bluuebunny/crossref_metadata_2025 huggingface dataset:
A NEW METHOD TO MEASURE BULK ELECTRICAL CONDUCTIVITY IN SOILS WITH TIME DOMAIN REFLECTOMETRY
Authors: LOON W. K. P. VAN , PERFECT E. , GROENEVELT P. H. , KAY B. D.
Published: March 2010

The bulk electrical conductivity of a porous medium can be determined by measuring the reflection of an electromagnetic pulse in transmission lines which are installed in this medium (the method is known as Time Domain Reflectometry (TDR)). The reflection is not only influenced by the medium, but also by the measuring system. A new method is described which corrects for influences of the measuring system by comparing a reflection measurement with a reference measurement performed in air. Calibration measurements were made in water and in water-saturated sand and loam soils. Columns with different, well-determined solute concentrations were prepared. Linear regression analyses were performed between the electrical conductivity determined with TDR and the electrical conductivity of the solutions. All slopes were close to one and the correlation coefficients were high: 0.993, 0.993 and 0.968 for water, sand and loam, respectively. For the two soils significant intercepts were found. These might be related to the surface charge of the soil particles. Key words: Dielectric constant, soil water, electrical conductivity, solutes
RELATIVE MEASURES OF SOIL BULK DENSITY TO CHARACTERIZE COMPACTION IN TILLAGE STUDIES ON FINE SANDY LOAMS
Authors: CARTER M. R.
Published: March 2010

Field studies concerned with soil physical properties require methods to quantify and characterize soil compaction, especially for tillage experiments. The bulk densities of a Charlottetown and Gowanbrae fine sandy loam were related to a maximum or standard compaction state for each soil to obtain a measure of relative compaction. The two soils were both classified as Orthic Humo-Ferric Podzols. Relative compaction was closely related to the volume of macropores (r2 = 0.85). Over a 3-yr period, mouldboard ploughing loosened the soil to give an average relative compaction of 77%. Subsequent soil consolidation and settling increased relative compaction to 84% over the growing season. Direct-drilling maintained relative compaction at a limited range of 88–91%. Relative grain yield of cereals was related (r2 = 0.69) using a polynomial curve to relative compaction. A range of 77–84% relative compaction was associated with a relative grain yield ≥ 95%. A relative compaction of 84–89% was considered the equilibrium soil density level for the two soils under study. This range was related to a macropore volume of 13.5–10% which is adequate for permeability but possibly inadequate for optimum soil aeration under a humid soil moisture regime. Overall, relative compaction provided a useful index or standard to assess changes in soil bulk density and proved to be a biologically meaningful soil physical parameter. Key words: Soil compaction indices, relative compaction, Podzolic soil, fine sandy loam, cereal yield
EFFECTS OF INTENSIVE VEGETABLE PRODUCTION ON CHEMICAL PROPERTIES AND NUTRIENT MINERALIZATION OF A BRITISH COLUMBIA HUMISOL
Authors: OLSON B. M. , LOWE L. E.
Published: March 2010

A study was conducted to determine the effects of long-term vegetable production on some organic matter (OM) chemical properties in an organic soil located near Cloverdale, British Columbia. Producers in this area are concerned about yield reduction and some feel this is due to changes in the soil quality. Paired soil samples were collected from two transects: one in a 40-yr-old vegetable field, and the other in an adjacent fence row. The transects were positioned in order to collect samples from a relatively deep organic deposit and from a shallow deposit where a ridge of mineral subsoil had been exposed. Initial analysis showed that cultivation had changed some chemical properties only in the plow layer. The exception was pH which was higher throughout the sample depth of the cultivated transect. Organic matter loss from the cultivated field was estimated 28% by weight, based on ash accumulation. In the cultivated deep organic section (west of the ridge) OM and C contents were reduced by 7.1 and 5.6% respectively, whereas on the cultivated ridge OM, C, N and S contents and the amount of C, N and S mineralized were reduced by 43.3, 41.6, 43.4, 25.9, 42.8, 60.8 and 52.5%, respectively. On an ash-free basis there were no changes in the deep organic section. In the ridge, the OM sulphur content had increased and the amount of N and S mineralized were decreased compared with the uncultivated transect. In the cultivated surface layer, increased S content in the OM was caused by incorporation of a S-rich subsurface layer during tillage operations. Increases in P content in the cultivated transect were attributed to P fertilization. Within the cultivated transect, C, N and S contents in the exposed mineral ridge were 48, 48, and 44%, respectively, lower than in the deep organic surface layer on the west side of the ridge. The C:N ratios were unchanged at about 16. The chemical stability of the OM was attributed to its well-decomposed nature. At this particular site, the degradation due to excessive cultivation was manifested mainly in OM loss, rather than in changes in OM quality. The main concern of producers is to reduce or prevent further loss of soil OM. Key words: Humisol, organic soil, cultivation, mineralizable C, N and S, incubation
KINETICS OF ADSORPTION OF ORGANIC AND INORGANIC PHOSPHATES BY SHORT-RANGE ORDERED PRECIPITATE OF ALUMINUM
Authors: SHANG C. , HUANG P. M. , STEWART J. W. B.
Published: March 2010

