86 research outputs found
Photoemission study of the metal-insulator transition in VO_2/TiO_2(001) : Evidence for strong electron-electron and electron-phonon interaction
We have made a detailed temperature-dependent photoemission study of
VO_2/TiO_2(001) thin films, which show a metal-insulator transition at \sim 300
K. Clean surfaces were obtained by annealing the films in an oxygen atmosphere.
Spectral weight transfer between the coherent and incoherent parts accompanying
the metal-insulator transition was clearly observed. We also observed a
hysteretic behavior of the spectra for heating-cooling cycles. We have derived
the ``bulk'' spectrum of the metallic phase and found that it has a strong
incoherent part. The width of the coherent part is comparable to that given by
band-structure calculation in spite of its reduced spectral weight, indicating
that the momentum dependence of the self-energy is significant. This is
attributed to by ferromagnetic fluctuation arising from Hund's rule coupling
between different d orbitals as originally proposed by Zylbersztejn and Mott.
In the insulating phase, the width of the V 3d band shows strong temperature
dependence. We attribute this to electron-phonon interaction and have
reproduced it using the independent boson model with a very large coupling
constant.Comment: 7 pages, 7 figures, submitted to Phys. Rev.
Electronic Structure Calculation by First Principles for Strongly Correlated Electron Systems
Recent trends of ab initio studies and progress in methodologies for
electronic structure calculations of strongly correlated electron systems are
discussed. The interest for developing efficient methods is motivated by recent
discoveries and characterizations of strongly correlated electron materials and
by requirements for understanding mechanisms of intriguing phenomena beyond a
single-particle picture. A three-stage scheme is developed as renormalized
multi-scale solvers (RMS) utilizing the hierarchical electronic structure in
the energy space. It provides us with an ab initio downfolding of the global
band structure into low-energy effective models followed by low-energy solvers
for the models. The RMS method is illustrated with examples of several
materials. In particular, we overview cases such as dynamics of semiconductors,
transition metals and its compounds including iron-based superconductors and
perovskite oxides, as well as organic conductors of kappa-ET type.Comment: 44 pages including 38 figures, to appear in J. Phys. Soc. Jpn. as an
invited review pape
Moral judgments, gender, and antisocial preferences : an experimental study
Peer reviewedPostprin
Antisperm Antibody Testing: A Comprehensive Review of Its Role in the Management of Immunological Male Infertility and Results of a Global Survey of Clinical Practices
Antisperm antibodies (ASA), as a cause of male infertility, have been detected in infertile males as early as 1954. Multiple causes of ASA production have been identified, and they are due to an abnormal exposure of mature germ cells to the immune system. ASA testing (with mixed anti-globulin reaction, and immunobead binding test) was described in the WHO manual 5th edition and is most recently listed among the extended semen tests in the WHO manual 6th edition. The relationship between ASA and infertility is somewhat complex. The presence of sperm agglutination, while insufficient to diagnose immunological infertility, may indicate the presence of ASA. However, ASA can also be present in the absence of any sperm agglutination. The andrological management of ASA depends on the etiology and individual practices of clinicians. In this article, we provide a comprehensive review of the causes of ASA production, its role in immunological male infertility, clinical indications of ASA testing, and the available therapeutic options. We also provide the details of laboratory procedures for assessment of ASA together with important measures for quality control. Additionally, laboratory and clinical scenarios are presented to guide the reader in the management of ASA and immunological male infertility. Furthermore, we report the results of a recent worldwide survey, conducted to gather information about clinical practices in the management of immunological male infertility
Male Oxidative Stress Infertility (MOSI):proposed terminology and clinical practice guidelines for management of idiopathic male infertility
