Paul Brooks Research Articles

Learning Hidden Markov Models with Structured Transition Dynamics

The hidden Markov model (HMM) provides a natural framework for modeling the dynamic evolution of latent diseases. The unknown probability matrices of HMMs can be learned through the well-known Baum–Welch algorithm, a special case of the expectation-maximization algorithm. In many disease models, the probability matrices possess nontrivial properties that may be represented through a set of linear constraints. In these cases, the traditional Baum–Welch algorithm is no longer applicable because the maximization step cannot be solved by an explicit formula. In this paper, we propose a novel approach to efficiently solve the maximization step problem under linear constraints by providing a Lagrangian dual reformulation that we solve by an accelerated gradient method. The performance of this approach critically depends on devising a fast method to compute the gradient in each iteration. For this purpose, we employ dual decomposition and derive Karush–Kuhn–Tucker conditions to reduce our problem into a set of single variable equations, solved using a simple bisection method. We apply this method to a case study on sports-related concussion and provide an extensive numerical study using simulation. We show that our approach is in orders of magnitude computationally faster and more accurate than other alternative approaches. Moreover, compared with other methods, our approach is far less sensitive with respect to increases in problem size. Overall, our contribution lies in the advancement of accurately and efficiently handling HMM parameter estimation under linear constraints, which comprises a wide range of applications in disease modeling and beyond. History: Accepted by Paul Brooks, Area Editor for Applications in Biology, Medicine, & Healthcare. Funding: This research was funded by [Grant R01DE028283] from the National Institute of Dental and Craniofacial Research, National Institutes of Health. G.-G. Garcia was also funded by the Georgia Clinical & Translational Science Alliance National Institutes of Health award [Grant UL1-TR002378]. Supplemental Material: The software that supports the findings of this study is available within the paper and its Supplemental Information ( https://pubsonline.informs.org/doi/suppl/10.1287/ijoc.2022.0342 ) as well as from the IJOC GitHub software repository ( https://github.com/INFORMSJoC/2022.0342 ). The complete IJOC Software and Data Repository is available at https://informsjoc.github.io/ .

A Sequential Follower Refinement Algorithm for Robust Surgery Scheduling

An algorithm for the two-stage robust optimization surgery-to-operating room allocation problem is presented. The second-stage problem is an integer linear program whose convex hull is approximated using three types of specialized valid inequalities and Chvátal-Gomory cuts. The resulting linear relaxation of the second-stage problem is then dualized and integrated into the first-stage problem. The resulting mixed integer linear program, which is an approximation of the original problem, is then solved using a commercial solver. If the solution of this model is not optimal for the second-stage problem, valid inequalities for the second-stage problem are generated, yielding a type of column-generation based approach that we refer to as the sequential follower refinement (SFR) algorithm. Data from an academic medical center are used to compare the computational performance of SFR with the constraint and column generation (C&CG) algorithm, which is the only exact approach that has been specifically applied for this problem in the literature. An extensive numerical study of SFR and its computational characteristics is presented that shows that SFR yields better-quality solutions compared with C&CG, even as the termination criterion of SFR is met much sooner, especially for problems involving higher number of surgeries. History: Accepted by Paul Brooks, Area Editor for Applications in Biology, Medicine, & Healthcare. Supplemental Material: The software that supports the findings of this study is available within the paper and its Supplemental Information ( https://pubsonline.informs.org/doi/suppl/10.1287/ijoc.2022.0191 ) as well as from the IJOC GitHub software repository ( https://github.com/INFORMSJoC/2022.0191 ). The complete IJOC Software and Data Repository is available at https://informsjoc.github.io/ .