The kinetics of the adsorption of orthophosphate (Pi), inositol hexaphosphate (IHP), inositol monophosphate (IMP) and glucose 6-phosphate (G6P) by short-range ordered precipitate of Al were studied at the initial pH 4.50 and in the temperature range of 278–308 K. This information is essential for understanding the rate and energy relationship of the adsorption of phosphates by short-range ordered Al precipitate. The amounts of Pi and IHP adsorbed by the Al precipitate were much higher than those of IMP and G6P adsorbed in the temperature range and reaction periods studied. The adsorption can be divided into two stages, a fast adsorption before 1 h and a slow adsorption between 1 and 24 h. The adsorption at both stages obeyed the first-order kinetics. Among all the phosphates studied, the adsorption of Pi proceeded most rapidly. The rate constants for the adsorption of IHP were much greater than those of G6P and IMP at the same temperature; this was attributed to the functionality of multiple phosphate groups of IHP. The Arrhenius activation energies for the adsorption of Pi, IHP, IMP and G6P, which were estimated from the slow reaction, were 48 ± 2, 89 ± 4, 100 ± 8 and 108 ± 10 KJ/mol P adsorbed, respectively. Key words: Organic phosphate, precipitate of aluminum, adsorption, rate constant, Arrhenius activation energy
RELATIONSHIP BETWEEN PERCENTAGE EMERGENCE AND GROWING DEGREE DAYS FOR CORN
Authors: HAYHOE H. N. , DWYER L. M.
Published: March 2010

Seed bed temperature is often the limiting environmental factor affecting corn (Zea mays L.) emergence, particularly in short-season production areas or when conservation tillage practices are employed. In this study, observations of the percentage emergence and seed bed growing degree days (base 10 °C) are used to assess functions which model the emergence response to temperature. Key words: Percentage emergence, growing degree days, log transformation, logistic function
MANGANESE SOIL TESTS FOR BOTH DEFICIENT AND TOXIC LEVELS IN APPLE ORCHARDS
Authors: NEILSEN D. , Hoyt P. B. , DROUGHT B. G. , NEILSEN G. H.
Published: March 2010

Soil pH and Mn extracted by 1.0 M NH4OAc (pH 7.0), 0.02 M CaCl2, 0.25 M MgCl2, 0.03 M H3PO4, DTPA and HF/HC1 (total Mn) from two soil depths (0–15 cm, 15–30 cm) were compared to leaf Mn concentrations of Delicious apple trees (Malus domestica Borkh) from 34 Okanagan Valley orchards. Leaf Mn concentrations ranged from deficient (below 25 μg g−1) to toxic (above 60 μg g−1). For all orchards (pH 3.5–8.4), leaf Mn concentration varied directly with soil Mn extracted from 15–30 cm depth by all extractants except HF/HCl (total Mn) and 0.03 M H3PO4, and inversely with pH at both depths. For soils with pH > 6.5, DTPA and 0.25 M MgCl2 extractable soil Mn (15–30 cm depth) was most closely related to leaf Mn concentration, whereas for soils with pH < 6.5, pH (15–30 cm depth) was the best indicator of Mn availability. Thus soil tests for Mn availability to apple trees may not perform equally well in toxic and deficient situations. Key words: Manganese, soil test, apple trees, Malus domestica Borkh
LEACHING OF A HIGHLY SALINE-SODIC SOIL IN SOUTHERN ALBERTA: A LABORATORY STUDY
Authors: HARKER D. B. , MIKALSON D. E.
Published: March 2010

Moderate to highly saline-sodic soil cores extracted from a Brown Solodized Solonetzic soil were leached in the laboratory using good-quality irrigation water to determine relative salt removal with time. Leaching curves comparing the relative concentration of salts against the relative depth of leaching water applied were similar over a wide range of salinities and hydraulic conductivities. The time required to transmit an equivalent depth of water through the soil core and achieve a salinity reduction of about 75% ranged from less than 2 d to an estimated 15 mo. The primary limitation to reclamation in these soils was the low hydraulic conductivity rather than the initial salt content or depth of leaching water required. Key words: Reclamation, leaching, hydraulic conductivity, saline-sodic soil
ESTIMATING THE ATTERBERG LIMITS OF SOUTHERN SASKATCHEWAN SOILS FROM TEXTURE AND CARBON CONTENTS
Authors: JONG E. DE , ACTON D. F. , STONEHOUSE H. B.
Published: March 2010

The soil water contents at the liquid and plastic limits (the Atterberg limits) are widely used in the classification of soils for engineering purposes. Approximately 500 soil samples (129 Ap horizons and 417 B and C horizons) collected over several years as part of the ongoing soil survey program in Saskatchewan were analyzed for texture and Atterberg limits. On about half of the samples water retention (−33 kPa and −1500 kPa matric potential and air dryness), and organic and inorganic C were also determined. The relationship between the Atterberg limits and soil properties was explored through correlation and regression analysis. Clay and organic matter content explained most of the observed variation in the Atterberg limits of the Ap horizons. Clay was the most important independent variable in the B and C horizons, while inorganic C had only a relatively small impact. Key words: Atterberg limits, texture, organic and inorganic C
LONG-TERM EFFECT OF DEEP PLOWING SOLONETZIC SOIL ON CHEMICAL CHARACTERISTICS AND CROP YIELD
Authors: McANDREW D. W. , MALHI S. S.
Published: March 2010

