Objective: Maintenance hemodialysis (MHD) patients often have impaired quality of life (QOL), anxiety, depression, and reduced daily physical activity (DPA) and physical performance. The contributions of these latter ...Objective: Maintenance hemodialysis (MHD) patients often have impaired quality of life (QOL), anxiety, depression, and reduced daily physical activity (DPA) and physical performance. The contributions of these latter factors to reduced QOL in MHD are poorly understood. We examined the association of QOL with anxiety, depression, DPA, and physical performance.Methods: Seventy-two relatively healthy adult MHD patients, vintage≥6 months, and 39 normals of similar age range and gender distribution were studied. QOL was assessed using the Kidney Disease Quality of Life-Short Form (KDQOL-SF). Anxiety and depression were each evaluated with two questionnaires. DPA and physical performance were assessed with a physical activity monitor, Human Activity Profile, and 6-minute walk, sit-to-stand, and stair-climbing tests. Results: Most KDQOL components were reduced in MHD patients versus normals. KDQOL components in patients were commonly inversely correlated with measures of anxiety and depression (P<0.05) and were more reduced in patients with both anxiety and depression. KDQOL was often impaired in patients with either anxiety or depression. However, most KDQOL scores did not differ between patients and normals without anxiety or depression. DPA, Human Activity Profile, and physical per-formance often correlated with KDQOL scores in adjusted models, but after further adjustment for anxiety and depression, DPA, Human Activity Profile, and physical performance correlated less frequently with KDQOL scores. This reduction in significant correlations after adjustment for anxiety and depression was particularly pronounced for the association between KDQOL and DPA. Conclusion: In relatively healthy MHD patients, KDQOL scores are usually decreased in those with anxiety and/or depression but are usually normal in those without anxiety or depression. Lower DPA in MHD patients with reduced KDQOL scores often appears to be associated with anxiety and depression. The relationship between QOL and physical performance appears to be le展开更多
The development of formulas estimating glomerular filtration rate(eG FR) from serum creatinine and cystatin C and accounting for certain variables affecting the production rate of these biomarkers, including ethnicity...The development of formulas estimating glomerular filtration rate(eG FR) from serum creatinine and cystatin C and accounting for certain variables affecting the production rate of these biomarkers, including ethnicity, gender and age, has led to the current scheme of diagnosing and staging chronic kidney disease(CKD),which is based on e GFR values and albuminuria.This scheme has been applied extensively in various populations and has led to the current estimates of prevalence of CKD. In addition, this scheme is applied in clinical studies evaluating the risks of CKD and the efficacy of various interventions directed towards improving its course. Disagreements between creatinine-based and cystatin-based e GFR values and between e GFR values and measured GFR have been reported in various cohorts. These disagreements are the consequence of variations in the rate of production and in factors, other than GFR, affecting the rate of removal of creatinine and cystatin C. The disagreements create limitations for all e GFR formulas developed so far. The main limitations are low sensitivity in detecting early CKD in several subjects, e.g., those with hyperfiltration, and poor prediction of the course of CKD. Research efforts in CKD are currently directed towards identification of biomarkers that are better indices of GFR than the current biomarkers and,particularly, biomarkers of early renal tissue injury.展开更多
This paper conducts a comprehensive analysis of the export dynamics within the Ukrainian timber industry, emphasizing its pivotal role in the national economy. The study begins by outlining the research objectives, co...This paper conducts a comprehensive analysis of the export dynamics within the Ukrainian timber industry, emphasizing its pivotal role in the national economy. The study begins by outlining the research objectives, context, and innovative methodologies, setting the stage for a deep dive into the theoretical underpinnings of sustainable and competitive trade. It explores Ukraine’s rich forest biodiversity across varied vegetation zones and its geopolitical significance. Detailed evaluations of forest resource management, policy frameworks, and institutional support form the core of the analysis. Challenges such as imbalanced export structures and legal inconsistencies are critically examined. The research employs trade gravity models and competitive indicators like the Revealed Comparative Advantage (RCA) and Market Share (MS) to assess factors influencing exports and to forecast potential growth areas. The findings inform strategic recommendations aimed at enhancing export capacity through market diversification, brand development, and legal stability. The conclusion highlights the need for strategic interventions to harness Ukraine’s timber resources sustainably, balancing economic gains with environmental stewardship.展开更多
