bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of sliding mode observers in the homing guidance loop
Authors: Shkolnikov I A , Shtessel Y B , Lianos D P
Published: May 2005

Application of a second-order sliding mode observer, which is based on the nonlinear dynamic sliding manifold, as a nonlinear uncertain system estimator in the homing (terminal guidance) loop with augmented proportional navigation guidance is demonstrated. It is shown that sliding mode observers have an advantage over traditional Kalman filters in the homing loop upon target maneuvering at a short time-to-go.
Midcourse guidance law with neural networks
Authors: Han D , Balakrishnan S N , Ohlmeyer E J
Published: May 2005

A dual neural network ‘adaptive critic approach’ is used in this study to generate midcourse guidance commands for a missile to reach a predicted impact point while maximizing its final velocity. The adaptive critic approach is based on approximate dynamic programming. The first network, called a ‘critic’, network, outputs the Lagrangian multipliers arising in an optimal control formulation while the second network, called an ‘action’ network, outputs the optimal guidance/control. While a typical adaptive critic structure consists of a single critic and a single controller, the midcourse guidance problem needs indexing in terms of the independent variable and therefore there is a cascade of critics and controllers each set for a different index. Every controller learns from the critic at the previous stage. Though the networks are trained off-line, the resulting control is in a feedback form. A midcourse guidance problem is the first testbed for this approach where the input is vector-valued. The numerical results for a number of scenarios show that the network performance is excellent. Corroboration for optimality is provided by comparisons of the numerical solutions using a shooting method for a number of scenarios. Numerical results demonstrate some attractive features of the adaptive critic approach and show that this formulation works very well in guiding the missile to its final conditions from an envelope of initial conditions. This application also demonstrates the use of adaptive critics as a tool to solve a class of ‘free final time’ problems in optimal control, which are usually very difficult.
Minimizing manoeuvre advantage requirements for a hit-to-kill interceptor
Authors: Vincent T L , Cottrell R G , Morgan R W
Published: May 2005

Hit-to-kill requires extremely high intercept accuracies. Such performance places severe demands on interceptor manoeuvrability and flight control response time constant when engaging targets that are intentionally or unintentionally manoeuvring. A well-known guidance law for use against a manoeuvring target is augmented proportional navigation (APN). It is an optimal guidance law under various assumptions including a constant-lateral-acceleration target. It is also effective when used against other target manoeuvres provided that the lateral acceleration capabilities of the interceptor is significantly greater than the lateral acceleration capabilities of the target, and if the time constant of the interceptor flight control system is small. The advantage of using a new guidance algorithm for a hit-to-kill interceptor against a manoeuvring target in two dimensions is demonstrated in this paper. A large manoeuvre advantage is not required, and it is effective with time constants that would otherwise degrade the performance of APN. Results are based on a two-dimensional non-linear model with the target performing a weave manoeuvre. The new algorithm can achieve increased intercept accuracy under minimal manoeuvre advantage requirements over a wide range of initial conditions with reasonable levels of angle noise and target manoeuvre estimation error.
A multi-objective control approach for the synthesis of robust digital guidance laws
Authors: Léchevin N , Rabbath C A
Published: May 2005

This paper proposes a new approach for the synthesis of robust digital guidance laws with the objective of achieving stable and accurate missile guidance despite parametric uncertainties in the missile flight control system dynamics, prescribed limits on missile acceleration, and digital implementation at possibly slow sampling rates. The proposed approach is characterized by two consecutive steps. Firstly, a robust continuous-time guidance law is designed using mixed H2-H∞ minimization and pole placement such that the effects of noise and parametric uncertainties are attenuated. To carry out this first step of the approach, missile flight control dynamics are modelled as second-order interval transfer functions, where bounded time-varying parameters characterize the missile flight envelope. Secondly, digital redesign of the robust continuous-time missile control system (including guidance and flight control) is performed by solving an optimal control problem. The proposed global digital redesign strategy results in robust performance for the closed-loop sampled-data missile control system for a wider range of sampling rates than those obtained with currently available approaches and can be readily implemented on commercially available software by following the step-by-step procedure described in the paper. Numerical simulations consisting of a missile pursuing a manoeuvring target, described by the so-called Singer model, demonstrate the effectiveness of the proposed approach.
Robust augmented lateral acceleration flight control design for a quasi-linear parameter-varying missile
Authors: Bruyere L , Tsourdos A , White B A
Published: May 2005

An augmented lateral acceleration autopilot is designed for a model of a tactical missile and robust stability of the closed-loop system investigated. The tail-controlled missile in the cruciform fin configuration is modelled as a second-order quasi-linear parameter-varying system. This non-linear model is obtained from the Taylor linearized model of the horizontal motion by including explicit dependence of the aerodynamic derivatives on a state (side-slip velocity) and external parameters (longitudinal velocity and roll angle). The autopilot design is based on input-output pseudolinearization, which is a restriction of input-output feedback linearization to the set of equilibria of the non-linear model. The design makes Taylor linearization of the closed-loop system independent of the choice of equilibria. Thus, if the operating points are in the vicinity of the equilibria, then only one linear model will describe closed-loop dynamics, regardless of the rate of change in the operating points. Simulations for constant lateral acceleration demands show good tracking with fast response time. Robust autopilot design taking into account parametric stability margins for uncertainty aerodynamic derivatives is implemented using convex optimization and linear matrix inequalities.
Copy Correction and Concerted Evolution in the Conservation of Yeast Genes
Authors: Pyne Saumyadipta , Skiena Steven , Futcher Bruce
Published: May 2005

