Publications

Trends in hospital ownership of physician practices and the effect on processes to improve quality.

We found a significant increase in the use of CMPs among practices that were acquired by hospitals and no difference in health IT use. These findings suggest that a trend for hospitals to own physician practices may have a positive effect on chronic disease management and quality of care.

BARE: Leveraging Base Language Models for Few-Shot Synthetic Data Generation

As the demand for high-quality data in model training grows, researchers and developers are increasingly generating synthetic data to tune and train LLMs. However, current data generation methods rely on seed sets containing tens of thousands of examples to prompt instruction-tuned models. This reliance can be especially problematic when the curation of high-quality examples is expensive or difficult. In this paper we explore the novel few-shot synthetic data generation setting -- generating a high-quality dataset from a few examples. We show that when working with only a few seed examples, instruction-tuned models used in current synthetic data methods produce insufficient diversity for downstream tasks. In contrast, we show that base models without post-training, largely untapped for synthetic data generation, offer substantially greater output diversity, albeit with lower instruction following abilities. Leveraging this insight, we propose Base-Refine (BARE), a novel two-stage method that combines the diversity of base models with the quality assurance of instruction-tuned models. BARE excels in few-shot synthetic data generation: using only 3 seed examples it generates diverse, high-quality datasets that significantly improve downstream task performance. We show that fine-tuning Llama 3.1 8B with 1,000 BARE-generated samples achieves performance comparable to state-of-the-art similarly sized models on LiveCodeBench tasks. Furthermore, data generated with BARE enables a 101% improvement for a fine-tuned Llama 3.2 1B on GSM8K over data generated by only instruction-models, and an 18.4% improvement for a fine-tuned Llama 3.1 8B over the state-of-the-art RAFT method for RAG data generation.

(Invited) The Complex Mechanisms That Create High Li-Ion Mobility in Oxides and Sulfides

The exciting development of solids with extremely high Li-ion conductivity, higher than that in traditional liquid electrolytes, in the last decade has forced us to rethink the processes that make cations move in solids. Super-ionic Li conductors typically have very high Li concentration so that their conductivity behavior cannot be explained with simple point defect mechanisms. Instead, ideas of concerted motion or highly correlated motion have been proposed. I will discuss our current understanding of the mechanisms that provide high Li-ion conductivity. We find that due to the high screening power of S 2- Li mobility in sulfides is mostly determined by local anion coordination and its variation along the migration pathway, making anion topology the main determinant of Li-ion conductivity. As a result, we find that there is little coordinated or concerted motion in sulfides. In contrast, due to the lower screening power of oxides and their lower Li-Li distances, Li-ion conductivity is much more determined by the electrostatic interaction with the other cations, setting the stage for possible concerted motion of multiple ions. I will show how this leads to very specific, but precise rules for selecting structures that may accommodate very fast Li-ion motion. While fast motion of divalent cations is much less likely, I will show computational results that indicate that even super-ionic motion of ions such as Mg 2+ and Ca 2+ may be possible in the right framework.

SN 1983V in NGC 1365 and the Nature of Stripped Envelope Core‐Collapse Supernovae

We present CCD photometry and low-resolution spectra of the spectroscopic Type Ic supernova SN 1983V in NGC 1365. Photometry in the B band spans nearly 250 days after maximum light, while the spectra cover the photospheric epoch, from 9 days before up to 38 days after B maximum. We also compile and discuss infrared photometry that has been published elsewhere. The photometric evolution of SN 1983V is analyzed in comparison with other Type Ic supernovae and with SN 1983N and SN 1993J. The spectroscopic evolution is described, line identifications are proposed, and evidence for H, He, and Si is discussed. The photometric evolution of SN 1983V suggests that it is a close relative of SN 1983N and SN 1993J, events for which it is supposed that the external layers comprising most of the He/H and H shells, respectively, were lost before the explosion. The mass-to-energy ratios of SN 1983V and SN 1993J are substantially different if estimated from the expansion velocities. However, the similarity of the B light curves suggests that if the masses and mass-to-energy ratios are not similar, then the mass of SN 1983V has to be large enough to compensate for the higher mass-to-energy ratio. The latter possibility contradicts the standard scenarios that describe these events and implies a precise fine-tuning of the masses and mass-to-energy ratios of the two supernovae. This contradiction, however, could be resolved if a significant fraction of the inner ejecta containing 56Ni does not follow the decrease in density expected for a spherically symmetric, homologous expansion.

MIS CINCO LIBROS PREFERIDOS EN SOCIOLOGÍA (CON DISCULPAS DE LOS SIGUIENTES 95)

Es imposible seleccionar cinco libros de sociología sin dejar fuera importantes trabajos y desairar a muchos excelentes cientistas sociales, clásicos y contemporáneos, que merecen figurar en la mayoría de la lista de preferencias de cualquiera. Así que primero quisiera disculparme con los 95 autores que no tengo espacio para mencionar aquí....

