bluuebunny/crossref_metadata_2025 huggingface dataset:
Situational Features in Milgram's Experiment That Kept His Participants Shocking
Authors: Burger Jerry M.
Published: September 2014

Although people are often astonished by the high rates of obedience in Milgram's famous studies, research on social influence processes in other settings provides considerable insight into why so many of Milgram's participants continued to press the shock levers all the way to 450 volts. That research suggests that four situational features Milgram built into his experimental procedure contributed to the high levels of obedience. The four features are the incremental nature of the task, the novelty of the situation and the kind of normative information made available, the opportunity to deny or diffuse responsibility, and the limited opportunity to ponder decisions. When looked at in this light, Milgram's research can be seen as a dramatic example of some well‐documented psychological effects.
Authorities and Uncertainties: Applying Lessons from the Study of Jewish Resistance during the Holocaust to the Milgram Legacy
Authors: Einwohner Rachel L.
Published: September 2014

Milgram's experiments were born out of a desire to understand the Nazis’ persecution of Jews during the Holocaust. This article argues that the study of Jewish resistance against that persecution also furthers our understanding of Milgram's experiments. Case data from the Nazi‐created ghettos of Warsaw, Vilna, and Łódź—settings in which Jews reached very different decisions with regard to resistance—illustrate that decisions about resistance reflect obedience and disobedience to multiple authorities, including agents of the Nazi regime as well as moral and religious dictates. Whereas Milgram himself recognized the role of multiple authorities, these cases also point to the role of uncertainty, which is relevant to yet not discussed explicitly in Milgram's experiments. A recognition of uncertainty and multiple authorities provides a more nuanced understanding of obedience and shows that, contrary to common assumptions about both Milgram's experiments and the Holocaust, neither resistance nor obedience is “ordinary” or straightforward.
Observing Obedience: How Sophisticated are Social Perceivers?
Authors: Monroe Andrew E. , Reeder Glenn D.
Published: September 2014

How does the general public understand the behavior of Milgram's teachers—those participants who ostensibly tortured an innocent stranger? In our social perception analysis, we contrast two research traditions that attempt to answer this question. On one hand, lay dispositionism argues that people make harsh, person‐focused judgments of Milgram's teachers. On the other hand, a mental state account suggests that perceivers integrate information about social situations and agents’ behavior to infer the mental states of others. Mental state inferences then, in turn, drive social judgments of others. We review the theory of lay dispositionism, its application to the Milgram experiments, and several limitations of the theory. We then offer an alternative mental state account and support this view with recent studies on the Milgram experiments, and extensions to everyday behavior explanation. A final section considers the research and policy implications of our analysis.
Obedience, Self‐Control, and the Voice of Culture
Authors: Ent Michael R. , Baumeister Roy F.
Published: September 2014

Milgram's obedience studies dramatically demonstrated how obeying authority can have grim consequences. Nevertheless, we propose that obedience to legitimate authority is a vital aspect of human culture. Among other things, obedience to authority can encourage individuals to set aside their selfish desires for the good of their group. Often, such selfish desires are violent in nature. Thus, obedience can function to limit violence. We challenge the notion that people typically respond to the commands of authority with blind obedience. Last, we suggest that the implications of Milgram's findings have in some cases been overstated.
50:50 Hindsight: Appreciating Anew the Contributions of Milgram's Obedience Experiments
Authors: Jetten Jolanda , Mols Frank
Published: September 2014

Over the last 50 years, interest in Milgram's obedience experiments has hardly waned and debate about his contribution to our understanding of obedience is alive and well. Moreover, many questions remain. For example, is obedience blind and ordinary? Are people basically weak in the presence of an authority? Drawing on the contributions to this issue, we discuss the new insights that emerge from reflections on the experiments, theorizing, the communication of findings, and the way Milgram's experiments relate to the Holocaust. By focusing on aspects of Milgram's work that have received less attention and findings that have emerged since the Milgram archives were first accessed (e.g., previously unknown experiments, notes, recordings), contributions to this issue provide many fresh insights. This much is very clear: now 50 years on, the obedience experiments continue to inspire and there is still much more that can be learned from engagement with his work.
Melatonin attenuates inflammatory response‐induced brain edema in early brain injury following a subarachnoid hemorrhage: a possible role for the regulation of pro‐inflammatory cytokines
Authors: Chen Jingyin , Chen Gao , Li Jianru , Qian Cong , Mo Hangbo , Gu Chi , Yan Feng , Yan Wei , Wang Lin
Published: September 2014

