bluuebunny/crossref_metadata_2025 huggingface dataset:
Physical Activity and Healthy Eating in the After‐School Environment
Authors: Coleman Karen J. , Geller Karly S. , Rosenkranz Richard R. , Dzewaltowski David A.
Published: November 2008

BACKGROUND:  No research to date has extensively described moderate and vigorous physical activity (MVPA) and healthful eating (HE) opportunities in the after‐school environment. The current study described the quality of the after‐school environment for its impact on children’s MVPA and HE.

METHODS:  An alliance of 7 elementary schools and Boys and Girls Clubs who worked with the Cooperative Extension Service in Lawrence, KS, was selected to participate in a larger intervention study. After‐school settings were observed for information regarding session type, session context, leader behavior, physical activity, and snack quality using validated instruments such as the System for Observing Fitness Instruction Time. Data presented are baseline measures for all sites.

RESULTS:  Participating children (n = 144) were primarily non‐Hispanic white (60%) and in fourth grade (69%). After‐school sites offered 4 different sessions per day (active recreation, academic time, nonactive recreation, and enrichment activities). Children were provided with a daily snack. On 36% of the days observed, this snack included fruit, fruit juice, or vegetables. There was significantly more time spent in MVPA during free play sessions (69%) compared to organized adult‐led sessions (51%). There was also significantly more discouragement of physical activity during organized adult‐led sessions (29%) as compared to the free play sessions (6%).

CONCLUSIONS:  The quality of after‐school programs can be improved by providing fruits and vegetables as snacks; offering more free play activities; training the after‐school staff in simple, structured games for use in a variety of indoor and outdoor settings; and training after‐school staff to promote and model MVPA and HE in and out of the after‐school setting.
Blood volume, blood pressure and total body sodium: internal signalling and output control
Authors: Bie P.
Published: November 2008

Total body sodium and arterial blood pressure (ABP) are mutually dependent variables regulated by complex control systems. This review addresses the role of ABP in the normal control of sodium excretion (NaEx), and the physiological control of renin secretion. NaEx is a pivotal determinant of ABP, and under experimental conditions, ABP is a powerful, independent controller of NaEx. Blood volume is a function of dietary salt intake; however, ABP is not, at least not in steady states. A transient increase in ABP after a step‐up in sodium intake could provide a causal relationship between ABP and the regulation of NaEx via a hypothetical integrative control system. However, recent data show that subtle sodium loading (simulating salty meals) causes robust natriuresis without changes in ABP. Changes in ABP are not necessary for natriuresis. Normal sodium excretion is not regulated by pressure. Plasma renin is log‐linearly related to salt intake, and normally, decreases in renin secretion are a precondition of natriuresis after increases in total body sodium. Renin secretion is controlled by renal ABP, renal nerve activity and the tubular chloride concentrations at the macula densa (MD). Renal nerve activity is related to blood volume, also at constant ABP, and elevates renin secretion by means of β1‐adrenoceptors. Recent results indicate that renal denervation reduces ABP and renin activity, and that sodium loading may decrease renin without changes in ABP, glomerular filtration rate or β1‐mediated nerve activity. The latter indicates an essential role of the MD mechanism and/or a fourth mediator of the physiological control of renin secretion.
Vitamin C Content in Sea Buckthorn Berries (Hippophaë rhamnoides L. ssp. rhamnoides) and Related Products: A Kinetic Study on Storage Stability and the Determination of Processing Effects
Authors: Gutzeit D. , Baleanu G. , Winterhalter P. , Jerz G.
Published: November 2008

ABSTRACT:  The primary vitamin in sea buckthorn berries is vitamin C containing values of approximately 400 mg/100 g. Processing effects were investigated during juice and concentrate production from sea buckthorn berries (Hippophaë rhamnoides) and storage stability of juices was determined for up to 7 d using berries and juices from 2 different growing areas. During industrial juice production the technological processing of the berries caused a loss of about 5% to 11% total ascorbic acid (TAA) in the generated juice. The production of the concentrated juice resulted in 50% depletion of TAA. Sea buckthorn berries and juice were stored at 6, 25, and 40 °C for up to 7 d to investigate the temperature effects on TAA during storage. Analysis of kinetic data suggested that the degradation follows a 1st‐order model. The results of the experiments showed that storage of sea buckthorn juices for 7 d at cold temperature (6 °C) already resulted in a degradation of TAA of about 11% to 12%.
Chinese Cabbage (Brassica campestris L.) does not Improve Glucose Tolerance, Serum Insulin, or Blood Lipid Profiles in a Rat Model of Type‐2 Diabetes
Authors: Islam M.S. , Choi H.
Published: November 2008