Reflections and Thoughts on the Future of Science From AGU Hydrology Section Fellows

AbstractAt the inaugural Frontiers in Hydrology Meeting in San Juan, Puerto Rico in the summer of 2022, the Hydrology Section organized a poster session and invited our 2020 and 2021 Classes of AGU Fellows, with the initial goal of both celebrating their careers as well as to provide an opportunity for an informal exchange and connection between the section's early career members and our more senior and established scientists and engineers. Due to the challenges of time zones, virtual poster presentations and other logistics, the formal poster session was adjourned but continued as a hybrid “meet‐up” with six of our Section's Fellows (Suzanne Anderson, Paul Brooks, Aaron Packman, Remko Uijlenhoet, Andrew Western, and Xubin Zeng) from around the world. As you will see, what started as an informal chat quickly took deep dives into pressing issues in our section and science in general, including thoughts on how our community values (or in some cases doesn't value) multi‐ and interdisciplinary accomplishments, critiques of our system of rewards and awards including how we assess publication impacts and finally, a frank and honest discussion of our current efforts to diversify our community and where/why are we still failing. We hope that by sharing this open and impromptu dialogue that these discussions can expand to our entire community, and to encourage future Fellows exchanges such as this to reach our entire community of scientists and engineers.

An LSTM+ Model for Managing Epidemics: Using Population Mobility and Vulnerability for Forecasting COVID-19 Hospital Admissions

Worldwide epidemics, such as corona virus disease 2019 (COVID-19), cause unprecedented challenges for society and its healthcare systems. Governments attempt to mitigate those challenges by either reducing healthcare demand (“flattening the curve” by imposing restrictions, e.g., on travel or social gatherings) or by increasing healthcare capacity, for example, by canceling elective procedures or setting up field hospitals. To implement these mitigation procedures efficiently, accurate and timely forecasts of the epidemic’s progression are necessary. In this paper, we develop an innovative forecasting methodology based on the ideas of long short-term memory (LSTM) recurrent neural networks. LSTM models are shown to outperform traditional forecasting models, especially when the relationship between input and output is complex and not available in closed form. However, whereas LSTM models perform well for data that changes dynamically over time, one shortcoming is that they are not directly applicable when the data also includes static, nontemporal components. In this work, we propose an [Formula: see text] model that overcomes this limitation. Our model leverages a private partnership with a mobile data company in order to capture population mobility (using mobility indices derived from mobile device data), which allows us to anticipate an epidemic’s spread early and accurately. In addition, we also leverage a public partnership with a consortium of hospitals. Using hospital admissions (rather than, say, positive caseload) results in an unbiased measure of the severity of an epidemic because patients seek and are admitted to hospital care only when symptoms worsen beyond a critical point. We illustrate the effectiveness of our method on forecasting COVID-19 for a major U.S. metropolitan area where it has aided decision makers of the emergency policy group. Our model improves the predictive accuracy of hospital admission by a factor of 2.5× as compared with competing models in the same analytical space. History: Accepted by J. Paul Brooks, Area Editor for Applications in Biology, Medicine, & Healthcare. Funding: This research was funded by a monetary gift from Hillsborough County to establish the Pandemic Response Research Fund at University of South Florida. Supplemental Material: The software that supports the findings of this study is available within the paper and its Supplemental Information ( https://pubsonline.informs.org/doi/suppl/10.1287/ijoc.2023.1269 ) as well as from the IJOC GitHub software repository ( https://github.com/INFORMSJoC/2021.0027 ) at ( http://dx.doi.org/10.5281/zenodo.7112004 ).

