Some Free - Some Fee: The Emerging Business Model for e-Content Web Sites

The rapid emergence of E-commerce with its competitive characteristics has transformed the business landscape. In its short lifespan of little more than a decade, the Internet marketplace has already seen a dramatic cycle of high peaks and low valleys. E-content sites, whose primary product is information, have had the most difficulty sustaining profitability. The central proposition is that a firm’s business model is an important locus of innovation and a crucial source of revenue creation for its stakeholders. Consequently, the question has become how can an Internet business and e-content Web site, in particular, support a sustainable business model. There is a definite trend occurring away from the totally free content site to the hybrid model of charging for some e-content fittingly termed the ‘some free - some fee’ model. The ‘some free - some fee’ model is one approach that will enable online e-content businesses to create revenue while still offering free content to which many Web users have become accustomed. Understanding the underlying principles of, and the movement towards, the ‘some free - some fee’ model will assist e-content organizations in the transformation of their business model to ensure their survivability in the volatile Internet marketplace

Temperature in nonequilibrium systems with conserved energy

We study a class of nonequilibrium lattice models which describe local redistributions of a globally conserved energy. A particular subclass can be solved analytically, allowing to define a temperature T_{th} along the same lines as in the equilibrium microcanonical ensemble. The fluctuation-dissipation relation is explicitely found to be linear, but its slope differs from the inverse temperature T_{th}^{-1}. A numerical renormalization group procedure suggests that, at a coarse-grained level, all models behave similarly, leading to a two-parameter description of their macroscopic properties.Comment: 4 pages, 1 figure, final versio

A spectroscopic cell for fast pressure jumps across the glass transition line

We present a new experimental protocol for the spectroscopic study of the dynamics of glasses in the aging regime induced by sudden pressure jumps (crunches) across the glass transition line. The sample, initially in the liquid state, is suddenly brought in the glassy state, and therefore out of equilibrium, in a four-window optical crunch cell which is able to perform pressure jumps of 3 kbar in a time interval of ~10 ms. The main advantages of this setup with respect to previous pressure-jump systems is that the pressure jump is induced through a pressure transmitting fluid mechanically coupled to the sample stage through a deformable membrane, thus avoiding any flow of the sample itself in the pressure network and allowing to deal with highly viscous materials. The dynamics of the sample during the aging regime is investigated by Brillouin Light Scattering (BLS). For this purpose the crunch cell is used in conjunction with a high resolution double monochromator equipped with a CCD detector. This system is able to record a full spectrum of a typical glass forming material in a single 1 s shot. As an example we present the study of the evolution toward equilibrium of the infinite frequency longitudinal elastic modulus (M_infinity) of a low molecular weight polymer (Poly(bisphenol A-co-epichlorohydrin), glycidyl end capped). The observed time evolution of M_infinity, well represented by a single stretched exponential, is interpreted within the framework of the Tool-Narayanaswamy theory.Comment: 9 pages, 11 figure

Investigating the KNDy hypothesis in humans by co-administration of kisspeptin, neurokinin B and naltrexone in men

Context: A subpopulation of hypothalamic neurons co-localise three neuropeptides namely kisspeptin, neurokinin B (NKB) and dynorphin collectively termed KNDy neurons. Animal studies suggest they interact to affect pulsatile GnRH release (KNDy hypothesis); kisspeptin stimulates, NKB modulates and dynorphin (an opioid) inhibits. Objective: To investigate the KNDy hypothesis in humans, we assessed for the first time the effects of co-administration of kisspeptin-54, NKB and an opioid receptor antagonist, naltrexone on LH pulsatility (surrogate marker for GnRH pulsatility) and gonadotropin release. Design, setting and participants: Ethically approved prospective, single-blinded placebo-controlled study. Healthy male volunteers (n=5/group) attended our research facility for 8 study visits. Intervention and main outcome measure: After 1h baseline blood sampling, participants received a different intervention at each visit: oral 50mg naltrexone (NAL), 8h intravenous infusions of vehicle, 2.56nmol/kg/h NKB (NKB), 0.1nmol/kg/h kissspeptin-54 (KP) alone and in combination. Frequent blood sampling to measure plasma gonadotropins and sex steroids was conducted and LH pulsatility was determined using blinded deconvolution analysis. Results: All kisspeptin and naltrexone containing groups potently increased LH and LH pulsatility (p<0.001 vs vehicle). NKB alone did not affect gonadotropins. NKB+KP had significantly lower increases in gonadotropins compared with kisspeptin alone (p<0.01). NAL+KP was the only group to significantly increase LH pulse amplitude (p<0.001 vs vehicle). Conclusions: Our results suggest significant interactions between the KNDy neuropeptides on LH pulsatility and gonadotropin release in humans. This has important implications for improving our understanding of GnRH pulse generation in humans

On the Complexity Landscape of Connected f-Factor Problems

Given an n-vertex graph G and a function f:V(G) -> {0, ..., n-1}, an f-factor is a subgraph H of G such that deg_H(v)=f(v) for every vertex v in V(G); we say that H is a connected f-factor if, in addition, the subgraph H is connected. A classical result of Tutte (1954) is the polynomial time algorithm to check whether a given graph has a specified f-factor. However, checking for the presence of a connected f-factor is easily seen to generalize Hamiltonian Cycle and hence is NP-complete. In fact, the Connected f-Factor problem remains NP-complete even when f(v) is at least n^epsilon for each vertex v and epsilon<1; on the other side of the spectrum, the problem was known to be polynomial-time solvable when f(v) is at least n/3 for every vertex v. In this paper, we extend this line of work and obtain new complexity results based on restricting the function f. In particular, we show that when f(v) is required to be at least n/(log n)^c, the problem can be solved in quasi-polynomial time in general and in randomized polynomial time if c 1, the problem is NP-intermediate