Melatonin is a strong anti‐oxidant that has beneficial effects against early brain injury (EBI) following a subarachnoid hemorrhage (SAH) in rats; protection includes the reduction of both mortality and neurological deficits. The molecular mechanisms underlying these clinical effects in the SAH model have not been clearly identified. This study examined the influence of melatonin on brain edema secondary to disruption of the blood–brain barrier (BBB) and the relationship between these effects and pro‐inflammatory cytokines in EBI following SAH using the filament perforation model of SAH in male Sprague–Dawley rats. Melatonin (150 mg/kg) or vehicle was given via an intraperitoneal injection 2 hr after SAH induction. Brain samples were extracted 24 hr after SAH. Melatonin treatment markedly attenuated brain edema secondary to BBB dysfunctions by preventing the disruption of tight junction protein expression (ZO‐1, occludin, and claudin‐5). Melatonin treatment also repressed cortical levels of pro‐inflammatory cytokines (IL‐1β, IL‐6, and TNF‐α), which were increased in EBI 24 hr after SAH. To further identify the mechanism of this protection, we demonstrated that administration of melatonin attenuated matrix metallopeptidase 9 expression/activity and vascular endothelial growth factor expression, which are related to the inflammatory response and BBB disruption in EBI after SAH. Taken together, this report shows that melatonin prevents disruption of tight junction proteins which might play a role in attenuating brain edema secondary to BBB dysfunctions by repressing the inflammatory response in EBI after SAH, possibly associated with regulation of pro‐inflammatory cytokines.
Communities: are they groups of hidden interactions?
Authors: Michalet Richard , Chen Shu‐yan , An Li‐zhe , Wang Xiang‐tai , Wang Yu‐xin , Guo Peng , Ding Chen‐chen , Xiao Sa
Published: September 2014

Questions

Ecologists are increasingly interested in community‐level consequences of biotic interactions. However, community‐level studies have not considered that biotic interactions might have contrasting directions within communities, and indirect interactions are rarely quantified although they may influence community‐level outcomes. We tested the hypotheses that in species‐rich plant communities from intermediate severe environmental conditions: (1) direct facilitation by dominant functional groups is balanced by negative indirect interactions among beneficiary species with no net effect at the community level on diversity and biomass, and (2) both direct and indirect interactions contribute to community composition.

Location

A species‐rich subalpine community of the eastern Tibet Plateau (China).

Methods

We removed dominant shrubs and graminoids and quantified, at the community and species levels, their direct and indirect effects on 43 forb species. We used multivariate analyses to assess the contribution of direct and indirect effects on community composition.

Results

There were no community‐level effects of either dominant life form on forb diversity and biomass. There were multiple species‐level interactions that we grouped into six types based on the direction and intensity of indirect effects. We found significant relationships between species‐level interactions and community composition.

Conclusions

Our study highlights that communities are sets of hidden interactions that contribute to community composition, although no interaction might be detected at the community level because hidden interactions balance each other. Future studies should assess the ecological and functional drivers of these hidden interactions.
SENSITIVITY ANALYSIS OF NONLINEAR BEHAVIOR WITH DISTORTED PROBABILITY
Authors: Cao Xi‐Ren , Wan Xiangwei
Published: September 2014

In this paper, we propose a sensitivity‐based analysis to study the nonlinear behavior under nonexpected utility with probability distortions (or “distorted utility” for short). We first discover the “monolinearity” of distorted utility, which means that after properly changing the underlying probability measure, distorted utility becomes locally linear in probabilities, and the derivative of distorted utility is simply an expectation of the sample path derivative under the new measure. From the monolinearity property, simulation algorithms for estimating the derivative of distorted utility can be developed, leading to gradient‐based search algorithms for the optimum of distorted utility. We then apply the sensitivity‐based approach to the portfolio selection problem under distorted utility with complete and incomplete markets. For the complete markets case, the first‐order condition is derived and optimal wealth deduced. For the incomplete markets case, a dual characterization of optimal policies is provided; a solvable incomplete market example with unhedgeable interest rate risk is also presented. We expect this sensitivity‐based approach to be generally applicable to optimization problems involving probability distortions.
COHERENCE AND ELICITABILITY
Authors: Ziegel Johanna F.
Published: September 2014

The risk of a financial position is usually summarized by a risk measure. As this risk measure has to be estimated from historical data, it is important to be able to verify and compare competing estimation procedures. In statistical decision theory, risk measures for which such verification and comparison is possible, are called elicitable. It is known that quantile‐based risk measures such as value at risk are elicitable. In this paper, the existing result of the nonelicitability of expected shortfall is extended to all law‐invariant spectral risk measures unless they reduce to minus the expected value. Hence, it is unclear how to perform forecast verification or comparison. However, the class of elicitable law‐invariant coherent risk measures does not reduce to minus the expected value. We show that it consists of certain expectiles.
Qualitative and quantitative analysis of fibrosis in the kidney
Authors: Hewitson Tim D. , Smith Edward R. , Samuel Chrishan S.
Published: September 2014

Renal fibrosis results from an excess accumulation of connective tissue, primarily collagen, in response to tissue injury‐associated aberrant wound healing, which is over‐expressed in the renal vascular, glomerular and tubulointerstitial compartments. Despite being the final common pathway of end stage kidney disease, there is a lack of consensus on standardized approaches to measure fibrosis. In this article we therefore describe how a combination of immunohistochemical staining and biochemical measurement of hydroxyproline can be used to qualitatively and quantitatively examine the different forms of fibrosis. These techniques provide measures of both the composition of fibrosis, and a means of evaluating interventions in this significant process.
Digitaria isanensis sp. nov. and a reinstated taxon of Digitaria (Poaceae) from Thailand
Authors: Boonsuk Boonchuang , Chantaranothai Pranom , Hodkinson Trevor R.
Published: September 2014