Acuity-Based Allocation of ICU-Downstream Beds with Flexible Staffing

Intensive care units (ICUs) are crucial resources within hospitals, caring for the most critically ill patients. We propose a novel modeling framework that improves the outflow of ICU patients by anticipating unit interactions and resource sharing within the system. Across an arbitrary bipartite network of units, we consider two types of downstream staffing (baseline and flexible) and a two-stage decision process. In the first stage, we determine the level of flexible bed staffing using existing physical beds at downstream units in anticipation of incoming transfers from the ICUs. In the second stage, we determine the allocation of ICU patients to downstream beds. The goal of the model is to reduce inefficiencies and transfer delays causing ICU bed block due to lack of space in downstream units. We formulate a dynamic multiperiod model and analyze the dual of its (relaxed) stationary counterpart. Decomposing the relaxed stationary model into an ICU and downstream subproblems, we calculate the relative values of downstream beds and derive a practical acuity-based policy for the daily operational decisions. Using a large-scale simulation calibrated with historic hospital data, we demonstrate that our acuity-based policy reduces the number of long-run diverted ICU arrivals, particularly in high-demand scenarios, thus improving ICU throughput, when compared with a deterministic, a generalized randomized-most-idle, and static policies. History: Accepted by J. Paul Brooks, Area Editor for Applications in Biology, Medicine, & Healthcare. Funding: This work was partially supported by National Science Foundation [Grants CMMI-1635301/1635410/1635642]. Supplemental Material: The software that supports the findings of this study is available within the paper and its Supplemental Information ( https://pubsonline.informs.org/doi/suppl/10.1287/ijoc.2022.1267 ) as well as from the IJOC GitHub software repository ( https://github.com/INFORMSJoC/2021.0133 ) at ( http://dx.doi.org/10.5281/zenodo.7194693 ).

A Multiobjective Approach for Sector Duration Optimization in Stereotactic Radiosurgery Treatment Planning

Sector duration optimization (SDO) is a problem arising in treatment planning for stereotactic radiosurgery on Gamma Knife. Given a set of isocenter locations, SDO aims to select collimator size configurations and irradiation times thereof such that target tissues receive prescribed doses in a reasonable amount of treatment time and healthy tissues nearby are spared. We present a multiobjective linear programming model for SDO to generate a diverse collection of solutions so that clinicians can select the most appropriate treatment. We develop a generic two-phase solution strategy based on the ε-constraint method for solving multiobjective optimization models, 2phasε, which aims to systematically increase the number of high-quality solutions obtained, instead of conducting a traditional uniform search. To improve solution quality further and to accelerate the procedure, we incorporate some general and problem-specific enhancements. Moreover, we propose an alternative version of 2phasε, which makes use of machine learning tools to reduce the computational effort. In our computational study on eight previously treated real test cases, a significant portion of 2phasε solutions outperformed clinical results and those from a single-objective model from the literature. In addition to significant benefits of the algorithmic enhancements, our experiments illustrate the usefulness of machine learning strategies to reduce the overall run times nearly by half while maintaining or besting the clinical practice. History: Accepted by Paul Brooks, Area Editor for Applications in Biology, Medicine, and Healthcare. Funding: This work was supported in part by the Natural Sciences and Engineering Research Council of Canada [Discovery Grant RGPIN-2019-05588]. Supplemental Material: The software that supports the findings of this study is available within the paper and its Supplementary Information [ https://pubsonline.informs.org/doi/suppl/10.1287/ijoc.2022.1252 ] or is available from the IJOC GitHub software repository ( https://github.com/INFORMSJoC ) at [ http://dx.doi.org/10.5281/zenodo.7048848 ].

Disjunctive Rule Lists

In this study, we present an interpretable model, disjunctive rule list (DisRL) for regression. This research is motivated by the increasing need for model interpretability, especially in high-stakes decisions such as medicine, where decisions are made on or related to humans. DisRL is a generalized form of rule lists. A DisRL model consists of a list of disjunctive rules embedded in an if-else logic structure that stratifies the data space. Compared with traditional decision trees and other rule list models in the literature that stratify the feature space with single itemsets (an itemset is a conjunction of conditions), each disjunctive rule in DisRL uses a set of itemsets to collectively cover a subregion in the feature space. In addition, a DisRL model is constructed under a global objective that balances the predictive performance and model complexity. To train a DisRL model, we devise a hierarchical stochastic local search algorithm that exploits the properties of DisRL’s unique structure to improve search efficiency. The algorithm adopts the main structure of simulated annealing and customizes the proposing strategy for faster convergence. Meanwhile, the algorithm uses a prefix bound to locate a subset of the search area, effectively pruning the search space at each iteration. An ablation study shows the effectiveness of this strategy in pruning the search space. Experiments on public benchmark datasets demonstrate that DisRL outperforms baseline interpretable models, including decision trees and other rule-based regressors. History: Accepted by J. Paul Brooks, Area Editor for Applications in Biology, Medicine, & Healthcare. Supplemental Material: The software that supports the findings of this study is available within the paper and its Supplementary Information [ https://pubsonline.informs.org/doi/suppl/10.1287/ijoc.2022.1242 ] or is available from the IJOC GitHub software repository ( https://github.com/INFORMSJoC ) at [ http://dx.doi.org/10.5281/zenodo.6954927 ].

