bluuebunny/crossref_metadata_2025_split huggingface dataset:
The turnover of organic carbon in subsoils. Part 2. Modelling carbon turnover
Authors: Jenkinson D. S. , Coleman K. 
Published: March 2008

SummaryA new model, RothPC‐1, is described for the turnover of organic C in the top metre of soil. RothPC‐1 is a version of RothC‐26.3, an earlier model for the turnover of C in topsoils. In RothPC‐1 two extra parameters are used to model turnover in the top metre of soil: one, p, which moves organic C down the profile by an advective process, and the other, s, which slows decomposition with depth. RothPC‐1 is parameterized and tested using measurements (described in Part 1, this issue) of total organic C and radiocarbon on soil profiles from the Rothamsted long‐term field experiments, collected over a period of more than 100 years. RothPC‐1 gives fits to measurements of organic C and radiocarbon in the 0–23, 23–46, 46–69 and 69–92 cm layers of soil that are almost all within (or close to) measurement error in two areas of regenerating woodland (Geescroft and Broadbalk Wildernesses) and an area of cultivated land from the Broadbalk Continuous Wheat Experiment. The fits to old grassland (the Park Grass Experiment) are less close. Two other sites that provide the requisite pre‐ and post‐bomb data are also fitted; a prairie Chernozem from Russia and an annual grassland from California. Roth‐PC‐1 gives a close fit to measurements of organic C and radiocarbon down the Chernozem profile, provided that allowance is made for soil age; with the annual grassland the fit is acceptable in the upper part of the profile, but not in the clay‐rich Bt horizon below. Calculations suggest that treating the top metre of soil as a homogeneous unit will greatly overestimate the effects of global warming in accelerating the decomposition of soil C and hence on the enhanced release of CO2 from soil organic matter; more realistic estimates will be obtained from multi‐layer models such as RothPC‐1.
The effect of landscape processes upon gene flow and genetic diversity in an Australian freshwater fish, Neosilurus hyrtlii
Authors: HUEY J. A. , BAKER A. M. , HUGHES J. M. 
Published: March 2008

Summary1. Flow regime and riverine architecture are two important landscape characteristics that influence genetic diversity and gene flow in riverine species.2. Using population genetic markers (mtDNA, microsatellites and allozymes), this study aimed to investigate genetic diversity and gene flow in the freshwater fish, Neosilurus hyrtlii, across two major drainage divisions in northern and central Australia (the Gulf of Carpentaria and Lake Eyre basins). These basins lie adjacent to each other and differ in their hydrological inputs and riverine structure, providing an ideal opportunity to identify the impact of landscape processes upon population dynamics of freshwater fish.3. Populations were strongly structured among basins, among catchments within basins and were weakly structured within catchments in the Lake Eyre Basin, providing support for the Stream Hierarchy Model.4. Interestingly, mtDNA and microsatellite diversity was much higher in the Gulf of Carpentaria Basin compared to the Lake Eyre Basin. It was concluded that this difference was due to the extreme hydrological variability in this basin and boom‐bust population cycles resulting in smaller effective population sizes in the Lake Eyre Basin.
Upscaling leaf area index in an Arctic landscape through multiscale observations
Authors: WILLIAMS M. , BELL R. , SPADAVECCHIA L. , STREET L. E. , VAN WIJK M. T. 
Published: March 2008

