Equation of State of Wet Granular Matter

A theory is derived for the nonequilibrium probability currents of the capillary interaction which determines the pair correlation function near contact. This yields an analytic expression for the equation of state, P = P(N/V,T), of wet granular matter for D=2 dimensions, valid in the complete density range from gas to jamming. Driven wet granular matter exhibits a van-der-Waals-like unstable branch at granular temperatures T<T_c corresponding to a first order segregation transition of clusters. For the realistic rupture length of the liquid bridge, s_crit=0.07 d, the critical point is located at T_c = 0.274 E_cb. While the critical temperature weakly depends on the rupture length, the critical density phi_c is shown to scale with s_crit according to s_crit = 4d (sqrt(phi_J / phi_c) -1). The segregation transition is closely related to the precipitation of granular droplets reported for the free cooling of one-dimensional wet granular matter [Phys. Rev. Lett. 97, 078001 (2006)], and extends the effect to higher dimensional systems. Since the limiting case of sticky bonds, E_cb >> T, is of relevance for aggregation in general, simulations have been performed which show very good agreement with the theoretically predicted coordination K of capillary bonds as a function of the bond length s_crit. This result implies that particles that stick at the surface, s_crit=0, form isostatic clusters.Comment: 29 pages, 20 figure

Chaoticity of the Wet Granular Gas

In this work we derive an analytic expression for the Kolmogorov-Sinai entropy of dilute wet granular matter, valid for any spatial dimension. The grains are modelled as hard spheres and the influence of the wetting liquid is described according to the Capillary Model, in which dissipation is due to the hysteretic cohesion force of capillary bridges. The Kolmogorov-Sinai entropy is expanded in a series with respect to density. We find a rapid increase of the leading term when liquid is added. This demonstrates the sensitivity of the granular dynamics to humidity, and shows that the liquid significantly increases the chaoticity of the granular gas.Comment: 13 pages, 10 figures, Physical Review

What you get is what you need? The role of venture capitalists in managing growth of new ventures

The resource-based view is suggested as a useful concept to shed light on the particular challenges of high potential companies on their way to building a thriving and growing company. In order to be able to apply the theoretical constructs of the resource-based view in the present context, a categorization of resources is elaborated that fits particularly well to high potential companies. Existing literature provides evidence that these companies in general only dispose of a small resource base and that they are characterized by strong resource needs in all relevant resource categories. The role of venture capitalists is assumed to provide high potential companies with financial and non-financial resources that help to create core and non-core competencies. Ultimately, this bundle of core and non-core competencies would allow high potential companies to achieve a sustained competitive advantage. The empirical results of this paper are based on insights from three in-depth case studies on German start-ups, each representing a different investor-investee dyad. It comprises investees from different industries such as software, biotech, and energy as well as investors with an established track record, first fund investors, and semi-government-dependent investors. The cases show that venture capitalists provide a number of resources to their portfolio companies that allow building a competitive advantage. The role of the venture capitalists is thus to help high potential companies to complement existing resources and competences in order to develop their full economic potential. However, there is great variation between the resource provisions of the analyzed venture capital firms. --Entrepreneurship,Venture Capital,Resource-based View

Cooling and aggregation in wet granulates

Wet granular materials are characterized by a defined bond energy in their particle interaction such that breaking a bond implies an irreversible loss of a fixed amount of energy. Associated with the bond energy is a nonequilibrium transition, setting in as the granular temperature falls below the bond energy. The subsequent aggregation of particles into clusters is shown to be a self-similar growth process with a cluster size distribution that obeys scaling. In the early phase of aggregation the clusters are fractals with D_f=2, for later times we observe gelation. We use simple scaling arguments to derive the temperature decay in the early and late stages of cooling and verify our results with event-driven simulations.Comment: 4 pages, 6 figures, suggestions of the referees implemented, EPAPS supplementary material added: http://netserver.aip.org/cgi-bin/epaps?ID=E-PRLTAO-102-00391

Dilute Wet Granulates: Nonequilibrium Dynamics and Structure Formation

We investigate a gas of wet granular particles, covered by a thin liquid film. The dynamic evolution is governed by two-particle interactions, which are mainly due to interfacial forces in contrast to dry granular gases. When two wet grains collide, a capillary bridge is formed and stays intact up to a certain distance of withdrawal when the bridge ruptures, dissipating a fixed amount of energy. A freely cooling system is shown to undergo a nonequillibrium dynamic phase transition from a state with mainly single particles and fast cooling to a state with growing aggregates, such that bridge rupture becomes a rare event and cooling is slow. In the early stage of cluster growth, aggregation is a self-similar process with a fractal dimension of the aggregates approximately equal to D_f ~ 2. At later times, a percolating cluster is observed which ultimately absorbs all the particles. The final cluster is compact on large length scales, but fractal with D_f ~ 2 on small length scales.Comment: 14 pages, 20 figure

