Attention Allocation and Managerial Decision Making

One of the major problems of managerial behavior is the setting of priorities. Time is a scarce resource and managers have to find ways to deal with the multiple tasks that face them. This paper addresses the issue of priority-setting among tasks by managers by proposing analogies from job-shop scheduling theory. We develop a model that views managers employing a combination of rationality and affective judgments with a limited processing capacity.Information Systems Working Papers Serie

Magnetization steps in Zn_(1-x)Mn_xO: Four largest exchange constants and single-ion anisotropy

Magnetization steps (MST's) from Mn pairs in several single crystals of Zn_(1-x)Mn_xO (0.0056<=x<=0.030, and in one powder (x=0.029), were observed. The largest two exchange constants, J1/kB=-18.2+/-0.5K and J1'/kB=-24.3+/-0.6K, were obtained from large peaks in the differential susceptibility, dM/dH, measured in pulsed magnetic fields, H, up to 500 kOe. These two largest J's are associated with the two inequivalent classes of nearest neighbors (NN's) in the wurtzite structure. The 29% difference between J1 and J1' is substantially larger than 13% in CdS:Mn, and 15% in CdSe:Mn. The pulsed-field data also indicate that, despite the direct contact between the samples and a superfluid-helium bath, substantial departures from thermal equilibrium occurred during the 7.4 ms pulse. The third- and fourth-largest J's were determined from the magnetization M at 20 mK, measured in dc magnetic fields H up to 90 kOe. Both field orientations H||c and H||[10-10] were studied. (The [10-10] direction is perpendicular to the c-axis, [0001].) By definition, neighbors which are not NN's are distant neighbors (DN's). The largest DN exchange constant (third-largest overall), has the value J/kB=-0.543+/-0.005K, and is associated with the DN at r=c. Because this is not the closest DN, this result implies that the J's do not decrease monotonically with the distance r. The second-largest DN exchange constant (fourth-largest overall), has the value J/kB=-0.080 K. It is associated with one of the two classes of neighbors that have a coordination number z=12, but the evidence is insufficient for a definite unique choice. The dependence of M on the direction of H gives D/kB=-0.039+/-0.008K, in fair agreement with -0.031 K from earlier EPR work.Comment: 12 pages, 10 figures. Submitted to PR

Magnetization steps in a diluted Heisenberg antiferromagnetic chain: Theory and experiments on TMMC:Cd

A theory for the equilibrium low-temperature magnetization M of a diluted Heisenberg antiferromagnetic chain is presented. The magnetization curve, M versus B, is calculated using the exact contributions of finite chains with 1 to 5 spins, and the "rise and ramp approximation" for longer chains. Some non-equilibrium effects that occur in a rapidly changing B, are also considered. Specific non-equilibrium models based on earlier treatments of the phonon bottleneck, and of spin flips associated with cross relaxation and with level crossings, are discussed. Magnetization data on powders of TMMC diluted with cadmium [i.e., (CH_3)_4NMn_xCd_(1-x)Cl_3, with 0.16<=x<=0.50 were measured at 0.55 K in 18 T superconducting magnets. The field B_1 at the first MST from pairs is used to determine the NN exchange constant, J, which changes from -5.9 K to -6.5 K as x increases from 0.16 to 0.50. The magnetization curves obtained in the superconducting magnets are compared with simulations based on the equilibrium theory. Data for the differential susceptibility, dM/dB, were taken in pulsed magnetic fields (7.4 ms duration) up to 50 T, with the powder samples in a 1.5 K liquid-helium bath. Non-equilibrium effects, which became more severe as x decreased, were observed. The non-equilibrium effects are tentatively interpreted using the "Inadequate Heat Flow Scenario," or to cross-relaxation, and crossings of energy levels, including those of excited states.Comment: 16 pages, 14 figure

Quality of care for children with severe disease in the Democratic Republic of the Congo

BACKGROUND: Despite the almost universal adoption of Integrated Management of Childhood Illness (IMCI) guidelines for the diagnosis and treatment of sick children under the age of five in low- and middle-income countries, child mortality remains high in many settings. One possible explanation of the continued high mortality burden is lack of compliance with diagnostic and treatment protocols. We test this hypothesis in a sample of children with severe illness in the Democratic Republic of the Congo (DRC). METHODS: One thousand one hundred eighty under-five clinical visits were observed across a regionally representative sample of 321 facilities in the DRC. Based on a detailed list of disease symptoms observed, patients with severe febrile disease (including malaria), severe pneumonia, and severe dehydration were identified. For all three disease categories, treatments were then compared to recommended case management following IMCI guidelines. RESULTS: Out of 1180 under-five consultations observed, 332 patients (28%) had signs of severe febrile disease, 189 patients (16%) had signs of severe pneumonia, and 19 patients (2%) had signs of severe dehydration. Overall, providers gave the IMCI-recommended treatment in 42% of cases of these three severe diseases. Less than 15% of children with severe disease were recommended to receive in-patient care either in the facility they visited or in a higher-level facility. CONCLUSIONS: These results suggest that adherence to IMCI protocols for severe disease remains remarkably low in the DRC. There is a critical need to identify and implement effective approaches for improving the quality of care for severely ill children in settings with high child mortality

Effects of Noisy Oracle on Search Algorithm Complexity

Grover's algorithm provides a quadratic speed-up over classical algorithms for unstructured database or library searches. This paper examines the robustness of Grover's search algorithm to a random phase error in the oracle and analyzes the complexity of the search process as a function of the scaling of the oracle error with database or library size. Both the discrete- and continuous-time implementations of the search algorithm are investigated. It is shown that unless the oracle phase error scales as O(N^(-1/4)), neither the discrete- nor the continuous-time implementation of Grover's algorithm is scalably robust to this error in the absence of error correction.Comment: 16 pages, 4 figures, submitted to Phys. Rev.

Specific heat amplitude ratios for anisotropic Lifshitz critical behaviors

We determine the specific heat amplitude ratio near a $m$-axial Lifshitz point and show its universal character. Using a recent renormalization group picture along with new field-theoretical $\epsilon_{L}$-expansion techniques, we established this amplitude ratio at one-loop order. We estimate the numerical value of this amplitude ratio for $m=1$ and $d=3$. The result is in very good agreement with its experimental measurement on the magnetic material $MnP$. It is shown that in the limit $m \to 0$ it trivially reduces to the Ising-like amplitude ratio.Comment: 8 pages, RevTex, accepted as a Brief Report in Physical Review

Isospectral domains with mixed boundary conditions

We construct a series of examples of planar isospectral domains with mixed Dirichlet-Neumann boundary conditions. This is a modification of a classical problem proposed by M. Kac.Comment: 9 figures. Statement of Theorem 5.1 correcte