Broad Range Of Assumptions Research Articles

No Place to Hide: Investing in a World With No Risk-Free Asset

Now, more than perhaps at any time in the past 70 years, investors are concerned that there's no asset they can invest in which is truly risk-free. Worries of unsustainable public policies leading to debasement or default – through inflation, taxation or repudiation – have sapped confidence in the traditional safe assets of bills and bonds issued by the US and other rich countries. Investors are increasingly considering whether other assets – equities, real estate, commodities, crypto-currencies – should be used to construct an ersatz risk-free asset. In this note, we'll address this problem with a practical definition of the ideal personalized risk-free asset, and then we'll discuss how to construct an efficient portfolio when that ideal asset doesn't exist in investable form. Rather than the common practice of trying to construct a pseudo-risk-free asset from a set of available assets which don't really fit the bill, instead we should simply treat the opportunity set as consisting entirely of risky assets and optimize the real risk-adjusted return of the risky portfolio, using our personalized inflation index as the deflator. In practice, this approach to portfolio construction in the absence of a truly risk-free asset is flexible enough to handle an arbitrarily large number of different assets and a broad range of assumptions about possible outcomes in asset prices, including discontinuous jumps as well as changing risk and correlation patterns over time. The impact of this change in perspective will depend largely on the starting point of the investor's asset allocation. For investors with low to moderate risk-aversion– who start off with a high allocation to equities and other patently risky assets– treating the safest assets as being risky, but still the least risky of the available options, is likely to have a modest impact on optimal portfolio weights. But for investors who exhibit a high level of risk-aversion, who are mostly allocated to the safest assets to begin with, explicitly accounting for the risk in government bills and bonds can have a significant impact on their asset allocation. And for almost all investors, regardless of their degree of risk-aversion, moving to an Ideal Risk-Free Asset more closely aligned with per capita income growth will reduce the investor's risk-adjusted real return and thereby call for a lower long-term spending policy.

Time-varying optimization of COVID-19 vaccine prioritization in the context of limited vaccination capacity

Dynamically adapting the allocation of COVID-19 vaccines to the evolving epidemiological situation could be key to reduce COVID-19 burden. Here we developed a data-driven mechanistic model of SARS-CoV-2 transmission to explore optimal vaccine prioritization strategies in China. We found that a time-varying vaccination program (i.e., allocating vaccines to different target groups as the epidemic evolves) can be highly beneficial as it is capable of simultaneously achieving different objectives (e.g., minimizing the number of deaths and of infections). Our findings suggest that boosting the vaccination capacity up to 2.5 million first doses per day (0.17% rollout speed) or higher could greatly reduce COVID-19 burden, should a new wave start to unfold in China with reproduction number ≤1.5. The highest priority categories are consistent under a broad range of assumptions. Finally, a high vaccination capacity in the early phase of the vaccination campaign is key to achieve large gains of strategic prioritizations.

Personification of criterial resource validation and scientific and technical support for the life cycle of vertical transport

It has been proven that the vertical transport occupies a niche not so much technical objects, how many socially significant technological advances that provide comfort and accessibility for the population of different levels of mobility. Analysis of legal, regulatory documentation showed that the security and reliability of vertical transport is represented in the theory of risk as a scenario of possible events with a broad range of assumptions within the zone of progressing temporary uncertainty and coherence mechanism models of actual conditions (GOST r ISO 9000), in most cases, it is not. Evaluated scientific elaboration area studies in part integrity, functionality and consistency of the regulatory framework legal enforceability. The model of the complete life cycle of vertical transport. Algorithm of modal analysis of vertical transport parameters of criteria. Estimation of interference and strengthening process factors. Conducted simulation risk factor system the effects of vertical transport the negative socio-economic consequences. Proposed personalized predictive model of full life-cycle operation of vertical transport. Practical recommendations aimed at harmonizing the basic works on scientific and technical support and monitoring, simplification of the development programs of work, obtaining accurate and timely information on the state of vertical transport.