Augmenting Markov Cohort Analysis to Compute (Co)Variances: Implications for Strength of Cost-Effectiveness

Markov cohort analysis is a popular deterministic method in medical decision making for calculating mean outcomes in a Markov model by following a cohort of individuals through time. At present, obtaining outcome variances requires either forsaking cohort analysis in favor of a Markov decision process model or using Monte Carlo simulation (microsimulation), a more computationally demanding procedure that provides only statistical estimates. Here we derive an augmented version of cohort analysis that allows exact computation (not merely estimation) of (co)variances. In second-order models that incorporate parameter uncertainty, augmented cohort analysis can replace the “inner loop” required in Monte Carlo simulation, resulting in quicker and more accurate estimates.One reason for computing variances is to calculate a measure of the strength of an affirmative cost-effectiveness conclusion. In Markov cost-effectiveness analysis, an equivalent measure of cost-effectiveness is positivity of the expected incremental net monetary benefit. Augmented cohort analysis allows calculation of the number of standard deviations that this quantity falls above zero. As a measure of strength of cost-effectiveness, this quantity increases with cohort size. This means that the common practice of taking cohort size to be one can substantially underestimate the strength of a resulting cost-effectiveness conclusion under realistically large cohorts. Moreover, if realistic cohort size is large, then modelers can avoid microsimulation by using augmented cohort analysis and Chebyshev bounds to guarantee the probability of cost effectiveness is close to one.History: Accepted by J. Paul Brooks, Area Editor for Applications in Biology, Medicine, & Healthcare.Supplemental Material: The online appendix is available at https://doi.org/10.1287/ijoc.2022.1234 .

Naming of Homeopathic Medicines: A Morphological Language Construction

Homeopathic medicines are used abundantly, especially in eastern countries. Generally, their names are formulated using various word-formation processes. To understand their role in naming homeopathic medicines, morphological analysis is required. Hence, the current study scrutinized the process of naming homeopathic medicines to identify the occurrence of recurrent linguistic patterns. For this purpose, names of homeopathic medicines were randomly selected from companies such as Paul Brooks, Kamal Laboratories, and Dr Masood Homeopathic Pharmaceutical. The names of the medicine were analysed using the Onomasiological Theory of English Word-Formation by Pavol Stekauer. Using this theory, the morphological domain of the given medicine names along with their commercial purposes was identified and explored extensively. This analysis also discussed the lexical and semantic relations of the names with the componential features of homeopathic medicine.
 Keywords: homeopathic medicine, language construction, morphology, onomasiological theory

Dimensionless Analysis for Predicting High Temperature Alloys Corrosion in Molten Salt Systems for Concentrated Solar Power Systems