The yeast Saccharomyces cerevisiae and other members of the genus Saccharomyces are descendants of an ancient whole-genome duplication event. Although most of the duplicate genes have since been deleted, many remain, and so there are many pairs of related genes. We have found that poorly expressed genes diverge rapidly from their paralog, while highly expressed genes diverge little, if at all. This lack of divergence of highly expressed paralogous gene pairs seems to involve gene correction: one member of the pair “corrects” the sequence of its twin, and so the gene pair evolves as a unit. This correction presumably involves gene conversion and could occur via a reverse-transcribed cDNA intermediate. Such correction events may also occur in other organisms. These results support the idea that copies of poorly expressed genes are preserved when they diverge to take on new functions, while copies of highly expressed genes are preserved when they are needed to provide additional gene product for the original function.
A Genetic Interpretation of the Variation in Inbreeding Depression
Authors: Moorad Jacob A , Wade Michael J
Published: May 2005

Inbreeding depression is expected to play an important but complicated role in evolution. If we are to understand the evolution of inbreeding depression (i.e., purging), we need quantitative genetic interpretations of its variation. We introduce an experimental design in which sires are mated to multiple dams, some of which are unrelated to the sire but others are genetically related owing to an arbitrary number of prior generations of selfing or sib-mating. In this way we introduce the concept of “inbreeding depression effect variance,” a parameter more relevant to selection and the purging of inbreeding depression than previous measures. We develop an approach for interpreting the genetic basis of the variation in inbreeding depression by: (1) predicting the variation in inbreeding depression given arbitrary initial genetic variance and (2) estimating genetic variance components given half-sib covariances estimated by our experimental design. As quantitative predictions of selection depend upon understanding genetic variation, our approach reveals the important difference between how inbreeding depression is measured experimentally and how it is viewed by selection.
Models of General Frequency-Dependent Selection and Mating-Interaction Effects and the Analysis of Selection Patterns in Drosophila Inversion Polymorphisms
Authors: Álvarez-Castro José M , Alvarez Gonzalo
Published: May 2005

We investigate mechanisms of balancing selection by extending two deterministic models of selection in a one-locus two-allele genetic system to allow for frequency-dependent fitnesses. Specifically we extend models of constant selection to allow for general frequency-dependent fitness functions for sex-dependent viabilities and multiplicative fertilities, while non-multiplicative mating-dependent components remain constant. We compute protected polymorphism conditions that take the form of harmonic means involving both the frequency- and the mating-dependent parameters. This allows for a direct comparison of the equilibrium properties of the frequency-dependent models with those of the constant models and for an analysis of equilibrium of the general model of constant fertility. We then apply the theory to analyze the maintenance of inversion polymorphisms in Drosophila subobscura and D. pseudoobscura, for which data on empirical fitness component estimates are available in the literature. Regression on fitness estimates obtained at different starting frequencies enables us to implement explicit fitness functions in the models and therefore to perform complete studies of equilibrium and stability for particular sets of data. The results point to frequency dependence of fitness components as the main mechanism responsible for the maintenance of the inversion polymorphisms considered, particularly in relation to heterosis, although we also discuss the contribution of other selection mechanisms.
Rapid and Repeatable Elimination of a Parental Genome-Specific DNA Repeat (pGc1R-1a) in Newly Synthesized Wheat Allopolyploids
Authors: Han Fangpu , Fedak George , Guo Wanli , Liu Bao
Published: May 2005

Recent work in the Triticum-Aegilops complex demonstrates that allopolyploidization is associated with an array of changes in low-copy coding and noncoding sequences. Nevertheless, the behavior and fate of repetitive DNA elements that constitute the bulk of nuclear DNA of these plant species is less clear following allopolyploidy. To gain further insight into the genomic events that accompany allopolyploid formation, we investigated fluorescence in situ hybridization (FISH) patterns of a parental-specific, tandem DNA repeat (pGc1R-1) on three sets of newly synthesized amphiploids with different parental species. It was found that drastic physical elimination of pGc1R-1 copies occurred in all three amphiploids in early generations. DNA gel-blot analysis confirmed the FISH data and estimates indicated that ∼70–90% of the copies of the pGc1R-1 repeat family were eliminated from the amphiploids by the second to third selfed generations. Thus, allopolyploidy in Triticum-Aegilops can be accompanied by rapid and extensive elimination of parental-specific repetitive DNA sequences, which presumably play a role in the initial stabilization of the nascent amphiploid plants.
Germline Bottlenecks, Biparental Inheritance and Selection on Mitochondrial Variants
Authors: Roze Denis , Rousset François , Michalakis Yannis
Published: May 2005