Strategies for Prescribing Aspirin to Prevent Preeclampsia

To evaluate the cost effectiveness of various preeclampsia screening and aspirin prophylaxis strategies, including a strategy based on biomarker and ultrasound measures. We designed a decision analysis to compare preeclampsia-related costs and effects of four strategies for aspirin use in pregnancy initiated before 16 weeks of gestation to prevent preeclampsia. The four strategies were: 1) no aspirin use, 2) biomarker and ultrasound measure-predicated use, 3) use based on the U.S. Preventive Services Task Force guidelines, and 4) universal aspirin use. Our outcomes were preeclampsia-related costs and number of cases per 100,000 pregnant women. Using a threshold of $90,843 per case of preeclampsia, one-way, two-way, and Monte-Carlo sensitivity analyses incorporating varying probabilities of risk reduction due to aspirin use, aspirin-related side effects, and costs were performed to identify ranges at which costs and risks of aspirin-related complications shifted the preferred strategy. Compared with universal aspirin administration, the use of U.S. Preventive Services Task Force guidelines is associated with $8,011,725 higher health care costs and 346 additional cases of preeclampsia per 100,000 pregnant women; biomarker and ultrasound screening is associated with an additional $19,216,551 and 308 additional cases. Similarly, no aspirin use is associated with an increased cost of $18,750,381 and 762 additional cases. Thus, universal aspirin use dominated all three other strategies. In a Monte Carlo simulation of 10,000 pregnant women, universal aspirin was the preferred strategy in 91% of simulations. The U.S. Preventive Task Force screen was preferred in 8.5% of simulations, and biomarker and ultrasound screening and no aspirin were preferred in 0% and 0.5% of simulations, respectively. Over a broad range of assumptions, universal aspirin administration is associated with fewer cases of preeclampsia and fewer costs relative to no aspirin administration and aspirin administration based on serum and ultrasound measures or clinical risk factors.

Smart house: model of resource management and safety of vertical transport

It has been proven that the vertical transport occupies a niche not so much technical objects, how many socially significant technological advances that provide comfort and accessibility for the population of different levels of mobility. Analysis of legal, regulatory documentation showed that the security and reliability of vertical transport is represented in the theory of risk as a scenario of possible events with a broad range of assumptions within the zone of progressing temporary uncertainty and coherence mechanism models of actual conditions, in most cases, it is not. Evaluated scientific elaboration area studies in part integrity, functionality and consistency of the regulatory framework legal enforceability. The model of the complete life cycle of vertical transport. Algorithm of modal analysis of vertical transport parameters of criteria. Estimation of interference and strengthening process factors. Conducted simulation risk factor system the effects of vertical transport the negative socio-economic consequences. Proposed personalized predictive model of full life-cycle operation of vertical transport. Practical recommendations aimed at harmonizing the basic works on scientific and technical support and monitoring, simplification of the development programs of work, obtaining accurate and timely information on the state of vertical transport.

Cost-effectiveness of percutaneous coronary intervention versus bypass surgery from a Dutch perspective

AimsRecent cost-effectiveness analyses of percutaneous coronary intervention (PCI) versus coronary artery bypass grafting (CABG) have been limited by a short time horizon or were restricted to the US healthcare perspective....

Locally assessing the economic viability of blue carbon: A case study from Panay Island, the Philippines

Previous blue carbon studies have focused on discrete carbon stock assessments and overarching systematic reviews which broadly speculate that it may be economically viable to incorporate mangroves into existing carbon finance platforms. There is a discernible need to test this hypothesis through case-specific investigations that determine this presumed viability in a local or regional context – at scales meaningful for policy development. The current study investigates whether the carbon values of mangrove forests on Panay Island, the Philippines, are sufficient to offset the opportunity costs of milkfish (Chanos chanos) aquaculture – the primary cause of mangrove deforestation in the Philippines. Profit margins associated with milkfish aquaculture are calculated through a municipality-wide survey (779±140US$ha−1yr−1). Concurrently, the carbon stocks of two heterogeneous mangrove forests are quantified and compared. Creditable CO2 emissions reductions are modelled under a broad range of assumptions. These emissions are valorised, and a sensitivity analysis is performed to establish the minimum price at which opportunity costs are offset across a range of methodological and accounting preferences. It is determined that carbon prices of around 5–12US$tCO2e−1 would be required to compensate landowners for their lost aquaculture profits. The implications of our findings are discussed.

