Recommender Systems

The ongoing rapid expansion of the Internet greatly increases the necessity of effective recommender systems for filtering the abundant information. Extensive research for recommender systems is conducted by a broad range of communities including social and computer scientists, physicists, and interdisciplinary researchers. Despite substantial theoretical and practical achievements, unification and comparison of different approaches are lacking, which impedes further advances. In this article, we review recent developments in recommender systems and discuss the major challenges. We compare and evaluate available algorithms and examine their roles in the future developments. In addition to algorithms, physical aspects are described to illustrate macroscopic behavior of recommender systems. Potential impacts and future directions are discussed. We emphasize that recommendation has a great scientific depth and combines diverse research fields which makes it of interests for physicists as well as interdisciplinary researchers.Comment: 97 pages, 20 figures (To appear in Physics Reports

Globalization, Superstars, and the Importance of Reputation: Theory & Evidence from the Wine Industry

We develop a simple model of the effects of reputation on wine prices. An increasing fraction of consumers who are “naïve” (less well informed about wine quality) results in a stronger sensitivity of wine prices to ratings of quality. We then use data on prices and Robert Parker’s ratings of wines, to show that prices have become more related to Parker ratings over time. In addition, we find that a change in Parker rating has a stronger effect on price, the stronger is the wine’s reputation.No; keywords

A Survey of Trust Management Models for Cloud Computing

Over the past few years, cloud computing has been widely adopted as a paradigm for large-scale infrastructures. In such a scenario, new security risks arise when different entities or domains share the same group of resources. Involved organizations need to establish some kind of trust relationships, able to define appropriate rules that can control which and how resources and services are going to be shared. The management of trust relationships represents a key challenge in order to meet high security requirements in cloud computing environments. This allows also to boost consumers confidence in cloud services, promoting its adoption. Establishing trust with cloud service providers supports to have confidence, control, reliability, and to avoid commercial issues like lock in. This paper proposes a survey of existing trust management models addressing collaboration agreements in cloud computing scenarios. Main limitations of current approaches are outlined and possible improvements are traced, as well as a future research path

Human neuromaturation, juvenile extreme energy liability, and adult cognition/cooperation

Human childhood and adolescence is the period in which adult cognitive competences (including those that create the unique cooperativeness of humans) are acquired. It is also a period when neural development puts a juvenile’s survival at risk due to the high vulnerability of their brain to energy shortage. The brain of a 4 year-old human uses ≈50% of its total energy expenditure (TEE) (cf. adult ≈12%). This brain expensiveness is due to (1) the brain making up ≈6% of a 4 year-old body compared to 2% in an adult, and (2) increased energy metabolism that is ≈100% greater in the gray matter of a child than in an adult (a result of the extra costs of synaptic neuromaturation). The high absolute number of neurons in the human brain requires as part of learning a prolonged neurodevelopment. This refines inter- and intraarea neural networks so they become structured with economical “small world” connectivity attributes (such as hub organization and high cross-brain differentiation/integration). Once acquired, this connectivity enables highly complex adult cognitive capacities. Humans evolved as hunter-gatherers. Contemporary hunter-gatherers (and it is also likely Middle Paleolithic ones) pool high energy foods in an egalitarian manner that reliably supported mothers and juveniles with high energy intake. This type of sharing unique to humans protects against energy shortage happening to the immature brain. This cooperation that protects neuromaturation arises from adults having the capacity to communicate and evaluate social reputation, cognitive skills that exist as a result of extended neuromaturation. Human biology is therefore characterized by a presently overlooked bioenergetic-cognition loop (called here the “HEBE ring”) by which extended neuromaturation creates the cooperative abilities in adults that support juveniles through the potentially vulnerable period of the neurodevelopment needed to become such adults

THEORETICAL ASPECTS OF ELABORATION THE THEORY OF ANTIMONOPOLY REGULATION

There are two main objects of this paper. The first object is to compare the most important theories and opinions about competition, monopoly and antimonopoly policy. The second object is to summarize some monopoly regulation of these economics theories. All these theories are subdivided into five parts started from the oldest time, e. g. from Aristotle, through mercantilism, early capitalism, theories of A. Smith to the classical Ricardian theories. There is discussed the competition and the origin of the first framework of anti-trust legislation at the break of the 19th and 20th centuries, the Karl Marx’s and his followers’ theories, the origin of imperfect competition and the system of neoliberal politics.monopoly, regulation, antimonopoly policy

Trojans in Early Design Steps—An Emerging Threat

Hardware Trojans inserted by malicious foundries during integrated circuit manufacturing have received substantial attention in recent years. In this paper, we focus on a different type of hardware Trojan threats: attacks in the early steps of design process. We show that third-party intellectual property cores and CAD tools constitute realistic attack surfaces and that even system specification can be targeted by adversaries. We discuss the devastating damage potential of such attacks, the applicable countermeasures against them and their deficiencies