Quark mass density- and temperature- dependent model for strange quark matter

It is found that the radius of a stable strangelet decreases as the temperature increases in a quark mass density-dependent model. To overcome this difficulty, we extend this model to a quark mass density- and temperature- dependent model in which the vacuum energy density at zero baryon density limit B depends on temperature. An ansatz is introduced and the regions for the best choice of the parameters are studied.Comment: 5 pages, 4 figure

Contracting for innovation : vertical disintegration and interfirm collaboration

Rapidly innovating industries are not behaving the way theory expects. Conventional industrial organization theory predicts that, when parties in a supply chain have to make transaction-specific investments, the risk of opportunism will drive them away from contracts and toward vertical integration. Despite the conventional theory, however, contemporary practice is moving in the other direction. Instead of vertical integration, we observe vertical disintegration in a significant number of industries, as producers recognize that they cannot themselves maintain cutting-edge technology in every field required for the success of their products. In doing this, the parties are developing forms of contracting beyond the reach of contract theory models. In this Article, we connect the emerging contract practice to theory, learning from what has happened in the real world to frame a theoretical explanation of this cross-organizational innovation and to reconceptualize the boundaries of the firm accordingly. We argue that the vertical disintegration of the supply chain in many industries is mediated neither by fully specified technical interfaces that allow suppliers to produce a modular piece of the ultimate product, nor by entirely implicit relational contracts supported only by norms of reciprocity and the expectation of future dealings. Rather, we suggest that the change in the boundary of the firm has given rise to a new form of contracting between firms -- what we call "contracting for innovation." This pattern braids explicit and implicit contracting to support iterative collaborative innovation by raising switching costs. These costs, represented by the parties' parallel transaction-specific investments in knowledge about their collaborators' capacities, deter opportunism under circumstances where explicit contracting, renegotiation, and the anticipation of future dealings cannot

Very Small Strangelets

We study the stability of small strangelets by employing a simple model of strange matter as a gas of non-interacting fermions confined in a bag. We solve the Dirac equation and populate the energy levels of the bag one quark at a time. Our results show that for system parameters such that strange matter is unbound in bulk, there may still exist strangelets with $A<100$ that are stable and/or metastable. The lifetime of these strangelets may be too small to detect in current accelerator experiments, however.Comment: 13 pages, MIT CTP#217

A reduction of the resonant three-wave interaction to the generic sixth Painleve' equation

Among the reductions of the resonant three-wave interaction system to six-dimensional differential systems, one of them has been specifically mentioned as being linked to the generic sixth Painleve' equation P6. We derive this link explicitly, and we establish the connection to a three-degree of freedom Hamiltonian previously considered for P6.Comment: 13 pages, 0 figure, J. Phys. A Special issue "One hundred years of Painleve' VI

Irradiation of Materials with Short, Intense Ion pulses at NDCX-II

We present an overview of the performance of the Neutralized Drift Compression Experiment-II (NDCX-II) accelerator at Berkeley Lab, and report on recent target experiments on beam driven melting and transmission ion energy loss measurements with nanosecond and millimeter-scale ion beam pulses and thin tin foils. Bunches with around 10^11 ions, 1-mm radius, and 2-30 ns FWHM duration have been created with corresponding fluences in the range of 0.1 to 0.7 J/cm^2. To achieve these short pulse durations and mm-scale focal spot radii, the 1.1 MeV He+ ion beam is neutralized in a drift compression section, which removes the space charge defocusing effect during final compression and focusing. The beam space charge and drift compression techniques resemble necessary beam conditions and manipulations in heavy ion inertial fusion accelerators. Quantitative comparison of detailed particle-in-cell simulations with the experiment play an important role in optimizing accelerator performance.Comment: 15 pages, 7 figures. revised manuscript submitted to Laser and Particle Beam

Thirty Years After Michael E. Porter: What Do We Know About Business Exit?

Although a business exit is an important corporate change initiative, the buyer’s side seems to be more appealing to management researchers than the seller’s because acquisitions imply growth, i.e., success. Yet from an optimistic viewpoint, business exit can effectively create value for the selling company. In this paper we attempt to bring the relevance of the seller’s side back into our consciousness by asking: What do we know about business exit? We start our exploration with Porter (1976), focusing on literature that investigates the antecedents of, barriers to, and outcomes of business exit. We also include studies from related fields such as finance and economics.1 Through this research we determine three clusters of findings: factors promoting business exit, exit barriers, and exit outcomes. Overall, it is the intention of this paper to highlight the importance of business exit for research and practice. Knowing what we know about business exits and their high financial value we should bear in mind that exit need not mean failure but a new beginning for a corporation