bluuebunny/crossref_metadata_2025 huggingface dataset:
On the importance of incorporating forest edge deposition for evaluating exceedance of critical pollutant loads
Authors: De Schrijver A. , Devlaeminck R. , Mertens J. , Wuyts K. , Hermy M. , Verheyen K.
Published: July 2009

The concept of critical load (CL) was defined to express the tolerance of natural and semi‐natural habitats for anthropogenic air pollution. Correct evaluation of the exceedance of critical loads is fundamental for the long‐term protection of ecosystems by limiting emissions of potential acidifying and eutrophying pollutants. For forest ecosystems, the exceedance of critical loads is often calculated using deposition data measured in the forest interior. However, several studies report forest edges acting as ‘hotspots’ of acidifying and nitrogen deposition, showing up to fourfold increases in atmospheric deposition compared to the forest interior. This paper estimates the relevance of considering the higher deposition load in forest edges for calculating exceedance of critical loads for nitrogen and potential acidifying deposition. If measures to control and reduce atmospheric deposition are based on mean deposition fluxes within forest stands, deposition reductions will not be enough for preventing adverse effects. In fact, emission reductions should be adjusted to deposition values at the forest edge, since these zones are most threatened. We thus conclude that there is an urgent need to reconsider the calculation of exceedance of critical loads, taking into account edge enhancement of deposition. This is an issue of high relevance, particularly in highly fragmented regions, such as Flanders (Belgium).
Plant responsiveness to variation in precipitation and nitrogen is consistent across the compositional diversity of a California annual grassland
Authors: St. Clair Samuel B. , Sudderth Erika A. , Castanha Cristina , Torn Margaret S. , Ackerly David D.
Published: July 2009

Question: How does responsiveness to water and Nitrogen (N) availability vary across the compositional and functional diversity that exists in a mesic California annual grassland plant community?

Location: Northern California annual grassland.

Methods: A mesocosm system was used to simulate average annual precipitation totals and dry and wet year extremes observed in northern California mesic grasslands. The effects of precipitation and N availability on biomass and fecundity were measured on three different vegetation types, a mixed grass forb community, and a forb and a grass monoculture. The treatment effects on plant community composition were examined in the mixed species community.

Results: While growth and seed production of the three vegetation types was inherently different, their responses to variation in precipitation and N were statistically similar. Plant density, shoot biomass, and seed production tended to increase with greater water availability in all vegetation types, with the exception of a consistent growth reduction in high precipitation (1245 mm) plots in the first year of the study. Shoot biomass responded positively to N addition, an effect that increased with greater water availability. Nitrogen addition had little effect on plant density or seed production. In the mixed grass‐forb community, biomass responsiveness to water and N treatments were consistently driven by the shoot growth of Avena barbata, the dominant grass species.

Conclusions: Vegetation responses to changes in precipitation and N availability were consistent across a range of composition and structural diversity in this study. Plant growth and seed production were sensitive to both increased and decreased precipitation totals, and the magnitude of these responses to N availability varied depending on soil moisture conditions. Our results suggest the impacts of changing precipitation regimes and N deposition on annual productivity of California grasslands may be predictable under different climate scenarios across a range of plant communities.
Fire and regeneration: the role of seed banks in the dynamics of northern heathlands
Authors: Måren Inger E. , Vandvik Vigdis
Published: July 2009

Questions: How do species composition and abundance of soil seed bank and standing vegetation vary over the course of a post‐fire succession in northern heathlands? What is the role of seed banks – do they act as a refuge for early successional species or can they simply be seen as a spillover from the extant local vegetation?

Location: Coastal Calluna heathlands, Western Norway.

Methods: We analysed vegetation and seed bank along a 24‐year post‐fire chronosequence. Patterns in community composition, similarity and abundances were tested using multivariate analyses, Sørensen's index of similarity, vegetation cover (%) and seedling counts.

Results: The total diversity of vegetation and seed bank were 60 and 54 vascular plant taxa, respectively, with 39 shared species, resulting in 68% similarity overall. Over 24 years, the heathland community progressed from open newly burned ground via species rich graminoid‐ and herb‐dominated vegetation to mature Calluna heath. Post‐fire succession was not reflected in the seed bank. The 10 most abundant species constituted 98% of the germinated seeds. The most abundant were Calluna vulgaris (49%; 12 018 seeds m−2) and Erica tetralix (34%; 8 414 seeds m−2). Calluna showed significantly higher germination the first 2 years following fire.