Deep plowing (DP) has been investigated as a possible ameliorative procedure for Solonetzic soils, but the long-term effects of DP on soil properties are not known. Soil sampling to determine the long-lasting effects of DP on some soil chemical properties and crop yields was conducted at four sites with Solonetzic soils in east-central Alberta. The soils had been deep plowed 11–29 yr prior to sampling. Compared to adjacent unplowed (check) treatments, DP resulted in significant improvements in soil chemical properties at most of the sites. The sodium adsorption ratio (SAR) of the AB horizon (12- or 15- to 30-cm depth) was lower after DP at all four sites. Extractable and soluble Ca increased in the Ap horizon (0–12 cm) of DP soils, whereas extractable Na decreased in the Ap or AB horizons at three sites. The pH of the Ap horizon increased from acidic to neutral at three sites, while EC of the Ap horizon decreased at two sites. Crop yield increased due to DP at the three sites where yields were measured. The results indicate a long-term amelioration of Solonetzic soils by DP. Key words: Amelioration, deep plowing, deep tillage, sodic soil
EFFECTS OF INTENSIVE VEGETABLE PRODUCTION ON THE HYDROLYZABLE CARBON, NITROGEN AND SULPHUR OF A BRITISH COLUMBIA HUMISOL
Authors: OLSON B. M. , LOWE L. E.
Published: March 2010

Acid hydrolysis was used to examine organic matter (OM), C, N and S in adjacent uncultivated and cultivated (40 yr) sections of a humisol. Paired soil samples were collected along two transects, both of which included deep organic soil and an exposed mineral ridge. About one-third of the OM was hydrolyzed. Cultivation had no effect on hydrolysis of the deep organic soil, whereas the amount hydrolyzed was significantly reduced by 4.1% in the ridge samples. Total C hydrolyzed ranged from 22.8 to 26.9% with no effect caused by cultivation or transect position relative to the ridge. In contrast, 71.1–80.4% of total N and 39.1 to 49.3% of total S were hydrolyzed. Cultivation significantly reduced the proportion of total N hydrolyzed in the deep organic soil and the proportion of total S hydrolyzed in both the deep organic soil and the ridge sections. On a total soil weight basis, cultivation reduced the amount of OM, C, N and S hydrolyzed in the ridge samples by 43, 38, 44 and 39%, respectively, but had much less effect on the deep organic soil samples. For the most part the distribution of N forms was similar for the four transect sections. Most of the S hydrolyzed was in the hydriodic acid-reducible sulphur (HI-S) form. The hydrolyzates from the cultivated soil samples had higher C-S:HI-S ratios. The amount of S hydrolyzed in the OM was not affected by cultivation, whereas residue-S was increased by 35.1 to 64.7%. The problems encountered with S hydrolysis analysis were discussed. Key words: Cultivation, humisol, hydrolysis, organic matter, carbon, nitrogen, sulphur
INFLUENCE OF AGGREGATE DIAMETER, SURFACE AREA AND ANTECEDENT WATER CONTENT ON THE DISPERSIBILITY OF CLAY
Authors: KAY B. D. , DEXTER A. R.
Published: March 2010

The percentages of spontaneously dispersed clay, Ms, and mechanically dispersed clay, Mm, in a suspension of a given ionic strength were hypothesized to be controlled by the specific area of exposed aggregate surfaces and the dispersibility of clay per unit specific aggregate surface area. This hypothesis was evaluated using different sized aggregates collected in 1988 from wheat-fallow and continuous pasture rotations established in 1925 on a red-brown earth in southern Australia. Aggregates which were initially air-dry were wetted to matric water potentials ranging from −10 to −0.3 kPa, then placed in distilled water and Ms and Mm measured. Ms increased, as hypothesized, with increasing surface area of aggregates. However, the spontaneously dispersed clay per unit surface area of aggregates increased with increasing size of aggregates and increasing antecedent soil water content. The effect of water content was greatest in the larger aggregates of the less stable wheat-fallow soil. Mm was approximately 12 times larger than Ms and increased with increasing initial aggregate size and increasing antecedent water content. The sensitivity of Mm to water content was greatest on the least stable soil. Calculations showed that the higher values of Mm on unstable soils were due to both larger exposed aggregate surface areas and higher dispersibility of the clay on these surfaces. Keywords: Soil structure, aggregate stability, dispersion
RATES OF SOIL CHEMICAL CHANGES WITH ELEVEN ANNUAL APPLICATIONS OF CATTLE FEEDLOT MANURE
Authors: CHANG C. , SOMMERFELDT T. G. , ENTZ T.
Published: March 2010

The rates of change of several soil chemical properties in response to repeated annual applications of cattle feedlot manure, in a long-term experiment, were determined from 1974 to 1984. Manure was applied at 0, 30, 60 and 90 Mg ha−1 and 0, 60, 120 and 180 Mg ha−1 (wet weight) to nonirrigated and irrigated Dark Brown Chernozemic soils, respectively, using three tillage methods of incorporation. Soil acidity (pH), estimate of soluble salts (EC), sodium adsorption ratio (SAR), and accumulation of Na, Ca + Mg, SO4 and Cl in the soil were determined annually. Regression analyses were used to determine the rates of accumulation of these parameters with time. The rates of change with time were mostly linear and varied with the level of manure applied and irrigation regime. The soil became more acidic with time. Soluble Na and Cl increased at rates similar to or less than those applied, and soluble Ca + Mg increased at rates greater than those applied. Changes in the soluble SO4 were poorly correlated with time. Regression analyses from 1974 to 1977 and 1978 to 1984, under irrigated conditions, indicated that the rates of change were generally less in the latter period. Thus, the losses of applied constituents were higher in the second period than in the first period under irrigation. However, various soluble constituents from the annually applied manure accumulated in the soil even at the recommended rate. These findings indicate that sustained agricultural production of this land with annual application of manure is in question, and the potential for problems due to leaching of various soluble salts and nutrients to groundwater is increased. Key words: EC, soluble salts, leaching, salinization, pH
Teaching Community Pediatrics: A Community Resource Fair for Residents
Authors: Keeley Meg , Pappas Diane
Published: March 2010