AbstractMonitoring and understanding global change requires a detailed focus on upscaling, the process for extrapolating from the site‐specific scale to the smallest scale resolved in regional or global models or earth observing systems. Leaf area index (LAI) is one of the most sensitive determinants of plant production and can vary by an order of magnitude over short distances. The landscape distribution of LAI is generally determined by remote sensing of surface reflectance (e.g. normalized difference vegetation index, NDVI) but the mismatch in scales between ground and satellite measurements complicates LAI upscaling. Here, we describe a series of measurements to quantify the spatial distribution of LAI in a sub‐Arctic landscape and then describe the upscaling process and its associated errors. Working from a fine‐scale harvest LAI–NDVI relationship, we collected NDVI data over a 500 m × 500 m catchment in the Swedish Arctic, at resolutions from 0.2 to 9.0 m in a nested sampling design. NDVI scaled linearly, so that NDVI at any scale was a simple average of multiple NDVI measurements taken at finer scales. The LAI–NDVI relationship was scale invariant from 1.5 to 9.0 m resolution. Thus, a single exponential LAI–NDVI relationship was valid at all these scales, with similar prediction errors. Vegetation patches were of a scale of ∼0.5 m and at measurement scales coarser than this, there was a sharp drop in LAI variance. Landsat NDVI data for the study catchment correlated significantly, but poorly, with ground‐based measurements. A variety of techniques were used to construct LAI maps, including interpolation by inverse distance weighting, ordinary Kriging, External Drift Kriging using Landsat data, and direct estimation from a Landsat NDVI–LAI calibration. All methods produced similar LAI estimates and overall errors. However, Kriging approaches also generated maps of LAI estimation error based on semivariograms. The spatial variability of this Arctic landscape was such that local measurements assimilated by Kriging approaches had a limited spatial influence. Over scales >50 m, interpolation error was of similar magnitude to the error in the Landsat NDVI calibration. The characterisation of LAI spatial error in this study is a key step towards developing spatio‐temporal data assimilation systems for assessing C cycling in terrestrial ecosystems by combining models with field and remotely sensed data.
Testicular dysgenesis syndrome and the origin of carcinoma in situ testis
Authors: Sonne Si Brask , Kristensen David Møbjerg , Novotny Guy W. , Olesen Inge Ahlmann , Nielsen John E. , Skakkebæk Niels E. , Rajpert‐De Meyts Ewa , Leffers Henrik 
Published: March 2008

SummaryRecent increases in male reproductive disorders have been linked to exposure to environmental factors leading to the testicular dysgenesis syndrome (TDS). Testicular cancer is the most severe condition in TDS and studies have shown a clear correlation between risk of testicular cancer and other components of TDS and that the geographical location of the mother during pregnancy can be a risk factor. This suggests that the dysgenesis has its origin in utero and that TDS is initiated by environmental factors, including possibly hormone‐disrupting compounds that act on the mother and the developing foetus, but the genetic background may also play a role. The morphological similarity of carcinoma in situ (CIS) cells (the precursor of the majority of invasive testicular cancers) with primordial germ cells and gonocytes, and overlap in expression of protein markers suggests an origin of CIS from primordial germ cells or gonocytes. CIS cells and germ cell‐derived cancers of the human type have so far not been described in any animal model of TDS, which could be caused by species differences in the development of the male gonad. Regardless of this, it is plausible that the dysgenesis, and hence the development of CIS cells, is a result of disturbed signalling between nurse cells and germ cells that allow embryonic germ cells to survive in the pre‐pubertal and adult testis. The post‐pubertal proliferation of CIS cells combined with aberrant signalling then leads to an accumulation of genetic changes in the CIS cells, which eventually results in the development of invasive testicular cancer in the adult.
Brominated flame retardants as possible endocrine disrupters
Authors: Darnerud P. O. 
Published: March 2008

SummaryBrominated flame retardants (BFR) are endocrine disrupters in experimental systems, both in vitro and in vivo. Although BFR effects on thyroid hormones are well confirmed, studies of effects on oestrogen/androgen systems are fewer but today growing in numbers. The effects of BFR on other hormone systems are still unknown. Hormonal effect levels in animals start from ca 1 mg/kg b.w., but there are exceptions: effects on spermatogenesis, suggesting hormonal causes, have been observed at a low dose (60 μg/kg b.w.) of a polybrominated diphenyl ether (PBDE) congener, BDE‐99. It could be concluded that hormonal effects are of importance in risk assessment, and in some cases where effects are seen at low levels safety margins may be insufficient. One additional uncertainty is the lack of reliable human data that could be used to support animal BFR observations. In spite of the recent regulation of PBDE production, levels of both PBDE and of other BFR groups are still present in environmental samples. Thus, we have to deal with the possible effects of human BFR exposure for times to come. In order to reduce BFR exposure, the routes of exposure should be carefully examined and ways to reduce levels in major exposure routes considered.
THERMODURIC ORGANISMS IN MILK. PART III. PROVISIONAL STANDARD TECHNIQUE FOR THE LABORATORY PASTEURIZATION TEST FOR MILK, AND RINSES AND SWABS OF DAIRY EQUIPMENT, WITH SUGGESTIONS FOR INTERPRETATION OF RESULTS
Authors: EGDELL J. W. , THOMAS S. B. , CLEGG L. F. L. , CUTHBERT W. A. 
Published: March 2008