Conclusions: Vegetation species richness, ranging from 23 to 46 species yr−1, showed a unimodal pattern over the post‐fire succession. In contrast, the seed bank species richness, ranging from 21 to 31 species yr−1, showed no trend. This suggests that the seed bank act as a refuge; providing a constant source of recruits for species that colonise newly burned areas. The traditional management regime has not depleted or destroyed the seed banks and continued management is needed to ensure sustainability of northern heathlands.
President Eisenhower and the Development of Active Labor Market Policy in the United States: A Revisionist View
Authors: WILSON HUGH A.
Published: July 2009

Revisionist analysis indicates that Dwight D. Eisenhower's administration was not hostile to the American welfare state, and even extended it in areas such as social security. However, one area of the welfare state—active labor market policy—has received minimal attention from scholars. This article analyzes the Eisenhower administration's efforts at advancing active labor market policies. The analysis bears out Eisenhower's active engagement in this policy arena and contributes to the revisionist literature. The analysis also challenges the prevailing orthodoxy on active labor market policy as a two‐stage process—the Employment Act of 1946 and the Kennedy‐era legislation on manpower training—which ignores the Eisenhower era.
The Law: Presidential Proclamation 6920: Using Executive Power to Set a New Direction for the Management of National Monuments
Authors: BELCO MICHELLE , ROTTINGHAUS BRANDON
Published: July 2009

Scholars in recent years have been interested in the use of presidential proclamations, but the scope and implications of their use have yet to be fully examined. Specifically, the Antiquities Act of 1906 granted the president broad discretionary authority to proclaim national monuments. Presidents have used this power, often despite the consternation of Congress, to implement changes in public policy. In this context, when President Clinton issued Proclamation 6920 to establish the Grand Staircase‐Escalante National Monument, his use of executive power initiated a significant congressional reaction, even though his delegation of the managing agency, which will have a lasting effect on public lands policy, received little attention. In this article, the authors argue first that, despite congressional efforts to limit the president's discretion to proclaim national monuments under the Antiquities Act, executive power was not curtailed, and second, that by delegating management authority to the Bureau of Land Management, President Clinton laid the groundwork for a new direction for both national monuments and the bureau.
Italian Multicenter Study on Low‐Density Lipoprotein Apheresis: Retrospective Analysis (2007)
Authors: Stefanutti Claudia ,   the Italian Multicenter Study on Low‐density Lipoprotein Apheresis Working Group
Published: July 2009

A retrospective study—the Italian Multicenter Study on Low‐density Lipoprotein Apheresis (IMS‐LDLa)—was carried out, which involved 19 centers for LDLa in Italy, distributed all over the country—in the north, center, south, and the major islands. The survey was conducted through two consecutive questionnaires, which can be downloaded online from a dedicated site. The total number of procedures performed until 2007 was 31 012, and the number of patients undergoing treatment until 2007 were 229. The treated patients still surviving consisted of 136 (74 males and 62 females); those surviving but not treated numbered 95, and those deceased numbered 14. The techniques utilized, listed by frequency of use, were the following: dextran sulfate cellulose adsorption, direct adsorption of lipids (DALI), heparin extracorporeal LDL precipitation, immunoadsorption, plasma‐exchange, cascade filtration, and Lipocollect 200. The mean treated plasma and blood volumes per session were 3916.5 mL and 8735.1 mL, respectively. The most frequently utilized vascular access points were: venous 84.4% and arteriovenous fistula 15.5%. Hematoma by venipuncture (230 episodes), low outlet flow (125 episodes), and circuit coagulation (44 episodes) were reported as to be the most frequent side effects. In the second questionnaire (filled in by 19 centers) the centers were asked to report their data on: quality diagnosis of dyslipidemia and referents for genetic‐molecular and clinical diagnosis, cholesterol‐lowering drugs and dosages, typology of cardiovascular check‐ups at the beginning of treatment and in follow‐up, non‐cholesterol‐lowering drugs with priority for cardiologic drugs, including oral anti‐coagulants, and, lastly, information related to the appropriateness of curing patients still under treatment with LDLa and, where possible, news on patients no longer under treatment.
Liver Transplantation Avoided in Patients With Fulminant Hepatic Failure Who Received Albumin Dialysis With the Molecular Adsorbent Recirculating System While on the Waiting List: Impact of the Duration of Therapy
Authors: Camus Christophe , Lavoué Sylvain , Gacouin Arnaud , Compagnon Philippe , Boudjéma Karim , Jacquelinet Christian , Thomas Rémi , Le Tulzo Yves
Published: July 2009

Eighteen patients with fulminant hepatic failure due to various medical causes were listed for emergency liver transplantation and treated with extracorporeal albumin dialysis sessions using the molecular adsorbent recirculating system (MARS) at our center over a 74‐month period. Due to improvement of liver function, transplantation could be avoided in 9 patients (50%, 95% confidence interval 29% to 71%) who fully recovered afterwards. This improvement rate was higher than the rate of improvement in the French cohort of fulminant hepatic failure patients with similar etiologies (19.3%, 95% confidence interval 14.9% to 24.6%, P = 0.002). In our 18 patients, there were no statistically significant differences in any baseline characteristics or in the time with liver failure meeting transplant criteria between the patients who improved while waiting and those who did not. However, the patients who improved received a greater number of sessions and a longer total duration of MARS therapy (all P < 0.001). In the whole study population, a MARS therapy duration ≥15 h was significantly associated with improvement of liver function without transplantation (adjusted adds ratio [OR] 65.76, 2.48–1743.11, P = 0.01). Tolerance of therapy was acceptable. These results suggest that MARS therapy could contribute to native liver recovery and is safe in patients on the waiting list for fulminant hepatic failure. A minimum duration of therapy (≥15 h) could be necessary to expect significant liver function improvement.
REDUCTION OF ROASTED PEANUT LIPID OXIDATIVE RANCIDITY BY POWER ULTRASOUND AND EDIBLE COATINGS CONTAINING NATURAL EXTRACTS
Authors: WAMBURA PETER , YANG WADE , MWAKATAGE NASSON
Published: July 2009