AIM： To investigate the role of small intestinal carcinoid tumor-derived fibrotic mediators, TGFβ1 and CTGF, in the mediation of fibrosis via activation of an ＂intestinal＂ stellate cell. METHODS： GI carcinoid tum...AIM： To investigate the role of small intestinal carcinoid tumor-derived fibrotic mediators, TGFβ1 and CTGF, in the mediation of fibrosis via activation of an ＂intestinal＂ stellate cell. METHODS： GI carcinoid tumors were collected for Q RT-PCR analysis of CTGF and TGFβ1. Markers of stellate cell desmoplasia were identified in peritoneal fibrosis by immunohistochemistry and stellate cells cultured from fresh resected fibrotic tissue. CTGF and TGFβ1 were evaluated using quantitative tissue array profiling （AQUA analysis） in a GI carcinoid tissue microarray （TMA） with immunostaining and correlated with clinical and histologically documented fibrosis. Serum CTGF was analyzed using a sandwich ELISA assay. RESULTS： Message levels of both CTGF and TGFβ1 in SI carcinoid tumors were significantly increased （〉 2-fold, P 〈 0.05） versus normal mucosa and gastric （non-fibrotic） carcinoids. Activated stellate cells and markers of stellate cell-mediated fibrosis （vimentin, desmin） were identified in histological fibrosis. An intestinal stellate cell was immunocytochemically and biochemically characterized and its TGFβ1 （10-7M） initiated CTGF transcription response （〉 3-fold, P 〈 0.05） demonstrated. In SI carcinoid tumor patients with documented fibrosis, TMA analysis demonstrated higher CTGF immunostaining （AQUA Score： 92 ± 8, P 〈0.05）, as well as elevated TGFβ1 （90.6 ± 4.4, P 〈 0.05）. Plasma CTGF （normal 12.5 ± 2.6 ng/mL） was increased in SI carcinoid tumor patients （31 ± 10 ng/mL, P 〈 0.05） compared to non-fibrotic GI carcinoids （〈 15 ng/mL） CONCLUSION： SI carcinoid tumor fibrosis is a CTGF/ TGFβl-mediated stellate cell-driven fibrotic response. The delineation of the biology of fibrosis will facilitate diagnosis and enable development of agents to obviate its local and systemic complications.展开更多
The last decade has been notable for increasing high-quality research and dramatic improvement in outcomes with dynamic liver preservation.Robust evidence from numerous randomized controlled trials has been pooled by ...The last decade has been notable for increasing high-quality research and dramatic improvement in outcomes with dynamic liver preservation.Robust evidence from numerous randomized controlled trials has been pooled by meta-analyses,providing the highest available evidence on the protective effect of machine perfusion(MP)over static cold storage in liver transplantation(LT).Based on a protective effect with less complications and improved graft survival,the field has seen a paradigm shift in organ preservation.This editorial focuses on the role of MP in LT and how it could become the new“gold standard”.Strong collaborative efforts are needed to explore its effects on long-term outcomes.展开更多
Storylines of Family Medicine is a 12-part series of thematically linked essays with accompanying illustrations that explore the many dimensions of family medicine,as interpreted by individual family physicians and me...Storylines of Family Medicine is a 12-part series of thematically linked essays with accompanying illustrations that explore the many dimensions of family medicine,as interpreted by individual family physicians and medical educators in the USA and elsewhere around the world.In‘Ⅴ:ways of thinking—honing the therapeutic self’,authors present the following sections:‘Reflective practice in action’,‘The doctor as drug—Balint groups’,‘Cultivating compassion’,‘Towards a humanistic approach to doctoring’,‘Intimacy in family medicine’,‘The many faces of suffering’,‘Transcending suffering’and‘The power of listening to stories.’May readers feel a deeper sense of their own therapeutic agency by reflecting on these essays.展开更多
This paper challenges the concept that the essential element in wound healing is to offload pressure. We suggest a change in approach that recognizes the integumentary system as one which, like all other body systems,...This paper challenges the concept that the essential element in wound healing is to offload pressure. We suggest a change in approach that recognizes the integumentary system as one which, like all other body systems, adapts to the stresses put upon it. We use a clinical case example to illustrate the use of intentional mechanical stress to promote wound healing and include a review of the relevant literature. The intent of this publication is to call for a new look at clinical practice regarding wound healing and to call for future research directed at investigation of this theory.展开更多