Background

Pediatric residency programs are required to provide community and child advocacy experiences, but providing such community knowledge within the context of a busy, largely hospital-based training program can be challenging.

Objective

To assess the effectiveness of a community resource fair as a tool for increasing residents' knowledge of community-oriented care resources.

Design/Methods

We organized a community resource fair for pediatrics and family medicine residents. Exhibitors (n  =  31) represented a wide range of pediatric resources. An anonymous preassessment and postassessment was administered.

Results

Thirty-two trainees participated in the resource fair. On the basis of the preassessment, 62% (8 of 13) of the pediatrics residents reported that they had little or no knowledge about community resources, while 38% (5 of 13) were neutral; none felt somewhat or very knowledgeable. After the fair, 91% (10 of 11) of residents felt somewhat knowledgeable and 9% (1 of 11) felt very knowledgeable about community resources. Of the resident participants, 92% (12 of 13) found this to be a “worthwhile experience.”

Conclusions

The community resource fair provides an interactive format that brings residents and community organizations face-to-face to discuss what services are offered and how they can work together to coordinate patient care.
Immediate Impact of Participation in the Electronic Residency Application Service on a Fellowship Program
Authors: Mokabberi Rasoul , Mohammadi Afsaneh Haftbaradaran , Kalejta Terri , Boker John , Shirani Jamshid
Published: March 2010

Objective

This study sought to evaluate the immediate impact of participation in the Electronic Residency Application Service (ERAS) on a single cardiology fellowship program.

Method

The study reviewed all applications (n = 1824) made to the Geisinger Medical Center cardiology fellowship program over a 4-year period (2004–2007). The aggregate data for the first 2 years (pre-ERAS, 2004 and 2005) was compared to that of the last 2 years (post-ERAS, 2006 and 2007).

Results

Compared to the pre-ERAS period, the total number of applications in the post-ERAS period increased by 49% (732 versus 1092; p<.05) and the number of complete applications increased by 70% (577 versus 983; p<.05). Other significant differences (p<.05) included a higher percentage of applications from female candidates (81 of 732 [11%] versus 186 of 1092 [17%]), and a greater geographic distance from applicants’ internal medicine residency institutions (420 ± 454 miles versus 585 ± 559 miles]. Comparison of applicants’ age, citizenship status, graduation origin, years since medical school graduation, and United States Medical Licensing Examination scores yielded no significant differences between pre-ERAS and post-ERAS periods.

Conclusion

Participation in ERAS resulted in an immediate increase in the total number of applications, higher proportion of applications with complete data, a higher number and proportion of female applicants, and a wider geographic distribution of applications. This likely reflects ease of application submission through a central electronic service. However, the administrative burden on fellowship programs and the effects of wider geographic distribution of applications on the fellowship-matching process merit further evaluation.
The Effect of Overnight In-House Attending Coverage on Perceptions of Care and Education on a General Medical Service
Authors: Trowbridge Robert L. , Almeder Lisa , Jacquet Marc , Fairfield Kathleen M.
Published: March 2010

Background

An increased emphasis on patient safety has led to calls for closer supervision of medical trainees. It is unclear what effect an increased degree of faculty presence will have on educational and clinical outcomes. The aim of this study was to evaluate resident and attending attitudes and preferences regarding overnight attending supervision.

Methods

This study was a cross-sectional electronic survey of physicians. Participants were resident and faculty physicians recently on inpatient service rotations after implementation of an overnight attending coverage system.

Results

Of 58 total respondents, most faculty (91%) and resident (92%) physicians reported they were satisfied with the overall quality of care delivered and believed the quality of care delivered overnight improved with an in-house attending system (90% and 85%, respectively). Most resident physicians (82%) believed the educational experience improved with the system of increased attending availability. Nearly all faculty (95%) and resident (97%) physicians preferred the in-house attending system to the traditional system of attendings being available by pager. The implementation of such coverage resulted in increased cost to the hospital for compensating covering hospitalist physicians.

Conclusion

In-house attending coverage was acceptable to both residents and faculty, with perceived improvements in quality and educational experience.
Balancing Knowledge Among Resident Specialties: Lecture-Based Training and the OUCH Card to Treat Children's Pain
Authors: Saroyan John M. , Schechter William S. , Tresgallo Mary Ellen , Pica Adrienne G. , Erlich Matthew D. , Sun Lena , Graham Mark J.
Published: March 2010

Background

There are well-established deficiencies in residents' knowledge of acute-pain assessment and treatment in hospitalized children.