The antioxidative potential of jujube extract, pomegranate extract and tocopherol mixed into carboxymethyl cellulose (CMC) solution then coated on roasted and roasted–sonicated peanuts was investigated. The concentration of jujube and pomegranate extracts added into the CMC solution was 1,000 ppm, while synthetic tocopherol was 250 ppm. Antioxidant effect was determined by the measurement of oxidative stability index. After 12 weeks of storage at 35C, the reduction in oxidation was 14.5 and 19.7% for samples roasted–coated with CMC added with extracts of jujube and pomegranate extract, respectively, as compared to uncoated sample (R as a control). Meanwhile, the oxidative stability of samples roasted–sonicated coated with CMC added with extracts of jujube and pomegranate was significantly (P < 0.05) improved by 24.8 and 31.8%, respectively, in relation to the control. However, it was observed that samples with tocopherol did not have any improvement in oxidative stability of the roasted peanuts. Sonication treatment beyond coating improved the storage stability of the samples mixed with jujube extract, pomegranate extract and tocopherol by 10.3, 12.1 and 3.2%, respectively. It is concluded that jujube and pomegranate extracts can control roasted peanut lipid oxidation during storage.

PRACTICAL APPLICATIONS

This study showed that a combination of power ultrasound treatment and an edible coating of carboxymethyl cellulose mixed with natural plant extracts can be used for delaying the oxidation of roasted peanuts. The delaying development of oxidation compounds in roasted peanuts is very useful to the peanut industry. This process can be used for the preparation of shelf‐stable peanut products for the purpose of reaching distant markets, to be used during extended storage period. Likewise, the peanuts can be packed without the need to modify the packaging atmosphere or use of expensive packages.
AIR IMPINGEMENT DRYING CHARACTERISTICS AND QUALITY OF CARROT CUBES
Authors: XIAO HONG‐WEI , GAO ZHEN‐JIANG , LIN HAI , YANG WEN‐XIA
Published: July 2009

The effects of air temperature (40, 50 and 60C), air velocity (3.0, 8.0 and 13.0 m/s) and air relative humidity (10, 20 and 40%) on air impingement drying characteristics of carrot cubes and the quality of dried carrots were investigated. The drying experiments were carried out according to orthogonal design method on the air impingement dryer. Results indicated that drying time of carrot cubes was more affected by drying air temperature, followed by air relative humidity and air velocity. The moisture effective diffusivity calculated from the second Fick's law of diffusion ranged from 0.265 × 10−9to 1.052 × 10−9 m2/s. The activation energy determined from the slope of the Arrhenius plot, ln(Deff) versus 1/(T + 273.15), was 20.17 kJ/mol. The color values L (white/dark), a (red/green) and b (yellow/blue) of the samples decreased from 50.02 to 32.71, 32.49 to 14.34 and 35.52 to 16.38 separately when the drying temperature increased from 40 to 60C. Rehydration experiments demonstrated that the rehydration ratio of dried carrot cubes was significantly affected by drying air temperature and air relative humidity. The surface microstructures of dried carrot cubes were observed using a scanning electron microscope, which showed that the outer layers of the samples dried at 60C drying temperature and 10% air relative humidity had more consolidated rigid and denser structure than the samples dried at 40C drying temperature and 40% air relative humidity.

PRACTICAL APPLICATIONS

Air impingement drying is used for food and agricultural product processing. But, it is a complicated process. Many factors such as drying temperature, air velocity and relative humidity can influence its drying characteristics and quality. Carrot is a typical vegetable, which is sensitive to microbial spoilage and deterioration reactions. Using drying technology can prolong its shelf life. Investigating air impingement drying characteristics and quality of carrots can help to understand its drying process and the effect of drying parameters on drying quality. This research was done to provide enough information to build a commercial impingement drying system.
Inter‐conversion of catalytic abilities in a bifunctional carboxyl/feruloyl‐esterase from earthworm gut metagenome
Authors: Vieites José María , Ghazi Azam , Beloqui Ana , Polaina Julio , Andreu José M. , Golyshina Olga V. , Nechitaylo Taras Y. , Waliczek Agnes , Yakimov Michail M. , Golyshin Peter N. , Ferrer Manuel
Published: July 2009