Pathway engineering by designed divergent evolution

Remaking Health Care in America: The Evolution of Organized Delivery Systems

Preface Acknowledgments Chapter One: The Problem and the Challenge Chapter Two: An Idealized Health Care System Chapter Three: Participants, Framework, and Approach Chapter Four: Functional Integration Chapter Five: Physician-System Integration Chapter Six: Clinical Integration Chapter Seven: Managing and Governing the Organized Delivery System Chapter Eight: Moving Forward: The Policy Issues and Implementation: Challenges: Resources References

Supernovae 1999dg and 1999dh

Pricing under the Threat of Piracy: Flexibility and Platforms for Digital Goods

We consider the optimal design of flexible use in a digital-rights-management policy for a digital good subject to piracy. Consumers can acquire the digital good either as a licensed product or as an unlicensed copy. The ease of access to unlicensed copies is increasing in the flexibility accorded to licensed copies. The content provider has to trade off consumers' valuation of a licensed copy against the sales lost to piracy. We enrich the basic model by introducing a "secure platform" that is required to use the digital good. We show that the platform allows for the socially optimal provision of flexibility for the digital good but only if both are sold by an integrated firm.

Elastic and plastic deformations

Abstract The decomposition of deformation into elastic and plastic parts is introduced in terms of transformations of the material symmetry group, due to plastic evolution, pertaining to a local undistorted state of the material. This leads naturally to the notion of dislocation density, interpreted as the torsion of the underlying material manifold. Torsion, in turn, implies that the elastic strain is incompatible, and hence that the material is residually stressed when unloaded.

Amphidynamic Character of Crystalline MOF-5:  Rotational Dynamics of Terephthalate Phenylenes in a Free-Volume, Sterically Unhindered Environment

Metal−organic frameworks (MOFs) have been the focus of much interest within the context of hydrogen storage and other materials applications. With static metal clusters linked by axially substituted organic spacers capable of experiencing internal rotations, MOFs are one of the most promising amphidynamic materials to investigate and exploit the dynamics of crystalline solids. In this communication we report an experimental study of the rotational dynamics of the 1,4-phenylenedicarboxylate bridge of MOF-5, which has no steric contacts that might contribute to the rotational barrier. Highly reproducible 1H T1 relaxation, high-resolution 13C CPMAS, and variable temperature quadrupolar echo 2H NMR data were obtained from high quality samples that were sealed at reduced pressure (ca. 3 mTorr). 2H NMR line shape simulation revealed an activation barrier for rotation of 11.3 ± 2.0 kcal/mol, which is lower than the 14−16 kcal/mol values reported in theoretical studies of truncated models. While our results suggest that the models used for MOF-5 are insufficient to account for the properties of the extended crystal lattice, they also suggest that the amphidynamic materials with static and dynamic components may reach the friction-free rotational motion characteristic of gas dynamics.

Ab initio modeling of the energy landscape for screw dislocations in body-centered cubic high-entropy alloys

In traditional body-centered cubic (bcc) metals, the core properties of screw dislocations play a critical role in plastic deformation at low temperatures. Recently, much attention has been focused on refractory high-entropy alloys (RHEAs), which also possess bcc crystal structures. However, unlike face-centered cubic high-entropy alloys (HEAs), there have been far fewer investigations on bcc HEAs, specifically on the possible effects of chemical short-range order (SRO) in these multiple principal element alloys on dislocation mobility. Here, using density functional theory, we investigate the distribution of dislocation core properties in MoNbTaW RHEAs alloys, and how they are influenced by SRO. The average values of the core energies in the RHEA are found to be larger than those in the corresponding pure constituent bcc metals, and are relatively insensitive to the degree of SRO. However, the presence of SRO is shown to have a large effect on narrowing the distribution of dislocation core energies and decreasing the spatial heterogeneity of dislocation core energies in the RHEA. It is argued that the consequences for the mechanical behavior of HEAs is a change in the energy landscape of the dislocations which would likely heterogeneously inhibit their motion.

Stereoselective Pericyclic Reactions, Cross Coupling, and C—H and C—X Activation

The major emphasis here is on enantioselective reactions using asymmetric catalysts. Examples from the total synthesis of various natural and unnatural targets validates the utility of the synthetic methods. Specific topics discussed: cycloaddition, cycloisomerization and sigmatropic rearrangement reactions, allylic and carbonyl functionalization reactions, metal-catalyzed cross-coupling reactions, desymmetrization, fluorination, polymerization and sulfide oxidation reactions. This volume is part of a 3-volume set: Science of Synthesis Stereoselective Synthesis Workbench Edition Further information about Stereoselective Synthesis (including sample pages and the table of contents)

A configurable wavelength demultiplexer using periodic filter chains

The ability to select an arbitrary wavelength out of a large set of wavelengths is important for future dense wavelength division multiple access (DWDM) systems. Current approaches use a spectrometer to demultiplex the wavelengths and use a switch at each wavelength to select or deselect that particular wavelength at the output. In a DWDM system with N wavelengths, N number of switches at each receiver need to be employed in order to select an arbitrary wavelength using the conventional approach. Since switches are active components, this is undesirable when N is large. A better scaling can be achieved if we can arrange a series of configurable filters in a way that half of the spectral energy is filtered out when the input spectrum is passed through each successive stage of the filter. So the first stage filters out half of the spectrum. The second stage filters out another half of the spectrum that is left from the output of the first stage, etc. Optical filters are usually interferometric devices which generate periodic complementary outputs at the same time, such as a Mach-Zehnder interferometer (MZI). The filters used at different stages could be MZIs for which the periodicity is controlled by varying the optical path differences between the two arms of the MZI. To generate more square like transmission functions, a periodic cavity structure in a form similar to a one-dimensional photonic crystal may be used.

