The Long Road: An Analysis of the 1557 Book of Mirrors by Seydi Ali Reis

In 1552, Piri Reis was relieved from the Admiralty of the Ottoman Imperial Navy. Seydi Ali Reis was appointed to replace him and his assignment was to return fifteen galleys from Basra to Egypt. This should have been a relatively short journey. Seydi failed miserably, however. He lost most of the ships in battle with the Portuguese and bad weather, which he documents in his travelogue The Mirror of Countries. With nowhere left to turn, he sold the remaining ships in Surat on the west coast of India. To make matters worse, he took the long road home to Istanbul: a circuitous route which stretched his journey for two years. This path went as far north as Samarqand in modern Uzbekistan. The question which arises is why did Seydi take so long to return home

First Evaluation of an Index of Low Vagally-Mediated Heart Rate Variability as a Marker of Health Risks in Human Adults: Proof of Concept.

Multiple studies have demonstrated low vagally-mediated heart rate variability (HRV) being associated with a range of risk factors for heart disease and stroke, including inflammation, hyperglycemia, hyperlipidemia, and hypertension. Yet, no cut point exists that indicates elevated risk. In the present study we sought to identify a cut point-value for HRV that is associated with elevated risk across a range of known risk factors. METHODS:A total of 9550 working adults from 19 study sites took part in a health assessment that included measures of inflammation, hyperglycemia, hyperlipidemia, and hypertension and vagally-mediated HRV (Root mean square of successive differences between normal heartbeats (RMSSD)). Multiple age and sex adjusted logistic regressions were calculated per risk factor (normal versus clinical range), with RMSSD being entered in binary at different cut points ranging from 15-39 msec with a 2 msec increment. RESULTS:For daytime RMSSD, values below 25 ± 4 indicated elevated risk (odds ratios (OR) 1.5-3.5 across risk factors). For nighttime RMSSD, values below 29 ± 4 indicated elevated risk (OR 1.2-2.0). CONCLUSION:These results provide the first evidence that a single value of RMSSD may be associated with elevated risk across a range of established cardiovascular risk factors and may present an easy to assess novel marker of cardiovascular risk

Christoffel-Minkowski flows

We provide a curvature flow approach to the regular Christoffel-Minkowski problem. The speed of our curvature flow is of an entropy preserving type and contains a global term.Comment: 25 page

Orlicz-Minkowski flows

We study the long-time existence and behavior for a class of anisotropic non-homogeneous Gauss curvature flows whose stationary solutions, if exist, solve the regular Orlicz-Minkowski problems. As an application, we obtain old and new results for the regular even Orlicz-Minkowski problems; the corresponding $L_p$ version is the even $L_p$-Minkowski problem for $p>-n-1$. Moreover, employing a parabolic approximation method, we give new proofs of some of the existence results for the general Orlicz-Minkowski problems; the $L_p$ versions are the even $L_p$-Minkowski problem for $p>0$ and the $L_p$-Minkowski problem for $p>1$. In the final section, we use a curvature flow with no global term to solve a class of $L_p$-Christoffel-Minkowski type problems.Comment: 30 page

The development of an integrated modelling system to support decisions on organic farms

This paper was presented at the UK Organic Research 2002 Conference of the Colloquium of Organic Researchers (COR). An Integrated Decision Support System (IDSS) is developed which synthesises current understanding of organic farming by means of a multiple objective framework incorporating GIS, biophysical models and socio-economic models of the farming goals. The IDSS uses a multitiered concept of a farming system as a collection of micro-enterprises at the field level, with individual resource endowments, objectives and activities. Farm-level decision drivers trickle down to affect the micro-level field enterprise selection. Biophysical models describe typical forage, cereal, root and legume output and a user-friendly interfaces permits easy access and output display via a GIS. A prototype of the IDSS framework, being developed as a part of the SAC organic research programme is presented

Surface Structure in an Accretion Disk Annulus with Comparable Radiation and Gas Pressure

We have employed a 3-d energy-conserving radiation MHD code to simulate the vertical structure and thermodynamics of a shearing box whose parameters were chosen so that the radiation and gas pressures would be comparable. The upper layers of this disk segment are magnetically-dominated, creating conditions appropriate for both photon bubble and Parker instabilities. We find little evidence for photon bubbles, even though the simulation has enough spatial resolution to see them and their predicted growth rates are high. On the other hand, there is strong evidence for Parker instabilities, and they appear to dominate the evolution of the magnetically supported surface layers. The disk photosphere is complex, with large density inhomogeneities at both the scattering and effective (thermalization) photospheres of the evolving horizontally-averaged structure. Both the dominant magnetic support and the inhomogeneities are likely to have strong effects on the spectrum and polarization of thermal photons emerging from the disk atmosphere. The inhomogeneities are also large enough to affect models of reflection spectra from the atmospheres of accretion disks.Comment: ApJ, in pres

Spatial Externalities and Vector-Borne Plant Diseases: Pierce’s Disease and the Blue-Green Sharpshooter in the Napa Valley

Pierce’s Disease (PD) is a bacterial disease that can kill grapevines over a span of one to three years. In this paper, we examine and model PD and vector control decisions made at the vineyard level in the Napa Valley in an effort to understand how the pest and disease affect individual growers, and to examine spatial externality issues and potential benefits from cooperation between adjacent vineyards. The model that we created adds to the literature by (a) treating grape vines as capital stocks that take time to reach bearing age and thus cannot be immediately replaced in the event of becoming diseased. We also (b) relax the assumption of an interior solution by examining the boundaries of parameter space for which winegrape growing is profitable and thus allowing growers to abandon land if it is not. We also explore (c) the effect of changing different policy parameters, such as PD control and vine replacement costs. Finally (d) we examine the potential benefits of cooperation between growers to manage vector populations, and determine that coordinated vector control could help riparian-adjacent growers to lessen grapevine losses and land abandonment, and thus to remain profitable in times of high PD pressure.Pierce’s Disease, winegrapes, perennial crop modeling, agricultural pests and diseases, optimal control theory, Crop Production/Industries, Production Economics, Resource /Energy Economics and Policy, Q12, Q24, C61,

The Benefits and Costs of Alternative Policies for the Management of Pierce's Disease: A Case Study of the Blue-Green Sharpshooter in the Napa Valley

Replaced with revised version of poster on 07/23/10.Production Economics, Resource /Energy Economics and Policy,