AIM:To investigate the safety and efficacy of adding bevacizumab to first-line chemotherapy in metastatic colorectal cancer patients with peritoneal disease.METHODS:We compared rates of gastrointestinal perforation in...AIM:To investigate the safety and efficacy of adding bevacizumab to first-line chemotherapy in metastatic colorectal cancer patients with peritoneal disease.METHODS:We compared rates of gastrointestinal perforation in patients with metastatic colorectal cancer and peritoneal disease receiving first-line chemotherapy with and without bevacizumab in three distinct cohorts:(1) the AGITG MAX trial(Phase Ⅲ randomised clinical trial comparing capecitabine vs capecitabine and bevacizumab vs capecitabine,bevacizumab and mitomycin C);(2) the prospective Treatment of Recurrent and Advanced Colorectal Cancer(TRACC) registry(any first-line regimen ± bevacizumab);and(3) two cancer centres in New South Wales,Australia [Macarthur Cancer Therapy Centre and Liverpool Cancer Therapy Centre(NSWCC) from January 2005 to Decenber 2012,(any first-line regimen ± bevacizumab).For the AGITG MAX trial capecitabine was compared to the other two arms(capecitabine/bevacizumab and capecitabine/bevacizumab/mitomycin C).In the AGITG MAX trial and the TRACC registry rates of gastrointestinal perforation were also collected in patients who did not have peritoneal metastases.Secondary endpoints included progression-free survival,chemotherapy duration,and overall survival.Time-toevent outcomes were estimated using the Kaplan-Meier method and compared using the log-rank test.RESULTS:Eighty-four MAX,179 TRACC and 69 NSWCC patients had peritoneal disease.There were no gastrointestinal perforations recorded in either the MAX subgroup or the NSWCC cohorts.Of the patients without peritoneal disease in the MAX trial,4/300(1.3%) in the bevacizumab arms had gastrointestinal perforations compared to 1/123(0.8%) in the capecitabine alone arm.In the TRACC registry 3/126(2.4%) patients who had received bevacizumab had a gastrointestinal perforation compared to 1/53(1.9%) in the chemotherapy alone arm.In a further analysis of patients without peritoneal metastases in the TRACC registry,the rate of gastrointestinal perforations was 9/369(2.4%) in the chemother展开更多
Euclidean Clifford analysis is a higher dimensional function theory centred around monogenic functions, i.e., null solutions to a first order vector valued rotation in- variant differential operator called the Dirac ...Euclidean Clifford analysis is a higher dimensional function theory centred around monogenic functions, i.e., null solutions to a first order vector valued rotation in- variant differential operator called the Dirac operator. More recently, Hermitian Clifford analysis has emerged as a new branch, offering yet a refinement of the Euclidean case; it focuses on the simultaneous null solutions, called Hermitian monogenic functions, to two Hermitian Dirac operators and which are invariant under the action of the unitary group. In Euclidean Clifford analysis, the Teodorescu operator is the right inverse of the Dirac operator __0. In this paper, Teodorescu operators for the Hermitian Dirac operators c9~_ and 0_~, are constructed. Moreover, the structure of the Euclidean and Hermitian Teodor- escu operators is revealed by analyzing the more subtle behaviour of their components. Finally, the obtained inversion relations are still refined for the differential operators is- suing from the Euclidean and Hermitian Dirac operators by splitting the Clifford algebra product into its dot and wedge parts. Their relationship with several complex variables theory is discussed.展开更多
The regulation of body fluid balance is a key concern in health and disease and comprises three concepts. The first concept pertains to the relationship between total body water(TBW) and total effective solute and is ...The regulation of body fluid balance is a key concern in health and disease and comprises three concepts. The first concept pertains to the relationship between total body water(TBW) and total effective solute and is expressed in terms of the tonicity of the body fluids. Disturbances in tonicity are the main factor responsible for changes in cell volume, which can critically affect brain cell function and survival. Solutes distributed almost exclusively in the extracellular compartment(mainly sodium salts) and in the intracellular compartment(mainly