Digitaria isanensis is described as a new species apparently endemic to sandy soils in open areas of northeastern Thailand. In addition, D. thwaitesii var. tonkinensis is reinstated and presented as a new record for Thailand. Descriptions and illustrations of both taxa are provided.
Monomeric IgA can be produced in planta as efficient as IgG, yet receives different N‐glycans
Authors: Westerhof Lotte B. , Wilbers Ruud H. P. , van Raaij Debbie R. , Nguyen Dieu‐Linh , Goverse Aska , Henquet Maurice G. L. , Hokke Cornelis H. , Bosch Dirk , Bakker Jaap , Schots Arjen
Published: September 2014

The unique features of IgA, such as the ability to recruit neutrophils and suppress the inflammatory responses mediated by IgG and IgE, make it a promising antibody isotype for several therapeutic applications. However, in contrast to IgG, reports on plant production of IgA are scarce. We produced IgA1κ and IgG1κ versions of three therapeutic antibodies directed against pro‐inflammatory cytokines in Nicotiana benthamiana: Infliximab and Adalimumab, directed against TNF‐α, and Ustekinumab, directed against the interleukin‐12p40 subunit. We evaluated antibody yield, quality and N‐glycosylation. All six antibodies had comparable levels of expression between 3.5 and 9% of total soluble protein content and were shown to have neutralizing activity in a cell‐based assay. However, IgA1κ‐based Adalimumab and Ustekinumab were poorly secreted compared to their IgG counterparts. Infliximab was poorly secreted regardless of isotype backbone. This corresponded with the observation that both IgA1κ‐ and IgG1κ‐based Infliximab were enriched in oligomannose‐type N‐glycan structures. For IgG1κ‐based Ustekinumab and Adalimumab, the major N‐glycan type was the typical plant complex N‐glycan, biantennary with terminal N‐acetylglucosamine, β1,2‐xylose and core α1,3‐fucose. In contrast, the major N‐glycan on the IgA‐based antibodies was xylosylated, but lacked core α1,3‐fucose and one terminal N‐acetylglucosamine. This type of N‐glycan occurs usually in marginal percentages in plants and was never shown to be the main fraction of a plant‐produced recombinant protein. Our data demonstrate that the antibody isotype may have a profound influence on the type of N‐glycan an antibody receives.
Techniques for Toddlers: Linear Band Incision for Harlequin Ichthyosis with Associated Compartment Syndrome
Authors: Tontchev Gramen , Silverberg Nanette B. , Shlasko Edward , Henry Carol , Roberts Jaclyn L. , Roth Malcolm Z.
Published: September 2014

Harlequin ichthyosis (HI) is a rare autosomal recessive disorder of cornification in which children are born with an extremely thick stratum corneum that becomes a restrictive circumferential encasement around the orifices, limbs, chest, and abdomen, resulting in limb contractures. We present a neonate diagnosed in utero with HI. The infant was born with encasing bands of thickened skin creating strictures that were causing digital and limb cyanosis (compartment syndrome). We treated the child using a new technique of lysis of the encasing bands that we call linear band incision, using a new escharotomy‐like procedure while the infant was undergoing a 3‐week course oral acitretin therapy. The technique involved linear incision and lysis of encasements that resulted in reperfusion of the injured limbs and prevention of further digital necrosis. The child is currently a healthy 8‐year‐old boy with skin manifestations resembling congenital ichthyosiform erythroderma. He has use of all of the limbs that were released in the procedures and is maintained on frequent application of bland emollients. Linear band incision is a potentially life‐ and limb‐saving technique in children with HI.
Photosynthesis in extreme environments: responses to different light regimes in the Antarctic alga Koliella antarctica
Authors: La Rocca Nicoletta , Sciuto Katia , Meneghesso Andrea , Moro Isabella , Rascio Nicoletta , Morosinotto Tomas
Published: September 2014

Antarctic algae play a fundamental role in polar ecosystem thanks to their ability to grow in an extreme environment characterized by low temperatures and variable illumination. Here, for prolonged periods, irradiation is extremely low and algae must be able to harvest light as efficiently as possible. On the other side, at low temperatures even dim irradiances can saturate photosynthesis and drive to the formation of reactive oxygen species. Colonization of this extreme environment necessarily required the optimization of photosynthesis regulation mechanisms by algal organisms. In order to investigate these adaptations we analyzed the time course of physiological and morphological responses to different irradiances in Koliella antarctica, a green microalga isolated from Ross Sea (Antarctica). Koliella antarctica not only modulates cell morphology and composition of its photosynthetic apparatus on a long‐term acclimation, but also shows the ability of a very fast response to light fluctuations. Koliella antarctica controls the activity of two xanthophyll cycles. The first, involving lutein epoxide and lutein, may be important for the growth under very low irradiances. The second, involving conversion of violaxanthin to antheraxanthin and zeaxanthin, is relevant to induce a fast and particularly strong non‐photochemical quenching, when the alga is exposed to higher light intensities. Globally K. antarctica thus shows the ability to activate a palette of responses of the photosynthetic apparatus optimized for survival in its natural extreme environment.
Role of gibberellins during arbuscular mycorrhizal formation in tomato: new insights revealed by endogenous quantification and genetic analysis of their metabolism in mycorrhizal roots
Authors: Martín‐Rodríguez José Ángel , Ocampo Juan Antonio , Molinero‐Rosales Nuria , Tarkowská Danuše , Ruíz‐Rivero Omar , García‐Garrido José Manuel
Published: September 2014