Selection on mitochondrial mutations potentially occurs at different levels: at the mitochondria, cell, and organism levels. Several factors affect the strength of selection at these different levels; in particular, mitochondrial bottlenecks during germline development and reduced paternal transmission decrease the genetic variance within cells, while they increase the variance between cells and between organisms, thus decreasing the strength of selection within cells and increasing the strength of selection between cells and organisms. However, bottlenecks and paternal transmission also affect the effective mitochondrial population size, thus affecting genetic drift. In this article, we use a simple model of a unicellular life cycle to investigate the effects of bottlenecks and paternal transmission on the probability of fixation of mitochondrial mutants and their frequency at mutation-selection equilibrium. We find that bottlenecks and reduced paternal transmission decrease the mean frequency of alleles with sm > sc (approximately), where sm and sc are the strengths of selection for an allele within and between cells, respectively, and increase the frequency of alleles with sm < sc. Effects on fixation probabilities are different; for example, bottlenecks reduce the fixation probability of mutants with sm > 0 (unless sm is very small relative to sc) and increase the fixation probability of mutants with sm < 0.
Evolutionary Capacitance May Be Favored by Natural Selection
Authors: Masel Joanna
Published: May 2005

Evolutionary capacitors phenotypically reveal a stock of cryptic genetic variation in a reversible fashion. The sudden and reversible revelation of a range of variation is fundamentally different from the gradual introduction of variation by mutation. Here I study the invasion dynamics of modifiers of revelation. A modifier with the optimal rate of revelation mopt has a higher probability of invading any other population than of being counterinvaded. mopt varies with the population size N and the rate θ at which environmental change makes revelation adaptive. For small populations less than a minimum cutoff Nmin, all revelation is selected against. Nmin is typically quite small and increases only weakly, with θ−1/2. For large populations with N > 1/θ, mopt is ∼1/N. Selection for the optimum is highly effective and increases in effectiveness with larger N ≫ 1/θ. For intermediate values of N, mopt is typically a little less than θ and is only weakly favored over less frequent revelation. The model is analogous to a two-locus model for the evolution of a mutator allele. It is a fully stochastic model and so is able to show that selection for revelation can be strong enough to overcome random drift.
The Course of Malaria in Mice: Major Histocompatibility Complex (MHC) Effects, but No General MHC Heterozygote Advantage in Single-Strain Infections
Authors: Wedekind Claus , Walker Mirjam , Little Tom J
Published: May 2005

A general MHC-heterozygote advantage in parasite-infected organisms is often assumed, although there is little experimental evidence for this. We tested the response of MHC-congenic mice (F2 segregants) to malaria and found the course of infection to be significantly influenced by MHC haplotype, parasite strain, and host gender. However, the MHC heterozygotes did worse than expected from the average response of the homozygotes.
EGO-1, a Putative RNA-Directed RNA Polymerase, Promotes Germline Proliferation in Parallel With GLP-1/Notch Signaling and Regulates the Spatial Organization of Nuclear Pore Complexes and Germline P Granules in Caenorhabditis elegans
Authors: Vought Valarie E , Ohmachi Mitsue , Lee Min-Ho , Maine Eleanor M
Published: May 2005

Caenorhabditis elegans EGO-1, a putative cellular RNA-directed RNA polymerase, promotes several aspects of germline development, including proliferation, meiosis, and gametogenesis, and ensures a robust response to RNA interference. In C. elegans, GLP-1/Notch signaling from the somatic gonad maintains a population of proliferating germ cells, while entry of germ cells into meiosis is triggered by the GLD-1 and GLD-2 pathways. GLP-1 signaling prevents germ cells from entering meiosis by inhibiting GLD-1 and GLD-2 activity. We originally identified the ego-1 gene on the basis of a genetic interaction with glp-1. Here, we investigate the role of ego-1 in germline proliferation. Our data indicate that EGO-1 does not positively regulate GLP-1 protein levels or GLP-1 signaling activity. Moreover, GLP-1 signaling does not positively regulate EGO-1 activity. EGO-1 does not inhibit expression of GLD-1 protein in the distal germline. Instead, EGO-1 acts in parallel with GLP-1 signaling to influence the proliferation vs. meiosis fate choice. Moreover, EGO-1 and GLD-1 act in parallel to ensure germline health. Finally, the size and distribution of nuclear pore complexes and perinuclear P granules are altered in the absence of EGO-1, effects that disrupt germ cell biology per se and probably limit germline growth.
Repeat-Induced Point Mutation and the Population Structure of Transposable Elements in Microbotryum violaceum
Authors: Hood Michael E , Katawczik Melanie , Giraud Tatiana
Published: May 2005

Repeat-induced point mutation (RIP) is a genome defense in fungi that hypermutates repetitive DNA and is suggested to limit the accumulation of transposable elements. The genome of Microbotryum violaceum has a high density of transposable elements compared to other fungi, but there is also evidence of RIP activity. This is the first report of RIP in a basidiomycete and was obtained by sequencing multiple copies of the integrase gene of a copia-type transposable element and the helicase gene of a Helitron-type element. In M. violaceum, the targets for RIP mutations are the cytosine residues of TCG trinucleotide combinations. Although RIP is a linkage-dependent process that tends to increase the variation among repetitive sequences, a chromosome-specific substructuring was observed in the transposable element population. The observed chromosome-specific patterns are not consistent with RIP, but rather suggest an effect of gene conversion, which is also a linkage-dependent process but results in a homogenization of repeated sequences. Particular sequences were found more widely distributed within the genome than expected by chance and may reflect the recently active variants. Therefore, sequence variation of transposable elements in M. violaceum appears to be driven by selection for transposition ability in combination with the context-specific forces of the RIP and gene conversion.
A New Reversion Assay for Measuring All Possible Base Pair Substitutions in Saccharomyces cerevisiae
Authors: Williams Teresa-Marie , Fabbri Rebecca M , Reeves Jason W , Crouse Gray F
Published: May 2005