Methods

Among residents in 3 specialties (anesthesiology, orthopedics, and pediatrics), we investigated whether a pediatric pain management (PPM) curriculum that offered a lecture combined with a demonstration of how to use the OUCH card would yield higher performance on a subsequent PPM knowledge assessment. The OUCH card was created as a portable reference tool for trainees to provide analgesic dosing information, pain-assessment tools, and treatment of opioid-induced adverse effects. There was an initial convenience sample of 60 residents randomized to Form A or B of the pretest. From this, 39 residents (15 anesthesiology, 13 orthopedic, 11 pediatric) completed a PPM knowledge posttest approximately 4 weeks after the pretest, PPM lecture, and OUCH card instruction.

Results

Using a repeated measure design, the interaction of resident specialty and pretest to posttest scores was significant (P  =  .01) along with the covariate of residency year (P  =  .026).

Conclusions

These preliminary data based on a convenience sample of residents suggest that PPM training along with use of the OUCH card may help to reduce knowledge differences among residents. Faculty whose clinical practice includes children with acute pain should consider including learning or performance aids like the OUCH card in education and clinical care for its potential benefit in resident learning.
Measuring Progressive Independence With the Resident Supervision Index: Theoretical Approach
Authors: Kashner T. Michael , Byrne John M. , Henley Steven S. , Golden Richard M. , Aron David C. , Cannon Grant W. , Chang Barbara K. , Gilman Stuart C. , Holland Gloria J. , Kaminetzky Catherine P. , Keitz Sheri A. , Muchmore Elaine A. , Kashner Tetyana K. , Wicker Annie B.
Published: March 2010

Background

Graduate medical education is based on an on-the-job training model in which residents provide clinical care under supervision. The traditional method is to offer residents graduated levels of responsibility that will prepare them for independent practice. However, if progressive independence from supervision exceeds residents' progressive professional development, patient outcomes may be at risk. Leaders in graduate medical education have called for “optimal” supervision, yet few studies have conceptually defined what optimal supervision means and whether optimal care is theoretically compatible with progressive independence, nor have they developed a test for progressive independence.

Objective

This research develops theory and analytic models as part of the Resident Supervision Index to quantify the intensity of supervision.

Methods

We introduce an explicit set of assumptions for an ideal patient-centered theory of optimal supervision of resident-provided care. A critical assumption is that informed attending staff will use available resources to optimize patient outcomes first and foremost, with residents gaining clinical competencies by contributing to optimal care. Next, we derive mathematically the consequences of these assumptions as theoretical results.

Results

Under optimal supervision, (1) patient outcome is expected to be no worse than if residents were not involved, (2) supervisors will avoid undersupervising residents (when patients are at increased risk for poor outcomes) or oversupervising residents (when residents miss clinical opportunities to practice care), (3) optimal patient outcomes will be compatible with progressive independence, (4) progressive development can be inferred from progressive independence whenever residents contribute to patient care, and (5) analytic models that test for progressive independence will emphasize adjusting the association between length of graduate medical education training and supervision for case complexity and clinic workload, but not patient health outcomes.

Conclusion

An explicit theoretical framework is critical to measure scientifically progressive independence from supervision using graduate medical education data.
Using the Cross-Cultural Care Survey to Assess Cultural Competency in Graduate Medical Education
Authors: Chun Maria B. J. , Yamada Ann-Marie , Huh John , Hew Cynthia , Tasaka Shari
Published: March 2010

Background

Cultural competency is an important part of medical policy and practice, yet the evidence base for the effectiveness of training in this area is weak. One reason is the lack of valid, reliable, and feasible tools to quantify measures of knowledge, skill, and attitudes before and/or after cultural training. Given that cultural competency is a critical aspect of “professionalism” and “interpersonal and communication skills,” such a tool would aid in assessing the impact of such training in residency programs.

Objectives

The aim of this study is to enhance the feasibility and extend the validity of a tool to assess cultural competency in resident physicians. The work contributes to efforts to evaluate resident preparedness for working with diverse patient populations.

Method

Eighty-four residents (internal medicine, psychiatry, obstetrics-gynecology, and surgery) completed the Cross-Cultural Care Survey (CCCS) to assess their self-reported knowledge, skill, and attitudes regarding the provision of cross-cultural care. The study entailed descriptive analyses, factor analysis, internal consistency, and validity tests using bivariate correlations.

Results

Feasibility of using the CCCS was demonstrated with reduced survey completion time and ease of administration, and the survey reliably measures knowledge, skill, and attitudes for providing cross-cultural care. Resident characteristics and amount of postgraduate training relate differently to the 3 different subscales of the CCCS.

Conclusions

Our study confirmed that the CCCS is a reliable and valid tool to assess baseline attitudes of cultural competency across specialties in residency programs. Implications of the subscale scores for designing training programs are discussed.
Environmental Factors Affecting Growth in Venus mercenaria1
Authors: PRATT DAVID M. , CAMPBELL DONALD A.
Published: March 2010

The results of a five years’ study of variations in quahog growth rates in Narragansett Bay are summarized. Linear increments are inversely proportional to initial length over the size range 35–70 mm (greatest dimension), whereas volumetric increments in this range are approximately constant. Growth in some parts of the Bay is three times as fast as in others. Most of the year’s growth occurs before mid‐July, and growth rates showed no significant variation from year to year. Annual increments in Narragansett Bay are considerably greater than at Prince Edward Island, and they appear to fall in the same general range as those reported for New Jersey and the south side of Cape Cod.