ABSTRACT:  The present study was conducted to investigate the effects of a low (0.5%) and a high (2.0%) dietary dose of freeze‐dried Chinese cabbage (CC) (Brassica campestris L.) powder in a type‐2 diabetes (T2D) model of rats. Five‐week‐old male Sprague–Dawley rats were fed a high fat (HF)‐containing diet for 2 wk then randomly divided into 4 groups of 8 animals, namely: normal control (NC), diabetic control (DBC), Chinese cabbage low (CCL, 0.5%), and Chinese cabbage high (CCH, 2.0%) groups. Diabetes was induced by an intraperitoneal injection of streptozotocin (STZ; 40 mg/kg body weight) in all groups except the NC group. After 4 wk feeding of experimental diets, although food intake was not different among the DBC, CCL, and CCH groups, body weight gain was significantly (P < 0.05) higher in the CCH group compared to the DBC group. Relatively higher serum insulin concentrations and better glucose tolerance were observed in the CC‐fed groups compared to the DBC group; however, the results were not significantly different. Fasting blood glucose, blood glycated hemoglobin (HbA1c), liver weight, and liver glycogen levels were not influenced by the CC‐containing diets. Additionally, hypertriglyceridemic tendencies were observed in the CC‐fed groups compared to the NC and DBC groups, while difference observed for total‐, HDL‐, and LDL‐cholesterols between the groups were negligible. Results of this study suggest that up to 2% dietary dose of freeze‐dried CC is not significantly effective to reduce diabetes‐related symptoms in an HF diet‐fed STZ‐induced T2D model of rats.
Evaluation of Changes in Listeria monocytogenes Populations on Frankfurters at Different Stages from Manufacturing to Consumption
Authors: Byelashov O.A. , Simpson C.A. , Geornaras I. , Kendall P.A. , Scanga J.A. , Sofos J.N.
Published: November 2008

ABSTRACT:  This study evaluated the fate of inoculated Listeria monocytogenes on frankfurters stored under conditions simulating those that may be encountered between manufacturing and consumption. Frankfurters with or without 1.5% potassium lactate and 0.1% sodium diacetate (PL/SD) were inoculated (1.8 ± 0.1 log CFU/cm2) with a 10‐strain composite of L. monocytogenes, vacuum‐packaged, and stored under conditions simulating predistribution storage (24 h, 4 °C), temperature abuse during transportation (7 h, 7 °C followed by 7 h, 12 °C), and storage before purchase (60 d, 4 °C; SBP). At 0, 20, 40, and 60 d of SBP, samples were exposed to conditions simulating delivery from stores to homes or food establishments (3 h, 23 °C), and then opened or held vacuum‐packaged at 4 or 7 °C for 14 d (SHF). Pathogen counts remained relatively constant on frankfurters with PL/SD regardless of product age and storage conditions; however, they increased on product without antimicrobials. In vacuum‐packaged samples, during SHF at 4 °C, the pathogen grew faster (P < 0.05) on older product (20 d of SBP) compared to product that was fresh (0 d of SBP); a similar trend was observed in opened packages. At 7 °C, the fastest growth (0.35 ± 0.02 log CFU/cm2/d) was observed on fresh product in opened packages; in vacuum‐packages, growth rates on fresh and aged products were similar. By day 40 of SBP the pathogen reached high numbers and increased slowly or remained unchanged during SHF. This information may be valuable in L. monocytogenes risk assessments and in development of guidelines for storage of frankfurters between package opening and product consumption.
Membrane Fractionation Processes for Removing 90% to 95% of the Lactose and Sodium from Skim Milk and for Preparing Lactose and Sodium‐Reduced Skim Milk
Authors: Morr C.V. , Brandon S.C.
Published: November 2008

ABSTRACT:  Pilot‐scale microfiltration (MF), microfiltration‐diafiltration (MDF), ultrafiltration (UF), ultrafiltration‐diafiltration (UDF), and nanofilration (NF) membrane fractionation processes were designed and evaluated for removing 90% to 95% of the lactose and sodium from skim milk. The study was designed to evaluate several membrane fractionation schemes as a function of: (1) membrane types with and without diafiltration; (2) fractionation process temperatures ranging from 17 to 45 °C; (3) sources of commercial drinking water used as diafiltrant; and (4) final mass concentration ratios (MCR) ranging from about 2 to 5. MF and MDF membranes provided highest flux values, but were unsatisfactory because they failed to retain all of the whey proteins. UDF fractionation processes removed more than 90% to 95% of the lactose and sodium from skim milk. NF permeate prepared from UDF cumulative permeate contained sodium and other mineral concentrations that would make them unsuitable for use as a diafiltrant for UDF applications. A method was devised for preparing simulated milk permeate (SMP) formulated with calcium, magnesium, and potassium hydroxides, and phosphoric and citric acids for use as UDF diafiltrant or for preparing lactose and sodium reduced skim milk (L‐RSM). MF retentates with MCR values of 4.7 to 5.0 exhibited extremely poor frozen storage stabilities of less than 1 wk at −20 °C, whereas MCR 1.77 to 2.95 MDF and UDF retentates and skim milk control exhibited frozen storage stabilities of more than 16 wk. L‐RSM exhibited a whiter appearance and a lower viscosity than skim milk, lacked natural milk flavor, and exhibited a metallic off‐flavor.
Antilisterial Activity of Hops Beta Acids in Broth with or Without Other Antimicrobials
Authors: Shen C. , Sofos J.N.
Published: November 2008