A TRP5-based reversion system that allows the rates of all possible base pair substitutions to be measured when the TRP5 locus is in both orientations relative to a defined origin of replication has been developed. This system should be useful for a wide variety of mutation and repair studies in yeast.
Hardy-Weinberg Testing of a Single Homozygous Genotype
Authors: Chen John J , Duan Tao , Single Richard , Mather Kristie , Thomson Glenys
Published: May 2005

No proper statistical test is available for the evaluation of deviation of a single homozygous genotype from Hardy-Weinberg equilibrium (HWE) proportion. We propose a 1-d.f. χ2-test. The power of the proposed test is favorable compared to existing HWE testing procedures. The applications of this test are discussed.
Genome-Wide Screen for Inner Nuclear Membrane Protein Targeting in Saccharomyces cerevisiae
Authors: Murthi Athulaprabha , Hopper Anita K
Published: May 2005

Appropriate nuclear membrane structure is important for all eukaryotic organisms as evidenced by the numerous human diseases and alterations in gene expression caused by inappropriate targeting of proteins to the inner nuclear membrane (INM). We report here the first genome-wide screen to identify proteins functioning in INM targeting. We transformed to near completion the 4850 members of the Saccharomyces cerevisiae deletion collection of unessential genes in the 96-well format with a plasmid encoding a reporter protein, Trm1-II-GFP, which normally resides at the INM. We found that deletion of genes encoding subunits of the N-terminal acetyltransferase, NatC, cause mislocation of Trm1-II-GFP from the INM to the nucleoplasm. Mass spectroscopic analysis indicates that Trm1-II-GFP is N-acetylated. N-terminal mutations of Trm1-II-GFP predicted to ablate N-acetylation cause nucleoplasmic location, whereas a variant with an N-terminal alteration predicted to allow N-acetylation by NatC is located at the INM, providing genetic support that Trm1p-II N-acetylation is necessary for its subnuclear INM location. However, because N-acetylation appears not to be sufficient for INM targeting, it may provide a necessary role for INM targeting by affecting Trm1-II-GFP structure and exposure of cis-acting INM targeting motifs. We also discovered that YIL090W/Ice2p, an integral membrane protein located in the endoplasmic reticulum, is necessary for efficient targeting of Trm1-II-GFP to the INM. YIL090W/Ice2p may serve as a tether for INM proteins or as a regulator of INM tethers. Our methodology can be extrapolated to obtain genome-wide perspectives of mechanisms necessary to achieve appropriate subcellular and/or suborganellar location for any resident protein.
A Reluctant Writer's Entry Into a Community of Writers
Authors: Street Chris
Published: May 2005

By drawing upon numerous real‐world experiences with reluctant writers, the author illustrates how tapping their interests can lead to improved writing skills and attitudes toward writing. The critical link between identity and writing is emphasized. Though the experiences in this article are drawn from the author's work with basic writers at the community college level, the article is applicable for writing teachers of all levels. The author presents both practical applications and research‐based responses to many of the issues facing teachers who are charged with the task of improving the writing skills of reluctant writers.
Finding a New Way: Reinventing a Sixth‐Grade Reading Program
Authors: Ahrens Brooke Carey
Published: May 2005

The author found that the reading program at her school did not address the needs of struggling readers and that reading teachers lacked the materials and knowledge needed to make improvements. As part of an action research project, she redesigned the reading program and introduced her colleagues to research‐based teaching methods. The author observed and interviewed teachers to evaluate the successes and failures of the program over the course of one 18‐week semester. She learned the new reading program was highly effective in improving most sixth‐grade students' reading skills and positively altered many teachers' perceptions and attitudes about their instructional abilities in reading classes. Program implementation also required negotiating with the school administration and reading departments.
“It Would Be Fun to Do Again”: Multigenre Responses to Literature
Authors: Gillespie Joanne
Published: May 2005

Middle school students are often asked to reflect on what they read by writing in journals or writing analytic essays. Another approach is to compile multigenre papers. Seventh‐grade students each created a booklet containing 10 items in different genres, based onA Single Shardby Linda Sue Park. Students also wrote reflections explaining how they came up with their ideas and how they connected to the novel. The activity encouraged students to think deeply about the text. Writing diary entries, letters, obituaries, essays, extensions to the story, and personal narratives; constructing word games and tests; and designing catalogs and certificates provided ways for students to solidify their understanding of what they read and showed their ability to think critically and imaginatively about the novel.
Leading Double Lives: Literacy and Technology in and out of School
Authors: Williams Bronwyn T.
Published: May 2005

The author acknowledges that there is often a gap in how and for what ends technology is used—a gap between some students and their teachers and a gap among different groups of students. What is less obvious is the nature of these gaps in terms of literacy practices. He then asks, “Could we be missing ways to connect with our students and help reinforce and enlarge their literate identities?”
A Major State Tobacco Tax Increase, the Master Settlement Agreement, and Cigarette Consumption: The California Experience
Authors: Sung Hai-Yen , Hu Teh-wei , Ong Michael , Keeler Theodore E. , Sheu Mei-ling
Published: May 2005

Objectives. We evaluated the combined effects on California cigarette consumption of an additional 50¢ per pack state tax imposed by Proposition 10 of January 1999 and a 45¢ per pack increase in cigarette prices stemming from the Master Settlement Agreement (MSA) of November 1998.