In the development of concentrated solar power systems (CSPs), the high-temperature corrosion of alloys in receivers and heat exchangers can affect the performance on CSPs and influence the apparent durability. [1-4] The extent to which high-temperature corrosion is reversible may improve the commercialization. To understand corrosion mechanisms and their impact on alloys, experimental coupon (1.2mm×12mm×30mm) studies were conducted to the 700-1000°C within halide and fluoride salts in a thermosiphon. The thermosiphon reactor was designed to allow exposure the coupons to the both isothermal and non-isothermal condition. That is, the thermal gradients between top and bottom of the reactor could induce natural convection of the salts. The corrosion experiments such as coupon test and post mortem analysis highlighted main corrosion mechanisms of Cr depletion and diffusion along the grain boundaries. [5-6] A multi-physics corrosion model that include the main corrosion mechanism of Cr oxidation along with diffusion-limited corrosion as the limiting step allow to predict corrosion rates (i.e., current density) and corrosion potentials. Also, a CFD model has shown that temperatures and fluid flows can be accurately predicted in molten salt heat transfer systems including coupons. The CFD predictions allow to characterize natural convection flows in the reactor by analyzing engineering parameters such as Rayleigh number, Nutssel number, and Grashof number, etc. As the temperature and mass transports are coupled in the natural convection system, the analysis of these dimensionless numbers helps to correlate different physics to understand the system better and to reduce complication to solve the problem. These dimensionless numbers around coupons incorporated into the corrosion model allow to predict mass transfer coefficients and boundary layer thickness that determine corrosion rates (i.e., current density). The model predictions and experiment results suggest that the use of thicker materials to improve the lifetime may not be a good strategy in molten salt systems due to the localized nature of the corrosion. Acknowledgements The authors gratefully acknowledge the support for this work by the DOE EERE SunShot Initiative under a subcontract from SRNL to the University of Alabama and to the University of South Carolina. R eferences [1] C. Forsberg, Progress in Nuclear Energy, 47, 32-43, 2005.[2] C. Forsberg, P.F. Peterson, and H.H. Zhao, J. Sol. Energy Eng. Trans.-ASME, 129, 141-146, 2007.[3] D. Ludwig, L. Olson, K. Sridahran, M. Anderson, and T. Allen, Corrosion Engineering Science and Technology, 46, 360-364, 2011.[4] P. Sabharwall, Matt Ebner, Manohar Sohal, Phil Sharpe, Mark Anderson, Kumar Sridharan, James Ambrosek, Luke Olson, Paul Brooks, Molten Salts for High Temperature Reactors: University of Wisconsin Molten Salt Corrosion and Flow Loop Experiments – Issues Identified and Path Forward, 2010. [5] B. L. Garcia-Diaz, L. Olson, M. Martinez-Rodriguez, R. Fuentens, J. Gray, “Electrochemical study of corrosion in high temperature molten salts,” paper #741, 2014 ECS and SMEQ Joint International Meeting, Cancun, Mexico, Oct. 08, 2014. [6] R. Fuentens, L. Olson, M. Martinez-Rodriguez, J. Gray, B. L. Garcia-Diaz, “Corrosion of high temperature materials in fluoride and chloride molten salts,” paper #743, 2014 ECS and SMEQ Joint International Meeting, Cancun, Mexico, Oct. 08, 2014.

Complexity at large

ComplexityVolume 20, Issue 5 p. 1-6 Complexity at Large Complexity at large First published: 25 February 2015 https://doi.org/10.1002/cplx.21667Read the full textAboutRelatedInformationPDFPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessClose modalShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Volume20, Issue5May/June 2015Pages 1-6 RelatedInformation RecommendedComplexity TheoryTanya Sammut-Bonnici, Wiley Encyclopedia of Management, [1]The Foundations of ComplexitySmart Decisions in Complex Systems, [1]Complexity, Chaos and EmergenceSteven M. Manson, A Companion to Environmental Geography, [1]Human Research and Complexity TheoryJames Horn, Complexity Theory and the Philosophy of Education, [1]Measurable Notions of Complexity and Their Relationship to Biological ComplexityJ. Paul Brooks, Chemistry & Biodiversity

Mambises in Whiteface: U.S. versus Cuban Depictions of Freedom Fighters in the War of Independence against Spain