Carboxyl esterases (CE) exhibit various reaction specificities despite of their overall structural similarity. In present study we have exploited functional metagenomics, saturation mutagenesis and experimental protein evolution to explore residues that have a significant role in substrate discrimination. We used an enzyme, designated 3A6, derived from the earthworm gut metagenome that exhibits CE and feruloyl esterase (FAE) activities with p‐nitrophenyl and cinnamate esters, respectively, with a [(kcat/Km)]CE/[(kcat/Km)]FAE factor of 17. Modelling‐guided saturation mutagenesis at specific hotspots (Lys281, Asp282, Asn316 and Lys317) situated close to the catalytic core (Ser143/Asp273/His305) and a deletion of a 34‐AA–long peptide fragment yielded mutants with the highest CE activity, while cinnamate ester bond hydrolysis was effectively abolished. Although, single to triple mutants with both improved activities (up to 180‐fold in kcat/Km values) and enzymes with inverted specificity ((kcat/Km)CE/(kcat/Km)FAE ratio of ∼0.4) were identified, no CE inactive variant was found. Screening of a large error‐prone PCR‐generated library yielded by far less mutants for substrate discrimination. We also found that no significant changes in CE activation energy occurs after any mutation (7.3 to −5.6 J mol−1), whereas a direct correlation between loss/gain of FAE function and activation energies (from 33.05 to −13.7 J mol−1) was found. Results suggest that the FAE activity in 3A6 may have evolved via introduction of a limited number of ‘hot spot’ mutations in a common CE ancestor, which may retain the original hydrolytic activity due to lower restrictive energy barriers but conveys a dynamic energetically favourable switch of a second hydrolytic reaction.
Men’s Psychological Functioning in the Context of Women’s Breast Cancer
Authors: Baucom Donald H. , Kirby Jennifer S. , Pukay‐Martin Nicole D. , Porter Laura S. , Fredman Steffany J. , Gremore Tina M. , Keefe Francis J. , Atkins David
Published: July 2009

Previous research indicates that men are affected when their female partners have breast cancer. However, little is known about what predicts men’s psychological well‐being in this context. The current investigation involved couples in which the woman had early stage breast cancer and explored the degree to which men’s positive and negative well‐being was related to women’s well‐being, women’s physical symptoms, relationship functioning, and relationship duration. The findings indicate that all of these factors play a role and interact in predicting men’s well‐being. In particular, when women have a high level of physical symptoms, the typical associations between men’s well‐being with women’s well‐being and relationship adjustment no longer persist. Implications for working with couples addressing health problems are provided.
Family Functioning and Depression in Low‐Income Latino Couples
Authors: Sarmiento Ingrid A. , Cardemil Esteban V.
Published: July 2009

Although extensive research has found a strong relationship between poor family functioning and depression, previous research has not examined this relationship among low‐income Latinos. In this study, we examined how family functioning may be associated with depression in a sample of low‐income Latino couples. In addition, we examined how acculturative stress moderates the relationship between family functioning and depression. Our results indicate that the relationship between family functioning and depression is stronger in women and that acculturative stress moderates this relationship in women. Probing this interaction indicates that women who reported high acculturative stress coupled with poor family functioning experienced more depression. Clinical implications are discussed.
Complication following lower third molar surgery: myositis ossificans traumatica of the muscles of mastication
Authors: Seehra J. , Lloyd R.
Published: July 2009

Trismus is a frequent post‐op sequelae of third molar surgery. A history of long‐standing post‐operative trismus warrants further investigation. Myositis ossificans traumatica (MOT), as its name implies, is ossification and bone formation within muscle following an episode of trauma. When it affects the muscles of mastication, it causes severe trismus. This rare disorder and its limited treatment options can potentially have debilitating effects to the patient's normal oral functioning and health. The following is a case report of a patient who developed MOT of the muscles of mastication following surgical exodontia of a lower wisdom tooth, the progress over a 15 year period and a review of the literature. This case demonstrates the long‐term difficulties in managing MOT of the muscles of mastication.
IgG4‐related sclerosing sialadenitis in bilateral submandibular glands
Authors: Kato K. , Kawashiri S. , Nakagawa K. , Yamamoto E. , Zen Y.
Published: July 2009

Chronic sclerosing sialadenitis (CSS) is a totally inflammatory lesion. In a 60‐year‐old male with CSS, serum immunoglobulin G (IgG) concentration was markedly increased and abundant infiltration of IgG4‐positive plasma cells was observed in the salivary glands. Autoimmune pancreatitis occurred during follow‐up. CSS and autoimmune pancreatitis would appear to show essentially the same pathophysiological mechanism. The abundance of IgG4‐positive plasma cells in the lesions would be useful for revealing other IgG4‐related disease in patients with CSS.
The influence of interfering septa on the incidence of Schneiderian membrane perforations during maxillary sinus elevation surgery: a retrospective study of 52 consecutive lateral window procedures
Authors: Malkinson S. , Irinakis T.
Published: July 2009

Aim:  Sinus lifts are a predictable method of augmenting the height of bone in maxillary posterior sextants. These procedures can be complicated by anatomical factors, such as the presence of interfering bony septa in the sinus. The objectives of this study were to investigate the incidence of interfering septa in patients undergoing sinus lifts and to see if the presence of interfering septa increased the chance of intra‐operative membrane perforation.

Materials and methods:  This retrospective cohort study assessed presence of interfering antral septa and their effect on Schneiderian membrane elevation in 45 patients with pneumatised sinuses undergoing sinus lifts. Chart audits and radiographic assessments were performed for 52 surgeries. The sinus lift procedure followed established guidelines. Presence of septa and occurrence of perforations were noted, and when perforations occurred, they were repaired with resorbable membranes.