ABSTRACT:  Hops beta acids (HBA) are parts of hops flowers used to preserve wort and provide flavor in beer, and are reported as having antimicrobial properties. This study evaluated the antilisterial activity of HBA alone or in combination with other known antimicrobials in a culture broth medium. Listeria monocytogenes (10‐strain mixture) was inoculated (2.6 to 2.8 log CFU/mL) into tryptic soy broth supplemented with 0.6% yeast extract (TSBYE) without (control) or with HBA (0.5 to 5.0 μg/mL), potassium lactate (1.0%), sodium diacetate (0.25%), or acetic acid (0.1%), alone or in combination with HBA (0.5 to 3.0 μg/mL). Survival/growth of the pathogen during storage at 4 °C (35 d), 10 °C (20 d), or 25 °C (2 d) was periodically monitored by spiral plating onto tryptic soy agar plus 0.6% yeast extract. As expected, TSBYE without antimicrobials (control) supported rapid pathogen growth with growth rates of 0.40, 2.88, and 9.58 log CFU/mL/d at 4, 10, and 25 °C, respectively; corresponding Yend values exceeded 9.0 log CFU/mL at 35, 20, and 2 d storage. HBA used alone (1.0 to 5.0 μg/mL) inhibited growth of L. monocytogenes at all 3 temperatures, with inhibition being more pronounced at higher concentrations and at the lower storage temperature (4 °C). The antilisterial activity of HBA (0.5 to 3.0 μg/mL) was enhanced when combined with sodium diacetate, acetic acid, or potassium lactate, achieving complete inhibition at 4 °C when 3.0 μg/mL HBA were used in combination with each of the above antimicrobials. Overall, HBA exhibited promising antilisterial activity in a broth medium and further studies are needed to investigate its potential antilisterial effects in food products.
Nutrient‐Rich Foods: Applying Nutrient Navigation Systems to Improve Public Health
Authors: Drewnowski A. , Fulgoni V.L. , Young M.K. , Pitman S.
Published: November 2008

ABSTRACT:  The American diet is high in calories, but low in nutrients. To help consumers obtain more nutrition from the calories they consume, research is underway to develop a nutrient profiling approach that can be used to evaluate individual foods and help people build healthful diets. A nutrient profiling system that rates individual foods based on their nutrient content needs to be both science‐driven and user‐friendly, allowing consumers to make more healthful food choices within and across all the food groups. A recent survey, commissioned by the Nutrient Rich Food Coalition, reveals that the majority of consumers and nutrition professionals believe that better information about a food's total combined nutrient content would be effective and useful in helping them make more nutrient‐rich food choices.
Favorable Glycemic Response of Type 2 Diabetics to Low‐Calorie Cranberry Juice
Authors: Wilson T. , Meyers S.L. , Singh A.P. , Limburg P.J. , Vorsa N.
Published: November 2008

ABSTRACT:  Fruit and vegetable intake is typically low for type 2 diabetics, possibly due to a perceived adverse effect on glycemic control. Cranberry juice (CBJ) may represent an attractive means for increasing fruit intake and simultaneously affording positive health benefits. This single cross‐over design compared metabolic responses of type 2 diabetics (n= 12) to unsweetened low‐calorie CBJ (LCCBJ; 19 Cal/240 mL), carbohydrate sweetened normal calorie CBJ (NCCBJ; 120 Cal/240 mL), isocaloric low‐calorie sugar water control (LCC), and isocaloric normal calorie sugar water control (NCC) interventions. CBJ flavonols and anthocyanins, and proanthocyanidins were quantified with HPLC, LC‐MS, and MALDI‐TOF that includes an original characterization of several large oligomeric proanthocyanidins. Blood glucose peaked 30 min postingestion after NCCBJ and NCC at 13.3 ± 0.5 and 12.8 ± 0.9 (mmol/L), and these responses were significantly greater than the LCCBJ and LCC peaks of 8.1 ± 0.5 and 8.7 ± 0.5, respectively. Differences in glycemic response remained significant 60 min, but not 120 min postingestion. Plasma insulin values 60 min postingestion for NCCBJ and NCC interventions were 140 ± 19 and 151 ± 18 (pmol/L), respectively, and significantly greater than the LCCBJ and LCC values of 56 ± 10 and 54 ± 10; differences were not significant 120 min postingestion. Metabolic responses within the 2 high and 2 low‐calorie beverages were virtually identical; however, exposure to potentially beneficial nutrients was greater with CBJ. Relative to conventionally sweetened preparation, LCCBJ provides a favorable metabolic response and should be useful for promoting increased fruit consumption among type 2 diabetics or others wishing to limit carbohydrate intake.
Functional Properties of Honey, Propolis, and Royal Jelly
Authors: Viuda‐Martos M. , Ruiz‐Navajas Y. , Fernández‐López J. , Pérez‐Álvarez J.A.
Published: November 2008

ABSTRACT:  Honey, propolis, and royal jelly, products originating in the beehive, are attractive ingredients for healthy foods. Honey has been used since ancient times as part of traditional medicine. Several aspects of this use indicate that it also has functions such as antibacterial, antioxidant, antitumor, anti‐inflamatory, antibrowning, and antiviral. Propolis is a resinous substance produced by honeybees. This substance has been used in folk medicine since ancient times, due to its many biological properties to possess, such as antitumor, antioxidant, antimicrobial, anti‐inflammatory, and immunomodulatory effects, among others. Royal jelly has been demonstrated to possess numerous functional properties such as antibacterial activity, anti‐inflammatory activity, vasodilative and hypotensive activities, disinfectant action, antioxidant activity, antihypercholesterolemic activity, and antitumor activity. Biological activities of honey, propolis, and royal jelly are mainly attributed to the phenolic compounds such as flavonoids. Flavonoids have been reported to exhibit a wide range of biological activities, including antibacterial, antiviral, anti‐inflammatory, antiallergic, and vasodilatory actions. In addition, flavonoids inhibit lipid peroxidation, platelet aggregation, capillary permeability and fragility, and the activity of enzyme systems including cyclo‐oxygenase and lipoxygenase.
Bayan Obo Controversy: Carbonatites versus Iron Oxide‐Cu‐Au‐(REE‐U)
Authors: Wu Chengyu
Published: November 2008