Mambises in Whiteface: U.S. versus Cuban Depictions of Freedom Fighters in the War of Independence against Spain Philip Beidler (bio) Whether in war, politics, trade, or popular-culture history, the U.S. has always constructed an image of Cuba in terms of its own ideological presuppositions. This has been emphatically true of the racial imagination, from the days of the pre–Civil War annexationists through the current half-century of the Communist era. At no time was this more apparent than when it mattered the most, at the crucial moment of U.S.-Cuban military collaboration concluding the 1895–98 Cuban War of Independence. The racially inflected images produced and circulated at that time—of U.S. military liberators on one hand, and of their Cuban revolutionary counterparts on the other—would prefigure the political and cultural history of the two peoples for the next century and beyond. Indeed, with the first stirrings of an active Cuban revolutionary independence movement against Spain in the mid-nineteenth century, response in the United States was dictated by a distinct racial subtext. From the highest levels of government to the arena of popular myth, pervaded a fear among supporters and opponents alike that the Cuban Revolution would be in large measure racially “black”—a re-imaging of Toussaint L’Ouverture’s Haitian overthrow of colonial mastery a century earlier, but now in a place ninety miles off the southern tip of Jim Crow America. This, too, was an island, after all, so entrenched in its own institutional history of a white minority’s enslaving of a vast population of African chattel and their descendants that pre–Civil War Southerners had been tempted to several schemes of annexation—most famously those led by the [End Page 89] Venezuelan filibustero Narciso López, finally garroted in Havana after a third ill-fated try. As to post–Civil War and post-emancipation attempts by U.S. leaders to manipulate official perceptions of and policy toward the revolutionary patriots, negotiating a racial politics of whiteness versus blackness seems to have been a primary consideration from the outset, with whiteness always visibily figured in the featured role. In this regard, one influential American fresh from the scene felt impelled to assure the American Secretary of State that this was “no nigger rabble.” Thus, asserted Paul Brooks, the American owner of a large sugar plantation near Guantanamo in Oriente Province, Cuba, during an 1895 call on Richard Olney, Grover Cleveland’s new appointee, at Olney’s office in Washington, DC. Brooks, perhaps nervously recalling an earlier anti-Spanish uprising of 1868–78 begun by the patriot Carlos Manuel de Céspedes by freeing his slaves and exhorting them to join him in revolution, was attempting to give an insider’s assessment of the new Cuban military independence movement making its latest renewal of the decades-old war with a recent invasion into western Cuba. At the same time, these were the same bands of rebels Olney had also heard described by Spanish Minister to the U.S. Enrique Dupuy de Lôme as belonging to the lowest social orders. “A rebel victory,” Lôme warned Olney, “would devastate the island; independence would presage only anarchy.” But there was more than that. It would also be black anarchy. “If this were so,” Olney offered in return, “all right-thinking Americans should pray for Spanish success.”1 Popular culture representations of the era likewise pandered to such racial anxieties, working for a variety of reasons to disguise what might seem to Americans the disquieting racial demographics of a movement that, in fact, from the outset, was never less than 30% Afro-Cuban and by the time of direct U.S. military involvement was 60%—with the latter figure, by no surprise, corresponding exactly to the late nineteenth-century racial demographics of the island itself.2 (As will be seen, in some individual units, the percentage may indeed have run as high as 85%, according to Cuban sources.) This was done mainly by focusing on mediagenic leadership figures in the traditional Western (read Anglo-European and American) revolutionary patriot-statesman mold—a Kosciuszko, a Garibaldi, a Higgins, a Bolivar. Early response...