Influence of genomics on adjuvant treatments for pre-invasive and invasive breast cancer

Introduction and aimTribute to the improved quality of tumor marker studies all major national and international practice guidelines now recognized the potential clinical value of multivariate genomic prognostic tests. There are several diagnostic companies that offer these products for clinical use. This paper reviews recent trends in genomic prognostic testing in the clinic and briefly discusses future trends. Methods and resultsPublished manuscripts on breast cancer biomarkers, genomic prognostic and predictive tests were reviewed along with abstracts and proceedings of major conferences to extract information on the clinical utility, cost-effectiveness and usage of molecular tests in the management of early stage breast cancers. Genomic test use has steadily increased over the past 5 years, approximately 30%, 13% and 1% of stage I, II and III ER-positive breast cancer breast cancers are tested. Among those who are tested, approximately, 25–30% of the time treatment recommendations change due to test results. Testing is associated with decreased use of chemotherapy overall, however in clinically low risk patients who are tested tend to receive chemotherapy more frequently than low risk patients who are untested. Almost all cost-effectiveness studies concluded that genomic testing is cost effective under a broad range of assumptions when used within current guidelines. Simple immunohistochemistry based assays when performed following a standard operating procedure and combined into a multivariate prognostic model, have the potential to substitute for genomic tests in the future. Discussion and conclusionsGenomic testing, when available, is widely used to assist in adjuvant chemotherapy treatment recommendations for clinically intermediate risk (e.g. grade 2, stage I–II) ER-positive breast cancers.

Global economic potential for reducing carbon dioxide emissions from mangrove loss

Mangroves are among the most threatened and rapidly disappearing natural environments worldwide. In addition to supporting a wide range of other ecological and economic functions, mangroves store considerable carbon. Here, we consider the global economic potential for protecting mangroves based exclusively on their carbon. We develop unique high-resolution global estimates (5' grid, about 9 × 9 km) of the projected carbon emissions from mangrove loss and the cost of avoiding the emissions. Using these spatial estimates, we derive global and regional supply curves (marginal cost curves) for avoided emissions. Under a broad range of assumptions, we find that the majority of potential emissions from mangroves could be avoided at less than $10 per ton of CO(2). Given the recent range of market price for carbon offsets and the cost of reducing emissions from other sources, this finding suggests that protecting mangroves for their carbon is an economically viable proposition. Political-economy considerations related to the ability of doing business in developing countries, however, can severely limit the supply of offsets and increases their price per ton. We also find that although a carbon-focused conservation strategy does not automatically target areas most valuable for biodiversity, implementing a biodiversity-focused strategy would only slightly increase the costs.

Beyond Shannon: the quest for fundamental performance limits of wireless ad hoc networks

We describe a new theoretical framework for determining fundamental performance limits of wireless ad hoc networks. The framework expands the traditional definition of Shannon capacity to incorporate notions of delay and outage. Novel tools are described for upper and lower bounding the network performance regions associated with these metrics under a broad range of assumptions about channel and network dynamics, state information, and network topologies. We also develop a flexible and dynamic interface between network applications and the network performance regions to obtain the best end-to-end performance. Our proposed framework for determining performance limits of wireless networks embraces an interdisciplinary approach to this challenging problem that incorporates Shannon Theory along with network theory, combinatorics, optimization, stochastic control, and game theory. Preliminary results of this approach are described and promising future directions of research are outlined.

Identifying Key Metrics for Reducing Premature Departure from the Pediatric Emergency Department

Approximately 2% to 5% of children presenting to pediatric emergency departments (PEDs) leave prior to a complete evaluation. This study assessed risk factors for premature departure (PD) from a PED to identify key metrics and cutoffs for reducing the PD rate. A 3-year cohort (June 2004-May 2007) of children presenting to a PED was evaluated. Children were excluded if they presented for psychiatric issues, were held awaiting hospital admission in the PED due to a lack of inpatient beds, were more than 21 years old, or died before disposition. Univariate analyses, multivariable logistic regression, and recursive partitioning were used to identify factors associated with PD. A fourth year of data (June 2007-May 2008) was used for validation and sensitivity analysis. There were 132,324 patient visits in the 3-year derivation data set with a 3.8% PD rate, and 45,001 visits in the fourth-year validation data set with a 4.3% PD rate. PDs were minimized when average wait time was below 110 minutes, concurrent PDs were fewer than two, and average length of stay (LOS) was less than 224 minutes in the derivation set, with similar results in the validation set. When these metrics were exceeded, PD rates were over 10% among low-acuity patients. These findings were robust across a broad range of assumptions during sensitivity analysis. The authors identified five key metrics associated with PD in the PED: average wait time, average LOS, acuity, concurrent PDs, and arrival rate. Operational cutoffs for these metrics, determined by recursive partitioning, may be useful to physicians and administrators when selecting specific interventions to address PDs from the PED.