The Bayan Obo Fe‐REE‐Nb deposit is the world’s largest rare earth element (REE) resource and its genesis has been the subject of much debate for many years. The most popular are the carbonatite‐related and hydrothermal Fe oxide‐Cu‐Au‐(REE‐U) genetic models. Comparisons of geologic setting, lithology, mineral assemblages, metal associations, geochemistry (particularly REE and light REE/heavy REE ratios), fluid chemistry and isotopics indicate that the Bayan Obo deposit shares features of both types, which are classified differently; that is, the carbonatites model is host‐rock based, while the Fe oxide‐Cu‐Au‐(REE‐U) model is essentially mineral assemblage and metal association based. A speculative classification scheme is tentatively put forward to link the two models, but many questions remain for further studies.
REE Abundance and REE Minerals in Granitic Rocks in the Nanling Range, Jiangxi Province, Southern China, and Generation of the REE‐rich Weathered Crust Deposits
Authors: Ishihara Shunso , Hua Renmin , Hoshino Mihoko , Murakami Hiroyasu
Published: November 2008

Studies of Mesozoic granites associated with rare earth element (REE)‐rich weathered crust deposits in southernmost Jiangxi Province indicate that they have high‐K to shoshonite compositions and belong to ilmenite‐series I‐type granites. Of the studied rocks at 59–292 ppm of bulk REE content, the highest are seen in the biotite granites of Dingnan (358, 429 ppm) and mafic biotite granite of the Wuliting Granite (344 ppm) near the Dajishan tungsten mine, both areas where weathered‐crust REE deposits occur. REE‐bearing accessory minerals in these granites are mainly zircon, apatite and allanite, and REE‐fluorocarbonates are common. REE enrichment occurs in the rims of apatite crystals, and in fluorocarbonates that occur along grain boundaries of and cracks in major silicate minerals, and in fluorocarbonates that replaced altered biotite. It is therefore thought that a major part of the REE content of these granites was concentrated during deuteric activity, rather than during magmatic crystallization. The crack‐filling REE‐fluorocarbonates could subsequently have been easily leached out and deposited in weathered crust developed during a long period of exposure.
Rare Earth Magnets: Conservation of Energy and the Environment
Authors: Minowa Takehisa
Published: November 2008

Rare earth sintered magnets (Nd magnet) have been used in many applications such as computer and industrial equipment, automobile manufacturing and many others. They are highly efficient and reduce energy consumption because of their superior magnetic properties. The element dysprosium (Dy) contained in the Nd magnet is important and indispensable. It improves the stability of the Nd magnet by enhancing the coercive force of its magnetic properties at high temperature. Dy is not so abundant. The rapid growth of the Nd magnet may result in Dy shortage. Exploration for new deposits of Dy is desired.
Geochemistry, Petrography and Spectroscopy of Organic Matter of Clay‐Associated Kerogen of Ypresian Series: Gafsa‐Metlaoui Phosphatic Basin, Tunisia
Authors: Felhi Mongi , Tlili Ali , Montacer Mabrouk
Published: November 2008

This work presents geochemical characterization of isolated kerogen out of clay fraction using petrography studies, infrared absorption and solid state 13C nuclear magnetic resonance (NMR) spectroscopy, with N‐alkane distributions of saturated hydrocarbon. Mineralogical study of clay mineral associations was carried out using X‐ray diffraction (XRD), on Ypresian phosphatic series from Gafsa‐Metlaoui basin, Tunisia. The XRD data indicate that smectite, palygorskite and sepiolite are the prevalent clay minerals in the selected samples. In this clay mineral association, the N‐alkane (m/z = 57) distribution indicates that the marine organic matter is plankton and bacterial in origin. The kerogens observed on transmitted light microscopy, however, appear to be totally amorphous organic matter, without any appearance of biological form. The orange gel‐like amorphous organic matter with distinct edges and homogenous texture is consistent with a high degree of aliphaticity. This material has relatively intense CH2 and CH3 infrared bands in 13C NMR peaks. This aliphatic character is related to bacterial origin. Brown amorphous organic matter with diffuse edges has a lower aliphatic character than the previous kerogen, deduced from relatively low CH2 and CH3 infrared and 13C NMR band intensities.
Pseudohyperkalaemia is a common finding in myeloproliferative disorders that may lead to inappropriate management of patients
Authors: ONG Y. L. , DEORE R. , EL‐AGNAF M.
Published: November 2008

