Auctions for Split-Award Contracts

The buyer of a homogeneous input employs split-award contracting to divide his input requirements into two contracts that are awarded to different suppliers. The buyer uses a sequential second-price auction to award a larger primary contract and a smaller secondary contract. With a fixed number of suppliers participating in the auctions, we find that the buyer pays a higher expected price than with a sole-source auction. The premium paid to the winner of the secondary contract must also be paid to the winner of the primary contract as an opportunity cost of not winning the secondary contract. With fixed costs of participating in the auction, we identify the conditions under which a secondary contract can increase the number of suppliers and lower the expected price paid by the buyer. An optimal secondary contract can internalize the cost reductions from the new industry capacity and extract the rents of the suppliers. An optimal secondary contract can be particularly beneficial when the number of suppliers is limited by high fixed costs.

Preferred Suppliers in Auction Markets

In a procurement setting, this paper examines agreements between a buyer and one of the suppliers which would increase their joint surplus. The provisions of such agreements depend on the buyer's ability to design the rules of the final procurement auction. When the buyer has no such ability, their joint surplus can be increased by an agreement which grants to the preferred supplier a right-of-first-refusal on the lowest price offer from the other suppliers. When the buyer does have this ability, one agreement which maximizes their joint surplus includes a revelation game for the cost of the preferred supplier and a reserve price in the procurement auction based on that cost.procurement auctions, bilateral agreements

Double Play: The Need for 4-H to Partner in Youth Sports

Fewer children in the United States are playing team-based sports, and the trend is making national headlines. While there is no complete agreement as to the predominant reason for this trend, it is clear that a national conversation on this problem has begun, and Cooperative Extension holds the potential for getting kids back in the game. At its core, this conversation is about the healthful development of our children and their advancement as contributors to society. Cooperative Extension has decades of experience creating a playbook for youth development, and it is time to put that playbook into action

Under the influence of genetics: how transdisciplinarity leads us to rethink social pathways to illness

This article describes both sociological and genetic theories of illness causation and derives propositions expected under each and under a transdisciplinary theoretical frame. The authors draw propositions from three theories -- fundamental causes, social stress processes, and social safety net theories -- and tailor hypotheses to the case of alcohol dependence. Analyses of a later wave of the Collaborative Study on the Genetics of Alcoholism reveal a complex interplay of the GABRA2 gene with social structural factors to produce cases meeting DSM/ICD diagnoses. Only modest evidence suggests that genetic influence works through social conditions and experiences. Further, women are largely unaffected in their risk for alcohol dependence by allele status at this candidate gene; family support attenuates genetic influence; and childhood deprivation exacerbates genetic predispositions. These findings highlight the essential intradisciplinary tension in the role of proximal and distal influences in social processes and point to the promise of focusing directly on dynamic, networked sequences that produce different pathways to health and illness

The Antiferromagnetic Band Structure of La2CuO4 Revisited

Using the Becke-3-LYP functional, we have performed band structure calculations on the high temperature superconductor parent compound, La2CuO4. Under the restricted spin formalism (rho(alpha) equal to rho(beta)), the R-B3LYP band structure agrees well with the standard LDA band structure. It is metallic with a single Cu x2-y2/O p(sigma) band crossing the Fermi level. Under the unrestricted spin formalism (rho(alpha) not equal to rho(beta)), the UB3LYP band structure has a spin polarized antiferromagnetic solution with a band gap of 2.0 eV, agreeing well with experiment. This state is 1.0 eV (per formula unit) lower than that calculated from the R-B3LYP. The apparent high energy of the spin restricted state is attributed to an overestimate of on-site Coulomb repulsion which is corrected in the unrestricted spin calculations. The stabilization of the total energy with spin polarization arises primarily from the stabilization of the x2-y2 band, such that the character of the eigenstates at the top of the valence band in the antiferromagnetic state becomes a strong mixture of Cu x2-y2/O p(sigma) and Cu z2/O' p(z). Since the Hohenberg-Kohn theorem requires the spin restricted and spin unrestricted calculations give exactly the same ground state energy and total density for the exact functionals, this large disparity in energy reflects the inadequacy of current functionals for describing the cuprates. This calls into question the use of band structures based on current restricted spin density functionals (including LDA) as a basis for single band theories of superconductivity in these materials.Comment: 13 pages, 8 figures, to appear in Phys. Rev. B, for more information see http://www.firstprinciples.co

Effects on osteoclast and osteoblast activities in cultured mouse calvarial bones by synovial fluids from patients with a loose joint prosthesis and from osteoarthritis patients