Gibberellins (GAs) are key regulators of plant growth and development and recent studies suggest also a role during arbuscular mycorrhizal (AM) formation. Here, complementary approaches have been used to obtain a clearer picture that correlates AM fungal development inside roots with GA metabolism. An extensive analysis of genes associated with GA metabolism as well as a quantification of GA content in roots was made. Application of GA3 and its biosynthesis inhibitor prohexadione calcium (PrCa) combined with a GA‐constitutive response mutant (procera) were used to determine whether fungal colonization is altered by the level of these hormones or by changes in the GA‐signaling pathway. The increased levels of specific GAs from the 13‐hydroxylation pathway in mycorrhizal roots correlate closely with the increased expression of genes coding enzymes from the GA biosynthetic trail. The imbalance of GAs in tomato roots caused by exogenous applications of GA3 or PrCa affects arbuscules in both negative and positive ways, respectively. In addition, procera plants were adversely affected by the mycorrhization process. Our findings demonstrate that an imbalance in favor of an increased amount of GAs negatively affects the frequency of mycorrhization and particularly the arbuscular abundance in tomato mycorrhizal roots and the results point out that AM formation is associated with a change in the 13‐hydroxylation pathway of GAs.
Frequentist Accuracy of Bayesian Estimates
Authors: Efron Bradley
Published: September 2014

In the absence of relevant prior experience, popular Bayesian estimation techniques usually begin with some form of ‘uninformative’ prior distribution intended to have minimal inferential influence. The Bayes rule will still produce nice looking estimates and credible intervals, but these lack the logical force that is attached to experience-based priors and require further justification. The paper concerns the frequentist assessment of Bayes estimates. A simple formula is shown to give the frequentist standard deviation of a Bayesian point estimate. The same simulations as required for the point estimate also produce the standard deviation. Exponential family models make the calculations particularly simple and bring in a connection to the parametric bootstrap.
Quasi-Likelihood for Spatial Point Processes
Authors: Guan Yongtao , Jalilian Abdollah , Waagepetersen Rasmus
Published: September 2014

Fitting regression models for intensity functions of spatial point processes is of great interest in ecological and epidemiological studies of association between spatially referenced events and geographical or environmental covariates. When Cox or cluster process models are used to accommodate clustering that is not accounted for by the available covariates, likelihoodbased inference becomes computationally cumbersome owing to the complicated nature of the likelihood function and the associated score function. It is therefore of interest to consider alternative, more easily computable estimating functions. We derive the optimal estimating function in a class of first-order estimating functions. The optimal estimating function depends on the solution of a certain Fredholm integral equation which in practice is solved numerically. The derivation of the optimal estimating function has close similarities to the derivation of quasi-likelihood for standard data sets. The approximate solution is further equivalent to a quasi-likelihood score for binary spatial data. We therefore use the term quasi-likelihood for our optimal estimating function approach. We demonstrate in a simulation study and a data example that our quasi-likelihood method for spatial point processes is both statistically and computationally efficient.
ENVIRONMENTAL TAX AND TARIFFS UNDER THE INTERNATIONAL TRADE OF PRODUCTS
Authors: Kawasaki Akio , Ohno Tadahisa
Published: September 2014

Cross‐border consumption has become more popular, prompting a growing interest in the problems related to international trade. At the same time, trans‐boundary air pollution has become a major environmental problem, meriting increased attention in environmental economics literature. This study considers these problems in the context of environmental taxes and tariffs (or customs duties on imports), assuming quadratic environmental damage. We compare the environmental tax rate with and without a tariff and demonstrate that the former is lower than the latter. We then compare the level of social welfare with and without a tariff and demonstrate that when the degree of trans‐boundary air pollution is low (high), welfare without the tariff is higher (lower) than with it. Thus, a tariff is not always necessary from the viewpoint of social welfare.
Bayesian Estimators for Small Area Models when Auxiliary Information is Measured with Error
Authors: Arima Serena , Datta Gauri S. , Liseo Brunero
Published: September 2014

Small area estimators in linear models are typically expressed as a convex combination of direct estimators and synthetic estimators from a suitable model. When auxiliary information used in the model is measured with error, a new estimator, accounting for the measurement error in the covariates, has been proposed in the literature. Recently, for area‐level model, Ybarra & Lohr (Biometrika, 95, 2008, 919) suggested a suitable modification to the estimates of small area means based on Fay & Herriot (J. Am. Stat. Assoc., 74, 1979, 269) model where some of the covariates are measured with error. They used a frequentist approach based on the method of moments. Adopting a Bayesian approach, we propose to rewrite the measurement error model as a hierarchical model; we use improper non‐informative priors on the model parameters and show, under a mild condition, that the joint posterior distribution is proper and the marginal posterior distributions of the model parameters have finite variances. We conduct a simulation study exploring different scenarios. The Bayesian predictors we propose show smaller empirical mean squared errors than the frequentist predictors of Ybarra & Lohr (Biometrika, 95, 2008, 919), and they seem also to be more stable in terms of variability and bias. We apply the proposed methodology to two real examples.
Person‐related determinants of TV viewing and computer time in a cohort of young Dutch adults: Who sits the most?
Authors: Uijtdewilligen L. , Singh A. S. , Chinapaw M. J. M. , Twisk J. W. R. , van Mechelen W.
Published: September 2014