The effects of various environmental factors on growth have been investigated over a three‐year period. Growth was not appreciably influenced by existing differences in current speed, dissolved oxygen content, or salinity of the bottom water. Temperature imposes an upper limit to the potential rate of growth, which is negligible below 10°C and rises with increasing temperature at least to 23°C. Comparisons of growth rates with phytoplankton concentrations suggest that small diatoms, either living or as detritus, are an important source of quahog nutrition in these waters. Growth is retarded in sediments with a high silt‐clay content. This effect is discussed in relation to the concomitant reduction in sediment permeability, the possible accumulation of inhibitory substances, and the necessity for more frequent clearing of the animals’ filtering apparatus.
Observations on Dinoflagellate Blooms1
Authors: POMEROY LAWRENCE R. , TIASKIN HAROLD H. , RAGOTZKIE ROBERT A.
Published: March 2010

Dinoflagellate blooms were observed in Delaware Bay from 1952 to 1954 and in tidal creeks on Sapelo Island, Georgia, during 1955. In all cases the blooms were concentrated at the surface of the water. The organisms were positively phototactic and swam toward the light at 0.3 to 0.8 cm/sec. Because of their tendency to remain at the surface, the dinoflagellates were concentrated by weak convergences.

One of the blooms was associated with unusual rainfall but the others occurred during dry weather. The concentrations of phosphorus found in the blooms could be accounted for on the basis of concentration mechanisms without postulating a special nutrient source, such as river flow. However, river flow may contribute other biologically important substances.
Photosynthesis in the Ocean as a Function of Light Intensity1
Authors: RYTHER JOHN H.
Published: March 2010

Photosynthesis was measured in 14 species of marine plankton algae in relation to light intensites within the entire range to which natural phytoplankton populations may be exposed. A mean curve was constructed showing relative photosynthesis in marine phytoplankton as related to light intensity. From this curve and surface radiation data, relative values for photosynthesis were determined throughout the day at the surface and at depths in the ocean at which the surface intensity is reduced by given amounts. Integration of these values over the entire day gave values for daily relative photosynthesis at each depth considered, and integration of the daily values with depth resulted in a single figure for daily relative photosynthesis beneath a unit of sea surface.

An empirically derived relationship was discovered between daily surface radiation and daily relative photosynthesis within the water column. From this relationship the effect of light intensity upon photosynthesis throughout the year at a temperate latitude was demonstrated.

A preliminary method is described for estimating absolute daily photosynthesis beneath a square meter of sea surface from measurement of (1) photosynthesis of a sample of the population at light saturation, (2) the extinction coefficient of light in the water, and (3) the daily surface radiation.

From an estimate of the ratio of photosynthesis to respiration at light saturation, the daily ratio P:R for the entire population is calculated. It is shown that phytoplankton populations cannot photosynthesize sufficiently to compensate for their own respiration during periods of low solar radiation, as may occur in the winter months at temperate or northern latitudes.
Primary Production of Vascular Aquatic Plants
Authors: PENFOUND WM. T.
Published: March 2010

In this paper, data are presented on the productivity of four hay crops, five prairie plots, one floodplain community, one cultivated aquatic crop, two emergent plant populations, and two floating mat communities. The productivity (production rate) of the communities investigated varied with the amount of light, water, and nutrients available. The average productivity, in grams of carbon per square meter per day, based on the terminal crop, was moderate (1.5) in hay crops, tall grass prairie and rice, relatively high (3.6) in giant ragweed and presumably still higher in certain aquatic plants. The terminal standing crop was found to be less than the sum of periodic measurements of the developing crop. It was noted also that the magnitude of productivity values depended upon the time of harvest. The productivity of vascular aquatic plants was usually highest in spring and autumn and lowest during the summer. Low summer productivity was due primarily to the relatively low rate of photosynthesis, compared with that of respiration, during hot summer weather. On the basis of present data it appears that productivity in the terrestrial habitat was greatest along shorelines of water bodies and did not increase continuously in the hydrarch succession toward the regional climax.
Bioactivity, Production, and Energy Utilization of Lakes
Authors: OHLE WALDEMAR
Published: March 2010

Unter Verzicht auf die verwirrende Vielzahl von ökologischen und anderen Seetypen können alle Gewässer der Erdoberfläche nach dem Umfang der organischen Produktion in ein System steigenden Trophiegrades eingeordnet werden. Oligo‐, Meso‐, Eu‐, und Poly‐Trophie bezeichnen den ungefähren Grössenbereich der Produktivität.

Nicht nur die Primärproduktion, sondern auch alle sekundären Produktionsstufen, einschliesslich der bakteriellen, charakterisieren den Trophiegrad der Gewässer. Daher wird die Bioaktivität des Biosystems, die diesen gesamten Komplex der organischen Umsetzungen umfassen soll, als Grundlage für den produktionsbiologischen Vergleich der Gewässer angesehen. Die Bioaktivität schliesst in sich die Bildung potentieller Energie sowohl die Rückführung derselben in kinetische.

Der Umfang der Primärproduktion und die Menge der biogen ausnutzbaren organischen Substanzen allochthoner Herkunft werden mit Hilfe der Kohlendioxyd‐Akkumulation des Hypolimnions bestimmt. Die Primärproduktion ist nicht immer von der mittleren Tiefe der Seebecken abhängig. Produktionstiefe und Produktionsdichte beeinflussen sich gegenseitig entseheidend.