What you get is what you need? The role of venture capitalists in managing growth of new ventures

The resource-based view is suggested as a useful concept to shed light on the particular challenges of high potential companies on their way to building a thriving and growing company. In order to be able to apply the theoretical constructs of the resource-based view in the present context, a categorization of resources is elaborated that fits particularly well to high potential companies. Existing literature provides evidence that these companies in general only dispose of a small resource base and that they are characterized by strong resource needs in all relevant resource categories. The role of venture capitalists is assumed to provide high potential companies with financial and non-financial resources that help to create core and non-core competencies. Ultimately, this bundle of core and non-core competencies would allow high potential companies to achieve a sustained competitive advantage. The empirical results of this paper are based on insights from three in-depth case studies on German start-ups, each representing a different investor-investee dyad. It comprises investees from different industries such as software, biotech, and energy as well as investors with an established track record, first fund investors, and semi-government-dependent investors. The cases show that venture capitalists provide a number of resources to their portfolio companies that allow building a competitive advantage. The role of the venture capitalists is thus to help high potential companies to complement existing resources and competences in order to develop their full economic potential. However, there is great variation between the resource provisions of the analyzed venture capital firms

Hydrogen penetration into titanium from environment in different states

In this paper, the accumulation of hydrogen in titanium from media of different aggregate states is considered, since the accumulation of hydrogen in structural and functional materials, which ultimately can lead to the destruction of structures, essentially depends on the environments in which these structures operate. Obtained: electrolytic and plasma saturation is characterized by hydrogen entrapment by low-temperature traps with weak binding energy (point defects and their complexes, vacancies and their complexes, etc. The method of Siwerst is characterized by capture of high-temperature traps (microcracks of microcracks, intergranular boundaries, etc.)

Renal Proliferative and Phenotypic Changes in Rats With Two-Kidney, One-Clip Goldblatt Hypertension

Angiotensin II (All) is a vasoconstrictive peptide with hypertrophic and mitogenic effects on many cell types. Previous studies have shown that in vivo administration of All in rats results in proliferation of, and phenotypic changes in, many renal cell populations, but in doses also causing hypertension. Thus, it was not possible to differentiate nonhemodynamic from hypertensive effects of All. Therefore, we studied rats with renin-dependent, All-mediated hypertension (the two-kidney, oneclip Goldblatt model; mean systolic blood pressure 238 ± 48 ν 140 ± 6 mm Hg in sham-operated controls). The undipped kidneys, which were exposed to high blood pressure, developed significant glomerular and tubulointerstitial injury, tubulointerstitial cell proliferation, dense focal interstitial monocyte-macrophage influx, increased deposition of types I and IV collagen, as well as increased cellular expression of desmin and actin, in tubulointerstitial areas when examined at 11 weeks. In contrast, clipped kidneys, protected from hypertension but with high local renin expression, had minimal abnormalities. These studies suggest that in this model increased renin, and presumably All, does not mediate significant proliferative or phenotypic changes in the kidney in the absence of hypertension at 11 weeks. Am J Hypertens 1994;7:177-18

Relativistic Fluctuation Theorems: Theory and explicit examples

To reveal how nonequilibrium physics and relativity theory intertwine, this articles studies relativistic Brownian motion under cosmic expansion. Two fluctuation theorems for the entropy ds, which is locally produced in this extreme nonequilibrium situation, are presented and proven. The first, =1, is a generalization of the second law of thermodynamics, that remains valid at relativistic particle energies and under high cosmic expansion rates. From this relation follows, that the probability to observe a local reduction of entropy is exponentially small even if the universe was to recollapse. For the special case of the Einstein-de Sitter universe an additional relation, =1, is derived which holds simultaneously with the first relation and where dh is proportional to the Hubble constant. Furthermore, the fluctuation theorems are shown to provide a physical criterion to resolve the known discretization dilemma arising in special-relativistic Brownian motion. Explicit examples and a general method for the computation of non-Gaussian entropy fluctuations are provided.Comment: 27 pages, 6 figures, Comptes rendus - Physiqu