Methods. We used quarterly cigarette sales data for the period 1984–2002 to estimate a time-series intervention model adjusting for seasonal variations and time trend.

Results. Over the period 1999 through 2002, the combined effect was to reduce cigarette consumption by 2.4 packs per capita per quarter (1.3 billion packs total over the 4-year period) and to raise state tax revenues by $2.1 billion. These effects were similar to the effects of a 25¢ per pack tax increase enacted by Proposition 99 a decade earlier, although with decreased relative effectiveness as measured by percentage of reduction in cigarette consumption divided by percentage of increase in taxation (−0.44 vs −0.60).

Conclusions. A major increase in price through taxation and the MSA provided a strong economic disincentive for smokers in a state with a low smoking prevalence. This effect could be reinforced if part of the MSA payments were devoted to tobacco control programs.
Smoking in 6 Diverse Chicago Communities—A Population Study
Authors: Dell Jade L. , Whitman Steven , Shah Ami M. , Silva Abigail , Ansell David
Published: May 2005

Objectives. We analyzed smoking survey data across communities in Chicago, Ill, to explore community-level variations in smoking behavior.

Methods. We conducted a health survey of 6 racially and ethnically diverse Chicago communities during 2002–2003. The survey included questions about current smoking, smoking history, and cessation attempts.

Results. Smoking prevalence varied from 18% in the wealthiest (predominately White) community to 39% in the poorest (predominately Black) community. In a contiguous pair of communities, one Mexican and the other Black, smoking prevalence varied by a factor of 2. Men, residents in poorer households and households without telephones, and residents with less education were most likely to smoke.

Conclusions. The high proportions of current smokers who had attempted to quit indicate a prevalent desire to stop smoking. However, less than 4% of the Master Tobacco Settlement Agreement funds are being spent on smoking prevention, or even on health in general, in Illinois. Although much is known about the prevalence of smoking at the national level, few studies of smoking have been done at the community level, presenting difficulties for the allocation of resources and the design of smoking cessation programs in response to community needs. Understanding community-level smoking rates could improve the allocation of resources and assist the shaping of culturally meaningful prevention efforts.
Access to Low-Taxed Cigarettes Deters Smoking Cessation Attempts
Authors: Hyland Andrew , Higbee Cheryl , Li Qiang , Bauer Joseph E. , Giovino Gary A. , Alford Terry , Cummings K. Michael
Published: May 2005

We examined whether smokers who purchased low-taxed cigarettes from American Indian reservations had lower quit attempt and cessation rates than did smokers who purchased cigarettes from full-price outlets. Smokers who bought cigarettes from American Indian reservations were half as likely to make a quit attempt and had a nonsignificant trend toward lower cessation rates (20% vs 10%) compared with those who bought full-priced cigarettes. Interventions that reduce price differentials are suggested to maximize the public health benefit of cigarette excise taxes.
Adult Tobacco Use Levels After Intensive Tobacco Control Measures: New York City, 2002–2003
Authors: Frieden Thomas R. , Mostashari Farzad , Kerker Bonnie D. , Miller Nancy , Hajat Anjum , Frankel Martin
Published: May 2005

Objectives. We sought to determine the impact of comprehensive tobacco control measures in New York City.

Methods. In 2002, New York City implemented a tobacco control strategy of (1) increased cigarette excise taxes; (2) legal action that made virtually all work-places, including bars and restaurants, smoke free; (3) increased cessation services, including a large-scale free nicotine-patch program; (4) education; and (5) evaluation. The health department also began annual surveys on a broad array of health measures, including smoking.

Results. From 2002 to 2003, smoking prevalence among New York City adults decreased by 11% (from 21.6% to 19.2%, approximately 140000 fewer smokers). Smoking declined among all age groups, race/ethnicities, and education levels; in both genders; among both US-born and foreign-born persons; and in all 5 boroughs. Increased taxation appeared to account for the largest proportion of the decrease; however, between 2002 and 2003 the proportion of cigarettes purchased outside New York City doubled, reducing the effective price increase by a third.

Conclusions. Concerted local action can sharply reduce smoking prevalence. However, further progress will require national action, particularly to increase cigarette taxes, reduce cigarette tax evasion, expand education and cessation services, and limit tobacco marketing.
Why Wonder Why?
Authors: Patel Jayshil J.
Published: February 2024

This essay describes how a physician’s encounter with a patient with repeated intensive care unit admissions illuminated the value of wonder in clinical care and medical education.
Lifetime Exposure to Depression and Neuroimaging Measures of Brain Structure and Function
Authors: Wang Xinyi , Hoffstaedter Felix , Kasper Jan , Eickhoff Simon B. , Patil Kaustubh R. , Dukart Juergen
Published: February 2024

Importance

Despite decades of neuroimaging studies reporting brain structural and functional alterations in depression, discrepancies in findings across studies and limited convergence across meta-analyses have raised questions about the consistency and robustness of the observed brain phenotypes.

Objective

To investigate the associations between 6 operational criteria of lifetime exposure to depression and functional and structural neuroimaging measures.