Telemedicine in the management of chronic pain: a cost analysis study

Telemedicine provides patients with easy and remote access to consultant expertise irrespective of geographic location. In a randomized controlled trial, this study has applied a rigorous costing methodology to the use of telemedicine in chronic pain management. We performed a randomized two-period crossover trial comparing in-person (IP) consultation with telemedicine (TM) consultation in the management of chronic pain. Over an 18-month period, 26 patients each completed two diaries capturing their direct and indirect travel costs, daily pain scores, and satisfaction with physician consultation. Costing models were developed to account for direct, indirect, fixed, and variable costs in order to perform break-even analyses. Sensitivity analysis was performed over a broad range of assumptions. Direct patient costs were significantly lower in the TM group than in the IP group, with median cost and interquartile range 133 dollars (28-377) vs 443 dollars (292-1075), respectively (P = 0.001). More patients were highly satisfied with the TM consultation than with the IP consultation (56 and 24%, respectively; P < 0.05). Break-even annual patient volume was estimated at 57 patients. A two-way sensitivity analysis controlling for annual patient volume and round-trip distance indicated that TM remains cost-effective at volumes >50 patients/year or at round-trip distances >200 km. Telemedicine is cost-effective over a broad range of assumptions, including annual patient volumes, travel distance, fuel costs, amortization, and discount rates. This study provides data from a real-world setting to determine relevant thresholds and targets for establishing a TM program for patients who are undergoing chronic pain therapy.

A simulation analysis to characterize the dynamics of vaccinating behaviour on contact networks

BackgroundHuman behavior influences infectious disease transmission, and numerous "prevalence-behavior" models have analyzed this interplay. These previous analyses assumed homogeneously mixing populations without spatial or social structure. However, spatial and social heterogeneity are known to significantly impact transmission dynamics and are particularly relevant for certain diseases. Previous work has demonstrated that social contact structure can change the individual incentive to vaccinate, thus enabling eradication of a disease under a voluntary vaccination policy when the corresponding homogeneous mixing model predicts that eradication is impossible due to free rider effects. Here, we extend this work and characterize the range of possible behavior-prevalence dynamics on a network.MethodsWe simulate transmission of a vaccine-prevetable infection through a random, static contact network. Individuals choose whether or not to vaccinate on any given day according to perceived risks of vaccination and infection.ResultsWe find three possible outcomes for behavior-prevalence dynamics on this type of network: small final number vaccinated and final epidemic size (due to rapid control through voluntary ring vaccination); large final number vaccinated and significant final epidemic size (due to imperfect voluntary ring vaccination), and little or no vaccination and large final epidemic size (corresponding to little or no voluntary ring vaccination). We also show that the social contact structure enables eradication under a broad range of assumptions, except when vaccine risk is sufficiently high, the disease risk is sufficiently low, or individuals vaccinate too late for the vaccine to be effective.ConclusionFor populations where infection can spread only through social contact network, relatively small differences in parameter values relating to perceived risk or vaccination behavior at the individual level can translate into large differences in population-level outcomes such as final size and final number vaccinated. The qualitative outcome of rational, self interested behaviour under a voluntary vaccination policy can vary substantially depending on interactions between social contact structure, perceived vaccine and disease risks, and the way that individual vaccination decision-making is modelled.

Reduced Effectiveness of Selection Caused by a Lack of Recombination

Genetic recombination associated with sexual reproduction is expected to have important consequences for the effectiveness of natural selection. These effects may be evident within genomes, in the form of contrasting patterns of molecular variation and evolution in regions with different levels of recombination. Previous work reveals patterns that are consistent with a benefit of recombination for adaptation at the level of protein sequence: both positive selection for adaptive variants and purifying selection against deleterious ones appear to be compromised in regions of low recombination [1-11]. Here, we re-examine these patterns by using polymorphism and divergence data from the Drosophila dot chromosome, which has a long history of reduced recombination. To avoid confounding selection and demographic effects, we collected these data from a species with an apparently stable demographic history, Drosophila americana. We find that D. americana dot loci show several signatures of ineffective purifying and positive selection, including an increase in the rate of protein evolution, an increase in protein polymorphism, and a reduction in the proportion of amino acid substitutions attributable to positive selection.