Results:  Septa were present in 40% of cases, and were found to be ‘interfering’ septa in 28.8% of cases. Membrane perforation occurred in 11.5% of cases. There was no statistically significant association between the presence of interfering septa and membrane perforation.

Conclusion:  With enough experience and appropriate armamentarium and technique, an operator can overcome the presence of an interfering antral septum during a sinus lift procedure such that it does not increase the chance of perforating the Schneiderian membrane during elevation.
Antecedent caloric intake and glucose excursion following a subsequent meal in Type 1 diabetes
Authors: MEHRA Rinku , RAMAN Ramesh , BAYLESS Margaret L. , SIVITZ William I.
Published: July 2009

Background:  In the present study, we tested the hypothesis that calories consumed at a prior meal (lunch) may impair glycemic control after a subsequent meal (supper) even if the pre‐supper glucose did not differ regardless of the size of the lunch meal.

Methods:  Nine subjects with Type 1 diabetes using continuous subcutaneous (s.c.) insulin infusion (CSII) therapy were studied on two separate days. Lunch (1200 h) was randomly assigned as 25% or 50% of the usual daily intake on alternate study days. The CSII was stopped at 1000 h on the day of the study and glucose was controlled until supper by adjusting the rate of intravenous (i.v.) insulin based on glucose measurements every 15 min. The CSII was restarted 1 h before supper and i.v. insulin discontinued 15 min before the first bite of supper. An identical supper meal and pre‐supper s.c. bolus of short‐acting insulin were administered on both visits.

Results:  Pre‐supper glycemia was nearly identical on each of the two study days. However, the post‐supper glucose area under the curve was 27.5% greater on the day of the antecedent large lunch compared with the small lunch (P = 0.0039).

Conclusions:  For optimal postprandial glucose control, people with Type 1 diabetes may need to consider not only anticipated meal calories, but also prior food intake, a practice not commonly recommended based on currently used insulin dosing algorithms.
An Asian Triangle: India's Relationship With China and Japan
Authors: Roehrig Terence
Published: July 2009

Many studies of Asia's future have focused on the shifting power relationships in the region, particularly between China, Japan, and India. A prominent part of this debate is India's rise and potential role as a balancer in the evolving strategic relationships in the region. This article examines India's relations with these two Asian powers and argues that India is unlikely to play the role of balancer unless relations between China and Japan deteriorate significantly. Instead, India may be well situated to act as a stabilizer, not only between China and Japan but also between the United States and China, should tension escalate in the region.
Corruption and Foreign Direct Investment Attractiveness in Asia
Authors: Woo Jung‐Yeop , Heo Uk
Published: July 2009

There have been debates on how political corruption may affect foreign direct investment (FDI) attractiveness. Some scholars argue that corruption increases economic uncertainty due to arbitrariness and thereby affects FDI negatively. On the other hand, another group of scholars contends that corruption leads to greater FDI because it can create a business environment that is more friendly to foreign investors. In this article, we empirically test the relationship between the level of corruption and FDI attractiveness in eight non‐OECD (Organisation for Economic Co‐operation and Development) Asian countries (Bangladesh, India, Indonesia, Malaysia, Pakistan, Philippines, Sri Lanka, and Thailand) using data for the perceived corruption level (according to the International Country Risk Guide data set) available from Political Risk Services, a private international investment risk service company, for 1984–2004. The analysis reveals that corruption in non‐OECD countries in Asia generally harms FDI attractiveness.
From “Veshyas” to “Entertainment Workers”: Evolving Discourses of Bodies, Rights, and Prostitution in India
Authors: Kole Subir K.
Published: July 2009

The discursive terrain of prostitution has undergone several changes with modernity/postmodernity. Various groups of feminists hold contentious, often conflicting, ideologies on this issue. Two broad groups emerge from these debates: One takes a clear abolitionist perspective, while the other takes a sex work position. Both these groups actively lobby and join forces with individuals and institutions to influence global and national policy‐making. There is a great degree of variation and overlap within and across each camp. Among those taking a sex work position, some argue that selling sex is equal to using any other part of the body for making a living. This article examines the discursive terrain of prostitution in India, focusing on what it means to treat sex as any other use of the body in commerce. It concludes that prohibition is a prejudice that India must overcome to develop sound public health policies.
Regulation of cerebral blood flow in mammals during chronic hypoxia: a matter of balance
Authors: Ainslie Philip N. , Ogoh Shigehiko
Published: July 2009