We aimed to assess the associations of person‐related factors with leisure time television (TV) viewing and computer time among young adults. We analyzed self‐reported TV viewing (h/week) and leisure computer time (h/week) from 475 Dutch young adults (47% male) who had participated in the Amsterdam Growth and Health Longitudinal Study at the age of 32 and 36 years. Sociodemographic factors (i.e., marital and employment status), physical factors (i.e., skin folds, aerobic fitness, neuromotor fitness, back problems), psychological factors (i.e., problem‐ and emotion‐focused coping, personality), lifestyle (i.e., alcohol consumption, smoking, energy intake, physical activity), and self‐rated health (i.e., general health status, mild health complaints) were assessed. Univariable and multivariable generalized estimating equations were performed. Male gender, higher sum of skin folds, lower values of aerobic fitness, higher rigidity, higher self‐sufficiency/recalcitrance, and smoking were positively associated with TV time. Male gender, higher sum of skin folds, higher scores on self‐esteem, low energy intake, and a not so good general health status were significantly associated with higher computer time. Determinants of TV viewing and computer time were not identical, suggesting that both behaviors (a) have different at‐risk populations and (b) should be targeted differently.
Local high relief at the southern margin of the Andean plateau by 9 Ma: evidence from ignimbritic valley fills and river incision
Authors: Montero‐López Carolina , Strecker Manfred R. , Schildgen Taylor F. , Hongn Fernando , Guzmán Silvina , Bookhagen Bodo , Sudo Masafumi
Published: September 2014

A valley‐filling ignimbrite re‐exposed through subsequent river incision at the southern margin of the Andean (Puna) plateau preserves pristine geological evidence of pre‐late Miocene palaeotopography in the north western Argentine Andes. Our new 40Ar/39Ar dating of the Las Papas Ignimbrites yields a plateau age of 9.24 ± 0.03 Ma, indicating valley‐relief and orographic‐barrier conditions comparable to the present‐day. A later infill of Plio–Pleistocene coarse conglomerates has been linked to wetter conditions, but resulted in no additional net incision of the Las Papas valley, considering that the base of the ignimbrite remains unexposed in the valley bottom. Our observations indicate that at least 550 m of local plateau margin relief (and likely >2 km) existed by 9 Ma at the southern Puna margin, which likely aided the efficiency of the orographic barrier to rainfall along the eastern and south eastern flanks of the Puna and causes aridity in the plateau interior.
Significant reduction of BiFC non‐specific assembly facilitates in planta assessment of heterotrimeric G‐protein interactors
Authors: Gookin Timothy E. , Assmann Sarah M.
Published: September 2014

Protein networks and signaling cascades are key mechanisms for intra‐ and intercellular signal transduction. Identifying the interacting partners of a protein can provide vital clues regarding its physiological role. The bimolecular fluorescence complementation (BiFC) assay has become a routine tool for in vivo analysis of protein–protein interactions and their subcellular location. Although the BiFC system has improved since its inception, the available options for in planta analysis are still subject to very low signal‐to‐noise ratios, and a systematic comparison of BiFC confounding background signals has been lacking. Background signals can obscure weak interactions, provide false positives, and decrease confidence in true positives. To overcome these problems, we performed an extensive in planta analysis of published BiFC fragments used in metazoa and plants, and then developed an optimized single vector BiFC system which utilizes monomeric Venus (mVenus) split at residue 210, and contains an integrated mTurquoise2 marker to precisely identify transformed cells in order to distinguish true negatives. Here we provide our streamlined double ORF expression (pDOE) BiFC system, and show that our advance in BiFC methodology functions even with an internally fused mVenus210 fragment. We illustrate the efficacy of the system by providing direct visualization of Arabidopsis MLO1 interacting with a calmodulin‐like (CML) protein, and by showing that heterotrimeric G‐protein subunits Gα (GPA1) and Gβ (AGB1) interact in plant cells. We further demonstrate that GPA1 and AGB1 each physically interact with PLDα1 in planta, and that mutation of the so‐called PLDα1 ‘DRY’ motif abolishes both of these interactions.
AUXIN RESPONSE FACTOR 3 integrates the functions of AGAMOUS and APETALA2 in floral meristem determinacy
Authors: Liu Xigang , Dinh Thanh Theresa , Li Dongming , Shi Bihai , Li Yongpeng , Cao Xiuwei , Guo Lin , Pan Yanyun , Jiao Yuling , Chen Xuemei
Published: September 2014