potassium salts) contribute to tonicity, while solutes distributed in TBW have no effect on tonicity. The second body fluid balance concept relates to the regulation and measurement of abnormalities of sodium salt balance and extracellular volume. Estimation of extracellular volume is more complex and error prone than measurement of TBW. A key function of extracellular volume, which is defined as the effective arterial blood volume(EABV), is to ensure adequate perfusion of cells and organs. Other factors, including cardiac output, total and regional capacity of both arteries and veins, Starling forces in the capillaries, and gravity also affect the EABV. Collectively, these factors interact closely with extracellular volume and some of them undergo substantial changes in certain acute and chronic severe illnesses. Their changes result not only in extracellular volume expansion, but in the need for a larger extracellular volume compared with that of healthy individuals. Assessing extracellular volume in severe illness is challenging because the estimates of this volume by commonly used methods are prone to large errors in many illnesses. In addition, the optimal extracellular volume may vary from illness to illness, is only partially based on volume measurements by traditional methods, and has not been determined for each illness. Further research is needed to determine optimal extracellular volume levels in several illnesses. For these reasons, extracellular volume in展开更多
New two-dimensional systems such as the surfaces of topological insulators （TIs） and graphene offer the possibility of experimentally investigating situations considered exotic just a decade ago. These situations in...New two-dimensional systems such as the surfaces of topological insulators （TIs） and graphene offer the possibility of experimentally investigating situations considered exotic just a decade ago. These situations include the quantum phase transition of the chiral type in electronic systems with a relativistic spectrum. Phonon-mediated （conventional） pairing in the Dirac semimetal appearing on the surface of a TI causes a transition into a chiral superconducting state, and exciton condensation in these gapless systems has long been envisioned in the physics of narrow-band semiconductors. Starting from the microscopic Dirac Hamiltonian with local attraction or repulsion, the Bardeen- Cooper-Schrieffer type of Gaussian approximation is developed in the framework of functional integrals. It is shown that owing to an ultrarelativistic dispersion relation, there is a quantum critical point governing the zero-temperature transition to a superconducting state or the exciton condensed state. Quantum transitions having critical exponents differ greatly from conventional ones and belong to the chiral universality class. We discuss the application of these results to recent experiments in which surface superconductivity was found in TIs and estimate the feasibility of phonon pairing.展开更多
文摘Objective: Maintenance hemodialysis (MHD) patients often have impaired quality of life (QOL), anxiety, depression, and reduced daily physical activity (DPA) and physical performance. The contributions of these latter factors to reduced QOL in MHD are poorly understood. We examined the association of QOL with anxiety, depression, DPA, and physical performance.Methods: Seventy-two relatively healthy adult MHD patients, vintage≥6 months, and 39 normals of similar age range and gender distribution were studied. QOL was assessed using the Kidney Disease Quality of Life-Short Form (KDQOL-SF). Anxiety and depression were each evaluated with two questionnaires. DPA and physical performance were assessed with a physical activity monitor, Human Activity Profile, and 6-minute walk, sit-to-stand, and stair-climbing tests. Results: Most KDQOL components were reduced in MHD patients versus normals. KDQOL components in patients were commonly inversely correlated with measures of anxiety and depression (P<0.05) and were more reduced in patients with both anxiety and depression. KDQOL was often impaired in patients with either anxiety or depression. However, most KDQOL scores did not differ between patients and normals without anxiety or depression. DPA, Human Activity Profile, and physical per-formance often correlated with KDQOL scores in adjusted models, but after further adjustment for anxiety and depression, DPA, Human Activity Profile, and physical performance correlated less frequently with KDQOL scores. This reduction in significant correlations after adjustment for anxiety and depression was particularly pronounced for the association between KDQOL and DPA. Conclusion: In relatively healthy MHD patients, KDQOL scores are usually decreased in those with anxiety and/or depression but are usually normal in those without anxiety or depression. Lower DPA in MHD patients with reduced KDQOL scores often appears to be associated with anxiety and depression. The relationship between QOL and physical performance appears to be le