Summary:A standard method for the application of the laboratory pasteurization test for milk, and rinses and swabs of dairy equipment, is described. The interpretation of the thermoduric colony counts so obtained is discussed, and tentative advisory standards are suggested.
THE EFFECT OF PENICILLIN ON THE METHYLENE BLUE REDUCTION TIME AND KEEPING QUALITY OF MILK
Authors: ROWLANDS A. 
Published: March 2008

Summary:The addition to 32 samples of freshly produced milk from 16 farms of 0.25, 0.5 and 1.0 unit/ml. of penicillin tended to increase the methylene blue reduction time at 37—38°, and to improve the keeping quality at 22°, irrespective of season. In no case was the reduction time decreased or the keeping quality made worse. In general, the effects were almost as marked with 0.25 unit as with the higher concentrations. The increases in the reduction time ranged from 0 to over 3 hr. in winter and from 0 to 2.5 hr. in summer. The delay in reaching the end‐point of the keeping quality test ranged from 0 to 15 hr. in winter and from 0 to over 18 hr. in summer. The response to penicillin differed with the two tests in individual samples. In some cases the methylene blue reduction time was markedly increased but keeping quality was little affected: in others, the reverse was observed.In both winter and summer streptococci predominated in the control samples at the keeping quality end‐point, but with penicillin added Gram‐negative rods often gained the ascendancy. At the time of reduction of methylene blue the flora of the winter control samples consisted mainly of streptococci and micrococci, but in the presence of penicillin the proportion of Gram‐negative rods generally increased: in summer Gram‐negative rods predominated in the control samples and in the presence of penicillin.Practically all the Gram‐negative rods were resistant to penicillin. All the micrococci and most of the streptococci were sensitive to penicillin; the resistant streptococci were strains of Str. faecalis. The variable distribution of resistant and sensitive organisms. coupled with the possible production of penicillinase, probably accounts for the variable effect of penicillin on the methylene blue and keeping quality tests in different samples.
THE GROWTH OF CLOSTRIDIUM BOTULINUM IN ACID BREAD MEDIA
Authors: INGRAM M. , ROBINSON R. H. M. 
Published: March 2008

Summary:The effect of acidity on the growth of Cl. botulinum was studied by following changes in the viable count of cultures in acid buffered broths containing bread crumbs, after inoculation with about 104 vegetative cells or spores/ml. In 9 out of 10 experiments growth did not occur below pH 5.0; in the tenth it took place at pH 4.8. There was no significant difference between vegetative cells and spores.
THE NUTRITIONAL REQUIREMENTS OF THE PREDOMINANT BACTERIAL FLORA OF THE SOIL
Authors: TAYLOR C. B. 
Published: March 2008

Summary:Several aspects of techniques for nutritional classification of soil bacteria have been critically investigated. The methods used by recent Canadian workers are found to be unsatisfactory; (a) because their seven standard media fail in several respects to give an unequivocal grouping; (b) because some of the media used contain inadequate concentrations of essential nutrients; (c) because recommended incubation times are in some cases too short.A simpler method of classification into five nutritional groups, using longer periods of incubation and more satisfactory differential media, has been used to compare soils receiving different manurial treatments. Results indicate that other factors, such as the well‐known rapid fluctuation in bacterial numbers which occurs in all soils, may obscure any effects of soil treatment unless a very elaborate system of controls is adopted. It is suggested that an even simpler method of nutritional grouping into three classes may be of value: (a) organisms capable of using ammonia nitrogen; (b) organisms requiring amino‐acid nitrogen, with or without vitamin supplements; (c) organisms requiring more complex nitrogenous materials.The possibility of developing a grouping technique by direct plating on differential solid media has been studied. It is considered that this is not possible; association effects on plates with mixed colonies suffice to obscure differences between a series of media of increasing nutritional complexity.The growth‐promoting properties of soil‐extract are believed to be due in part to complex nitrogenous substances, which can be replaced by certain concentrations of suitable peptones, and in part to such cations as calcium, magnesium and strontium. The concentration of such cations needed to allow growth of exacting strains is related to the concentration of peptone in the medium and it is suggested that they may act by antagonising in some way the inhibitive effects of certain peptone constituents.
THE BACTERIOLOGY OF FARM WATER SUPPLIES: A STUDY OF THE COLONY COUNT IN 48 HOURS AT 37°
Authors: THOMAS S. B. , THOMAS BLODWEN F. , FRANKLIN PATRICIA M. 
Published: March 2008