Respiratory‐induced changes in the partial pressures of arterial carbon dioxide
and oxygen
play a major role in cerebral blood flow (CBF) regulation. Elevations in
(hypercapnia) lead to vasodilatation and increases in CBF, whereas reductions in
(hypocapnia) lead to vasoconstriction and decreases in CBF. A fall in
(hypoxia) below a certain threshold (<40–45 mmHg) also produces cerebral vasodilatation. Upon initial exposure to hypoxia, CBF is elevated via a greater relative degree of hypoxia compared with hypocapnia. At this point, hypoxia‐induced elevations in blood pressure and loss of cerebral autoregulation, stimulation of neuronal pathways, angiogenesis, release of adenosine, endothelium‐derived NO and a variety of autocoids and cytokines are additional factors acting to increase CBF. Following 2–3 days, however, the process of ventilatory acclimatization results in a progressive rise in ventilation, which increases
and reduces
, collectively acting to attenuate the initial rise in CBF. Other factors acting to lower CBF include elevations in haematocrit, sympathetic nerve activity and local and endothelium‐derived vasoconstrictors. Hypoxia‐induced alterations of cerebrovascular reactivity, autoregulation and pulmonary vascular tone may also affect CBF. Thus, the extent of change in CBF during exposure to hypoxia is dependent on the balance between the myriad of vasodilators and constrictors derived from the endothelium, neuronal innervations and perfusion pressure. This review examines the extent and mechanisms by which hypoxia regulates CBF. Particular focus will be given to the marked influence of hypoxia associated with exposure to high altitude and chronic lung disease. The associated implications of these hypoxia‐induced integrative alterations for the regulation of CBF are discussed, and future avenues for research are proposed.
Specific control of sympathetic nerve activity to the mammalian heart and kidney
Authors: May C. N. , Frithiof R. , Hood S. G. , McAllen R. M. , McKinley M. J. , Ramchandra R.
Published: July 2009

There is a large body of evidence indicating that sympathetic nerves to individual organs are specifically controlled, but only few studies have compared the control of cardiac sympathetic nerve activity (CSNA) with activity in other sympathetic nerves. In this review, changes in sympathetic activity to the heart and kidneys are described during increases in brain [Na+] and in heart failure (HF). In conscious sheep, increases in brain [Na+] increased CSNA and arterial pressure and, conversely, decreased renal sympathetic nerve activity (RSNA), promoting urinary sodium loss. These organ‐specific effects are mediated via a neural pathway that includes an angiotensinergic synapse, the lamina terminalis and the paraventricular nucleus of the hypothalamus. There is also evidence of differential control of SNA in HF. In normal sheep, the resting burst incidence of CSNA was much lower than that of RSNA, whereas in HF they increased to similar, almost maximal levels in both nerves. Arterial baroreflex control of both these nerves was unchanged in HF, but the response of CSNA to changes in blood volume was almost absent. These data indicate that in HF the lower arterial pressure leads to reduced baroreflex inhibition of SNA, which, together with the lack of an inhibitory response to the increased volume and cardiac pressures, would contribute to the sympathoexcitation observed. These studies demonstrate differences in the control of CSNA and RSNA, enabling selective actions on the heart and kidney to restore fluid and electrolyte homeostasis in the case of elevated brain [Na+] and to increase cardiac output in HF.
Robust Fixture Layout Design for a Product Family Assembled in a Multistage Reconfigurable Line
Authors: Izquierdo L. Eduardo , Hu S. Jack , Du Hao , Jin Ran , Jee Haeseong , Shi Jianjun
Published: July 2009

Reconfigurable assembly systems enable a family of products to be assembled in a single system by adjusting and reconfiguring fixtures according to each product. The sharing of fixtures among different products impacts their robustness to fixture variation due to trade offs in fixture design (to allow the accommodation of the family in the single system) and to frequent reconfigurations. This paper proposes a methodology to achieve robustness of the fixture layout design through an optimal distribution of the locators in a multistation assembly system for a product family. This objective is accomplished by (1) the use of a multistation assembly process model for the product family, and (2) minimizing the combined sensitivity of the products to fixture variation. The optimization considers the feasibility of the locator layout by taking into account the constraints imposed by the different products and the processes (assembly sequence, data scheme, and reconfigurable tools’ workspace). A case study where three products are assembled in four stations is presented. The sensitivity of the optimal layout was benchmarked against the ones obtained using dedicated assembly lines for each product. This comparison demonstrates that the proposed approach does not significantly sacrifice robustness while allowing the assembly of all products in a single reconfigurable line.
Production of Open Cell Aluminum Foams by Using the Dissolution and Sintering Process (DSP)
Authors: Barletta M. , Gisario A. , Guarino S. , Rubino G.
Published: July 2009

The manufacture of open cell metal foams by dissolution and sintering process (DSP) is the matter of the present work. Aluminum foams were produced by mixing together carbamide particles with different mesh sizes (i.e., space-holder) and very fine aluminum powders. Attention was first paid at understanding the leading phenomena of the different stages the manufacturing process gets through: Compaction of the main constituents, space-holder dissolution, and aluminum powders sintering. Then, experimental tests were performed to analyze the influence of several process parameters, namely, carbamide grain size, carbamide wt %, compaction pressure, and compaction speed on the overall mechanical performance of the aluminum foams. Meaningfulness of each operational parameter was assessed by analysis of variance. Metal foams were found to be particularly sensitive to changes in compaction pressure, exhibiting their best performances for values not higher than 400 MPa. Neural network solutions were used to model the DSP. Radial basis function (RBF) neural network trained with back propagation algorithm was found to be the fittest model. Genetic algorithm (GA) was developed to improve the capability of the RBF network in modeling the available experimental data, leading to very low overall errors. Accordingly, RBF network with GA forms the basis for the development of an accurate and versatile prediction model of the DSP, hence becoming a useful support tool for the purposes of process automation and control.
Characteristics of Residual Stress Profiles in Hard Turned Versus Ground Surfaces With and Without a White Layer
Authors: Warren A. W. , Guo Y. B.
Published: July 2009

