Influence of cold storage time on the softening prediction in Spring Bright nectarines

With Time-resolved Reflectance Spectroscopy (TRS) the maturity of nectarines at harvest can be assessed by measuring the absorption coefficient at 670 nm (µa 670) in the fruit flesh. A kinetic model has been developed linking the optical properties as measured by TRS with the models of µa 670 and firmness decay in shelf-life at 20°C, making the prediction of the softening time for individual fruit possible. In order to study the influence of cold storage time prior to shelf life on the softening prediction, 540 (year 2003) and 870 (year 2004) ‘Spring Bright’ nectarines were measured at harvest with TRS; then fruit were put in shelf life after various periods of cold storage at 0°C (4 and 10 d, year 2003; 6, 13 and 20 days, year 2004). During the 5-day period of shelf life at 20°C, fruit were analysed for firmness by pressure test after 30, 48, 54, 72, 78, 96, 102 and 120h in 2003 and after 36, 43, 62, 87, 108 and 135h in 2004. For each year and cold storage time, the parameters of the logistic model of softening as a function of µa 670 at harvest were computed. The cold storage up to 13 days did not significantly influence the estimates of the softening rate constant (kf), of the maximum firmness at minus infinite time (Fmax) and of parameter alpha (a) in both years, whereas parameter beta (ß) in 2003 significantly decreased from -1.867 at day 4 to -2.237 at day 10. The further 7 days of cold storage in 2004 significantly affected kf, which decreased from 0.00084 at days 6 and 13 to 0.00069 at day 20, and ß which increased from -2.395 at day 6 to -2.053 at day 20. Our results indicate that the cold storage time significantly influences the softening prediction of nectarines as the longer the cold storage, the lower the softening rat

Additive logistic processes in option pricing

In option pricing, it is customary to first specify a stochastic underlying model and then extract valuation equations from it. However, it is possible to reverse this paradigm: starting from an arbitrage-free option valuation formula, one could derive a family of risk-neutral probabilities and a corresponding risk-neutral underlying asset process. In this paper, we start from two simple arbitrage-free valuation equations, inspired by the log-sum-exponential function and an ℓp vector norm. Such expressions lead respectively to logistic and Dagum (or “log-skew-logistic”) risk-neutral distributions for the underlying security price. We proceed to exhibit supporting martingale processes of additive type for underlying securities having as time marginals two such distributions. By construction, these processes produce closed-form valuation equations which are even simpler than those of the Bachelier and Samuelson–Black–Scholes models. Additive logistic processes provide parsimonious and simple option pricing models capturing various important stylised facts at the minimum price of a single market observable input

TRS-measurements as a nondestructive method assessing stage of maturity and ripening in plum (Prunus domestica L.)

n plum fruit with dark red or blue blush colour covering the whole fruit, the change in ground colour from green to yellow during maturation and ripening is masked. Hence, the maturity stage is difficult to judge. Time-resolved reflectance spectroscopy (TRS) has been used as a nondestructive method to assess changes in important internal quality factors in ‘Jubileum’ plums (Prunus domestica L.). Absorption coefficients (µa) and scattering coefficients (µs) were measured at both 670 and 758 nm during 5 days of storage. The changes in soluble solids content, titratable acidity and firmness were as expected. No change in soluble solids content was observed, while the plums became less acid and softer during storage. The TRS-measurements of plums indicated that TRS could give interesting information on internal quality factors in plums as the absorption at 670 nm was closely related to firmness, TA and TSS at the time of picking. Absorption at 758 nm was more closely related to the quality parameters after storage. The study did not indicate that scattering could be used in assessing maturity stage in plum

Asymptotic analysis of a family of non-local functionals on sets

We study the asymptotic behavior of a family of functionals which penalize a short-range interaction of convolution type between a finite perimeter set and its complement. We first compute the pointwise limit and we obtain a lower estimate on more regulars sets. Finally, some examples are discussed

Assessing the Harvest Maturity of Brazilian Mangoes

No clear criterion exists to determine the optimum time to harvest mango. Some empirical relations are used to assess maturity, such as shoulder development. Moreover, as a result of the typical growing conditions in tropical climates, a huge variation in maturity and ripeness exists, seriously hampering the export of fruit in the global chain. The consequence for consumers in western countries is that sometimes mangoes are overripe at the retailer, or have to be kept for several days, even weeks, to reach the edible state, provided they do not rot in the meantime. To ensure an edible quality, the chlorophyll content in the fruit flesh, measured at harvest by Time-resolved Reflectance Spectroscopy (TRS), could be used as a maturity criterion for mango fruit. Commercially grown fruit were harvested in Brazil and transported to Italy by plane. Fruits were measured using TRS at 630 nm for absorption coefficient (µa) and skin colour. The development of µa was followed on 60 fruits during 15 days of storage at 20°C. The remainders of fruit were used to measure firmness destructively. Absorption coefficient decreased during shelf life according to a logistic pattern, as expected for colour development. Taking the variation between the individual fruit into account, 72% of the variation was accounted for. Nevertheless, µa assessed at harvest could be converted into a biological shift factor (BSF), as an expression of the maturity at harvest of each individual fruit. This biological shift factor explained about 70% of the variation in firmness development in individual fruit. These preliminary results indicate that TRS methodology coupled with BSF theory could be useful in assessing maturity at harvest and assuring acceptable eating quality of mango

Optical Absorption and Scattering Phenomena in 'Jubileum' Plums in Relation to Their Colour Properties

Absorption and scattering of laser light pulse passing through the fruit determine among others, the optical properties of the product. Efforts have been made in the recent past to utilize innovative techniques such as time-resolved reflectance spectroscopy (TRS) to study the quality aspects of different fruit such as nectarines. These optical properties have been well related to firmness, sugars, acids and other quality attributes. TRS measurements were performed on ‘Jubileum’ plums at two different wavelengths: 670 nm and 758 nm. The fruit were harvested in Norway and brought to Italy under protected conditions. After sorting the fruit by size, TRS measurements were made and the fruit were randomized for different examinations of quality aspects. It was observed that the absorption coefficient (µa) increased for both wavelengths as ripening progressed towards the melting stage of the fruit. The µa values at 670 nm were higher than those at 758 nm. The higher rate in the µa was distinguishable from the third day onwards as the fruit ripened. Similarly, it was interesting to note that the internal colour measured after destructing the fruit related well with the TRS absorption coefficient (µa), i.e., a decrease in the CIE L* (towards darker region) and b* (towards blue) value along with an increase in a* (towards red) from third day of storag

Modeling of volatility-linked financial products

This thesis is the collation of four papers, adapted from their original versions as to form here four distinct chapters. In the first chapter we illustrate and solve the pricing problem of a target volatility option (TVO) using three different methodologies. In the second chapter we study the pricing PDE for a general contingent claim involving an asset and its realized volatility, and then solve it for a variety of actual models and payoffs. The third chapter introduces a class of time-changed stochastic processes based on which a martingale asset price evolution can be devised. Pricing equations for volatility-linked derivatives are also obtained in this framework. In the final chapter we analyze one specific model of this class; we conclude that it does show high flexibility in explaining the forward volatility skew dynamics and that it can capture certain interesting stylized facts