In Arabidopsis, AUXIN RESPONSE FACTOR 3 (ARF3) belongs to the auxin response factor (ARF) family that regulates the expression of auxin‐responsive genes. ARF3 is known to function in leaf polarity specification and gynoecium patterning. In this study, we discovered a previously unknown role for ARF3 in floral meristem (FM) determinacy through the isolation and characterization of a mutant of ARF3 that enhanced the FM determinacy defects of agamous (ag)‐10, a weak ag allele. Central players in FM determinacy include WUSCHEL (WUS), a gene critical for FM maintenance, and AG and APETALA2 (AP2), which regulate FM determinacy by repression and promotion of WUS expression, respectively. We showed that ARF3 confers FM determinacy through repression of WUS expression, and associates with the WUS locus in part in an AG‐dependent manner. We demonstrated that ARF3 is a direct target of AP2 and partially mediates AP2's function in FM determinacy. ARF3 exhibits dynamic and complex expression patterns in floral organ primordia; altering the patterns spatially compromised FM determinacy. This study uncovered a role for ARF3 in FM determinacy and revealed relationships among genes in the genetic network governing FM determinacy.
Modeling Inelastic Collisions With the Hunt–Crossley Model Using the Energetic Coefficient of Restitution
Authors: Jacobs Daniel A. , Waldron Kenneth J.
Published: September 2014

Modeling collision and contact accurately is essential to simulating many multibody systems. The three parameter Hunt–Crossley model is a continuous collision model for representing the contact dynamics of viscoelastic systems. By augmenting Hertz's elastic theory with a nonlinear damper, Hunt and Crossley captured part of the viscoelastic and velocity dependent behavior found in many systems. In the Hunt–Crossley model, the power parameter and the elastic coefficient can be related to the physical properties through Hertz's elastic theory but the damping coefficient cannot. Generally, the damping coefficient is related to an empirical measurement, the coefficient of restitution. Over the past few decades, several authors have posed relationships between the coefficient of restitution and the damping constant but key challenges remain. In the first portion of the paper, we derive an approximate expression for Stronge's (energetic) coefficient of restitution that has better accuracy for high velocities and low coefficient of restitution values than the published solutions based on Taylor series approximations. We present one method for selecting the model parameters from five empirical measurements using a genetic optimization routine. In the second portion of the paper, we investigate the application of the Hunt–Crossley model to an inhomogeneous system of a rubber covered aluminum sphere on a plate. Although this system does not fit the inclusion criteria for the Hunt–Crossley, it is representative of many systems of interest where authors have chosen the Hunt–Crossley model to represent the contact dynamics. The results show that a fitted model well predicts collision behavior at low values of the coefficient of restitution.
Intrinsic Localized Modes of Harmonic Oscillations in Pendulum Arrays Subjected to Horizontal Excitation
Authors: Ikeda Takashi , Harata Yuji , Nishimura Keisuke
Published: September 2014

The behavior of intrinsic localized modes (ILMs) is investigated for an array with N pendula which are connected with each other by weak, linear springs when the array is subjected to horizontal, sinusoidal excitation. In the theoretical analysis, van der Pol's method is employed to determine the expressions for the frequency response curves for fundamental harmonic oscillations. In the numerical calculations, the frequency response curves are presented for N = 2 and 3 and compared with the results of the numerical simulations. Patterns of oscillations are classified according to the stable steady-state solutions of the response curves, and the patterns in which ILMs appear are discussed in detail. The influence of the connecting springs of the pendula on the appearance of ILMs is examined. Increasing the values of the connecting spring constants may affect the excitation frequency range of ILMs and cause Hopf bifurcation to occur, followed by amplitude modulated motions (AMMs) including chaotic vibrations. The influence of the imperfections of the pendula on the system response is also investigated. Bifurcation sets are calculated to examine the influence of the system parameters on the excitation frequency range of ILMs and determine the threshold value for the connecting spring constant above which ILMs do not appear. Experiments were conducted for N = 2, and the data were compared with the theoretical results in order to confirm the validity of the theoretical analysis.
A New Method to Intra-Operatively Measure Local Bone Strength in Osteoporotic Bone Using a Modified Surgical Tool
Authors: Liddle Kate , Buckley Jenni M. , Matitiyahu Amir , Marmor Meir
Published: September 2014

The aim of this study was to test a novel method for intra-operative assessment of osteoporotic bone fracture strength using a surgical tool instrumented with a strain gauge and compare the device with cortical width (CW) measurements in the distal radius. The force needed to puncture the cortex (FNP) was quantified with the device and found to strongly correlate with bone mineral density (BMD) in the diaphysis (adj. R2 = 0.66, p < 0.001). Screw pullout studies were performed and correlation between FNP and screw pullout strength (SPS) was modest (adj. R2 = 0.34 with p < 0.05). CW correlated well with BMD (adj. R2 = 0.7, p < 0.0001) and SPS (adj. R2 = 0.5, p = 0.002) in the diaphysis. This technology may allow objective intra-operative assessment of bone strength to provide surgeons another tool for decision making on fixation strategies appropriate to the area of bone treated.
Two-Bar Thermal Ratcheting for Alloy 617—Part II: Ratcheting Results
Authors: Wang Yanli , Sham T.-L. , Jetter R. I.
Published: September 2014

