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Although economic growth has historically been an engine of prosperity in the United States, recent trends in demographics, social insurance programs, technological progress, human capital, immigration, income inequality, and fiscal policy have generated uncertainty regarding the prospects for sustaining such growth. Economists disagree about the relative importance of many factors affecting future growth, including rapid technological advances, immigration, the growth of the financial sector, problems with the educational system, increasing income inequality, an aging population, and large fiscal imbalances that have not been addressed by the political system. This collection of articles, authored by many of today's leading economists, addresses the prospects for economic growth in the United States over the next few decades. During a time of great economic uncertainty, this book engages with both sides in the debate over economic growth, focusing on policy options that increase the prospects for vigorous economic growth in the future.
In this impressive volume, the editors have pulled together an international cast of distinguished authors, who present a detailed account of sperm function testing in terms of rationale, methodologies and clinical significance. In this introduction, my intention is to give a historical perspective on the evolution of these techniques and a view of where this field will head in the future. For what it is worth, I should also mention that these reflections are presented from the standpoint of someone who has spent the best part of half-a-century considering how we can reliably and effectively monitor the functional quality of human spermatozoa.
Apoptosis, a physiological process for the controlled deletion of cells, is critical for the regulation of cell numbers, the management of morphogenesis during embryonic development, and the orchestration of many cellular processes in the adult. Spermatogenesis, the production of functional spermatozoa from spermatogonial stem cells, is no exception. It appears that a functional apoptotic pathway is necessary for normal spermatogenesis to develop, and without it infertility ensues. Apoptosis also plays a crucial role in the maintenance of the testis and its response to external toxicants, as well as in the programmed senescence of terminally differentiated spermatozoa. This chapter focuses specifically on how apoptosis affects sperm quality and function, and the implications of this process for both embryonic development and the health and well-being of the offspring.
Catheter ablation is a safe and effective therapy for the treatment of supraventricular tachycardia in children. Current improvements in technology have allowed progressive reduction in radiation exposure associated with the procedure. To assess the impact of three-dimensional mapping, we compared acute procedural results collected from the Catheter Ablation with Reduction or Elimination of Fluoroscopy registry to published results from the Prospective Assessment after Pediatric Cardiac Ablation study.
Methods:
Inclusion and exclusion criteria from the Prospective Assessment after Pediatric Cardiac Ablation study were used as guidelines to select patient data from the Catheter Ablation with Reduction or Elimination of Fluoroscopy registry to compare acute procedural outcomes between cohorts. Outcomes assessed include procedural and fluoroscopy exposure times, success rates of procedure, and complications.
Results:
In 786 ablation procedures, targeting 498 accessory pathways and 288 atrioventricular nodal reentrant tachycardia substrates, average procedural time (156.5 versus 206.7 minutes, p < 0.01), and fluoroscopy time (1.2 versus 38.3 minutes, p < 0.01) were significantly shorter in the study group. Success rates for the various substrates were similar except for manifest accessory pathways which had a significantly higher success rate in the study group (96.4% versus 93.0%, p < 0.01). Major complication rates were significantly lower in the study group (0.3% versus 1.6%, p < 0.01).
Conclusions:
In a large, multicentre study, three-dimensional systems show favourable improvements in clinical outcomes in children undergoing catheter ablation of supraventricular tachycardia compared to the traditional fluoroscopic approach. Further improvements are anticipated as technology advances.
Corporations maximize shareholder returns—or so goes the conventional wisdom. It was not always so. In the middle decades of the last century, lawmakers, business leaders, and journalists agreed that the nation's largest and most powerful corporations had obligations to a raft of stakeholders that included (in addition to shareholders) employees, customers, and the localities in which they had set up shop. Some historians have labeled this consensus “corporate liberalism”; contemporaries called it “social responsibility.” Still others, including, most notably, Alfred D. Chandler Jr., regarded these corporate obligations as emblematic of a new stage in economic development—“managerial capitalism”—whose origins could be traced back to the railroad, the country's first “big business.” This consensus had durable consequences, as Kenneth J. Lipartito and others demonstrated in Corporate Responsibility: The American Experience (2012), a multiauthor survey of shifting assumptions regarding corporate governance in the United States from the colonial era to the present.