Pseudohyperkalaemia in conditions with increased platelet counts is caused by an in vitro rise of the serum potassium concentration during whole blood coagulation and the lysis of the platelets and other cellular components, in the presence of normal renal function and normal plasma potassium levels. The association between pseudohyperkalaemia and aetiology of thrombocytosis was studied in a 6‐year retrospective audit on 90 patients with thrombocytosis referred to the Haematology Department in Ulster Hospital Dundonald, a large district general hospital. Over two‐thirds of this study population had myeloproliferative disorders, and the most common diagnosis was primary thrombocythaemia (41%, n = 37). Reactive thrombocytosis was observed in approximately one‐third of the cases (32%, n = 29). Pseudohyperkalaemia with apparent potassium level above the upper limit of the normal range (reference range K 3.5–5.1 mmol/l) was observed in the majority of patients with thrombocytosis from any aetiology (60%, n = 54). The likelihood of finding pseudohyperkalaemia was highest among patients with primary thrombocythaemia (75.7%, n = 28/37) and polythaemia rubra vera (75%, n = 12/16), followed by myelofibrosis (50%, 4/8) and reactive thrombocytosis (34.5%, n = 10/29). A highly significant positive correlation was observed between the platelet counts and the serum potassium level (Spearman’s correlation coefficient, R = 0.998, P = 0.01). Awareness of pseudohyperkalemia in disease conditions with increased platelet counts will lead to the withholding of potentially harmful treatment.
Gazprom's export strategies under the institutional constraint of the Russian gas market
Authors: Locatelli Catherine
Published: November 2008

The strategy of the Russian gas company Gazprom is today at the centre of the debate surrounding the security of the European gas supply. The European gas market liberalisation is changing the industrial and commercial (that is to say, contractual) strategies of Gazprom in order to deal with the institutional changes in its main export market. In this context, to secure its market shares Gazprom try to acquire a presence downstream, which will give it access to final consumers. However, exports to Europe are affected by conditions in the Russian domestic market, not only in terms of supply and demand, but also in terms of prices. Russia's internal market can hardly be viewed as a genuine market where supply and demand are regulated by price fluctuations.
US access to the global LNG market
Authors: Urban Julie A.
Published: November 2008

This paper discusses US participation in the global liquefied natural gas (LNG) market. Although recent US production of natural gas is up, Canadian production is decreasing and LNG imports by the United States have been on the rise. The current US portfolio of LNG importers is described and the future prospects for each of the current importers are discussed. Changing conditions in the global marketplace have resulted in higher prices and more recent declines in US importation of LNG. With temporary increases in US domestic supply and transportation costs rising, the United States will find it increasingly difficult to compete with other global consumers of LNG. Overcapacity of regasification and high prices are pushing the industry into increased integration. Under these conditions, it seems unlikely that consumers of LNG will experience price declines. In addition, because of global reserve distribution, increased reliance on LNG may jeopardise even further US energy security.
The lichen genus Henrica (Verrucariaceae, Eurotiomycetes) in northern Europe
Authors: Savić S. , Tibell L.
Published: November 2008

In a previous three gene phylogeny study (nuITS rDNA, nuLSU rDNA and RPB1 region A–D) a well supported clade, most closely related to Verrucaria rupestris and also close to Sporodictyon and Atla, was found. Here this clade is identified as Henrica. A phylogeny of these genera based on the nuITS rDNA is supplied, and also a key to crustose species in Verrucariaceae with large, brown muriform spores. Based on material from northern Europe, Henrica is emended to include H. theleodes and H. melaspora, both new combinations in the previously monotypic genus. Verrucaria theleodes and V. scotinospora are lectotypified.
Cinnamomum tamala var. elliptifolium var. nov. (Lauraceae) from northeast India
Authors: Baruah Akhil , Nath Subhan C.
Published: November 2008

Cinnamomum tamala Nees var. elliptifolium Baruah & S. C. Nath var. nov. is illustrated and described as a new variety, with a note on its leaf essential oil characters reported earlier as a ‘variant’ of the species.
THE GENERATIVE POWER OF AIR FREIGHT IN THE TRADE OPENNESS – ECONOMIC GROWTH NEXUS IN AFRICAN COUNTRIES
Authors: Chang Chun‐ping , Ying Yung‐hsiang
Published: November 2008

Foreign trade matters considerably more than ever in today's integrated economies, and the wealth of benefits afforded by air transport is one of the cornerstones of international trade. Therefore, to shed light on the precise role of air cargo, seen as an important motor of growth, this paper provides an empirical model to examine the relationships among trade openness, air freight volume and GDP per capita using panel cointegration techniques for a sample of Economic Commission for Africa (ECA) countries during the 1970‐2002 period.

The analysis substantiates that there are cointegrated relationships among the three variables and that they are bound together in a long‐run equilibrium. Furthermore, evidence from fully modified Ordinary Least Squares panel estimations also indicates that positive trade and air freight shocks contribute to real GDP per capita. In addition, improvements in air cargo services are accompanied by an increase in trade openness in ECA countries and vice versa. These results underscore the important role of air freight and demonstrate that it should not have been overlooked in earlier studies. Finally, the empirical findings have important policy implications for our sample countries.
THE RECENT DECLINE IN THE EMPLOYMENT OF PERSONS WITH DISABILITIES IN SOUTH AFRICA, 1998‐2006
Authors: Mitra Sophie
Published: November 2008

This paper shows that there has been a significant decline in the employment and labour force participation of persons with disabilities in South Africa over the 1998 through 2006 period. Disability is defined based on activity limitations. Data are from the October and the General Household Surveys. The paper also deals with the possible causes of the decline. While several causes can be invoked, preliminary evidence suggests that the rise of the Disability Grant programme might be responsible for a part of the decline. Recommendations are made for future research and data collection on disability and employment.
THE CHANGING VOLATILITY OF THE SOUTH AFRICAN ECONOMY
Authors: Burger Philippe
Published: November 2008

