Dark-matter QCD-axion searches Rosenberg, Leslie J
Proceedings of the National Academy of Sciences - PNAS,
10/2015, Letnik:
112, Številka:
40
Journal Article
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In the late 20th century, cosmology became a precision science. Now, at the beginning of the next century, the parameters describing how our universe evolved from the Big Bang are generally known to ...a few percent. One key parameter is the total mass density of the universe. Normal matter constitutes only a small fraction of the total mass density. Observations suggest this additional mass, the dark matter, is cold (that is, moving nonrelativistically in the early universe) and interacts feebly if at all with normal matter and radiation. Thereâs no known such elementary particle, so the strong presumption is the dark matter consists of particle relics of a new kind left over from the Big Bang. One of the most important questions in science is the nature of this dark matter. One attractive particle dark-matter candidate is the axion. The axion is a hypothetical elementary particle arising in a simple and elegant extension to the standard model of particle physics that nulls otherwise observable CP-violating effects (where CP is the product of charge reversal C and parity inversion P) in quantum chromo dynamics (QCD). A light axion of mass 10 â»â½â¶â³⾠eV (the invisible axion) would couple extraordinarily weakly to normal matter and radiation and would therefore be extremely difficult to detect in the laboratory. However, such an axion is a compelling dark-matter candidate and is therefore a target of a number of searches. Compared with other particle dark-matter candidates, the plausible range of axion dark-matter couplings and masses is narrowly constrained. This focused search range allows for definitive searches, where a nonobservation would seriously impugn the dark-matter QCD-axion hypothesis. Axion searches use a wide range of technologies, and the experiment sensitivities are now reaching likely dark-matter axion couplings and masses. This article is a selective overview of the current generation of sensitive axion searches. Not all techniques and experiments are discussed, but I hope to give a sense of the current experimental landscape of the search for dark-matter axions.
Conventional criteria for tumor progression may not fully reflect the clinical benefit of immunotherapy or appropriately guide treatment decisions. The phase II IMvigor210 study demonstrated the ...efficacy and safety of atezolizumab, a programmed death-ligand 1-directed antibody, in patients with platinum-treated locally advanced or metastatic urothelial carcinoma. Patients could continue atezolizumab beyond Response Evaluation Criteria In Solid Tumors (RECIST) v1.1 progression at the investigator’s discretion: this analysis assessed post-progression outcomes in these patients.
Patients were treated with atezolizumab 1200 mg i.v. every 3 weeks until loss of clinical benefit. Efficacy and safety outcomes in patients who experienced RECIST v1.1 progression and did, or did not, continue atezolizumab were analyzed descriptively.
In total, 220 patients who experienced progression from the overall cohort (n = 310) were analyzed: 137 continued atezolizumab for ≥ 1 dose after progression, 19 received other systemic therapy, and 64 received no further systemic therapy. Compared with those who discontinued, patients continuing atezolizumab beyond progression were more likely to have had a baseline Eastern Cooperative Oncology Group performance status of 0 (43.1% versus 31.3%), less likely to have had baseline liver metastases (27.0% versus 41.0%), and more likely to have had an initial response to atezolizumab (responses in 11.7% versus 1.2%). Five patients (3.6%) continuing atezolizumab after progression had subsequent responses compared with baseline measurements. Median post-progression overall survival was 8.6 months in patients continuing atezolizumab, 6.8 months in those receiving another treatment, and 1.2 months in those receiving no further treatment. Atezolizumab exposure-adjusted adverse event frequencies were generally similar before and following progression.
In this single-arm study, patients who continued atezolizumab beyond RECIST v1.1 progression derived prolonged clinical benefit without additional safety signals. Identification of patients most likely to benefit from atezolizumab beyond progression remains an important challenge in the management of metastatic urothelial carcinoma.
NCT02108652.
To compare long-term, updated overall survival (OS) of patients with advanced transitional cell carcinoma of the urothelium (TCCU) treated with vinflunine plus best supportive care (BSC) or BSC ...alone, after failure of platinum-based chemotherapy.