Design, Setting, and Participants

This cross-sectional study analyzed data from a UK Biobank cohort of individuals aged 45 to 80 years who were enrolled between January 1, 2014, and December 31, 2018. Participants included individuals with a lifetime exposure to depression and matched healthy controls without indications of psychosis, mental illness, behavior disorder, and disease of the nervous system. Six operational criteria of lifetime exposure to depression were evaluated: help seeking for depression; self-reported depression; antidepressant use; depression definition by Smith et al; hospital International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) diagnosis codes F32 and F33; and Composite International Diagnostic Interview Short Form score. Six increasingly restrictive depression definitions and groups were defined based on the 6 depression criteria, ranging from meeting only 1 criterion to meeting all 6 criteria. Data were analyzed between January and October 2022.

Main Outcomes and Measures

Functional measures were calculated using voxel-wise fractional amplitude of low-frequency fluctuation (fALFF), global correlation (GCOR), and local correlation (LCOR). Structural measures were calculated using gray matter volume (GMV).

Results

The study included 20 484 individuals with lifetime depression (12 645 females [61.7%]; mean [SD] age, 63.91 [7.60] years) and 25 462 healthy controls (14 078 males [55.3%]; mean [SD] age, 65.05 [7.8] years). Across all depression criteria, individuals with lifetime depression displayed regionally consistent decreases in fALFF, LCOR, and GCOR (Cohen d range, −0.53 [95% CI, −0.88 to −0.15] to −0.04 [95% CI, −0.07 to −0.01]) but not in GMV (Cohen d range, −0.47 [95 % CI, −0.75 to −0.12] to 0.26 [95% CI, 0.15-0.37]). Hospital ICD-10 diagnosis codes F32 and F33 (median [IQR] difference in effect sizes, −0.14 [−0.17 to −0.11]) and antidepressant use (median [IQR] difference in effect sizes, −0.12 [−0.16 to −0.10]) were criteria associated with the most pronounced alterations.

Conclusions and Relevance

Results of this cross-sectional study indicate that lifetime exposure to depression was associated with robust functional changes, with a more restrictive depression definition revealing more pronounced alterations. Different inclusion criteria for depression may be associated with the substantial variation in imaging findings reported in the literature.
Realizing High‐Flux Lithium‐Ion Conduction by LaF3 Doping in Quasi‐Solid‐State Electrolytes
Authors: Bi Linnan , He Liang , Song Yaochen , Wang Yi , Xie Qingyu , Dong Peng , Zhang Yingjie , Yao Yao , Liao Jiaxuan , Wang Sizhe
Published: February 2024

The inherent low ionic conductivity of PVDF‐based electrolytes at room temperature and lithium dendrite penetration hinder its further application. Herein, a LaF3 doped Poly(vinylidene fluoride‐chlorotrifluoroethylene) (P(VDF‐ctfe)) quasi‐solid electrolyte is developed. High‐flux channels are created due to the optimization of the lithium environment that lanthanum preferentially competes coordination with anionic species for relaxing lithium hopping. Lithium carriers are therefore highly free and unbound at the molecular level, resulting in a high ionic conductivity (σ) of 0.7 mS cm−1 and a transfer number (tLi+) of 0.79 at 25 °C. Moreover, the in situ organic–inorganic LiF‐rich dielectric layer effectively improves the stability and compatibility of the electrode/electrolyte interface, ensuring interfacial lithium conduction while facilitating stable Li+ plating/stripping. As a result, the optimized Li/ATCSE‐3%/Li can deliver favorable compatibility at 0.1 and 0.3 mA cm−2 for stable Li+ plating/stripping for 2000 and 1200 h, respectively. The high‐mass loading (6.4 mg cm−2) pouch cell delivers a stable cycling performance over 100 cycles with a capacity retention of 85.8% at 0.3 °C. This work is anticipated to provide considerable insight into the creative design of lithium transport of polymer‐based for practical quasi‐solid‐state lithium metal batteries.
Monolithic Fabrication of Metal‐Free On‐Paper Self‐Charging Power Systems
Authors: Su Yingchun , Xue Han , Fu Yujie , Chen Shiqian , Li Zheng , Li Lengwan , Knoks Ainars , Bogdanova Olga , Lesničenoks Pēteris , Palmbahs Roberts , Laurila Mika‐Matti , Mäntysalo Matti , Hammar Mattias , Hallén Anders , Nordell Nils , Li Jiantong
Published: February 2024

Self‐charging power systems (SCPSs) are envisioned as promising solutions for emerging electronics to mitigate the increasing global concern about battery waste. However, present SCPSs suffer from large form factors, unscalable fabrication, and material complexity. Herein, a type of highly stable, eco‐friendly conductive inks based on poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) are developed for direct ink writing of multiple components in the SCPSs, including electrodes for miniaturized spacer‐free triboelectric nanogenerators (TENGs) and microsupercapacitors (MSCs), and interconnects. The principle of “one ink, multiple functions” enables to almost fully print the entire SCPSs on the same paper substrate in a monolithic manner without post‐integration. The monolithic fabrication significantly improves the upscaling capability for manufacturing and reduces the form factor of the entire SCPSs (a small footprint area of ≈2 cm × 3 cm and thickness of ≈1 mm). After pressing/releasing the TENGs for ≈79000 cycles, the 3‐cell series‐connected MSC array can be charged to 1.6 V while the 6‐cell array to 3.0 V. On‐paper SCPSs are promising to serve as lightweight, thin, sustainable, and low‐cost power supplies.
Surface Reconditioning of Lithium Metal Electrodes by Laser Treatment for the Industrial Production of Enhanced Lithium Metal Batteries
Authors: Kriegler Johannes , Ballmes Heiko , Dib Serge , Demir Ali Gökhan , Hille Lucas , Liang Yunhao , Wach Lovis , Weinmann Steffen , Keilhofer Josef , Kim Kun Joong , Rupp Jennifer L. M. , Zaeh Michael F.
Published: February 2024