During the last decade economic literature explored the presence of and reasons for what became known as “the great moderation” in the US and other G7 countries. “The great moderation” describes the decrease in economic volatility experienced in many of the G7 countries. This paper finds that in South Africa volatility is also not constant (it even finds that there are autoregressive conditional heteroskedastic effects present) and that volatility also decreased, particularly since 1994. Following the literature, the paper explores several reasons for this decrease and finds that smaller shocks, better monetary policy and improvements in the financial sector that place less liquidity constraints on individuals and allow them to manage their debt better are some of the main reasons for the reduction in the volatility of the South African economy. The literature on the G7 also suggests that better inventory management contributed to the lower volatility. However, this seems not to be true for South Africa.
MONEY, OUTPUT AND INFLATION IN AFRICAN ECONOMIES1
Authors: Thornton John
Published: November 2008

This paper examines the long‐run money‐inflation relation for 36 African countries using cross‐section and panel data analysis. The focus is on the recent claim by De Grauwe and Polan that the common finding in multi‐country studies of a strong positive link typically reflects the presence of high‐inflation countries in the sample and on Nelson's criticisms of the data and methodology employed in that study. Adjusting the De Grauwe and Polan methodology to take account of many of Nelson's criticisms, I confirm a weak long‐run relation between money growth and inflation for countries when money growth and inflation are below 10%, but a strong relation when money growth and inflation move much above that number. This result is not dependent on the inclusion of high inflation countries in the cross‐section and panel data samples.
LONG MEMORY IN SOUTHERN AFRICAN STOCK MARKETS
Authors: Jefferis Keith , Thupayagale Pako
Published: November 2008

The paper examines long memory in equity returns and volatility for stock markets in Botswana, South Africa and Zimbabwe using the ARFIMA‐FIGARCH model in order to assess the efficiency of these markets in processing information. The findings are diverse. Significant long memory is demonstrated in the equity returns of Botswana; while, in South Africa this result is not statistically different from zero. For Zimbabwe returns are characterised by an anti‐persistent process. Furthermore, all the markets investigated provide evidence of long memory in volatility with the exception of Botswana where there is no evidence of volatility persistence and hence the return from taking risk in this market cannot be predicted on the basis of previous values.
COMPARATIVE FISCAL RESPONSE EFFECTS OF DEBT RELIEF: AN APPLICATION TO AFRICAN HIPCS
Authors: Cassimon Danny , Van Campenhout Bjorn
Published: November 2008

As part of the efforts of the international donor community to scale up aid to Africa, substantial debt relief has been granted in recent years through the Heavily Indebted Poor Countries (HIPC) Initiative and its successor, the Multilateral Debt Relief Initiative. This paper tries to assess, for a sample of 24 African countries that have at least reached decision point status in the HIPC Initiative, to what extent this debt relief has created fiscal space in recipient country budgets, and what, on average, the actual fiscal response effects have been, relative to other types of aid. Inspired by the fiscal response literature, we model public finance behaviour as a system of structural equations and estimate the reduced form parameters in a Vector Autoregressive framework. In general, we are unable to find evidence that debt relief might provoke no or even perverse fiscal responses. On average, debt relief affects public finance behaviour in a desired way, with effects being most similar to those of its most direct substitute, programme grants.
OPPORTUNITIES AND COSTS OF PORTFOLIO DIVERSIFICATION IN SADC'S SMALLEST EQUITY MARKETS
Authors: Hearn Bruce , Piesse Jenifer
Published: November 2008

This paper contrasts the performance of three time series models, a simple stochastic drift, GARCH, and a time varying parameter CAPM for three of SADC's smallest equity markets: Namibia, Swaziland and Mozambique. Analysis of the portfolio characteristics for each reveals the level of integration with South Africa using optimised portfolio frontiers. In addition, the implications of adopting a minimum investment retention levy by the smaller states is examined. Namibia is found to exhibit the greatest degree of integration with South Africa, followed to a much lesser extent by Swaziland with Mozambique. The evidence suggests that investors in the smaller markets would face considerable additional costs should such a policy be adopted.
PRODUCT DIFFERENTIATION: AN ALTERNATIVE TO CVDS
Authors: Wang Yu‐ter
Published: November 2008

By using a Cournot model where a domestic firm competes with a foreign firm in the domestic market, this paper suggests that, in addition to countervailing duty measures allowed by the World Trade Organization, product differentiation between the goods produced by the domestic and foreign firms could be considered as a way of eliminating foreign export subsidies.
FORECASTING CURRENCY CRISES: WHICH METHODS SIGNALED THE SOUTH AFRICAN CRISIS OF JUNE 2006?
Authors: Knedlik Tobias , Scheufele Rolf
Published: November 2008

In this paper we test the ability of three of the most popular methods to forecast South African currency crises with a special emphasis on their out‐of‐sample performance. We choose the latest crisis of June 2006 to conduct an out‐of‐sample experiment. The results show that the signals approach was not able to forecast the out‐of‐sample crisis correctly; the probit approach was able to predict the crisis but only with models, that were based on raw data. The Markov‐regime‐switching approach predicts the out‐of‐sample crisis well. However, the results are not straightforward. In‐sample, the probit models performed remarkably well and were also able to detect, at least to some extent, out‐of‐sample currency crises before their occurrence. The recommendation is to not restrict the forecasting to only one approach.
FACTORS THAT AFFECT THE LONG‐TERM SURVIVAL OF MICRO, SMALL AND MEDIUM ENTERPRISES IN ETHIOPIA
Authors: Bekele Eshetu , Worku Zeleke
Published: November 2008