More than 50 years of randomized clinical trials for youth psychotherapies have resulted in moderate effect sizes for treatments targeting the most common mental health problems in children and adolescents (i.e., anxiety, depression, conduct problems, and attention disorders). Despite having psychotherapies that are effective for many children, there has been a dearth of progress in identifying the contextual factors that likely influence who will respond to a given psychotherapy, and under what conditions. The developmental psychopathology evidence base consistently demonstrates that psychosocial risk exposures (e.g., childhood adversities, interpersonal stressors, family dysfunction) significantly influence the onset and course of youth psychopathology. However, the developmental psychopathology framework remains to be well integrated into treatment development and psychotherapy research. We argue that advances in basic developmental psychopathology research carry promising implications for the design and content of youth psychotherapies. Research probing the effects of psychosocial risks on youth development can enrich efforts to identify contextual factors in psychotherapy effectiveness and to personalize treatment. In this article we review empirically supported and hypothesized influences of individual- and family-level risk factors on youth psychotherapy outcomes, and we propose a framework for leveraging developmental psychopathology to strengthen psychotherapies.
Turbulent mixing exerts a significant influence on many physical processes in the ocean. In a stably stratified Boussinesq fluid, this irreversible mixing describes the conversion of available potential energy (APE) to background potential energy (BPE). In some settings the APE framework is difficult to apply and approximate measures are used to estimate irreversible mixing. For example, numerical simulations of stratified turbulence often use triply periodic domains to increase computational efficiency. In this set-up, however, BPE is not uniquely defined and the method of Winters et al. (J. Fluid Mech., vol. 289, 1995, pp. 115–128) cannot be directly applied to calculate the APE. We propose a new technique to calculate APE in periodic domains with a mean stratification. By defining a control volume bounded by surfaces of constant buoyancy, we can construct an appropriate background buoyancy profile $b_\ast (z,t)$ and accurately quantify diapycnal mixing in such systems. This technique also permits the accurate calculation of a finite-amplitude local APE density in periodic domains. The evolution of APE is analysed in various turbulent stratified flow simulations. We show that the mean dissipation rate of buoyancy variance $\chi$ provides a good approximation to the mean diapycnal mixing rate, even in flows with significant variations in local stratification. When quantifying measures of mixing efficiency in transient flows, we find significant variation depending on whether laminar diffusion of a mean flow is included in the kinetic energy dissipation rate. We discuss how best to interpret these results in the context of quantifying diapycnal diffusivity in real oceanographic flows.
Crary Ice Rise formed after the Ross Ice Shelf re-grounded ~1 kyr BP. We present new ice-penetrating radar data from two systems operating at center frequencies of 7 and 750 MHz that confirm the ice rise is composed of a former ice shelf buried by subsequent accumulation. Stacks of englacial diffraction hyperbolas are present almost everywhere across the central ice rise and extend up to ~350 m above the bed. In many cases, bed reflections beneath the diffraction hyperbolas are obscured for distances up to 1 km. Waveform modeling indicates that the diffraction hyperbolas are likely caused by marine ice deposits in former basal crevasses and rifts. The in-filling of rifts and basal crevasses may have strengthened the connection between the ice rise and the surrounding ice shelf, which could have influenced local and regional ice dynamics. Three internal reflection horizons mark the upper limit of disturbed ice and diffraction hyperbolas in different sections of the ice rise, indicating at least three stages of flow stabilization across the ice rise. A surface lineation visible in MODIS imagery corresponds spatially to deepening and strong deformation of these layers, consistent with the characteristics of former grounding lines observed elsewhere in Antarctica.
Antidepressant medication and interpersonal psychotherapy (IPT) are both recommended interventions in depression treatment guidelines based on literature reviews and meta-analyses. However, ‘conventional’ meta-analyses comparing their efficacy are limited by their reliance on reported study-level information and a narrow focus on depression outcome measures assessed at treatment completion. Individual participant data (IPD) meta-analysis, considered the gold standard in evidence synthesis, can improve the quality of the analyses when compared with conventional meta-analysis.
Aims
We describe the protocol for a systematic review and IPD meta-analysis comparing the efficacy of antidepressants and IPT for adult acute-phase depression across a range of outcome measures, including depressive symptom severity as well as functioning and well-being, at both post-treatment and follow-up (PROSPERO: CRD42020219891).
Method
We will conduct a systematic literature search in PubMed, PsycINFO, Embase and the Cochrane Library to identify randomised clinical trials comparing antidepressants and IPT in the acute-phase treatment of adults with depression. We will invite the authors of these studies to share the participant-level data of their trials. One-stage IPD meta-analyses will be conducted using mixed-effects models to assess treatment effects at post-treatment and follow-up for all outcome measures that are assessed in at least two studies.
