The absence of finite-temperature phase transitions in low-dimensional many-body models: a survey and new results

After a brief discussion of the Bogoliubov inequality and possible generalizations thereof, we present a complete review of results concerning the Mermin-Wagner theorem for various many-body systems, geometries and order parameters. We extend the method to cover magnetic phase transitions in the periodic Anderson Model as well as certain superconducting pairing mechanisms for Hubbard films. The relevance of the Mermin-Wagner theorem to approximations in many-body physics is discussed on a conceptual level.Comment: 33 pages; accepted for publication as a Topical Review in Journal of Physics: Condensed Matte

Advantages and Disadvantages of Using St. John\u27s Wort as a Treatment for Depression

BACKGROUND AND OBJECTIVES: St. John\u27s wort (SJW) extracts are currently being used to treat depression of various degrees of severity. While many studies have shown it to be superior to placebo, data regarding the effectiveness of using SJW as a stand-alone treatment compared with standard antidepressants has yet to be proven conclusively. This study aims to understand the advantages and disadvantages of SJW as a treatment modality for depression. METHODS: The authors searched PubMed, JAMA network, Springer Link, Elsevier, Google Scholar, and Scientific Progress databases, from 2011 through August 2021, using the following keywords: St John\u27s wort, Hypericum perforatum, depression, antidepressant, complementary alternative medicine, economic evaluation depression St. wort, St John\u27s wort and depression, antidepressant interactions. This yielded a total of 27 papers following a thorough removal of irrelevant content and dissemination in languages other than English. RESULTS: In patients with mild and moderate depression, SJW proved superior to placebo. Certain studies comparing the efficacy of SJW versus selective serotonin reuptake inhibitors (SSRIs), especially fluoxetine, reported SJW to be more efficacious, while the majority reported no significant difference. Tricyclic antidepressants were also found to have similar efficacy as SJW. Moreover, treatment with SJW was also found to reduce postmenopausal depression. Regarding the safety profile, although SJW is better tolerated with fewer adverse effects when compared to standardized antidepressants, its predisposition to causing fatal serotonin syndrome, when used in conjunction with other serotonergic agents and drug interactions noted with CYP 450 drugs, raises a question in the safety profile. CONCLUSION: It is essential to acknowledge that SJW has been used as a treatment measure in Germany. Despite being only listed as a dietary supplement by the FDA and not a drug, SJW has shown to be comparable, if not more efficacious, than most standard treatment options for depression. SJW does prove to be an exciting piece of pharmacotherapy in the realm of mental health and post-menopausal treatment. More prospective studies will help us better understand its efficacy in mild and moderate depression and its ability to serve as a long-term agent. Considering its mechanism of action, its role in relieving patients suffering from an anxiety disorder is also worth considering

Novel insights into an old controversy: Is coronary artery ectasia a variant of coronary atherosclerosis?

Coronary artery ectasia (CAE) is defined as a localized or diffuse non-obstructive lesion of the epicardial coronary arteries with a luminal dilation exceeding 1.5-fold the diameter of the normal adjacent arterial segment. The incidence of CAE has been reported to range between 2% and 4%, which might be an overestimation of the true frequency. The coincidence of CAE with other systemic vascular dilatations has suggested that the mechanism underlying CAE is not only localized to coronary arteries, but also to other vascular compartments such as aorta or peripheral veins. Although the pathophysiology of CAE remains largely unknown, it was supposed to represent a variant of coronary atherosclerosis. This review focuses on this controversy of whether CAE and coronary artery disease (CAD) are two manifestations of the same underlying process. There are clear differences between CAD and CAE with respect to cardiovascular risk factors such as diabetes mellitus, and pathogenic steps in disease progress such as inflammation or extracellular matrix remodeling. As this review will underscore, the current knowledge of the field is insufficient to finally clarify the causative interrelation between CAE and CAD. The clinical course and treatment of CAE mainly depends on its coexistence with CAD. When coexisting with CAD, the prognosis and treatment of CAE are the same as for CAD alone. In isolated CAE, prognosis is better and anti-platelet drugs are the mainstay of treatment. Surgical treatment can be considered in selected patients. For clarifying the mechanism underlying CAE, additional clinical, histopathological and pathophysiological investigations are required. In fact, every patient with CAE should be evaluated systematically for pathological changes in other vascular territories, both in the arterial system as well as in the venous system, which might occur in the disease process