There is an increasing recognition of the potential importance of micro, small and medium enterprises (MSMEs) for employment, income and poverty reduction in Ethiopia. Although the MSME sector contributes significantly to the national economy, the high failure rate among well established small businesses and enterprises is a matter of major concern. A random sample of 500 small businesses and enterprises selected from five major cities in Ethiopia were followed up for 6 years in order to assess the impact of influential factors that affect the long‐term survival and viability of small enterprises. Hazard ratios estimated from the Cox Proportional Hazards Model were used to quantify the impact of key predictors of survival. Businesses that ceased operation were characterised by inadequate finance (61%), low level of education (55%), poor managerial skills (54%), shortage of technical skills (49%), and inability to convert part of their profit to investment (46%). The study shows that participation in social capital and networking (iqqub schemes) was critically helpful for long‐term survival. Businesses that did not participate in iqqub schemes regularly were found to be 3.25 times more likely to fail in comparison with businesses that did. Results of the study have implications that could be used for developing policy initiatives that are aimed at fostering long‐term growth in small businesses and enterprises.
Gas Turbines or Electric Drives in Offshore Applications
Authors: Kurz Rainer , Sheya Cynthia
Published: November 2008

Offshore oil and gas production requires both electric and mechanical power for various applications. Traditionally, gas turbines have been the driver of choice for both the power generation, compression and larger pump applications. Today, an alternate approach of electric motor drivers is sometimes considered for pump and compressor drivers. In this case, the power for the electric motor and utility power is supplied by larger gas turbines used as a central power generation plant. This is sometimes referred to as the “All Electric” solution. There are several important factors to be evaluated when considering options and selecting the optimum solution for this type of application. Based on general assumptions on the parameters and characteristics of possible solutions, decision criteria are derived and the sensitivity of the results relative to varying assumptions is determined.
On-Line Transient Engine Diagnostics in a Kalman Filtering Framework
Authors: Borguet S. , Dewallef P. , Le´onard O.
Published: November 2008

A common assumption made in the performance assessment of a turbine engine for aircraft propulsion consists in restricting the data processing to steady-state data. This especially holds for onboard performance monitoring of a commercial aircraft which spends up to 90% of the time in cruise flight where such conditions are satisfied. The present contribution is intended to investigate the ability of a diagnosis method to process unsteady data rather than steady-state data. The aim of this unsteady approach is to strongly reduce the time and the efforts spent to obtain a reliable diagnosis. In order to assess the improvements in terms of diagnosis efficiency and engine operability, the resulting diagnostic method is tested for different degradations that can be expected on commercial turbofans. The results are also compared to those obtained from cruise flight steady-state data in order to balance the two approaches.
CO2 Sequestration From IGCC Power Plants by Means of Metallic Membranes
Authors: Chiesa Paolo , Kreutz Tom , Lozza Giovanni
Published: November 2008

This paper investigates novel IGCC plants that employ hydrogen separation membranes in order to capture carbon dioxide for long-term storage. The thermodynamic performance of these membrane-based plants are compared with similar IGCCs that capture CO2 using conventional (i.e. solvent absorption) technology. The basic plant configuration employs an entrained-flow, oxygen-blown coal gasifier with quench cooling, followed by an adiabatic water gas shift (WGS) reactor that converts most of CO contained in the syngas into CO2 and H2. The syngas then enters a WGS membrane reactor where the syngas undergoes further shifting; simultaneously, H2 in the syngas permeates through the hydrogen-selective, dense metal membrane into a counter-current nitrogen “sweep” flow. The permeated H2, diluted by N2, constitutes a decarbonized fuel for the combined cycle power plant whose exhaust is CO2-free. Exiting the membrane reactor is a hot, high pressure “raffinate” stream composed primarily of CO2 and steam, but also containing “fuel species” such as H2S, unconverted CO, and unpermeated H2. Two different schemes (oxygen catalytic combustion and cryogenic separation) have been investigated to both exploit the heating value of the fuel species and produce a CO2-rich stream for long term storage. Our calculations indicate that, when 85%vol of the H2+CO in the original syngas is extracted as H2 by the membrane reactor, the membrane-based IGCC systems are more efficient by ∼1.7 percentage points than the reference IGCC with CO2 capture based on commercially ready technology.
Artificial Intelligence for the Diagnostics of Gas Turbines: Part I — Neural Network Approach
Authors: Bettocchi R. , Pinelli M. , Spina P. R. , Venturini M.
Published: November 2008

In the paper, Neural Network (NN) models for gas turbine diagnostics are studied and developed. The analyses carried out are aimed at the selection of the most appropriate NN structure for gas turbine diagnostics, in terms of computational time of the NN training phase, accuracy and robustness with respect to measurement uncertainty. In particular, feed-forward NNs with a single hidden layer trained by using a back-propagation learning algorithm are considered and tested. Moreover, Multi-Input/Multi-Output NN architectures (i.e. NNs calculating all the system outputs) are compared to Multi-Input/Single-Output NNs, each of them calculating a single output of the system. The results obtained show that NNs are robust with respect to measurement uncertainty, if a sufficient number of training patterns are used. Moreover, Multi-Input/Multi-Output NNs trained with data corrupted with measurement errors seem to be the best compromise between the computational time required for NN training phase and the NN accuracy in performing gas turbine diagnostics.
Simulation of Compressor Transient Behavior Through Recurrent Neural Network Models
Authors: Venturini M.
Published: November 2008

