Steganographer Identification

Conventional steganalysis detects the presence of steganography within single objects. In the real-world, we may face a complex scenario that one or some of multiple users called actors are guilty of using steganography, which is typically defined as the Steganographer Identification Problem (SIP). One might use the conventional steganalysis algorithms to separate stego objects from cover objects and then identify the guilty actors. However, the guilty actors may be lost due to a number of false alarms. To deal with the SIP, most of the state-of-the-arts use unsupervised learning based approaches. In their solutions, each actor holds multiple digital objects, from which a set of feature vectors can be extracted. The well-defined distances between these feature sets are determined to measure the similarity between the corresponding actors. By applying clustering or outlier detection, the most suspicious actor(s) will be judged as the steganographer(s). Though the SIP needs further study, the existing works have good ability to identify the steganographer(s) when non-adaptive steganographic embedding was applied. In this chapter, we will present foundational concepts and review advanced methodologies in SIP. This chapter is self-contained and intended as a tutorial introducing the SIP in the context of media steganography.Comment: A tutorial with 30 page

MODELING TECHNICAL TRADE BARRIERS UNDER UNCERTAINTY

As traditional forms of agricultural protection continue to decline, agricultural interests will likely seek alternative protection in the form of technical barriers. A flexible framework for theoretically and empirically analyzing technical barriers under various sources of uncertainty is derived. Attention is focused on uncertainty arising from the variation in the product attribute levels, a source not yet considered by the literature. Ex ante and ex post densities of domestic and international quantities and prices as well as the densities of their respective extreme-order statistics are derived. An example is presented to illustrate the application of the developed framework.International Relations/Trade,

Degrees by Independent Learning: a case study of practice at Otago Polytechnic, Dunedin, New Zealand

This project constitutes a critical enquiry into the Independent Learning Pathway (ILP) approach to acquiring degrees offered by Otago Polytechnic in New Zealand. The ILP approach is for professionally experienced adults who are often poorly served by traditional taught approaches to achieving degree qualifications. These learners already have considerable degree-relevant knowledge and skill, yet this usually does not count as part of a taught degree, and these learners usually do not enrol in such degree programmes because they do not have the time to study within the typical delivery framework. The ILP approach provides equity of access for this group but is a significantly different learning process which challenges traditional conceptions of degree level learning and in turn is challenged as a valid approach by academics and regulatory agencies. Hence this study aims both to illuminate and validate the degree level learning which occurs in the ILP and to develop a model of practice for facilitators to assure the quality of this degree level learning. In pursuit of these aims I undertook, as a participant researcher, a work-based enquiry using an interpretive approach, drawing on the principles of grounded theory (Glaser and Strauss 1967), (Strauss and Corbin 2015). The project research phase commenced with an extensive survey sent to all (423) learners who studied with Capable NZ from 2006-2014, followed up with ten in-depth interviews with current learners, and eight interviews with facilitators of the ILP model. I captured the themes emerging from the feedback and analysis to identify clear signposts for both effective learning and effective facilitation in an independent learning context. This study has resulted in a (grounded) model of practice for the teachers, referred to in Capable NZ as facilitators, who guide ILP learners. This model of practice includes a competency framework, successful practice guidelines and practical learning tools. The study has also resulted in guidelines and learning tools for learners, and for both facilitators and learners the ‘SPRINGBOARD’ tool has been developed as a reflective framework for effective facilitation and learning respectively. Another key outcome of the study is the illumination and validation of the degree level learning which occurs through the ILP process

Impact of global change on coastal oxygen dynamics and risk of hypoxia

Climate change and changing nutrient loadings are the two main aspects of global change that are linked to the increase in the prevalence of coastal hypoxia - the depletion of oxygen in the bottom waters of coastal areas. However, it remains uncertain how strongly these two drivers will each increase the risk of hypoxia over the next decades. Through model simulations we have investigated the relative influence of climate change and nutrient run-off on the bottom water oxygen dynamics in the Oyster Grounds, an area in the central North Sea experiencing summer stratification. Simulations were performed with a one-dimensional ecosystem model that couples hydrodynamics, pelagic biogeochemistry and sediment diagenesis. Climatological conditions for the North Sea over the next 100 yr were derived from a global-scale climate model. Our results indicate that changing climatological conditions will increase the risk of hypoxia. The bottom water oxygen concentration in late summer is predicted to decrease by 24 mu M or 11.5% in the year 2100. More intense stratification is the dominant factor responsible for this decrease (58 %), followed by the reduced solubility of oxygen at higher water temperature (27 %), while the remaining part could be attributed to enhanced metabolic rates in warmer bottom waters (15 %). Relative to these climate change effects, changes in nutrient runoff are also important and may even have a stronger impact on the bottom water oxygenation. Decreased nutrient loadings strongly decrease the probability of hypoxic events. This stresses the importance of continued eutrophication management in coastal areas, which could function as a mitigation tool to counteract the effects of rising temperatures