This is Part II of a study on two-bar thermal ratcheting for Alloy 617. The ratcheting strains were evaluated for conditions with the same temperature range but with different mean stresses, heating and cooling rates, time delays, and thermal histories. These testing conditions were designed to be closely aligned to the development of design rules for strain limits at very high temperatures for Alloy 617. These new design rules have been formulated to address the fact that the effects of plastic deformation and creep deformation on the ratcheting strains are not separable at very high temperatures for this alloy.
ANCF Tire Assembly Model for Multibody System Applications
Authors: Shabana Ahmed A.
Published: September 2014

The aim of this paper is to propose a new numerical approach for modeling tires in multibody system (MBS) applications. In this approach, the tires, including the rigid rim, are modeled using one mesh developed using the finite element (FE) absolute nodal co-ordinate formulation (ANCF). The FE tire mesh, which allows for high spinning speed, has a constant inertia matrix and zero Coriolis and centrifugal forces. The connectivity conditions between the tire tread and rim are imposed at a preprocessing stage using linear constraint equations, thereby allowing for the elimination of dependent variables before the start of the simulation. The concept of the rim node is introduced in this paper to allow for the tire/axle assembly in MBS vehicle simulations. The rim node, which is not associated with a particular FE, is used to define the inertia of the rim, treated in this investigation as a rigid body. The procedure for evaluating the inertia coefficients associated with the rim node gradients is described. It is shown how fully parameterized ANCF beam and plate elements can be used to develop new tire geometry that captures details that cannot be captured using existing tire models. The concept of mixed ANCF FEs can also be used with both higher order fully parameterized and gradient deficient ANCF FEs to obtain a better distribution of the tire contact forces.
Effect of Sintering Parameters and Flow Agent on the Mechanical Properties of High Speed Sintered Elastomer
Authors: Norazman Farhana , Hopkinson Neil
Published: September 2014

High speed sintering (HSS) is an additive manufacturing (AM) process that creates parts by sintering powder particles using inkjet and infrared (IR) lamp technology rather than laser systems employed in laser sintering (LS). This research investigated the effects of machine parameters (lamp speed, bed temperature) and the addition of fumed silica flow agent on the tensile properties of thermoplastic elastomer (TPE) parts processed using HSS. The results showed improved elongation at break (EaB) values by a factor of more than 2× compared to reported values for LS of the same TPE. At constant parameters, improved tensile strength and tensile modulus were observed with the addition of flow agent into the sintering mixture.
Development and Modeling of Melt Electrohydrodynamic-Jet Printing of Phase-Change Inks for High-Resolution Additive Manufacturing
Authors: Wei Chuang , Dong Jingyan
Published: September 2014

This paper presents the development and modeling a high-resolution electrohydrodynamic-jet (EHD-jet) printing process using phase-change ink (i.e., wax), which is capable of producing sub-10 μm footprints (sub-10 fL in volume) for super-resolution additive manufacturing. In this study, we successfully apply EHD-jet printing for phase-change ink (wax), which is widely used as modeling and supporting material for additive manufacturing, to achieve micron-scale features. The resolution for single droplet on substrate is around 5 μm with the thickness in the range of 1–2 μm, which provides great potential in both high-resolution 3D printing and 2D drop-on-demand microfabrication. The droplet formation in EHD printing is modeled by finite element analysis (FEA). Two important forces in EHD printing, electrostatic force and surface tension force, are modeled separately by FEA. The droplet size is obtained by balancing the electrostatic force and surface tension of the pending droplets around meniscus apex. Furthermore, to predict the droplet dimension at different process conditions, a dimensionless scaling law is identified to describe the relationship between dimensionless droplet diameter and modified nondimensional electrical bond number. Finally, the droplets in-flight velocity and impact characteristics (e.g., Reynolds number and Weber number) are modeled using the results from FEA analysis.
On Process Temperature in Powder-Bed Electron Beam Additive Manufacturing: Model Development and Validation
Authors: Cheng Bo , Price Steven , Lydon James , Cooper Kenneth , Chou Kevin
Published: September 2014

Powder-bed beam-based metal additive manufacturing (AM) such as electron beam additive manufacturing (EBAM) has a potential to offer innovative solutions to many challenges and difficulties faced in the manufacturing industry. However, the complex process physics of EBAM has not been fully understood, nor has process metrology such as temperatures been thoroughly studied, hindering part quality consistency, efficient process development and process optimizations, etc., for effective EBAM usage. In this study, numerical and experimental approaches were combined to research the process temperatures and other thermal characteristics in EBAM using Ti–6Al–4V powder. The objective of this study was to develop a comprehensive thermal model, using a finite element (FE) method, to predict temperature distributions and history in the EBAM process. On the other hand, a near infrared (NIR) thermal imager, with a spectral range of 0.78 μm–1.08 μm, was employed to acquire build surface temperatures in EBAM, with subsequent data processing for temperature profile and melt pool size analysis. The major results are summarized as follows. The thermal conductivity of Ti–6Al–4V powder is porosity dependent and is one of critical factors for temperature predictions. The measured thermal conductivity of preheated powder (of 50% porosity) is 2.44 W/m K versus 10.17 W/m K for solid Ti–6Al–4V at 750 °C. For temperature measurements in EBAM by NIR thermography, a method was developed to compensate temperature profiles due to transmission loss and unknown emissivity of liquid Ti–6Al–4V. At a beam speed of about 680 mm/s, a beam current of about 7.0 mA and a diameter of 0.55 mm, the peak process temperature is on the order around 2700 °C, and the melt pools have dimensions of about 2.94 mm, 1.09 mm, and 0.12 mm, in length, width, and depth, respectively. In general, the simulations are in reasonable agreement with the experimental results with an average error of 32% for the melt pool sizes. From the simulations, the powder porosity is found critical to the thermal characteristics in EBAM. Increasing the powder porosity will elevate the peak process temperature and increase the melt pool size.
On Process Temperature in Powder-Bed Electron Beam Additive Manufacturing: Process Parameter Effects
Authors: Price Steven , Cheng Bo , Lydon James , Cooper Kenneth , Chou Kevin
Published: September 2014