Three hundred and seventy patients were randomly assigned in a phase III trial and allocated (2:1) to vinflunine (320 or 280 mg/m2) plus BSC or BSC alone. The first report (Bellmunt J, Theodore C, Demkov T et al. Phase III trial of vinflunine plus best supportive care compared with best supportive care alone after a platinumcontaining regimen in patients with advanced transitional cell carcinoma of the urothelial tract. J Clin Oncol 2009; 27(27): 4454–4461) had a median follow-up of 22.1 m and the current report has a follow-up of 45.4 m.
Three hundred and fifty-two patients had died (censoring rate 5%). In the intention-to-treat (ITT) population, the median OS was 6.9 m and 4.6 m for vinflunine plus BSC versus BSC alone, respectively (n.s.). In multivariate Cox analysis, the addition of vinflunine was independently correlated with improved survival (HR: 0.719; 95% CI:0.570–0.906, P = 0.0052). In the eligible population, the median OS in both the arms was 6.9 and 4.3 m, respectively (HR: 0.78; 95% CI:0.61–0.96; P = 0.0227), indicating an estimated 22% reduction in the risk of death.
The updated OS data confirm the positive treatment effect of vinflunine on survival that was previously reported. These results are consistent over time and confirm that vinflunine is a valuable option for second-line treatment in patients with advanced TCCU after failure of platinum-based regimens.
We present here a brief review of direct force measurements between hydrophobic surfaces in aqueous solutions. For almost 70 years, researchers have attempted to understand the hydrophobic effect ...(the low solubility of hydrophobic solutes in water) and the hydrophobic interaction or force (the unusually strong attraction of hydrophobic surfaces and groups in water). After many years of research into how hydrophobic interactions affect the thermodynamic properties of processes such as micelle formation (self-assembly) and protein folding, the results of direct force measurements between macroscopic surfaces began to appear in the 1980s. Reported ranges of the attraction between variously prepared hydrophobic surfaces in water grew from the initially reported value of 80-100 Å to values as large as 3,000 Å. Recent improved surface preparation techniques and the combination of surface force apparatus measurements with atomic force microscopy imaging have made it possible to explain the long-range part of this interaction (at separations >200 Å) that is observed between certain surfaces. We tentatively conclude that only the short-range part of the attraction (<100 Å) represents the true hydrophobic interaction, although a quantitative explanation for this interaction will require additional research. Although our force-measuring technique did not allow collection of reliable data at separations <10 Å, it is clear that some stronger force must act in this regime if the measured interaction energy curve is to extrapolate to the measured adhesion energy as the surface separation approaches zero (i.e., as the surfaces come into molecular contact).
Aim
Colorectal anastomotic leakage is a serious complication. Despite extensive research, no consensus on the most important preoperative risk factors exists. The aim of this systematic review and ...meta‐analysis was to evaluate risk factors for anastomotic leakage in patients operated with colorectal resection.
Method
The databases MEDLINE, Embase and CINAHL were searched for prospective observational studies on preoperative risk factors for anastomotic leakage. Meta‐analyses were performed on outcomes based on odds ratios (OR) from multivariate regression analyses. The Newcastle–Ottawa scale was used for bias assessment within studies, and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used for quality assessment of evidence on outcome levels.
Results
This review included 23 studies evaluating 110 272 patients undergoing colorectal resection for cancer. The meta‐analyses found that a low rectal anastomosis OR = 3.26 (95% CI: 2.31–4.62), male gender OR = 1.48 (95% CI: 1.37–1.60) and preoperative radiotherapy OR = 1.65 (95% CI: 1.06–2.56) may be risk factors for anastomotic leakage. Primarily as a result of observational design, the quality of evidence was regarded as moderate or low for these risk factors according to the GRADE approach.
Conclusion
Based on the best available evidence, important preoperative risk factors for colorectal anastomotic leakage have been identified. Knowledge on risk factors may influence treatment and procedure‐related decisions, and possibly reduce the leakage rate.
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