Conclusions
This will be the first IPD meta-analysis examining antidepressants versus IPT efficacy. This study has the potential to enhance our knowledge of depression treatment by comparing the short- and long-term effects of two widely used interventions across a range of outcome measures using state-of-the-art statistical techniques.
Morley’s trisector theorem says that the three intersections of the trisectors of the angles of a triangle, lying near the three sides respectively, form an equilateral triangle. See Figure 1. Morley discovered his theorem in 1899, and news of it quickly spread. Over the years many proofs have been published, by trigonometry or by geometry, but a simple angle-chasing argument is elusive. See [1] for a list up to 1978. Perhaps the easiest proof is that of John Conway [2], who assembles a triangle similar to the given triangle by starting with an equilateral triangle and surrounding it by triangles with very carefully chosen angles.
COVID-19 has presented society with a public health threat greater than any in living memory, leaving us to question almost every aspect of our society. An ever increasing concern is how we protect the global population from mental illness and whether public mental health policies can achieve this. In this article I reflect on the history of mental health service development, and furthermore on how COVID-19 might impact on the delivery of public mental health strategies into the future.
We report an idealized numerical study of a melting and freezing solid adjacent to a turbulent, buoyancy-affected shear flow, in order to improve our understanding of topography generation by phase changes in the environment. We use the phase-field method to dynamically couple the heat equation for the solid with the Navier–Stokes equations for the fluid. We investigate the evolution of an initially flat and horizontal solid boundary overlying a pressure-driven turbulent flow. We assume a linear equation of state for the fluid and change the sign of the thermal expansion coefficient, such that the background density stratification is either stable, neutral or unstable. We find that channels aligned with the direction of the mean flow are generated spontaneously by phase changes at the fluid–solid interface. Streamwise vortices in the fluid, the interface topography and the temperature field in the solid influence each other and adjust until a statistical steady state is obtained. The crest-to-trough amplitude of the channels is larger than approximately 10$\delta _{\nu }$ in all cases, with $\delta _{\nu }$ the viscous length scale, but is much larger and more persistent for an unstable stratification than for a neutral or stable stratification. This happens because a stable stratification makes the cool melt fluid buoyant such that it shields the channel from further melting, whereas an unstable stratification makes the cool melt fluid sink, inducing further melting by rising hot plumes. The statistics of flow velocities and melt rates are investigated, and we find that channels and keels emerging in our simulations do not significantly change the mean drag coefficient.
Native tungsten (IMA2011-004), W, is officially described as a new mineral from gold placers in the Bol'shaya Pol'ya river valley, Prepolar Urals, Russia, associated with yttriaite-(Y) and from quartz veins in the Mt Neroyka rock-crystal field, Ust–Puiva, Tyumenskaya Oblast', Russia. Tungsten forms polycrystalline grains and masses, and rarely cubo-octahedra. It is silver white to steel grey in colour, with metallic lustre and grey streak. The calculated density is 19.226 g/cm3. The Vickers hardness (VHN25) is 571.45 kg/mm2. In plane polarised light, tungsten is white with a pale-yellow tint and optically isotropic. Electron microprobe analyses of Bol'shaya Pol'ya river valley material provided W 99.27, Mo 0.06, Mn 0.04, Fe 0.01, total 99.38 wt.%. The five strongest powder X-ray diffraction lines are [dobs Å(I)(hkl)]: 2.2422(100)(110), 1.5835(25)(200), 1.2929(48)(211), 1.0010(23)(310) and 0.8457(24)(321). Tungsten is cubic, Im$\bar{3}$m, a = 3.1648(4) Å, V = 31.69(4) Å3 and Z = 2. Some additional occurrences of native tungsten and technogenic tungsten found in Nature are also described.
To evaluate broad-spectrum intravenous antibiotic use before and after the implementation of a revised febrile neutropenia management algorithm in a population of adults with hematologic malignancies.
Design:
Quasi-experimental study.
Setting and population:
Patients admitted between 2014 and 2018 to the Adult Malignant Hematology service of an acute-care hospital in the United States.