Despite advances in the field of male reproductive health, idiopathic male infertility, in which a man has altered semen characteristics without an identifiable cause and there is no female factor infertility, remains a challenging condition to diagnose and manage. Increasing evidence suggests that oxidative stress (OS) plays an independent role in the etiology of male infertility, with 30% to 80% of infertile men having elevated seminal reactive oxygen species levels. OS can negatively affect fertility via a number of pathways, including interference with capacitation and possible damage to sperm membrane and DNA, which may impair the sperm's potential to fertilize an egg and develop into a healthy embryo. Adequate evaluation of male reproductive potential should therefore include an assessment of sperm OS. We propose the term Male Oxidative Stress Infertility, or MOSI, as a novel descriptor for infertile men with abnormal semen characteristics and OS, including many patients who were previously classified as having idiopathic male infertility. Oxidation-reduction potential (ORP) can be a useful clinical biomarker for the classification of MOSI, as it takes into account the levels of both oxidants and reductants (antioxidants). Current treatment protocols for OS, including the use of antioxidants, are not evidence-based and have the potential for complications and increased healthcare-related expenditures. Utilizing an easy, reproducible, and cost-effective test to measure ORP may provide a more targeted, reliable approach for administering antioxidant therapy while minimizing the risk of antioxidant overdose. With the increasing awareness and understanding of MOSI as a distinct male infertility diagnosis, future research endeavors can facilitate the development of evidence-based treatments that target its underlying cause
Male oxidative stress infertility (MOSI): proposed terminology and clinical practice guidelines for management of idiopathic male infertility
Despite advances in the field of male reproductive health, idiopathic male infertility, in which a man has altered semen characteristics without an identifiable cause and there is no female factor infertility, remains a challenging condition to diagnose and manage. Increasing evidence suggests that oxidative stress (OS) plays an independent role in the etiology of male infertility, with 30% to 80% of infertile men having elevated seminal reactive oxygen species levels. OS can negatively affect fertility via a number of pathways, including interference with capacitation and possible damage to sperm membrane and DNA, which may impair the sperm's potential to fertilize an egg and develop into a healthy embryo. Adequate evaluation of male reproductive potential should therefore include an assessment of sperm OS. We propose the term Male Oxidative Stress Infertility, or MOSI, as a novel descriptor for infertile men with abnormal semen characteristics and OS, including many patients who were previously classified as having idiopathic male infertility. Oxidation-reduction potential (ORP) can be a useful clinical biomarker for the classification of MOSI, as it takes into account the levels of both oxidants and reductants (antioxidants). Current treatment protocols for OS, including the use of antioxidants, are not evidence-based and have the potential for complications and increased healthcare-related expenditures. Utilizing an easy, reproducible, and cost-effective test to measure ORP may provide a more targeted, reliable approach for administering antioxidant therapy while minimizing the risk of antioxidant overdose. With the increasing awareness and understanding of MOSI as a distinct male infertility diagnosis, future research endeavors can facilitate the development of evidence-based treatments that target its underlying cause
Post-Vasectomy Semen Analysis: Optimizing Laboratory Procedures and Test Interpretation through a Clinical Audit and Global Survey of Practices
Purpose: The success of vasectomy is determined by the outcome of a post-vasectomy semen analysis (PVSA). This article describes a step-by-step procedure to perform PVSA accurately, report data from patients who underwent post vasectomy semen analysis between 2015 and 2021 experience, along with results from an international online survey on clinical practice.
Materials and methods: We present a detailed step-by-step protocol for performing and interpretating PVSA testing, along with recommendations for proficiency testing, competency assessment for performing PVSA, and clinical and laboratory scenarios. Moreover, we conducted an analysis of 1,114 PVSA performed at the Cleveland Clinic's Andrology Laboratory and an online survey to understand clinician responses to the PVSA results in various countries.
Results: Results from our clinical experience showed that 92.1% of patients passed PVSA, with 7.9% being further tested. A total of 78 experts from 19 countries participated in the survey, and the majority reported to use time from vasectomy rather than the number of ejaculations as criterion to request PVSA. A high percentage of responders reported permitting unprotected intercourse only if PVSA samples show azoospermia while, in the presence of few non-motile sperm, the majority of responders suggested using alternative contraception, followed by another PVSA. In the presence of motile sperm, the majority of participants asked for further PVSA testing. Repeat vasectomy was mainly recommended if motile sperm were observed after multiple PVSA's. A large percentage reported to recommend a second PVSA due to the possibility of legal actions.
