Polymer Brush‐Modified Microring Resonators for Partition‐Enhanced Small Molecule Chemical Detection

Silicon photonic microring resonators have emerged as a promising technology for the sensitive detection of biological macromolecules, including proteins and nucleic acids. However, not all species of interest are large biologics that can be targeted by highly specific capture agents. For smaller organic chemicals, including many toxic and regulated species, a general approach to improving sensitivity would be desirable. By functionalizing the surface of silicon photonic microring resonators with polymer brushes, small molecules can selectively partition into the surface‐confined sensing region of the optical resonators. This in turn leads to response enhancements in excess of 1000% percent, relative to non‐functionalized sensors, for representative targets including 4‐methylumbelliferyl phosphate, a simulant for highly toxic organophosphates, Bisphenol A, an industrial pollutant, as well as other small organic analytes of interest. There are many polymer brush chemistries compatible with silicon resonators, making this a general strategy towards tuning sensor selectivity and specificity by optimizing interactions between the agent(s) of interest and the polymer construct.Polymer brush‐modified microring resonators sensors can be utilized to enhance sensitivity and specificity for the detection of small molecule organic chemicals.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136268/1/slct201700082.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136268/2/slct201700082-sup-0001-misc_information.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136268/3/slct201700082_am.pd

The International-Trade Network: Gravity Equations and Topological Properties

This paper begins to explore the determinants of the topological properties of the international - trade network (ITN). We fit bilateral-trade flows using a standard gravity equation to build a "residual" ITN where trade-link weights are depurated from geographical distance, size, border effects, trade agreements, and so on. We then compare the topological properties of the original and residual ITNs. We find that the residual ITN displays, unlike the original one, marked signatures of a complex system, and is characterized by a very different topological architecture. Whereas the original ITN is geographically clustered and organized around a few large-sized hubs, the residual ITN displays many small-sized but trade-oriented countries that, independently of their geographical position, either play the role of local hubs or attract large and rich countries in relatively complex trade-interaction patterns

Null Models of Economic Networks: The Case of the World Trade Web

In all empirical-network studies, the observed properties of economic networks are informative only if compared with a well-defined null model that can quantitatively predict the behavior of such properties in constrained graphs. However, predictions of the available null-model methods can be derived analytically only under assumptions (e.g., sparseness of the network) that are unrealistic for most economic networks like the World Trade Web (WTW). In this paper we study the evolution of the WTW using a recently-proposed family of null network models. The method allows to analytically obtain the expected value of any network statistic across the ensemble of networks that preserve on average some local properties, and are otherwise fully random. We compare expected and observed properties of the WTW in the period 1950-2000, when either the expected number of trade partners or total country trade is kept fixed and equal to observed quantities. We show that, in the binary WTW, node-degree sequences are sufficient to explain higher-order network properties such as disassortativity and clustering-degree correlation, especially in the last part of the sample. Conversely, in the weighted WTW, the observed sequence of total country imports and exports are not sufficient to predict higher-order patterns of the WTW. We discuss some important implications of these findings for international-trade models.Comment: 39 pages, 46 figures, 2 table

Impact of the Topology of Global Macroeconomic Network on the Spreading of Economic Crises

Throughout economic history, the global economy has experienced recurring crises. The persistent recurrence of such economic crises calls for an understanding of their generic features rather than treating them as singular events. The global economic system is a highly complex system and can best be viewed in terms of a network of interacting macroeconomic agents. In this regard, from the perspective of collective network dynamics, here we explore how the topology of the global macroeconomic network affects the patterns of spreading of economic crises. Using a simple toy model of crisis spreading, we demonstrate that an individual country's role in crisis spreading is not only dependent on its gross macroeconomic capacities, but also on its local and global connectivity profile in the context of the world economic network. We find that on one hand clustering of weak links at the regional scale can significantly aggravate the spread of crises, but on the other hand the current network structure at the global scale harbors higher tolerance of extreme crises compared to more “globalized” random networks. These results suggest that there can be a potential hidden cost in the ongoing globalization movement towards establishing less-constrained, trans-regional economic links between countries, by increasing vulnerability of the global economic system to extreme crises

Allogeneic Hematopoietic Stem Cell Transplantation Following the Use of Hypomethylating Agents among Patients with Relapsed or Refractory AML: Findings from an International Retrospective Study

Abstract Patients with primary refractory or relapsed acute myeloid leukemia (RR-AML) have very poor prognosis. Due to limited treatment options, some patients are treated with hypomethylating agents (HMAs) due to their tolerability. Little is known about the role of allogeneic hematopoietic stem cell transplantation (HSCT) following HMA therapy in this setting. We retrospectively analyzed an international cohort of 655 RR-AML patients who received HMA therapy to study patterns and outcomes with HSCT. Only 37 patients (5.6%) patients underwent HSCT after HMA therapy. The conditioning regimen was myeloablative in 57% and nonmyeloablative in 43%. Patients received matched unrelated donor, matched sibling, haploidentical and mismatched unrelated HSCT in 56%, 24%, 16% and 4% of cases, respectively. Acute GvHD and chronic GvHD were observed in 40% and 17% of patients. While the median OS for the entire cohort of patients was 15.3 months (95% CI 9.5 – 21.7 months), OS reached 29.7 months (95% CI 7.01 – not-reached) for patients who achieved a complete remission (CR) to HMA and no intervening therapies between HMA therapy and HSCT. Our study suggests that HMA therapy can effectively bridge some patients with RR-AML to HSCT