Contributors

Contributors

Peddling Scents: Merchandise and Meaning in 2 Corinthians 2:14-17

(ProQuest: ... denotes non-US-ASCII text omitted.) Scholars have long puzzled over diction and imagery that Paul employs in 2 Cor 2:14-17, where, from an attempt to account for his prior travels, shifts abruptly into prayer of thanksgiving. 14But thanks be to God, who in Christ always us in and through us spreads fragrance of knowledge of him everywhere. 15For we are aroma of Christ to God among those who are being saved and among those who are perishing, 16to one fragrance from death to death, to other fragrance from life to life. Who is sufficient for these things? 17For we are not, like so many, peddlers of God's word; but as men of sincerity, as commissioned by God, in sight of God we speak in Christ.1 Most exegetes concentrate their attention on word ... in 2:14, rendered above as leads . . . in triumph, and on relationship, if any, between this word and odor imagery that pervades vv. 15-16. Comparatively little attention has been lavished on peddlers (...) of v. 17, and almost none on what role image of peddler might play in connection with scene detailed in preceding verses.2 Harold W. Attridge's article on passage offers both generally persuasive explanation of 2:14-16 and rare if very cursory attempt to integrate v. 17.3 According to Attridge, building especially on work of Paul Brooks Duff, v. 14 references not military triumph but religious processions partly modeled on triumph and undertaken in veneration of likes of Isis and Dionysius.4 Incense and unguents figured importantly in such processions as means of honoring or making manifest deity. Paul thus imagines himself as a slave to triumphing deity, but slave in his ongoing service, heralding deity's approach by strewing incense, or possibly even as the vessel in which fragrant ointment is contained.5 And what of peddlers? In article's final footnote, Attridge ventures that Paul means to underline that he is part of procession itself, not on sidelines working, as ... [sic], for gain.6 While not discounting latter possibility, I argue in this note for different understanding of relationship between 2:14-16 and 2:17. Paul's reference to peddlers in v. 17 depends, I suggest, on prominence of spices in inventory of goods furnished by peddlers. To illustrate their prominence, I draw on evidence from rabbinic literature, which paints vivid portrait of small-scale commerce that is, to all appearances, typical of Mediterranean world in which Paul operated. Greek ... enters into rabbinic literature as ..., shopkeeper or tavern keeper.7 But it and related verbal form ... cover wide range of mercantile activities, indeed, most anything short of wholesale trade. The itinerant peddler falls within this range.8 Thus, nothing precludes us from supposing that Paul has in mind specifically peddler. The positive evidence for this possibility lies in close connection between peddler (lkwr) and aromatics in rabbinic literature.9 Let us consider two illustrative texts, in both of which aromatics serve, as in 2 Cor 2:14-17, as metaphor for knowledge. The first comes from Abot R. Nat. A, ch. 18 (ed. Schechter, 34a). [R. Judah Patriarch] called R. Eleazar b. Azarya peddler's bundle. And to what was R. Eleazar comparable? To peddler who took up his bundle and entered town, and people of town came and said to him: Have you fine oil? Have you spikenard oil [...]?10 Have you balsam [...)]? And they found everything on him. So was R. Eleazar b. Azarya. When students of sages would enter beside him, one would ask him about Scripture and would tell him, about mishnah and would tell him, about midrash and would tell him, about legal traditions and would tell him, about homiletics and would tell him. Thus when left him, would be full of blessed good. …

Children with disabilities

Children With Disabilities. Edited by M.L. Batshaw. Paul Brooks Publishing Co., Baltimore, 1997, 960 p.

L. B. ADAMSON & M. A. ROMSKI (editors), Communication and language acquisition: discoveries from atypical development. Baltimore/London: Paul Brooks Publishing Co, 1997. Pp. xvi+336.

L. B. ADAMSON & M. A. ROMSKI (editors), Communication and language acquisition: discoveries from atypical development. Baltimore/London: Paul Brooks Publishing Co, 1997. Pp. xvi+336. - Volume 26 Issue 2

Evaluation of Atlantic salmon parr responses to habitat improvement structures in an experimental channel in Newfoundland, Canada