Hard turning and grinding are precision processes in many cases for manufacturing various mechanical products. Product performance is highly dependent on the process induced residual stress. However, the basic differences in residual stress profiles generated by hard turning and grinding with and without the presence of a thermal white layer have not been well understood. This study aims to compare basic characteristics of the residual stress profiles using an extensive residual stress measurement for five surface types: hard turned fresh, hard turned with a white layer, ground fresh, ground with a white layer, and as heat treated. The X-ray diffraction data revealed distinct differences in the residual stress profiles for the five surface types. Hard turning with a sharp cutting tool generates a unique “hook” shaped residual stress profile characterized by compressive residual stress at the surface and maximum compressive residual stress in the subsurface, while “gentle” grinding only generates maximum compressive residual stress at the surface. The depth of compressive residual stress in the subsurface by hard turning is much larger than that by grinding. The high hertz pressure induced by the cutting tool in turning is the determining factor for the differences in residual stress. High tensile residual stress associates with the existence of a turned or a ground white layer. The coupled effects of high hertz pressure and rapid temperature change induced by tool wear play an important role in the resultant tensile residual stress. In addition, residual stress by grinding is more scattered than that by turning. Compared with the deterministic influence of machining process on the magnitudes and profiles of residual stress, the effect of heat treatment is minor.
Chatter Stability of General Turning Operations With Process Damping
Authors: Eynian M. , Altintas Y.
Published: July 2009

The accurate prediction of chatter stability in general turning operations requires the inclusion of tool geometry and cutting conditions. This paper presents regenerative chip and regenerative chip area/cutting edge contact length based dynamic cutting force models, which consider cutting conditions and turning tool geometry. The cutting process is modeled as it takes place along the equivalent chord length between the two end points of the cutting edge. The regenerative chip model is simple, and the stability can be solved directly. However, the three-dimensional model considers the effect of tool vibrations at the present and previous spindle revolutions on the chip area, chord length, and force directions and is solved using Nyquist stability criterion. The penetration of worn tool flank into the finish surface is considered as a source of process damping. The effects of the nose radius, approach angle of the tool, and feedrate are investigated. The proposed stability model is compared favorably against the experimental results.
Systematic Study of Ultrasonic Vibration Assisted Electron Beam Irradiation Process
Authors: Wang Z. G. , Kobayashi S. , Matsumoto I. , Yamazaki K. , Cheng X. , Delplanque J.-P.
Published: July 2009

Large area electron beams (EBs) have recently been successfully used to machine dies and tool steels. This large area EB process can greatly improve the machined surface quality as well as its corrosion resistance. However, some craters would still exist on the machined surface, which limits the further improvement of the surface quality of the machined workpieces. One possible solution is to apply external forces to workpieces by using high-frequency vibrations to smooth craters during melting and solidification in the EB process. In this study, a vibration system is designed to generate a high-frequency vibration with a certain amplitude by using sound wave’s transfer inside solids. Then, the performance of the designed vibration system is evaluated. Finally, the experiments of the vibration assisted EB process are carried out to verify the performance of assisted vibration in the EB process.
Physics-Based Predictive Cutting Force Model in Ultrasonic-Vibration-Assisted Grinding for Titanium Drilling
Authors: Qin Na , Pei Z. J. , Treadwell C. , Guo D. M.
Published: July 2009

Ultrasonic-vibration-assisted grinding (UVAG) or rotary ultrasonic machining has been investigated both experimentally and theoretically. Effects of input variables on output variables in UVAG of brittle materials and titanium (Ti) have been studied experimentally. Models to predict the material removal rate in UVAG of brittle materials have been developed. However, there is no report on models of cutting force in UVAG. This paper presents a physics-based predictive model of cutting force in the UVAG of Ti. Using the model developed, influences of input variables on cutting force are predicted. These predicted influences are compared with those determined experimentally. This model can serve as a useful template and foundation for development of cutting force models in UVAG of other materials (such as ceramics and stainless steels) and models to predict torque, cutting temperature, tool wear, and surface roughness in UVAG.
Stiffness Computation and Identification of Parallel Kinematic Machine Tools
Authors: Bonnemains Thomas , Chanal Hélène , Bouzgarrou Belhassen-Chedli , Ray Pascal
Published: July 2009