Incorporating lithium metal anodes in next‐generation batteries promises enhanced energy densities. However, lithium's reactivity results in the formation of a native surface film, affecting battery performance. Therefore, precisely controlling the chemical and morphological surface condition of lithium metal anodes is imperative for producing high‐performance lithium metal batteries. This study demonstrates the efficacy of laser treatment for removing superficial contaminants from lithium metal substrates. To this end, picosecond‐pulsed laser radiation is proposed for modifying the surface of lithium metal substrates. Scanning electron microscopy (SEM) revealed that different laser process regimes can be exploited to achieve a wide spectrum of surface morphologies. Energy‐dispersive X‐ray spectroscopy (EDX) confirmed substantial reductions of ≈80% in oxidic and carbonaceous surface species. The contamination layer removal translated into interfacial resistance reductions of 35% and 44% when testing laser‐cleaned lithium metal anodes in symmetric all‐solid‐state batteries (ASSBs) with lithium phosphorus sulfur chloride (LPSCl) and lithium lanthanum zirconium oxide (LLZO) solid electrolytes, respectively. Finally, a framework for integrating laser cleaning into industrial battery production is suggested, evidencing the industrial feasibility of the approach. In summary, this work advances the understanding of lithium metal surface treatments and serves as proof of principle for its industrial applicability.
Bi/BSO Heterojunctions via Vacancy Engineering for Efficient Photocatalytic Nitrogen Fixation
Authors: Wu Runjie , Gao Shuai , Jones Colton , Sun Mingming , Guo Ming , Tai Ran , Chen Shaowei , Wang Qiang
Published: February 2024

Photocatalytic nitrogen reduction represents a viable technology for green ammonia synthesis under mild conditions. However, the performance of the photocatalysts is typically limited by high charge carrier recombination and low adsorption and activation of nitrogen molecules. Herein, Bi/Bi2Sn2O7 (Bi/BSO) heterojunction nanocomposites are prepared via a one‐step hydrothermal method, where NaOH etching of oxygen vacancies in the Bi─O bonds of Bi2Sn2O7 (BSO) is exploited for the in situ formation of metallic Bi and hence Schottky junctions with the semiconducting BSO. This leads to a high separation rate of photogenerated charge carriers. Consequently, compared to the pure‐phase BSO, the Bi/BSO heterostructures exhibit markedly enhanced ammonia production, reaching an optimum rate of 284.5 µmol g−1 h−1, where the rectifying contact between the semiconducting BSO and metallic Bi facilitates directional BSO to Bi electron transfer, leading to enrichment of photogenerated electrons at the active sites of metallic Bi. First‐principles calculations confirm the alteration of active sites and the guided electron flow by the Schottky junctions and surface oxygen vacancies. Results from this study offer an effective paradigm of structural engineering in manipulating the photocatalytic activity of bismuth‐based pyrochlore materials toward nitrogen fixation to ammonia.
A General Strategy for Enhancing Sensitivity and Suppressing Noise in Infrared Organic Photodetectors Using Non‐Conjugated Polymer Additives
Authors: Bills Tyler , Liu Chih‐Ting , Lim Jasmine , Eedugurala Naresh , Mahalingavelar Paramasivam , Seo Bogyeom , Hanna Ethan T. , Ng Tse Nga , Azoulay Jason D.
Published: February 2024

Photodetectors operating across the near‐ to short‐wave infrared (NIR–SWIR, λ = 0.9–1.8 µm) underpin modern science, technology, and society. Organic photodiodes (OPDs) based on bulk‐heterojunction (BHJ) active layers overcome critical manufacturing and operating drawbacks inherent to crystalline inorganic semiconductors, offering the potential for low‐cost, uncooled, mechanically compliant, and ubiquitous infrared technologies. A constraining feature of these narrow bandgap materials systems is the high noise current under an applied bias, resulting in specific detectivities (D*, the figure of merit for detector sensitivity) that are too low for practical utilization. Here, this study demonstrates that incorporating wide‐bandgap insulating polymers within the BHJ suppresses noise by diluting the transport and trapping sites as determined using capacitance‐frequency analysis. The resulting D* of NIR–SWIR OPDs operating from 600–1400 nm under an applied bias of −2 V is improved by two orders of magnitude, from 108 to 1010 Jones (cm Hz1/2 W−1), when incorporating polysulfone within the blends. This broadly applicable strategy can reduce noise in IR‐OPDs enabling their practical operation and the realization of emerging technologies.
Inflammation‐Responsive Cell Membrane‐Camouflaged Nanoparticles against Liver Fibrosis via Regulating Endoplasmic Reticulum Stress and Oxidative Stress
Authors: Bai Yang , Chen Jiaqi , Zhang Sitong , Xu Guangyu , Mao Zhengwei , Ding Yuan , Wang Weilin
Published: February 2024