SUMMARY: Colony counts in 48 hr. at 37° were much higher in farm water supplies derived from rivers, streams, canals and unprotected wells than in water from springs, protected wells, upland surface waters and chlorinated supplies. Relatively few of the upland surface waters had counts exceeding 102/ml., but the counts for unprotected shallow wells were as high as those for rivers, streams and canals.There was a general association between colony counts at 37° and presumptive coli‐aerogenes counts, but high 37° colony counts could not always be accepted as an indication of sewage or faecal pollution and obviously polluted waters sometimes had low colony counts at 37°.Irrespective of the magnitude of the colony count, the majority (63%) of the colonies were Gram‐negative rods, though they formed a higher proportion of the flora in high than in low count waters. Aerobic spore‐forming rods constituted nearly 20% of the colonies and micrococci 10%, while Gram‐positive rods which did not form spores were present in small numbers at all colony count ranges. Streptococci were relatively rare, forming less than 2% of the colonies.Approximately 25% of the 1,912 cultures isolated from colonies at 37° produced acid and gas in MacConkey's broth at 37°, but 7% of the 488 presumptive coli‐aerogenes cultures were aerobic spore‐forming rods. Typical coli‐aerogenes bacteria constituted 38% of the Gram‐negative rods and 24% of all the colonies examined. Surprisingly few colonies resembled Bact. coli type I in producing acid and gas in MacConkey's broth at 44°, and 13 (6.8%) of the 192 which did so were aerobic spore‐formers resembling Bacillus macerans.Slightly over a third of the cultures produced an acid or proteolytic reaction in litmus milk within 2 days at 22°.The results indicate that the colony count in 48 hr. at 37° does not contribute much useful information additional to that obtained from the presumptive coli‐aerogenes test at 37° and the Bact. coli test at 44°.
THE ENUMERATION OF LACTOBACILLI ON GRASS AND IN SILAGE
Authors: KEDDIE R. M. 
Published: March 2008

SUMMARY: For the enumeration of lactobacilli on grass and in silage the following medium has shown promise: peptone, meat extract and glucose, 10 g. each; tomato extract, 200 ml.; yeast autolysate, 50 ml.; Tween 80, 0.5 ml.; agar, 15 g., in a final volume of 1 1. and containing acetic acid/sodium acetate buffer in 0.2M concentration; pH 5–4. The medium was adjusted to pH 5–4 before sterilization and the requisite amount of concentrated pH 5.4 acetate buffer added just before plating. Double laver plates were used.The only other silage organisms which in this medium formed colonies comparable in size with those of lactobacilli were heterofermentative streptococci and a micrococcus.
SOME ORGANIC SUBSTANCES AND THE NITRIFYING BACTERIA
Authors: MEIKLEJOHN JANE 
Published: March 2008

SUMMARY: The rate of nitrification in mixed cultures was not affected by the simultaneous decomposition of cellulose. No stimultion of the rate of nitrification was observed in cultures containing: culture filtrates, soil extract, thiamin, yeast extract, urine, or β‐indolylacetic acid. These substances either had no effect or, in larger doses, delayed or stopped nitrification.Peptone was toxic to the nitrifying bacteria. Potassium chlorate did not affect the oxidation of ammonia to nitrite, but stopped the oxidation of nitrite to nitrate in cultures, as it does in soil. M/25 sodium fluorides stopped the oxidation of ammonia to nitrite.
OBSERVATIONS ON THE MICROFLORA OF FERMENTING CACAO BEANS IN TRINIDAD
Authors: ROMBOUTS J. E. 
Published: March 2008

SUMMARY: A numerical analysis is given of the average microflora of fermenting cocoa beans in Trinidad sweat boxes. Both the viable count of all micro‐organisms and the relative numbers of the main groups involved were estimated.The influence of the prevailing temperature and pH of the environment on the sequence of microbial development is considered, and the main chemical changes taking place are noted.The influence of atmospheric conditions is discussed and the desirability of a thorough microbiological analysis of the fermentation process in relation to cocoa quality is stressed.
THE ASSESSMENT OF THE BACTERIOLOGICAL CONDITION OF MILK BOTTLES
Authors: GRIFFITHS D. G. , MORGAN K. J. , PRITCHARD BARBARA , THOMAS S. B. 
Published: March 2008