MiR-133a in Human Circulating Monocytes: A Potential Biomarker Associated with Postmenopausal Osteoporosis

Background: Osteoporosis mainly occurs in postmenopausal women, which is characterized by low bone mineral density (BMD) due to unbalanced bone resorption by osteoclasts and formation by osteoblasts. Circulating monocytes play important roles in osteoclastogenesis by acting as osteoclast precursors and secreting osteoclastogenic factors, such as IL-1, IL-6 and TNF-a. MicroRNAs (miRNAs) have been implicated as important biomarkers in various diseases. The present study aimed to find significant miRNA biomarkers in human circulating monocytes underlying postmenopausal osteoporosis. Methodology/Principal Findings: We used ABI TaqManH miRNA array followed by qRT-PCR validation in circulating monocytes to identify miRNA biomarkers in 10 high and 10 low BMD postmenopausal Caucasian women. MiR-133a was upregulated (P = 0.007) in the low compared with the high BMD groups in the array analyses, which was also validated by qRT-PCR (P = 0.044). We performed bioinformatic target gene analysis and found three potential osteoclast-related target genes, CXCL11, CXCR3 and SLC39A1. In addition, we performed Pearson correlation analyses between the expression levels of miR-133a and the three potential target genes in the 20 postmenopausal women. We did find negative correlations between miR-133a and all the three genes though not significant. Conclusions/Significance: This is the first in vivo miRNA expression analysis in human circulating monocytes to identif

Emission wavelength-dependent decay of the 9-anthroyloxy-fatty acid membrane probes.

Using the phase-modulation technique, we have measured the fluorescence decay of 2- and 12-(9-anthroyloxy)-stearic acid (2- and 12-AS) and 16-(9-anthroyloxy)-palmitic acid (16-AP) bound to egg phosphatidylcholine vesicles or dissolved in nonpolar solvents. Heterogeneity analysis demonstrates that the decay is generally not monoexponential and exhibits large component variations across it emission spectrum. The mean decay time increases (and in parallel, the steady-state polarization decreases) monotonically with increasing wavelength from values at the blue end. The decay at the red side of the emission spectrum contains an exponential term with a negative amplitude, indicating that emission occurs from intermediates created in the excited-state. This behavior is interpreted as arising from intramolecular fluorophore relaxation occurring on the time scale of the fluorescence lifetime. We believe this to be the first study of wavelength-dependent fluorescent emission which is dominated by an intramolecular relaxation process. Although the three probes exhibit qualitatively similar effects, the emission band variations are greatest for 2-AS and smallest for 16-AP. The differences among the probes are not entirely due to environmental factors as demonstrated, for example, by the emission polarization differences observed in the isotropic solvent paraffin oil. In summary, while these findings point out some of the complexities in the 9-anthroyloxy-fatty acids as membrane probes, they also indicate how these complexities might be used as a sensitive measure of lipid-probe interaction

Forgetting curves and testing effect in an adaptive learning and assessment system

In the context of an adaptive learning and assessment system, ALEKS, we examine aspects of forgetting and aspects of a \u2018testing effect\u2019 (in which the act of simply being presented a problem in an assessment seems to assist in the learning process). Using a dataset consisting of over six million ALEKS assessments, we first look at the trend of student responses over the course of the assessment, finding little evidence for such a testing effect. We then refine our approach by looking at cases in which a question is repeated in an assessment; repeats are possible because some question is always chosen at random in an assessment for data-collection purposes. We find evidence of a testing effect for higher-performing students; for lower-performing students, we find a decreased willingness to attempt an answer the second time a problem is presented. Then, turning to forgetting, we find that the content representing the \u201chigh points\u201d of a student\u2019s learning sees a more precipitous drop in the student\u2019s memory than does other content (perhaps because the \u201chigh point\u201d skills and concepts may not have been practiced or developed much since the original learning event). Consequences and possible improvements for the ALEKS system, and also a brief comparison to recent work in the modeling of forgetting, are mentioned