Conclusions: Our results highlighted varying clinical practices around the globe, with controversy over the significance of non-motile sperm in the PVSA sample. Our data suggest that less stringent AUA guidelines would help improve test compliance. A large longitudinal multi-center study would clarify various doubts related to timing and interpretation of PVSA and would also help us to understand, and perhaps predict, recanalization and the potential for future failure of a vasectomy
Male Oxidative Stress Infertility (MOSI): Proposed Terminology and Clinical Practice Guidelines for Management of Idiopathic Male Infertility
Despite advances in the field of male reproductive health, idiopathic male infertility, in which a man has altered semen
characteristics without an identifiable cause and there is no female factor infertility, remains a challenging condition to diagnose
and manage. Increasing evidence suggests that oxidative stress (OS) plays an independent role in the etiology of male
infertility, with 30% to 80% of infertile men having elevated seminal reactive oxygen species levels. OS can negatively affect
fertility via a number of pathways, including interference with capacitation and possible damage to sperm membrane and
DNA, which may impair the sperm’s potential to fertilize an egg and develop into a healthy embryo. Adequate evaluation of
male reproductive potential should therefore include an assessment of sperm OS. We propose the term Male Oxidative Stress
Infertility, or MOSI, as a novel descriptor for infertile men with abnormal semen characteristics and OS, including many
patients who were previously classified as having idiopathic male infertility. Oxidation-reduction potential (ORP) can be a
useful clinical biomarker for the classification of MOSI, as it takes into account the levels of both oxidants and reductants
(antioxidants). Current treatment protocols for OS, including the use of antioxidants, are not evidence-based and have the
potential for complications and increased healthcare-related expenditures. Utilizing an easy, reproducible, and cost-effective
test to measure ORP may provide a more targeted, reliable approach for administering antioxidant therapy while minimizing
the risk of antioxidant overdose. With the increasing awareness and understanding of MOSI as a distinct male infertility diagnosis,
future research endeavors can facilitate the development of evidence-based treatments that target its underlying cause
Controversy and consensus on indications for sperm DNA fragmentation testing in male infertility: a global survey, current guidelines, and expert recommendations.
PURPOSE: Sperm DNA fragmentation (SDF) testing was recently added to the sixth edition of the World Health Organization laboratory manual for the examination and processing of human semen. Many conditions and risk factors have been associated with elevated SDF; therefore, it is important to identify the population of infertile men who might benefit from this test. The purpose of this study was to investigate global practices related to indications for SDF testing, compare the relevant professional society guideline recommendations, and provide expert recommendations. MATERIALS AND METHODS: Clinicians managing male infertility were invited to take part in a global online survey on SDF clinical practices. This was conducted following the CHERRIES checklist criteria. The responses were compared to professional society guideline recommendations related to SDF and the appropriate available evidence. Expert recommendations on indications for SDF testing were then formulated, and the Delphi method was used to reach consensus. RESULTS: The survey was completed by 436 experts from 55 countries. Almost 75% of respondents test for SDF in all or some men with unexplained or idiopathic infertility, 39% order it routinely in the work-up of recurrent pregnancy loss (RPL), and 62.2% investigate SDF in smokers. While 47% of reproductive urologists test SDF to support the decision for varicocele repair surgery when conventional semen parameters are normal, significantly fewer general urologists (23%; p=0.008) do the same. Nearly 70% would assess SDF before assisted reproductive technologies (ART), either always or for certain conditions. Recurrent ART failure is a common indication for SDF testing. Very few society recommendations were found regarding SDF testing. CONCLUSIONS: This article presents the largest global survey on the indications for SDF testing in infertile men, and demonstrates diverse practices. Furthermore, it highlights the paucity of professional society guideline recommendations. Expert recommendations are proposed to help guide clinicians
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