Trade Agreements, Political Economy and Endogenously Incomplete Contracts

We develop a political economy model of trade agreements following along the line of Grossman and Helpman (1995a) yet incorporating contracting costs, uncertainty and multiple policy instruments. We show that rent-seeking efforts do not affect tariff rates as they are offset by the substitution effect of domestic production subsidies. Similar to Horn et al (2010), we find the coexistence of uncertainty and contracting costs make optimal trade agreements incomplete contracts. Our model helps explain differential treatment on subsidies, countervailing duties, and the national treatment principle - all key provisions of the current WTO agreement.Trade agreement, political economy, contracting cost, uncertainty JEL Classification:, Agricultural and Food Policy, International Relations/Trade, Political Economy, Public Economics,

WEATHER-BASED ADVERSE SELECTION AND THE U.S. CROP INSURANCE PROGRAM: THE PRIVATE INSURANCE COMPANY PERSPECTIVE

Surprisingly, investigations of adverse selection have focused only on farmers. Conversely, this article investigates if insurance companies, not farmers, can generate excess rents from adverse selection activities. Currently political forces fashioning crop insurance as the cornerstone of U.S. agricultural policy make our analysis particularly topical. Focusing on El Nino/La Nina and winter wheat in Texas, we simulate out-of-sample reinsurance decisions during the 1978 through 1997 crop years while reflecting the realities imposed by the risk-sharing arrangement between the insurance companies and the federal government. The simulations indicate that economically and statistically significant excess rents may be garnered by insurance companies through weather-based adverse selection.Risk and Uncertainty,

Bigeminy and the bifid papillary muscle

Various structural anomalies of the left ventricular papillary muscles have been observed in recent years. Many of these have been linked to electrocardiographic aberrations

Transferring Water in the American West: 1987-2005

Rising urban and environmental demand for water has created growing pressure to re-allocate water from traditional agricultural uses. Water markets are powerful institutions for facilitating this re-allocation, yet the evolution of water markets has been more complicated than those for other resources. In this paper, we set the context for water marketing with an overview of western water law that highlights unique aspects of water law that affect how or whether a water market can develop. Second, we present new, comprehensive data on the extent, nature, and timing of water transfers across 12 western states from 1987-2005. We describe the methodology and decision rules used to collect water transfer information. Third, we identify water market trends and movements to provide a greater understanding of the institutional structure and the mechanisms by which water is transferred in the American West

Rating Crop Insurance Policies with Efficient Nonparametric Estimators that Admit Mixed Data Types

The identification of improved methods for characterizing crop yield densities has experienced a recent surge in activity due in part to the central role played by crop insurance in the Agricultural Risk Protection Act of 2000 (estimates of yield densities are required for the determination of insurance premium rates). Nonparametric kernel methods have been successfully used to model yield densities; however, traditional kernel methods do not handle the presence of categorical data in a satisfactory manner and have therefore tended to be applied on a county-by-county basis. By utilizing recently developed kernel methods that admit mixed data types, we are able to model the yield density jointly across counties, leading to substantial finite sample efficiency gains. Findings show that when we allow insurance companies to strategically reinsure with the government based on this novel approach they accrue significant rents.discrete data, insurance rating, kernel estimation, yield distributions, Risk and Uncertainty,

ON CHOOSING A BASE COVERAGE LEVEL FOR MULTIPLE PERIL CROP INSURANCE CONTRACTS

For multiple peril crop insurance, the U.S. Department of Agriculture'Â’s Risk Management Agency estimates the premium rate for a base coverage level and then uses multiplicative adjustment factors to recover rates at other coverage levels. Given this methodology, accurate estimation of the base coverage level from 65% to 50%. The purpose of this analysis was to provide some insight into whether such a change should or should not be carried out. Not surprisingly, our findings indicate that the higher coverage level should be maintained as the base.Risk and Uncertainty,