Liver fibrosis represents a reversible stage of various chronic liver diseases that progresses to cirrhosis. This condition is characterized by an imbalance between tissue damage and repair, and the production of fibers in the liver exceeds their degradation. Oxidative stress (OS) resulting from tissue injury and endoplasmic reticulum stress (ERS) triggered by the overproduction of proteins are pivotal factors in liver fibrosis. Melatonin demonstrates the capability to neutralize free radicals, shielding cells from oxidative harm. It is also a specific inhibitor of the ERS receptor transcription activating factor 6 (ATF6), indicating its great potential in ameliorating liver fibrosis. However, its limited water solubility and oral bioavailability of under 15% present hurdles in achieving therapeutic blood concentrations for treating liver fibrosis. The PLGA@Melatonin is constructed by loading melatonin with poly (lactic‐co‐glycolic acid) (PLGA). Platelet membranes (PM) and activated hepatic stellate cell membranes (HSCM) with high expression of the platelet‐derived growth factor receptor (PDGFR) are extracted to successfully construct PM@PLGA@Melatonin and HSCM@PLGA@Melatonin, which are subsequently utilized to treat mice with liver fibrosis. The results illustrated the remarkable therapeutic effects of the two nanoparticles on liver fibrosis, along with their excellent targeting and biosafety properties.
Efficient Ion Percolating Network for High‐Performance All‐Solid‐State Cathodes
Authors: Cheng Guangzeng , Sun Hao , Wang Haoran , Ju Zhengyu , Zhu Yue , Tian Weiqian , Chen Jingwei , Wang Huanlei , Wu Jingyi , Yu Guihua
Published: February 2024

All‐solid‐state lithium batteries (ASSLBs) face critical challenges of low cathode loading and poor rate performances, which handicaps their energy/power densities. The widely‐accepted aim of high ionic conductivity and low interfacial resistance seems insufficient to overcome these challenges. Here, it is revealed that an efficient ion percolating network in the cathode exerts a more critical influence on the electrochemical performance of ASSLBs. By constructing vertical alignment of Li0.35La0.55TiO3 nanowires (LLTO NWs) in solid‐state cathode through magnetic manipulation, the ionic conductivity of the cathode increases twice compared with the cathode consisted of randomly distributed LLTO NWs. The all‐solid‐state LiFePO4/Li cells using poly(ethylene oxide) as the electrolyte is able to deliver high capacities of 151 mAh g−1 (2 C) and 100 mAh g−1 (5 C) at 60 °C, and a room‐temperature capacity of 108 mAh g−1 can be achieved at a charging rate of 2 C. Furthermore, the cell can reach a high areal capacity of 3 mAh cm−2 even with a practical LFP loading of 20 mg cm−2. The universality of this strategy is also presented showing the demonstration in LiNi0.8Co0.1Mn0.1O2 cathodes. This work offers new pathways for designing ASSLBs with improved energy/power densities.
A 2D Cryptographic Hash Function Incorporating Homomorphic Encryption for Secure Digital Signatures
Authors: Wali Akshay , Ravichandran Harikrishnan , Das Saptarshi
Published: February 2024

User authentication is a critical aspect of any information exchange system which verifies the identities of individuals seeking access to sensitive information. Conventionally, this approachrelies on establishing robust digital signature protocols which employ asymmetric encryption techniques involving a key pair consisting of a public key and its matching private key. In this article, a user verification platform constructed using integrated circuits (ICs) with atomically thin two‐dimensional (2D) monolayer molybdenum disulfide (MoS2) memtransistors is presented. First, generation of secure cryptographic keys is demonstrated by exploiting the inherent stochasticity of carrier trapping and detrapping at the 2D/oxide interface trap sites. Subsequently, the ability to manipulate the functionality of logical NOR is leveraged to create a secure one‐way hash function which when homomorphically operated upon with NAND, XOR, OR, NOT, and AND logic circuits generate distinct digital signatures. These signatures when subsequently decrypted, verify the authenticity of the receiver while ensuring complete preservation of data integrity and confidentiality as the underlying information is never revealed. Finally, the advantages of implementing a NOR‐based hashing techniques in comparison to the conventional XOR‐based encryption method are established. This demonstration highlights the potential of 2D‐based ICs in developing critical hardware information security primitives.
Simple‐Structured Acceptor with Highly Interconnected Electron‐Transport Pathway Enables High‐Efficiency Organic Solar Cells
Authors: Gu Xiaobin , Zeng Rui , He Tengfei , Zhou Guanqing , Li Congqi , Yu Na , Han Fei , Hou Yuqi , Lv Jikai , Zhang Ming , Zhang Jianqi , Wei Zhixiang , Tang Zheng , Zhu Haiming , Cai Yunhao , Long Guankui , Liu Feng , Zhang Xin , Huang Hui
Published: February 2024

Achieving desirable charge‐transport highway is of vital importance for high‐performance organic solar cells (OSCs). Here, it is shown how molecular packing arrangements can be regulated via tuning the alkyl‐chain topology, thus resulting in a 3D network stacking and highly interconnected pathway for electron transport in a simple‐structured nonfused‐ring electron acceptor (NFREA) with branched alkyl side‐chains. As a result, a record‐breaking power conversion efficiency of 17.38% (certificated 16.59%) is achieved for NFREA‐based devices, thus providing an opportunity for constructing low‐cost and high‐efficiency OSCs.