Der Kohlenstoffgehalt des rezenten Sedimentes ist aus der Grösse der anaeroben Kohlendioxydbildung ableitbar. In den untersuchten Seen Norddeutschlands ist das Verhältnis der gesamten potentiellen Energie zu ihrem ungenutzt bleibenden Anteil, d.h. der Grad der Ausnutzung potentieller Energie, stets direkt proportional der mittleren Tiefe.

Der als organische Substanz je Oberflächeneinheit des Schlammareals abgelagerte Energierest ist proportional der gesamten potentiellen Energie je Volumeneinheit des ganzen Sees.

Auf Grund der beschriebenen Gesetzmässigkeiten, die das Leben in Gewässern beherrschen, ist ihre Bioaktivität in Gramm Kohlenstoff je Quadratmeter des Oberflächenareals je Zeiteinheit zu bestimmen aus den Grössen der Primärproduktion und der Energieausnutzung, die sich unmittelbar aus der mittleren Tiefe der Gewässerbeckens ableitet.
Estimates of the Minimum Size‐Limit for Maximum Yield and Production of Chain Pickerel, Esox niger LeSueur, in Rhode Island1
Authors: SAILA SAUL B.
Published: March 2010

Mortality rates for chain pickerel were deduced from weighted geometric means of age frequencies in an unexploited and an exploited population. Fishing mortality was considered to be the difference between the two total mortality rates. Calculated growth in length and weight was determined for a composite sample from 32 ponds. Relative yields were computed for six different size‐limits and two rates of fishing. It was found that a minimum size‐limit of approximately 12 inches (total length) was best. A ratio of production to relative yield was determined, which indicated that less than 39 per cent of total production was removed as crop. Management suggestions were made on the basis of these data.
Vitamin B12 in Suspended Solids and Marsh Muds Collected Along the Coast of Georgia1
Authors: BURKHOLDER PAUL R. , BURKHOLDER LILLIAN M.
Published: March 2010

Vitamin B12 content of suspended solids in river and sea waters and in marsh muds, collected along the coast of Georgia, was determined by means of the E. coli mutant assay. Appreciable amounts of vitamin B12 are carried on suspended particles of river water, the brown water types showing highest concentrations, up to 6.4 µg per gram of solids. Vitamin B12 content of particulate matter in the sea waters varied over the range 0.0027 to 0.130 µg per liter. Calculated in relation to dried solids, the highest concentration of B12 was 0.736 µg per gram of solids. Considerable variations were found at different times, stations, and depths. Samples of suspended matter taken from the Duplin River at Different phases of the tide showed maximal values of B12 up to about 0.06 µg per liter, on the outgoing tide. In settling experiments it appeared that a major portion of B12 is correlated with the organic fraction of solids in sea water. Enrichment cultures showed large increases of vitamin B12 produced by microorganisms in marine muds and waters. Many isolated bacteria were grown on extracts of marsh grass and found to produce significant quantities of the vitamin. It is concluded that suspended particles are important in the vitamin nutrition of the sea and that bacteria are significant producers and carriers of vitamin B12 in the marine environment.
The Effect of Removal of Fixed Percentages of the Newborn on Size and Variability in Populations of Daphnia pulicaria (Forbes)
Authors: SLOBODKIN L. BASIL , RICHMAN SUMNER
Published: March 2010

Populations of Daphnia pulicaria were maintained under laboratory conditions of constant food supply and temperature. Varying percentages of the newborn were removed from the populations at four‐day intervals. Mean size of the residual populations decreased with increasing removal rate, while yield and yield per individual increased. Mean differences between the number of animals present at successive censuses after removal of the newborn decreased with removal rate while mean differences between successive yields increased. The sum of mean differences in residual population and yield was a constant, independent of removal rate. That is, total variability in the population‐removal system was not changed by removal rate, although the variability was divided between yield and residual population. The ratio of yield variability to population variability was dependent on removal rate and on the fact that only newborn animals were removed, but was independent of food supply and temperature differences between populations. This ratio also may be independent of the physiological peculiarities of Daphnia. Median life expectancy of the survivors was increased 13–15 days when the removal rate was increased from 25% to 90% of the newborn. The median life expectancy with 90% removal was 32 to 36 days.
Epiphasic Carotenoids in Post‐Glacial Lake Sediments
Authors: VALLENTYNE J. R.
Published: March 2010

The presence of α‐ and β‐carotenes in surface mud from Lower Linsley Pond, Connecticut, and Little Round Lake, Ontario, was demonstrated by comparing the chromatographic positions and absorption spectra of the isolated compounds with authentic specimens of the same compounds prepared from carrots. Seven other carotenes were isolated from the Lower Linsley Pond mud, three of which were probably myxoxanthin, rhodoviolascin, and lycopene.