基金the Research Service of the Raymond G. Murphy VA Medical Center for its support of this work
文摘The development of formulas estimating glomerular filtration rate(eG FR) from serum creatinine and cystatin C and accounting for certain variables affecting the production rate of these biomarkers, including ethnicity, gender and age, has led to the current scheme of diagnosing and staging chronic kidney disease(CKD),which is based on e GFR values and albuminuria.This scheme has been applied extensively in various populations and has led to the current estimates of prevalence of CKD. In addition, this scheme is applied in clinical studies evaluating the risks of CKD and the efficacy of various interventions directed towards improving its course. Disagreements between creatinine-based and cystatin-based e GFR values and between e GFR values and measured GFR have been reported in various cohorts. These disagreements are the consequence of variations in the rate of production and in factors, other than GFR, affecting the rate of removal of creatinine and cystatin C. The disagreements create limitations for all e GFR formulas developed so far. The main limitations are low sensitivity in detecting early CKD in several subjects, e.g., those with hyperfiltration, and poor prediction of the course of CKD. Research efforts in CKD are currently directed towards identification of biomarkers that are better indices of GFR than the current biomarkers and,particularly, biomarkers of early renal tissue injury.
文摘This paper conducts a comprehensive analysis of the export dynamics within the Ukrainian timber industry, emphasizing its pivotal role in the national economy. The study begins by outlining the research objectives, context, and innovative methodologies, setting the stage for a deep dive into the theoretical underpinnings of sustainable and competitive trade. It explores Ukraine’s rich forest biodiversity across varied vegetation zones and its geopolitical significance. Detailed evaluations of forest resource management, policy frameworks, and institutional support form the core of the analysis. Challenges such as imbalanced export structures and legal inconsistencies are critically examined. The research employs trade gravity models and competitive indicators like the Revealed Comparative Advantage (RCA) and Market Share (MS) to assess factors influencing exports and to forecast potential growth areas. The findings inform strategic recommendations aimed at enhancing export capacity through market diversification, brand development, and legal stability. The conclusion highlights the need for strategic interventions to harness Ukraine’s timber resources sustainably, balancing economic gains with environmental stewardship.
基金Supported in part by the Bruggeman Medical Foundation
文摘AIM： To investigate the role of small intestinal carcinoid tumor-derived fibrotic mediators, TGFβ1 and CTGF, in the mediation of fibrosis via activation of an ＂intestinal＂ stellate cell. METHODS： GI carcinoid tumors were collected for Q RT-PCR analysis of CTGF and TGFβ1. Markers of stellate cell desmoplasia were identified in peritoneal fibrosis by immunohistochemistry and stellate cells cultured from fresh resected fibrotic tissue. CTGF and TGFβ1 were evaluated using quantitative tissue array profiling （AQUA analysis） in a GI carcinoid tissue microarray （TMA） with immunostaining and correlated with clinical and histologically documented fibrosis. Serum CTGF was analyzed using a sandwich ELISA assay. RESULTS： Message levels of both CTGF and TGFβ1 in SI carcinoid tumors were significantly increased （〉 2-fold, P 〈 0.05） versus normal mucosa and gastric （non-fibrotic） carcinoids. Activated stellate cells and markers of stellate cell-mediated fibrosis （vimentin, desmin） were identified in histological fibrosis. An intestinal stellate cell was immunocytochemically and biochemically characterized and its TGFβ1 （10-7M） initiated CTGF transcription response （〉 3-fold, P 〈 0.05） demonstrated. In SI carcinoid tumor patients with documented fibrosis, TMA analysis demonstrated higher CTGF immunostaining （AQUA Score： 92 ± 8, P 〈0.05）, as well as elevated TGFβ1 （90.6 ± 4.4, P 〈 0.05）. Plasma CTGF （normal 12.5 ± 2.6 ng/mL） was increased in SI carcinoid tumor patients （31 ± 10 ng/mL, P 〈 0.05） compared to non-fibrotic GI carcinoids （〈 15 ng/mL） CONCLUSION： SI carcinoid tumor fibrosis is a CTGF/ TGFβl-mediated stellate cell-driven fibrotic response. The delineation of the biology of fibrosis will facilitate diagnosis and enable development of agents to obviate its local and systemic complications.