Build part certification has been one of the primary roadblocks for effective usage and broader applications of metal additive manufacturing (AM) technologies including powder-bed electron beam additive manufacturing (EBAM). Process sensitivity to operating parameters, among others such as powder stock variations, is one major source of property scattering in EBAM parts. Thus, it is important to establish quantitative relations between the process parameters and process thermal characteristics that are closely correlated with the AM part properties. In this study, the experimental techniques, fabrications, and temperature measurements, developed in recent work (Cheng et al., 2014, "On Process Temperature in Powder-Bed Electron Beam Additive Manufacturing: Model Development and Experimental Validation," ASME J. Manuf. Sci. Eng., (in press)) were applied to investigate the process parameter effects on the thermal characteristics in EBAM with Ti-6Al-4 V powder, using the system-specific setting called “speed function (SF)” index that controls the beam speed and the beam current during a build. EBAM parts were fabricated using different levels of SF index (20–65) and examined in the part surface morphology and microstructures. In addition, process temperatures were measured by near infrared (NIR) thermography with further analysis of the temperature profiles and the melt pool size. The thermal model, also developed in recent work, was further employed for EBAM temperature predictions, and then compared with the experimental results. The major results are summarized as follows. SF index noticeably affects the thermal characteristics in EBAM, e.g., a melt pool length of 1.72 mm and 1.26 mm for SF20 and SF65, respectively, at 24.43 mm build height. SF setting also strongly affects the EBAM part quality including the surface morphology, surface roughness and part microstructures. In general, a higher SF index tends to produce parts of rougher surfaces with more pore features and large β grain columnar widths. Increasing the beam speed will reduce the peak temperatures, also reduce the melt pool sizes. Simulations conducted to evaluate the beam speed effects are in reasonable agreement compared to the experimental measurements in temperatures and melt pools sizes. However, the results of a lower SF case, SF20, show larger differences between the simulations and the experiments, about 58% for the melt pool size. Moreover, the higher the beam current, the higher the peak process temperatures, also the larger the melt pool. On the other hand, increasing the beam diameter monotonically decreases the peak temperature and the melt pool length.
Adjoint Method for Shape Optimization in Real-Gas Flow Applications
Authors: Pini M. , Persico G. , Pasquale D. , Rebay S.
Published: September 2014

An adjoint-based shape optimization approach for supersonic turbine cascades is proposed for application to organic Rankine cycle (ORC) turbines. The algorithm is based on an inviscid discrete adjoint method and encompasses a fast look-up table (LuT) approach to accurately deal with real-gas flows. The turbine geometry is defined by adopting state-of-the-art parameterization techniques (NURBS), enabling to handle both global and local control of the shape of interest. A preconditioned steepest descent method has been chosen as gradient-based optimization algorithm to efficiently search for the nearest minimum. The potential of the optimization approach is first verified by application on the redesign of an existing converging–diverging turbine nozzle operating in thermodynamic regions characterized by relevant real-gas effects. A significant efficiency improvement and a more uniform flow at the blade outlet section are achieved, with expected beneficial effects on the aerodynamics of the downstream rotor. The optimized configuration is also assessed by means of high-fidelity turbulent simulations, which point out the capability of the present inviscid approach in optimizing supersonic turbine cascades with very limited computational burdens. Finally, the newly developed real-gas adjoint method is compared against adjoints based on ideal equations of state on the same design problem. Results show that the performance gain obtained by a fully real-gas optimization strategy is by far higher than that achieved with simplified approaches in case of ORC turbines. This proves the relevance of including accurate thermodynamic models in all steps of ORC turbine design.
Comprehensive computer model for magnetron sputtering. II. Charged particle transport
Authors: Jimenez Francisco J. , Dew Steven K. , Field David J.
Published: September 2014

Discharges for magnetron sputter thin film deposition systems involve complex plasmas that are sensitively dependent on magnetic field configuration and strength, working gas species and pressure, chamber geometry, and discharge power. The authors present a numerical formulation for the general solution of these plasmas as a component of a comprehensive simulation capability for planar magnetron sputtering. This is an extensible, fully three-dimensional model supporting realistic magnetic fields and is self-consistently solvable on a desktop computer. The plasma model features a hybrid approach involving a Monte Carlo treatment of energetic electrons and ions, along with a coupled fluid model for thermalized particles. Validation against a well-known one-dimensional system is presented. Various strategies for improving numerical stability are investigated as is the sensitivity of the solution to various model and process parameters. In particular, the effect of magnetic field, argon gas pressure, and discharge power are studied.