How accurately can 21 cm tomography constrain cosmology?

There is growing interest in using 3-dimensional neutral hydrogen mapping with the redshifted 21 cm line as a cosmological probe. However, its utility depends on many assumptions. To aid experimental planning and design, we quantify how the precision with which cosmological parameters can be measured depends on a broad range of assumptions, focusing on the 21 cm signal from $6lzl20$. We cover assumptions related to modeling of the ionization power spectrum, to the experimental specifications like array layout and detector noise, to uncertainties in the reionization history, and to the level of contamination from astrophysical foregrounds. We derive simple analytic estimates for how various assumptions affect an experiment's sensitivity, and we find that the modeling of reionization is the most important, followed by the array layout. We present an accurate yet robust method for measuring cosmological parameters that exploits the fact that the ionization power spectra are rather smooth functions that can be accurately fit by 7 phenomenological parameters. We find that for future experiments, marginalizing over these nuisance parameters may provide constraints almost as tight on the cosmology as if 21 cm tomography measured the matter power spectrum directly. A future square kilometer array optimized for 21 cm tomography could improve the sensitivity to spatial curvature and neutrino masses by up to 2 orders of magnitude, to $\ensuremath{\Delta}{\ensuremath{\Omega}}_{k}\ensuremath{\approx}0.0002$ and $\ensuremath{\Delta}{m}_{\ensuremath{\nu}}\ensuremath{\approx}0.007\text{ }\text{ }\mathrm{eV}$, and give a $4\ensuremath{\sigma}$ detection of the spectral index running predicted by the simplest inflation models.

Elucidating strategic network dynamics through computational modeling

In this study we describe a comprehensive computational model of network dynamics (COM-NeD) and demonstrate how it may help us better understand and theorize the dynamics of strategic networks. Specifically, we model a population of firms characterized by idiosyncratic resource needs and productive capacities, while having to respond to the demands of external events by establishing ties and receiving needed resources from other firms. Through COM-NeD we investigate a set of established theoretical perspectives that represent distinct strategies for seeking and establishing interfirm ties. Rigorous computational experiments demonstrate the expected behavior of such a system under a broad range of assumptions. The results shed light on the complexity of strategic network dynamics, demonstrating novel interactions of firms' internal resource capacity, relational search approaches, and external resource growth.

The Welfare Consequences of Strategic Voting in Two Commonly Used Parliamentary Agendas

This paper studies the welfare consequences of strategic voting in two commonly used parliamentary agendas by comparing the average utilities obtained in simulated voting under two behavioural assumptions: expected utility maximising behaviour and sincere behaviour. The average utility obtained in simulations is higher with expected utility maximising behaviour than with sincere voting behaviour under a broad range of assumptions. Strategic voting increases welfare particularly if the distribution of preference intensities correlates with voter types.

Immediate computed tomography or admission for observation after mild head injury: cost comparison in randomised controlled trial

Objective To compare the costs of immediate computed tomography during triage for admission with those of observation in hospital in patients with mild head injury.Design Prospective cost effectiveness analysis within...

Self-Organization of Surface Transportation Networks

This research investigates the self-organization of surface transportation networks. Using a travel demand model coupled with revenue, cost, and investment models, experiments are run under a variety of parameters on a grid network. It is found that roads, contiguous sections of multiple links operating with similar characteristics, and hierarchies of roads emerge under a broad range of assumptions from networks with neither defined roads nor clearly organized hierarchies. The factors that drive this are the (dis)economies of scale, the presence of boundaries, and any initial asymmetry in the network. This research thus finds that roads and hierarchies, which are often thought to be the product of conscious design, can also arise without such intention.

Invasive aliens and sampling bias

AbstractTwo hypotheses have been proposed to explain the observation of increased vigour of invasive alien plants in their nonindigenous ranges: phenotypic plasticity, and the post‐invasion evolution of increased competitive ability (EICA). Here I specify how a general pattern of increased vigour may result from sampling bias. Ignoring failed invasions can account for the illusion of increased vigour over a broad range of assumptions. Plasticity and EICA need not be viewed as explanations for a general pattern of increased vigour even if they are the mechanisms underlying every occurrence.