In the paper, self-adapting models capable of reproducing time-dependent data with high computational speed are investigated. The considered models are recurrent feed-forward neural networks (RNNs) with one feedback loop in a recursive computational structure, trained by using a back-propagation learning algorithm. The data used for both training and testing the RNNs have been generated by means of a non-linear physics-based model for compressor dynamic simulation, which was calibrated on a multi-stage axial-centrifugal small size compressor. The first step of the analysis is the selection of the compressor maneuver to be used for optimizing RNN training. The subsequent step consists in evaluating the most appropriate RNN structure (optimal number of neurons in the hidden layer and number of outputs) and RNN proper delay time. Then, the robustness of the model response towards measurement uncertainty is ascertained, by comparing the performance of RNNs trained on data uncorrupted or corrupted with measurement errors with respect to the simulation of data both uncorrupted and corrupted with measurement errors. Finally, the best RNN model is tested on field data taken on the axial-centrifugal compressor on which the physics-based model was calibrated, by comparing physics-based model and RNN predictions against measured data. The comparison between RNN predictions and measured data shows that the agreement can be considered acceptable for inlet pressure, outlet pressure and outlet temperature, while errors are significant for inlet mass flow rate.
Liquid H2 Storage for Small Size Solar Power Plants
Authors: Cerri Giovanni , Corgnale Claudio , Salvini Coriolano
Published: November 2008

Many significant features lead to consider hydrogen as an interesting energy carrier. Hydrogen can be burned with pure oxygen thus the production of CO2 and NOx is avoided. Since molecular hydrogen does not exist on the earth it has to be produced from fossil fuels or from renewable energy sources. Energy from fossil fuels can be transferred into hydrogen and released elsewhere. So relevant reduction of emission of pollutant can be achieved in critical zones at the centres of large cities. Nevertheless the losses occurring during production, distribution and storage of hydrogen lead to an increased consumption of the primary energy source (fossil fuels) and to increased emission levels (CO2 and others). Hydrogen can be obtained from renewable sources such as the solar energy and used in situ for power generation. In this case hydrogen can act as an energy carrier which allows a local energy storage. In such a way the time dependent availability of the solar energy and the production level of the power plant can be decoupled. In a distributed generation context a small size solar power plant equipped with a hydrogen storage system has been studied. Different storage options have been investigated and compared. Finally a liquid hydrogen storage system is proposed. The peculiarities of the selected system allow a reduction of losses, size of machinery and energy requirements. The paper presents an analysis of the more relevant issues related to the different hydrogen storage options suitable for the present application. After the characterization of the solar field in terms of energy availability and the specifications of both the hydrogen production system and the power generation unit, the design of a liquid hydrogen storage system is presented and widely discussed. This method is particularly useful in the plants management (for example nuclear or coal plants), where it’s impossible or very difficult to modify power level, as well. So, such a static system would be useful in order to allow power modulation by H2 plant. In order to do this, a research for individuating high volumic (and mass) specific capacity systems should be driven.
Data Normalization for Engine Health Monitoring
Authors: Bronson Robert J. , Depold Hans R. , Rajamani Ravi , Deb Somnath , Morrison William H. , Pattipati Krishna R.
Published: November 2008

In this paper we present a systematic data-driven parameter correction and estimation process consisting of outlier detection and removal, relevant input parameter selection, advanced statistical and empirical correlation, and prediction fusion to reduce variance in relevant engine parameter estimates. We model engine parameter deviations from nominal, and show that these methods can result in significant reductions in bias and variance modeling errors. Reducing the error variance increases the signal-to-noise ratio, thereby increasing the reliability and speed of fault-detection algorithms. The overall objective function is to reduce the measurement variances without masking faults. Key parameters modeled include fuel flow, rotor speed(s), and measured temperatures.
Affordable Smaller Turbofans
Authors: Rodgers C.
Published: November 2008

Smaller smarter un-manned air vehicles (UAV’s) and missiles are being proposed and developed to function in a variety of roles previously performed by larger manned aircraft and limited range missiles. The endurance and stealth demanded of such advanced vehicles requires small turbofan engines possessing relatively higher power density combined with increased thermal efficiency. It is shown that these two major performance related criteria are indirectly related to improved affordability for a specific turbofan design configuration. Changing the design configuration by implementing lower component count and flowpath simplification however is an alternate trade-off route to improved affordability, albeit at a slight performance decrement. As an example the classic two spool (2SC) turbofan with concentric shafting for the inner spool is the engine of choice for extended range applications, but can present shaft dynamic and bearing lubrication mechanical design concerns as size is reduced and core rotational speeds approach and exceed 100Krpm. Preliminary design features of two alternate non concentric drive small turbofan flowpath candidates are presented, neither of which can match the full performance capability of the classic two spool concentric drive turbofan, yet they potentially offer several affordability virtues, inasmuch as lower component count, reduced cost, higher reliability, oil less lubrication, and electric driven accessories.