This paper deals with the stiffness computation and model identification of parallel kinematic machine tools (PKMs). Due to their high dynamic abilities, PKMs are subjected to high inertial and cutting loads while machining. These loads generate structure deflection, and it results in a low level of accuracy compared with serial machines. The aim of this paper is to present a “compact” and predictable model of PKM. This model could be useful to optimize part positioning in the workspace or adapt machining strategies in order to minimize the influence of structure deflections. The proposed model takes into account legs’ and joints’ compliances. Considering the geometry of most of parallel architectures, the legs are modeled as beams. The focus, here, is particularly on joints’ models. In literature, when the compliance of joints is considered, it is most of the time modeled with a constant stiffness. In this paper, a different approach is proposed, based on a technical analysis of the joints. Models proposed are applied to an existing PKM: the Tricept. The parameters of this model (i.e., the stiffness of the joints) are then identified; thanks to experimental stiffness measurements done on an ABB 940 Tricept robot. This robot is used in the industry for machining operations, such as grinding or drilling. A discussion about identifiable parameters is performed so as to best fit with experimental measurements. Finally, this model is used to define a static workspace where the machined parts are within the tolerances for a given operation.
Innovative Tape Placement Robotic Cell: High Flexibility System to Manufacture Composite Structural Parts With Variable Thickness
Authors: Sorrentino L. , Carrino L. , Tersigni L. , Leone A.
Published: July 2009

Until today, there are only automated processes able to manufacture composite components with a constant thickness. This work focuses on the need to find a system able to manufacture composite structural parts characterized by a variable thickness. An innovative tape placement robotic cell composed of a deposition integrated system and an anthropomorphic robot with 6DOF is shown in this work. The main characteristics of the designed deposition integrated system are (i) alternate deposition movement, (ii) tape compaction system, and (iii) tape tension control system by proportional-integral-derivative (PID) controllers. With these systems, it is possible to obtain a high flexibility robotic cell that allows to manufacture variable thickness components with good mechanical volumetric properties. After the design phase, the system has been realized and afterwards it has been validated by analyzing the experimental tests with the quality of some benchmark manufactured by the innovative cell.
Pressure Welding of Thin Sheet Metals: Experimental Investigations and Analytical Modeling
Authors: Mahabunphachai Sasawat , Koç Muammer , Ni Jun
Published: July 2009

Emerging applications, such as fuel cell, fuel processor, heat exchanger, microreactors, etc., require joining of thin metallic plates in confined places with small dimensions and minimal damage to the surrounding areas. In this study, the feasibility and modeling of pressure welding (solid state bonding) process are investigated, specifically for bonding of thin sheet metals. The effects of material type (e.g., copper, nickel, and stainless steel) and initial plate thickness (51–254 μm) as well as process conditions (e.g., welding pressure and temperature, 25–300°C) on the minimum welding pressure and the final bond strength are experimentally studied. A pressure welding apparatus was developed for testing of different materials and process conditions. Based on the experimental results, the effects of material and process conditions on the final bond quality are characterized. At room temperature, copper and nickel blanks were successfully bonded, while stainless steel blanks could only be joined at elevated temperature levels (150°C and 300°C). The material type (i.e., strength) and thickness were shown to have significant impact on the welding pressure; in that more pressure is required to bond the blanks with higher strength or thinner. To reduce the required welding pressure, the process can be carried out at elevated temperature levels. In this study, the bond strength of the welded blanks was characterized with uniaxial testing. The tensile test results showed that the bond strength could be increased by increasing the welding pressure or temperature. However, the increase in bond strength by increasing the welding pressure was shown to have an optimal point, after which the bond strength would decrease with further increase in pressure. This critical pressure value was found to be dependent on the material and process conditions. In addition, bond formation mechanisms for different materials were studied through microscopic analyses. The microscopy images of the weld spots showed that for a successful bonding to take place, the contaminant layers at the surfaces must be removed or broken to allow the virgin metal underneath to be extruded through. The metallic bonds only form at these locations where both surfaces are free of contaminant layers. Finally, a model for bond strength prediction in pressure welding was developed and validated. This model includes the sheet thickness parameter, which is shown to be a critical factor in bonding thin sheet metals with the sheet thickness in the range of a few hundred micrometers.
Microstructures and Properties of Cu–AISI304 Parts Fabricated by Improved Selective Laser Sintering
Authors: Lu Z. L. , Liu J. H. , Shi Y. S.
Published: July 2009

For fabricating complex AISI304 parts with high performance by advanced powder/metallurgy technologies, cold isostatic pressing (CIP) is introduced into selective laser sintering (SLS) combined with hot isostatic pressing (HIP), which is abbreviated to selective laser sintering/isostatic pressed (SLS/IP). The effect of processing parameters on the densification of Cu–AISI304 parts is analyzed and then the influence of Cu on their relative densities, metallurgical structures, and mechanical performances are investigated. The results show that relative densities of Cu–AISI304 parts fabricated by SLS/IP are mainly influenced by CIP pressure and sintering temperature, and it is interesting to find that the formula 1−D=(1−D0)e−kP is testified by the CIP of SLS/IP. There is an antidensification phenomenon resulting from Cu and AISI304 in liquid sintering, but the relative densities of Cu–AISI304 parts can be gradually improved in HIP with Cu content increasing from 1 wt % to 3 wt %. After the above-mentioned Cu–AIS304 parts are finally hot isostatic pressed, their metallurgical structures consist of sosoloid (Cu,Ni) and (Fe,Ni) besides austenite (Fe,Cr,Ni,C), their best mechanical performances are close to those of solution treated compact AISI304 when Cu content is 3 wt %.