SUMMARY: A study of the relative values of a number of bacteriological tests for assessing the condition of milk bottles indicated that the colony count of the bottle rinse solution on yeastrel milk agar incubated for 4 days at 30°, combined with a clot‐on‐boiling test applied to 1 ml. of rinse in 9 ml. of sterile milk after incubation for 72 hr. at 19–20°, gave the most useful results.The mean of the ratios of colony counts at 30° to those at 37° was 15·1, while it was as high as 22·9 for rinses with 37° of over 600 for an unsatisfactory bottle should be retained when the test is done at 30°. The thermoduric colony count of rinses of milk bottles, even when laboratory pasteurized in milk, did not provide any additional information to that given by the colony count at 30° made without pasteurization. A high proportion of the organisms in bottle rinses survived laboratory pasteurization in milk, the survival rate being highest in efficiently treated bottles.The clot‐on‐boiling test gave results in general agreement with colony counts and served to indicate the potential influence of badly contaminated bottles on the keeping quality of milk placed in them. A substantial proportion of rinses with satisfactory colony counts reduced methylene blue within 48 hr. at 19–20°.Colony counts at 37° were on the average much lower for bottles treated with steam than for bottles submitted to detergent treatment in various types of bottle washing machines. Treatment of bottles by steam or hypochlorite was more efficiently done on the farms than at the dairies.
THE ESTIMATION OF SULPHATE‐REDUCING BACTERIA (D. DESULPHURICANS)
Authors: GROSSMAN JOY P. , POSTGATE J. R. 
Published: March 2008

SUMMARY: Sodium sulphide or cysteine stimulated the growth of sulphate‐reducing bacteria; small populations often did not grow without such supplements. Ascorbic acid, glutathione or thiolacetic acid had similar properties but thiolacetic acid was sometimes inhibitory, Dilution counts in liquid media or colony counts in agar media did not bear any regular relation to the total count unless one of these supplements was present. With suitable precautions colony counts reaching 50 to 60% of the total count were obtained in media incorporating cysteine and a ferrous salt (as an indicator of sulphide formation).Samples of natural origin containing sulphate‐reducing bacteria gave greater viable counts in cysteine‐iron media than in unsupplemented media. Blackend culture tubes with natural populations were sometimes due to cysteine‐decomposing organisms; further examination of positive tubes was therefore necessary.
ROLL TUBES AND AGAR STRIP TUBES FOR THE BACTERIAL COLONY COUNT OF MILK
Authors: HIGGINBOTTOM CONSTANCE 
Published: March 2008

SUMMARY: Roll‐tube colony counts, using the Astell equipment, were lower than the corresponding Petri dish counts with 27 out of 31 raw milks (87%). The difference between the counts by the two methods was greater than 25% of the plate count for 12 (39%) of the samples.When the same dilution of milk was used for both strip‐tube and plate colony counts, about equal numbers of samples gave counts from the strip tubes above and below about the colony count from plates. When, in order to obtain a more reasonable strip‐tube count, the plates and strip tubes were prepared from different dilutions of the milk, the counts from the latter were, with only 3 exceptions out of 35 milks, below those from the former. The difference between the counts was greater than 25% of the plate count for 15 (43%) of the milks, a figure similar to that obtained in comparing roll‐tube and plate colony counts.
EXPERIMENTS ON GROWTH MEDIA FOR LACTOBACILLI
Authors: COX C. P. , BRIGGS MARY 
Published: March 2008

Summary:A medium permitting consistently good growth of known strains of lactobacilli was determined using nineteen strains considered difficult to grow. For the culture media tested various concentrations of albumin, starch, Tween 80, sodium oleate and Yeastrel were added to tomato dextrose broth and strain growth was measured by a photo‐electric absorptiometer. Statistical analysis showed that, of the combinations tested, the best response was achieved by the addition to tomato dextrose broth of Tween 80 (0.1% v/v) and Yeastrel (0–6% w/v) with or without 0.5% of starch.