of nicotine and neuroendocrine function in male smokers. Smoking-induced increase in the plasma nicotine level accounts for the observed responses, which are blunted in overweight smokers. This finding may have implications for potential weight gain following smoking cessation by normal weight individuals, related to lost smoking-induced thermogenesis.
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Devereux RB, Palmieri V, Sharpe N, De Quattro V, Bella JN, de Simone G, Walker JF, Hahn RT, Dahlöf B. Effects of once-daily angiotensin-converting enzyme inhibition and calcium channel blockade-based antihypertensive treatment regimens on left ventricular hypertrophy and diastolic filling in hypertension: the prospective randomized enalapril study evaluating regression of ventricular enlargement (preserve) trial. Circulation 2001; 104:1248-54. [PMID: 11551875 DOI: 10.1161/hc3601.095927] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND The Prospective Randomized Enalapril Study Evaluating Regression of Ventricular Enlargement (PRESERVE) study was designed to test whether enalapril achieves greater left ventricular (LV) mass reduction than does a nifedipine gastrointestinal treatment system by a prognostically meaningful degree on a population basis (10 g/m(2)). METHODS AND RESULTS An ethnically diverse population of 303 men and women with essential hypertension and increased LV mass at screening echocardiography were enrolled at clinical centers on 4 continents and studied by echocardiography at baseline and after 6- and 12-month randomized therapy. Clinical examination and blinded echocardiogram readings 48 weeks after study entry in an intention-to-treat analysis of 113 enalapril-treated and 122 nifedipine-treated patients revealed similar reductions in systolic/diastolic pressure (-22/12 versus -21/13 mm Hg) and LV mass index (-15 versus -17g/m(2), both P>0.20). No significant between-treatment difference was detected in population subsets defined by monotherapy treatment, sex, age, race, or severity of baseline hypertrophy. Similarly, there was no between-treatment difference in change in velocities of early diastolic or atrial phase transmitral blood flow. More enalapril-treated than nifedipine-treated patients required supplemental treatment with hydrochlorothiazide (59% versus 34%, P<0.001) but not atenolol (27% versus 22%, NS). CONCLUSIONS Once-daily antihypertensive treatment with enalapril or long-acting nifedipine, plus adjunctive hydrochlorothiazide and atenolol when needed to control blood pressure, both had moderately beneficial and statistically indistinguishable effects on regression of LV hypertrophy.
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FitzGerald GR, Walker JF, Cuddihy J. Clinical winter. IRISH MEDICAL JOURNAL 2000; 93:196-7. [PMID: 11142951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
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Walker JF, Collins LC, Rowell PP, Goldsmith LJ, Moffatt RJ, Stamford BA. The effect of smoking on energy expenditure and plasma catecholamine and nicotine levels during light physical activity. Nicotine Tob Res 1999; 1:365-70. [PMID: 11072434 DOI: 10.1080/14622299050011501] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
A number of studies have found that cigarette smoking causes an acute increase in resting energy expenditure, but the effect on energy expenditure during light physical activity is less clear. Since both smoking and activity have been shown to increase plasma catecholamines, these could produce additive effects on energy expenditure when smoking during light physical activity. In this study, the impact of cigarette smoking on energy expenditure, cardiovascular function, plasma nicotine and plasma catecholamine levels was determined in adult male subjects at rest and while engaged in light physical activity. Smoking at rest resulted in a 3.6% increase in energy expenditure above the resting baseline; whereas the increase in energy expenditure caused by smoking during light physical activity (compared with the light physical activity baseline) was 6.3%. This increase during light physical activity was significantly greater than the increase observed at rest (p < 0.025). As expected, plasma nicotine increased with smoking during both rest and light physical activity. An increase in plasma nicotine was associated with smoking during light physical activity. When this increase was adjusted as a covariate, the difference in smoking-related energy expenditure between light physical activity and rest disappeared, suggesting nicotine accounts for the effect. Plasma epinephrine and norepinephrine levels increased with smoking and showed a significantly greater increase during light physical activity compared to rest. Cigarette smoking caused a significantly greater increase in heart rate during light physical activity than it did while at rest, but there was no significant effect of smoking on mean blood pressure. It was concluded that there is enhanced energy expenditure associated with cigarette smoking during light physical activity when compared with smoking at rest which could be due in part to smoking-induced increases in circulating plasma catecholamines and perhaps nicotine.
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Nilsen ET, Walker JF, Miller OK, Semones SW, Lei TT, Clinton BD. Inhibition of seedling survival under Rhododendron maximum (Ericaceae): could allelopathy be a cause? AMERICAN JOURNAL OF BOTANY 1999; 86:1597-1605. [PMID: 10562250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In the southern Appalachian mountains a subcanopy species, Rhododendron maximum, inhibits the establishment and survival of canopy tree seedlings. One of the mechanisms by which seedlings could be inhibited is an allelopathic effect of decomposing litter or leachate from the canopy of R. maximum (R.m.) on seed germination, root elongation, or mycorrhizal colonization. The potential for allelopathy by R.m. was tested with two bioassay species (lettuce and cress), with seeds from four native tree species, and with three ectomycorrhizal fungi. Inhibitory influences of throughfall, fresh litter, and decomposed litter (organic layer) from forest with R.m. (+R.m. sites) were compared to similar extractions made from forest without R.m. (-R.m. sites). Throughfall and leachates of the organic layer from both +R.m. and -R.m. sites stimulated germination of the bioassay species above that of the distilled water control, to a similar extent. There was an inhibitory effect of leachates of litter from +R.m. sites on seed germination and root elongation rate of both bioassay species compared with that of litter from -R.m. sites. Native tree seed stratified in forest floor material from both forest types had a slightly higher seed germination rate compared with the control. A 2-yr study of seed germination and seedling mortality of two tree species, Quercus rubra and Prunus serotina, in field plots showed no significant influence of litter or organic layer from either forest type. Incorporating R.m. leaf material into the growth medium in vitro depressed growth of one ectomycorrhizal species but did not affect two other species. Leaf material from other deciduous tree species depressed ectomycorrhizal growth to a similar or greater extent as leaf material from R.m. In conclusion, R.m. litter can have an allelopathic effect on seed germination and root elongation of bioassay species as well as some ectomycorrhizal species. However, this allelopathic affect is not manifest in field sites and is not likely to be an important cause for the inhibition of seedling survival within thickets of R.m.
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Walker JF. New glue, zipper for closing wounds. OR MANAGER 1999; 15:6. [PMID: 10345137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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Walker JF. OR Manager of Year is 'player coach'. OR MANAGER 1998; 14:7. [PMID: 10185626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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Walker JF. Joint preop form smoothes process. OR MANAGER 1998; 14:21-3. [PMID: 10179490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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Walker JF. Beepers can ease families' anxieties. OR MANAGER 1998; 14:20. [PMID: 10179489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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Vatter HG, Walker JF. Support for baby-boom retirees--not to worry. JOURNAL OF ECONOMIC ISSUES 1998; 32:79-86. [PMID: 12349045 DOI: 10.1080/00213624.1998.11506012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Walker JF. Building employee satisfaction: what works? OR MANAGER 1998; 14:31-2. [PMID: 10177906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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