文摘The last decade has been notable for increasing high-quality research and dramatic improvement in outcomes with dynamic liver preservation.Robust evidence from numerous randomized controlled trials has been pooled by meta-analyses,providing the highest available evidence on the protective effect of machine perfusion(MP)over static cold storage in liver transplantation(LT).Based on a protective effect with less complications and improved graft survival,the field has seen a paradigm shift in organ preservation.This editorial focuses on the role of MP in LT and how it could become the new“gold standard”.Strong collaborative efforts are needed to explore its effects on long-term outcomes.
文摘Storylines of Family Medicine is a 12-part series of thematically linked essays with accompanying illustrations that explore the many dimensions of family medicine,as interpreted by individual family physicians and medical educators in the USA and elsewhere around the world.In‘Ⅴ:ways of thinking—honing the therapeutic self’,authors present the following sections:‘Reflective practice in action’,‘The doctor as drug—Balint groups’,‘Cultivating compassion’,‘Towards a humanistic approach to doctoring’,‘Intimacy in family medicine’,‘The many faces of suffering’,‘Transcending suffering’and‘The power of listening to stories.’May readers feel a deeper sense of their own therapeutic agency by reflecting on these essays.
文摘This paper challenges the concept that the essential element in wound healing is to offload pressure. We suggest a change in approach that recognizes the integumentary system as one which, like all other body systems, adapts to the stresses put upon it. We use a clinical case example to illustrate the use of intentional mechanical stress to promote wound healing and include a review of the relevant literature. The intent of this publication is to call for a new look at clinical practice regarding wound healing and to call for future research directed at investigation of this theory.
基金the National Health and Medical Research Council Clinical Trials Centre were received from Cancer Australia and the Cancer Institute New South Wales for the AGITG MAX Trial
文摘AIM:To investigate the safety and efficacy of adding bevacizumab to first-line chemotherapy in metastatic colorectal cancer patients with peritoneal disease.METHODS:We compared rates of gastrointestinal perforation in patients with metastatic colorectal cancer and peritoneal disease receiving first-line chemotherapy with and without bevacizumab in three distinct cohorts:(1) the AGITG MAX trial(Phase Ⅲ randomised clinical trial comparing capecitabine vs capecitabine and bevacizumab vs capecitabine,bevacizumab and mitomycin C);(2) the prospective Treatment of Recurrent and Advanced Colorectal Cancer(TRACC) registry(any first-line regimen ± bevacizumab);and(3) two cancer centres in New South Wales,Australia [Macarthur Cancer Therapy Centre and Liverpool Cancer Therapy Centre(NSWCC) from January 2005 to Decenber 2012,(any first-line regimen ± bevacizumab).For the AGITG MAX trial capecitabine was compared to the other two arms(capecitabine/bevacizumab and capecitabine/bevacizumab/mitomycin C).In the AGITG MAX trial and the TRACC registry rates of gastrointestinal perforation were also collected in patients who did not have peritoneal metastases.Secondary endpoints included progression-free survival,chemotherapy duration,and overall survival.Time-toevent outcomes were estimated using the Kaplan-Meier method and compared using the log-rank test.RESULTS:Eighty-four MAX,179 TRACC and 69 NSWCC patients had peritoneal disease.There were no gastrointestinal perforations recorded in either the MAX subgroup or the NSWCC cohorts.Of the patients without peritoneal disease in the MAX trial,4/300(1.3%) in the bevacizumab arms had gastrointestinal perforations compared to 1/123(0.8%) in the capecitabine alone arm.In the TRACC registry 3/126(2.4%) patients who had received bevacizumab had a gastrointestinal perforation compared to 1/53(1.9%) in the chemotherapy alone arm.In a further analysis of patients without peritoneal metastases in the TRACC registry,the rate of gastrointestinal perforations was 9/369(2.4%) in the chemother
文摘Euclidean Clifford analysis is a higher dimensional function theory centred around monogenic functions, i.e., null solutions to a first order vector valued rotation in- variant differential operator called the Dirac operator. More recently, Hermitian Clifford analysis has emerged as a new branch, offering yet a refinement of the Euclidean case; it focuses on the simultaneous null solutions, called Hermitian monogenic functions, to two Hermitian Dirac operators and which are invariant under the action of the unitary group. In Euclidean Clifford analysis, the Teodorescu operator is the right inverse of the Dirac operator __0. In this paper, Teodorescu operators for the Hermitian Dirac operators c9~_ and 0_~, are constructed. Moreover, the structure of the Euclidean and Hermitian Teodor- escu operators is revealed by analyzing the more subtle behaviour of their components. Finally, the obtained inversion relations are still refined for the differential operators is- suing from the Euclidean and Hermitian Dirac operators by splitting the Clifford algebra product into its dot and wedge parts. Their relationship with several complex variables theory is discussed.