IMPROVEMENTS IN STRENGTH AND TOUGHNESS OF EXPERIMENTAL Fe-Cr-C STEELS

Efforts to improve Fe-Cr-C steel by modification of heat treatment and alloying additions are described. An important result of this work is in the evaluation of toughness with austenitizing temperature. The resistance to fracture of the conventionally (870/sup 0/C) austenitized structure is greatest ahead of a rounded notch (i.e., in Charpy and K/sub A/ tests), whereas it is least ahead of a sharp crack (i.e., in K/sub Ic/ test). Therefore, the advantages of increased fracture touchness, K/sub Ic/, with increased austenitizing temperature, must be weighed against the deterioration of ductility and Charpy impact energy. However, an optimum austenitizing temperature can be chosen (in the range 1000 to 1100/sup 0/C), where a 30 to 50 percent increase occurs in fracture toughness, K/sub Ic/, with no loss of strength and little reduction in impact energy and ductility. Moreover, low alloy additions of Mn and Ni can further increase the toughness of the alloy without reduction in strength. This was possible because the strengthening in these quaternary alloys was achieved primarily through solid solution hardening and not from substructural twinning in martensite. The toughness properties obtained for Fe-4Cr-2Mn-0.26C steel are superior to conventional 4340 and 300-M steels at the 200 ksi yield strengthmore » level, and yet would be cheaper to produce in large quantities.« less

CCDC 1449009: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Genome-scale metabolic rewiring to achieve predictable titers rates and yield of a non-native product at scale

Abstract Achieving high titer rates and yields (TRY) remains a bottleneck in the production of heterologous products through microbial systems, requiring elaborate engineering and many iterations. Reliable scaling of engineered strains is also rarely addressed in the first designs of the engineered strains. Both high TRY and scale are challenging metrics to achieve due to the inherent trade-off between cellular use of carbon towards growth vs. target metabolite production. We hypothesized that being able to strongly couple product formation with growth may lead to improvements across both metrics. In this study, we use elementary mode analysis to predict metabolic reactions that could be targeted to couple the production of indigoidine, a sustainable pigment, with the growth of the chosen host, Pseudomonas putida KT2440. We then filtered the set of 16 predicted reactions using -omics data. We implemented a total of 14 gene knockdowns using a CRISPRi method optimized for P. putida and show that the resulting engineered P. putida strain could achieve high TRY. The engineered pairing of product formation with carbon use also shifted production from stationary to exponential phase and the high TRY phenotype was maintained across scale. In one design cycle, we constructed an engineered P. putida strain that demonstrates close to 50% maximum theoretical yield (0.33 g indigoidine/g glucose consumed), reaching 25.6 g/L indigoidine and a rate of 0.22g/l/h in exponential phase. These desirable phenotypes were maintained from batch to fed-batch cultivation mode, and from 100ml shake flasks to 250 mL ambr® and 2 L bioreactors.

Exceptional fracture toughness of CrCoNi-based medium- and high-entropy alloys at 20 kelvin

Medium- and high-entropy alloys based on the CrCoNi-system have been shown to display outstanding strength, tensile ductility and fracture toughness (damage-tolerance properties), especially at cryogenic temperatures. Here we examine the JIc and (back-calculated) KJIc fracture toughness values of the face-centered cubic, equiatomic CrCoNi and CrMnFeCoNi alloys at 20 K. At flow stress values of ~1.5 GPa, crack-initiation KJIc toughnesses were found to be exceptionally high, respectively 235 and 415 MPa(square-root)m for CrMnFeCoNi and CrCoNi, with the latter displaying a crack-growth toughness Kss exceeding 540 MPa(square-root)m after 2.25 mm of stable cracking, which to our knowledge is the highest such value ever reported. Characterization of the crack-tip regions in CrCoNi by scanning electron and transmission electron microscopy reveal deformation structures at 20 K that are quite distinct from those at higher temperatures and involve heterogeneous nucleation, but restricted growth, of stacking faults and fine nano-twins, together with transformation to the hexagonal closed-packed phase. The coherent interfaces of these features can promote both the arrest and transmission of dislocations to generate respectively strength and ductility which strongly contributes to sustained strain hardening. Indeed, we believe that these nominally single-phase, concentrated solid-solution alloys develop their fracture resistance through a progressive synergy of deformation mechanisms, including dislocation glide, stacking-fault formation, nano-twinning and eventually in situ phase transformation, all of which serve to extend continuous strain hardening which simultaneously elevates strength and ductility (by delaying plastic instability), leading to truly exceptional resistance to fracture.