Distributional patterns and microhabitat selection of Atlantic salmon (Salmo salar) parr were investigated in relation to habitat improvement structures in a controlled flow experiment channel at Noel Paul's Brook, Newfoundland. The channel consisted of six replicates, each containing three randomly arranged treatments. Each replicate included a control treatment with no habitat modification, a mid-channel treatment with a boulder cluster and low-head barrier dam, and a stream bank treatment with undercut banks and wing deflectors. The influence of size class, density, discharge and diurnal/nocturnal differences on microhabitat selection were evaluated. Results showed that the mid-channel treatment did not serve its purpose at lower discharges (0.032–0.063 m3 s−1), and as a result was not the treatment of choice. However, as the discharge increased (0.13 m3 s−1), more salmon took up residence in this treatment. In all experiments, greater depths were selected in the stream bank treatment, and salmon parr in the mid-channel treatment consistently selected positions closer to cover. Larger parr preferred greater depths and were found closer to the improvement structures. Benthic and drifting food availability were also estimated, and results showed that ‘funnelling effects’ of the drift were created near the structures. This study indicates that these structures have the potential to create favourable feeding sites, and provide the necessary physical characteristics required by salmon parr. © 1998 John Wiley & Sons, Ltd.

Writing Natural History ed. by Edward Lueders

Reviews 193 Writing Natural History. Edited by Edward Lueders. (Salt Lake City: Uni­ versity of Utah Press, 1989. 124 pages, $9.95.) As University Professor for 1987-88 at the University of Utah, Edward Lueders arranged a series of public programs called “Writing Natural History. Dialogues with Authors.” He invited Barry Lopez to speak with Edward O. Wilson, Robert Finch with Terry Tempest Williams, Gary Paul Nabhan with Ann Zwinger, and Paul Brooks with the program coordinator. The editor explains his choices: “The participating authors were selected not only for their eminence, but also for the variety of their perspectives on natural history and their stylistic diversity as celebrated writers for a broad reading audience.” Each pair engaged in a public dialogue that was relatively unstructured and unrehearsed. Writing Natural History is the result. With only minor edit­ ing of the audiotapes, Lueders was able to compile a unique set of exchanges. He added a brief introduction by Thomas J. Lyon, “The Continuities of Nature Writing,” and published the collection in a paperback that ought to be owned by anyone interested in the field. Each dialogue reflects the flavor of its participants. The first, between Lopez and Wilson, is at once more philosophical and more issue-oriented than the others. Prepared remarks by both men open their proceedings, and the conversation essentially consists of extended analyses of points raised. By con­ trast, the next two dialogues—between Finch and Williams and between Nabhan and Zwinger—are fast-paced, sprightly, and wide-ranging. The last dialogue, an informal exchange between two old friends, then acts as a kind of capstone to the other three. Yet all four discussions share common topics. All touch on the close rela­ tionship between the writer and the natural world, and all wrestle with the ways in which writers communicate that relationship to readers. “Nature writers attempt to create enduring myths,” says Robert Finch. “They story the landscape.” Ann Zwinger defines her rob somewhat differently. “My theory is that we should try to get the reader to really look at the natural world.” Barry Lopez perhaps synthesizes what the others would say. “We must estab­ lish some sense of reciprocity with the Earth.” In concert, these are the rich voices to be heard in Writing Natural History. ANN RONALD University of N evada, Reno Thom as Berger. By Brooks Landon. (Boston: Twayne Publishers, G. K. Hall & Co., 1989. 143 pages, $19.95.) What does one say of an intelligent, insightful, useful, well-written critical work—with whose basic approach one disagrees? Ah, just that. For Brooks Landon’s work on Berger is intelligent, etc., etc., etc. But . . . . Although this is the first full-length study of Berger, Berger has not really been ignored, as Landon points out. Berger’s works have, indeed, been exam­ ined from almost every wavelength on the critical spectrum. Landon refers ...

Speaking for Nature by Paul Brooks

Speaking for Nature by Paul Brooks

Speaking for Nature: How Literary Naturalists from Henry Thoreau to Rachel Carson Have Shaped America. Paul BrooksTalking to the Moon. John Joseph Mathews

<i>Speaking for Nature: How Literary Naturalists from Henry Thoreau to Rachel Carson Have Shaped America</i>. Paul Brooks<i>Talking to the Moon</i>. John Joseph Mathews