Methods:
Aggregate data for adult malignant hematology service were obtained for population-level antibiotic use: days of therapy (DOT), C. difficile infections, bacterial bloodstream infections, intensive care unit (ICU) length of stay, and in-hospital mortality. All rates are reported per 1,000 patient days before the implementation of an febrile neutropenia management algorithm (July 2014–May 2016) and after the intervention (June 2016–December 2018). These data were compared using interrupted time series analysis.
Results:
In total, 2,014 patients comprised 6,788 encounters and 89,612 patient days during the study period. Broad-spectrum intravenous (IV) antibiotic use decreased by 5.7% with immediate reductions in meropenem and vancomycin use by 22 (P = .02) and 15 (P = .001) DOT per 1,000 patient days, respectively. Bacterial bloodstream infection rates significantly increased following algorithm implementation. No differences were observed in the use of other antibiotics or safety outcomes including C. difficile infection, ICU length of stay, and in-hospital mortality.
Conclusions:
Reductions in vancomycin and meropenem were observed following the implementation of a more stringent febrile neutropenia management algorithm, without evidence of adverse outcomes. Successful implementation occurred through a collaborative effort and continues to be a core reinforcement strategy at our institution. Future studies evaluating patient-level data may identify further stewardship opportunities in this population.
Most patients with World Federation of Neurological Surgeons (WFNS) grade 5 subarachnoid hemorrhage (SAH) have poor outcomes. Accurate assessment of prognosis is important for treatment decisions and conversations with families regarding goals of care. Unjustified pessimism may lead to “self-fulfilling prophecy,” where withdrawal of life-sustaining measures (WLSM) is invariably followed by death.
Methods:
We performed a cohort study involving consecutive patients with WFNS grade 5 SAH to identify variables with >= 90% and >= 95% positive predictive value (PPV) for poor outcome (1-year modified Rankin Score >= 4), as well as findings predictive of WLSM.
Results:
Of 140 patients, 38 (27%) had favorable outcomes. Predictors with >= 95% PPV for poor outcome included unconfounded 72-hour Glasgow Coma Scale motor score <= 4, absence of >= 1 pupillary light reflex (PLR) at 24 hours, and intraventricular hemorrhage (IVH) score of >= 20 (volume >= 54.6 ml). Intracerebral hemorrhage (ICH) volume >= 53 ml had PPV of 92%. Variables associated with WLSM decisions included a poor motor score (p < 0.0001) and radiographic evidence of infarction (p = 0.02).
Conclusions:
We identified several early predictors with high PPV for poor outcome. Of these, lack of improvement in motor score during the initial 72 hours had the greatest potential for confounding from “self-fulfilling prophecy.” Absence of PLR at 24 hours, IVH score >= 20, and ICH volume >= 53 ml predicted poor outcome without a statistically significant effect on WLSM decisions. More research is needed to validate prognostic variables in grade 5 SAH, especially among patients who do not undergo WLSM.
We conducted a field experiment with 334 Canadian Members of Parliament exploring whether politicians seek out more information about an issue when they are farther offside the average opinion in their constituency on that issue. In the midst of a contentious national debate on the oil industry, we invited MPs and their staff to watch a webinar or read a written summary of the webinar created by experts and containing a variety of viewpoints on the issue. For politicians on either side, the information could prove useful in future debate and conversation. Some politicians were randomly assigned to information about the distribution of opinion in their constituency on the issue. We find no evidence that politicians are more likely to pursue policy information when they are offside their average constituency opinion, and none that this effect is enhanced when they learn about their relative position vis-a-vis constituency preferences.
The direct carbonate procedure for accelerator mass spectrometry radiocarbon (AMS 14C) dating of submilligram samples of biogenic carbonate without graphitization is becoming widely used in a variety of studies. We compare the results of 153 paired direct carbonate and standard graphite 14C determinations on single specimens of an assortment of biogenic carbonates. A reduced major axis regression shows a strong relationship between direct carbonate and graphite percent Modern Carbon (pMC) values (m = 0.996; 95% CI [0.991–1.001]). An analysis of differences and a 95% confidence interval on pMC values reveals that there is no significant difference between direct carbonate and graphite pMC values for 76% of analyzed specimens, although variation in direct carbonate pMC is underestimated. The difference between the two methods is typically within 2 pMC, with 61% of direct carbonate pMC measurements being higher than their paired graphite counterpart. Of the 36 specimens that did yield significant differences, all but three missed the 95% significance threshold by 1.2 pMC or less. These results show that direct carbonate 14C dating of biogenic carbonates is a cost-effective and efficient complement to standard graphite 14C dating.