Carotenoids were found in sediment cores taken from Upper Linsley Pond and Bethany Bog, Connecticut. On the basis of radiocarbon dates and pollen zonations the age of the oldest sediments in these cores was estimated to be approximately 11,000 years. Carotenoids were present in the organic sediments at all depths, but were present in traces or not at all in the basal clay‐silts. Five carotenoid zones of the paper chromatograms were estimated separately using an arbitrary concentration scale: carotene (consisting of α‐ and β‐carotenes and perhaps their cis‐isomers as well), myxoxanthin (?), rhodoviolascin (?), and two unidentified epiphasic carotenoids termed compounds A and B. In the core from Bethany Bog, rhodoviolascin was maximal in the upper part, carotene in the middle, and myxoxanthin and compound B in the middle and lower parts. Myxoxanthin, a pigment of the blue‐green algae, was present only in sediments of the mesotrophic phase of the history of Bethany Bog, and not in those of the dystrophic (bog) phase. The same pigments obtained from the Bethany Bog core were found in a core from Upper Linsley Pond, but the changes in concentration with depth were less striking. A new yellow pigment was present in the Upper Linsley Pond samples.

Data on the biochemical composition of mud may be important in determining the kind and amounts of plant tissues incorporated into the mud.
Some Oceanographic Applications of Recent Determinations of the Solubility of Oxygen in Sea Water1
Authors: RICHARDS FRANCIS A. , CORWIN NATHANIEL
Published: March 2010

The solubility of oxygen in fresh and sea water has recently been redetermined by Truesdale, Downing, and Lowden (1955), who found that the data of Fox (1909), long considered definitive, are in substantial error. The old and new data are compared, and the new are used to recompute the percentage saturation in the surface layer of the South Atlantic and equatorial North Atlantic Oceans from the METEOR observations. It is shown that most of the surface waters are in equilibrium with the atmosphere. The effects of the error on computations of oxygen consumption and of oxygen tension are discussed.

A new nomogram relating the equilibrium oxygen concentration, the temperature, and the salt content of the water is presented.
Factors That Control Species Numbers in Silver Springs, Florida1
Authors: YOUNT JAMES L.
Published: March 2010

The effect of productivity on species variety has been studied by counts of diatom species on glass slides at a high production and a low production station within Silver Springs. Species variety has been presented in a measure that is apparently independent of sample size. This measure is based on the linear increase of accumulated species with logarithmic increase of individuals counted. Diatom productivity was measured by the rate of chlorophyll accumulation. The poor station accumulated diatoms and chlorophyll slowly and was characterized by a large species variety during most of the experiment. The rich station accumulated diatoms and chlorophyll rapidly and was characterized by a rapid decrease in species variety as the density of the population increased. These results indicated that species variety was decreased by conditions of high productivity, possibly through the action of high densities and coactions. In addition, other factors that affect species variety were classified and discussed.
Bathypelagic Coelenterates1
Authors: HARTMAN OLGA , EMERY K. O.
Published: March 2010

Four different kinds of hydrozoan medusae, two of scyphozoans, and four of siphonophores are recorded from three basins of southern California, largely in depths greater than 4000 feet. The records are based on photographs made with a special underwater camera which is described. These coelenterates show specific distributional patterns which appear to reflect not only limited tolerances to temperatures, but also preferences for certain foods either near the sea floor or in the sound‐scattering layers.
The Chemical Composition of Lake Waters in Halifax County, Nova Scotia1
Authors: GORHAM EVILLE
Published: March 2010

Analyses for concentrations of total ions, Na, K, Ca, Mg, HCO3, Cl, SO4, and dissolved organic carbon, as well as optical density, pH, and specific conductivity, are presented for twenty‐three surface lake waters collected from heathy spruce forest in Halifax County, Nova Scotia, during December 1955. As compared with the average fresh water of the world, these waters are very dilute, and proportionally low in calcium bicarbonate while high in sodium chloride. The three main factors governing chemical composition are shown to be (1) the nature of the geological substratum, (2) the influence of topography as expressed in the accumulation of mineral sediments and peat in and around the lake basins, and (3) proximity to the sea.
Evidence for a Photo synthetic Daily Periodicity1
Authors: DOTY MAXWELL S. , OGURI MIKIHIKO
Published: March 2010

It appears that there is a variation of around 5.7‐fold in the ability of oceanic phytoplankton to photosynthetically fix carbon depending upon the time of day the productivity of fixed carbon is determined. The maximum photosynthetic ability appears to be during the few hours before mid‐day, and the minimum ability around 1900 hours as determined by the carbon14 “light‐dark bottle” technique. The original determinations were made in surface waters at surface temperature on three crossings of the equatorial region between about 110 and 140 degrees West Longitude.
Life History of a Dinoflagellate Bloom1
Authors: RAGOTZKIE ROBERT A. , POMEROY LAWRENCE R.
Published: March 2010

A bloom of Gymnodinium sp. is described in terms of its distribution, growth rate, production, and rate of diffusion. Production measurements on a second bloom of the same organism are also cited. In the center of the first bloom cell concentrations ranged from 1 to 18 million cells per liter. Net production ranged from 2.18 to 13.7 mg C/liter/day. Coefficients of horizontal eddy diffusion as calculated from the observed dinoflagellate distributions were low, ranging from near zero to 350 g/cm/sec.
Effects of Lake Fertilization by Volcanic Activity on Abundance of Salmon1
Authors: EICHER GEORGE J. , ROUNSEFELL GEORGE A.
Published: March 2010

Evidence from various sources—tree growth during the past century, chemical composition of waters of various lakes, plankton volumes, size of young salmon migrating seaward— tends to indicate that the fertilization of lake waters in western Alaska by volcanic ash during sporadic eruptions may be an important factor in determining the abundance of sockeye salmon.