Aseptic loosening of a joint prosthesis is associated with remodelling of bone tissue in the vicinity of the prosthesis. In the present study, we investigated the effects of synovial fluid (SF) from patients with a loose prosthetic component and periprosthetic osteolysis on osteoclast and osteoblast activities in vitro and made comparisons with the effects of SF from patients with osteoarthritis (OA). Bone resorption was assessed by the release of calcium 45 ((45)Ca) from cultured calvariae. The mRNA expression in calvarial bones of molecules known to be involved in osteoclast and osteoblast differentiation was assessed using semi-quantitative reverse transcription-polymerase chain reaction (PCR) and real-time PCR. SFs from patients with a loose joint prosthesis and patients with OA, but not SFs from healthy subjects, significantly enhanced (45)Ca release, effects associated with increased mRNA expression of calcitonin receptor and tartrate-resistant acid phosphatase. The mRNA expression of receptor activator of nuclear factor-kappa-B ligand (rankl) and osteoprotegerin (opg) was enhanced by SFs from both patient categories. The mRNA expressions of nfat2 (nuclear factor of activated T cells 2) and oscar (osteoclast-associated receptor) were enhanced only by SFs from patients with OA, whereas the mRNA expressions of dap12 (DNAX-activating protein 12) and fcrγ (Fc receptor common gamma subunit) were not affected by either of the two SF types. Bone resorption induced by SFs was inhibited by addition of OPG. Antibodies neutralising interleukin (IL)-1α, IL-1β, soluble IL-6 receptor, IL-17, or tumour necrosis factor-α, when added to individual SFs, only occasionally decreased the bone-resorbing activity. The mRNA expression of alkaline phosphatase and osteocalcin was increased by SFs from patients with OA, whereas only osteocalcin mRNA was increased by SFs from patients with a loose prosthesis. Our findings demonstrate the presence of a factor (or factors) stimulating both osteoclast and osteoblast activities in SFs from patients with a loose joint prosthesis and periprosthetic osteolysis as well as in SFs from patients with OA. SF-induced bone resorption was dependent on activation of the RANKL/RANK/OPG pathway. The bone-resorbing activity could not be attributed solely to any of the known pro-inflammatory cytokines, well known to stimulate bone resorption, or to RANKL or prostaglandin E(2 )in SFs. The data indicate that SFs from patients with a loose prosthesis or with OA stimulate bone resorption and that SFs from patients with OA are more prone to enhance bone formation

Preferred suppliers in auction markets

In a procurement setting, this paper examines agreements between a buyer and one of the suppliers which would increase their joint surplus. The provisions of such agreements depend on the buyer's ability to design the rules of the final procurement auction. When the buyer has no such ability, their joint surplus can be increased by an agreement which grants to the preferred supplier a right-of-first-refusal on the lowest price offer from the other suppliers. When the buyer does have this ability, one agreement which maximizes their joint surplus includes a revelation game for the cost of the preferred supplier and a reserve price in the procurement auction based on that cost

Studies on metal-organic frameworks of Cu(II) with isophthalate linkers for hydrogen storage

Hydrogen (H2) is a promising alternative energy carrier due to its environmental benefits, high energy density and its abundance. However, development of a practical storage system to enable the “Hydrogen Economy” remains a huge challenge. Metal-organic frameworks (MOFs) are an important class of crystalline coordination polymers constructed by bridging metal centers with organic linkers, and show promise for H2 storage due to their high surface area and tuneable properties. We summarize our research on novel porous materials with enhanced H2 storage properties, and describe frameworks derived from 3,5-substituted dicarboxylates (isophthalates) that serve as versatile molecular building blocks for the construction of a range of interesting coordination polymers with Cu(II) ions. A series of materials has been synthesised by connecting linear tetracarboxylate linkers to {Cu(II)2} paddlewheel moieties. These (4,4)-connected frameworks adopt the fof-topology in which the Kagomé lattice layers formed by {Cu(II)2} paddlewheels and isophthalates are pillared by the bridging ligands. These materials exhibit high structural stability and permanent porosity, and the pore size, geometry and functionality can be modulated by variation of the organic linker to control the overall H2 adsorption properties. NOTT-103 shows the highest H2 storage capacity of 77.8 mg g−1 at 77 K, 60 bar among the fof-type frameworks. H2 adsorption at low, medium and high pressures correlates with the isosteric heat of adsorption, surface area and pore volume, respectively. Tri-branched C3-symmetric hexacarboxylate ligands with Cu(II) give highly porous (3,24)-connected frameworks incorporating {Cu(II)2} paddlewheels. These ubt-type frameworks comprise three types of polyhedral cage: a cuboctahedron, truncated tetrahedron and a truncated octahedron which are fused in the solid state in the ratio 1:2:1, respectively. Increasing the length of the hexacarboxylate struts directly tunes the porosity of the resultant material from micro- to mesoporosity. These materials show exceptionally high H2 uptakes owing to their high surface area and pore volume. NOTT-112, the first reported member of this family reported, adsorbs 111 mg g−1 of H2 at 77 K , 77 bar. More recently, enhanced H2 adsorption in these ubt-type frameworks has been achieved using combinations of polyphenyl groups linked by alkynes to give an overall gravimetric gas capacity for NU-100 of 164 mg g−1 at 77 K, 70 bar. However, due to its very low density NU-100 shows a lower volumetric capacity of 45.7 g L-1 compared with 55.9 g L-1 for NOTT-112, which adsorbs 2.3 wt% H2 at 1 bar, 77K. This significant adsorption of H2 at low pressures is attributed to the arrangement of the {Cu24(isophthalate)24} cuboctahedral cages within the polyhedral structure. Free metal coordination positions are the first binding sites for D2, and in these ubt-type frameworks there are two types of Cu(II) centres, one with its vacant site pointing into the cuboctahedral cage and another pointing externally. D2 molecules bind first at the former position, and then at the external open metal sites. However, other adsorption sites between the cusp of three phenyl groups and a Type I pore window in the framework are also occupied. Ligand and complex design feature strongly in enhancing and maximising H2 storage, and, although current materials operate at 77 K, research continues to explore routes to high capacity H2 storage materials that can function at higher temperatures