文摘The regulation of body fluid balance is a key concern in health and disease and comprises three concepts. The first concept pertains to the relationship between total body water(TBW) and total effective solute and is expressed in terms of the tonicity of the body fluids. Disturbances in tonicity are the main factor responsible for changes in cell volume, which can critically affect brain cell function and survival. Solutes distributed almost exclusively in the extracellular compartment(mainly sodium salts) and in the intracellular compartment(mainly potassium salts) contribute to tonicity, while solutes distributed in TBW have no effect on tonicity. The second body fluid balance concept relates to the regulation and measurement of abnormalities of sodium salt balance and extracellular volume. Estimation of extracellular volume is more complex and error prone than measurement of TBW. A key function of extracellular volume, which is defined as the effective arterial blood volume(EABV), is to ensure adequate perfusion of cells and organs. Other factors, including cardiac output, total and regional capacity of both arteries and veins, Starling forces in the capillaries, and gravity also affect the EABV. Collectively, these factors interact closely with extracellular volume and some of them undergo substantial changes in certain acute and chronic severe illnesses. Their changes result not only in extracellular volume expansion, but in the need for a larger extracellular volume compared with that of healthy individuals. Assessing extracellular volume in severe illness is challenging because the estimates of this volume by commonly used methods are prone to large errors in many illnesses. In addition, the optimal extracellular volume may vary from illness to illness, is only partially based on volume measurements by traditional methods, and has not been determined for each illness. Further research is needed to determine optimal extracellular volume levels in several illnesses. For these reasons, extracellular volume in
基金Acknowledgements We are indebted to C. W. Luo, J. J. Lin, and W. B. Jian for explaining the details of their experiments, and T. Maniv and M. Lewkowicz for valuable discussions. The work of D. Li and B. Rosenstein was supported by the NSC of Taiwan, China, Grant No. 98-2112-M-009-014-MY3, and the MOE ATU program. The work of D. Li was also supported by the National Natural Science Foundation of China （Grant No. 11274018）. B. Rosenstein was grateful to the School of Physics of Peking University for its hospitality.
文摘New two-dimensional systems such as the surfaces of topological insulators （TIs） and graphene offer the possibility of experimentally investigating situations considered exotic just a decade ago. These situations include the quantum phase transition of the chiral type in electronic systems with a relativistic spectrum. Phonon-mediated （conventional） pairing in the Dirac semimetal appearing on the surface of a TI causes a transition into a chiral superconducting state, and exciton condensation in these gapless systems has long been envisioned in the physics of narrow-band semiconductors. Starting from the microscopic Dirac Hamiltonian with local attraction or repulsion, the Bardeen- Cooper-Schrieffer type of Gaussian approximation is developed in the framework of functional integrals. It is shown that owing to an ultrarelativistic dispersion relation, there is a quantum critical point governing the zero-temperature transition to a superconducting state or the exciton condensed state. Quantum transitions having critical exponents differ greatly from conventional ones and belong to the chiral universality class. We discuss the application of these results to recent experiments in which surface superconductivity was found in TIs and estimate the feasibility of phonon pairing.
