bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Studies on Coupled Treatment of Chromite Ore Processing Residue
Authors: Chrysochoou Maria , Dermatas Dimitris , Christodoulatos Christos
Published: February 2009

A study was performed to investigate the combined treatment of hexavalent chromium (Cr(VI)) and heaving in Chromite Ore Processing Residue (COPR). Treatment of heaving focused on the intentional exhaustion of the mineral brownmillerite, the hydration of which is considered responsible for volume expansion in COPR deposition sites in New Jersey. The addition of sufficient amounts of sulfate under different conditions of temperature, acidity, and particle size aimed in the quick transformation of brownmillerite to ettringite, a phenomenon observed during a COPR pilot scale study. Simultaneously, the reductive treatment of hexavalent chromium (Cr(VI)) in COPR was pursued using calcium polysulfide (CPS) and ferrous sulfate (FS). X-ray Absorption Near Edge Spectroscopy (XANES) analyses showed that neither reductant was able to reduce Cr(VI) below 1,000 mg/kg after three months (FS) and six months (CPS) of treatment. However, competitive sulfide oxidation by oxygen was much slower compared to ferrous iron oxidation, as evidenced by chemical analyses. Quantitative X-ray diffraction analyses showed that brownmillerite dissolved to form ettringite only in a sample treated with FS at 50°C; neither acidity or temperature alone were able to trigger brownmillerite dissolution and ettringite formation. Particle size reduction to <150 μm had also no apparent effect in the rate of brownmillerite dissolution. Thus, CPS is deemed a more appropriate reductant for Cr(VI) treatment, while the exhaustion of brownmillerite appears to be a challenging engineering task.
Dose Reconstruction: The Use of Dose Reconstruction in the Determination of Human Exposure
Authors: Behling Alison R. , Anderson Kim E.
Published: February 2009

Dose reconstruction is a scientifically acceptable means to perform a retrograde or retrospective analysis of the preceding dose or for numerous exposures of an individual. It is used in a wide range of scientific applications, especially when contemporaneous or near contemporaneous exposure measurements from the time of interest or consideration are undefined. Dose reconstruction is used to attempt to consider numerous individual exposures. It accommodates for fluctuations in the intensity of the exposures and totaling the exposures into an estimated dose over a definitive time period or duration. This paper reviews a method to perform dose reconstruction when limited information is provided concerning the relevant exposure parameters. This methodology is not intended to replace the use of other dose reconstruction models that are available when definitive exposure parameter values are available. We show through the scientific literature and several examples using maximal or near maximal parameter values in calculating the dose that “dose reconstruction” is a valid method to determine retrospective exposure assessments. These retrospective exposure assessments may be used for the purposes of determining the maximal risk or a safety assessment, risk comparison, or toxicological relatedness or risk. The application of such a methodology is at times challenging in the authors’ work due to the limitations in the facts that are provided to them which describe the exposure parameters of an individual. These methods to perform the dose reconstructions are based on sound scientific foundation and are extremely versatile models which can be used in a variety of situations.
STAT5 Mediates Antiapoptotic Effects of Methylprednisolone on Oligodendrocytes
Authors: Xu Jan , Chen Shawei , Chen Hong , Xiao Qingli , Hsu Chung Y. , Michael Drew , Bao Jianxin
Published: February 2009

Methylprednisolone (MP), a synthetic glucocorticoid agonist, is widely used for the clinical therapy of white matter diseases in the nervous system, such as spinal cord injury and multiple sclerosis. In addition to its potent anti-inflammatory and antioxidant properties, we recently discovered a selective antiapoptotic effect of MP on oligodendrocytes via the activation of the glucocorticoid receptor (GR) and the upregulation of bcl-XL, a splicing isoform of thebcl-xgene. Based on published findings of the functional interactions between GR and STAT5, a transcription factor from the family of signal transducers and activators of transcription (STAT), we examined whether the glucocorticoid signaling pathway interacts with STAT5 to upregulate bcl-XLand protect oligodendrocytes. We show herein that (1) the GR and STAT5 complex is present on the STAT5-binding site of the bcl-x promoter region in oligodendrocytes; (2) the overexpression of an activated form of STAT5 prevents α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid-induced oligodendrocyte cell death; and (3) this prevention is lost when theSTAT5gene is knocked down. Thus, our results provide one molecular mechanism underlying the postinjury protective effects of oligodendrocytes by stress hormones.
Cannabidiol Targets Mitochondria to Regulate Intracellular Ca2+Levels
Authors: Ryan Duncan , Drysdale Alison J. , Lafourcade Carlos , Pertwee Roger G. , Platt Bettina
Published: February 2009

Cannabinoids and the endocannabinoid system have attracted considerable interest for therapeutic applications. Nevertheless, the mechanism of action of one of the main nonpsychoactive phytocannabinoids, cannabidiol (CBD), remains elusive despite potentially beneficial properties as an anti-convulsant and neuroprotectant. Here, we characterize the mechanisms by which CBD regulates Ca2+homeostasis and mediates neuroprotection in neuronal preparations. Imaging studies in hippocampal cultures using fura-2 AM suggested that CBD-mediated Ca2+regulation is bidirectional, depending on the excitability of cells. Under physiological K+/Ca2+levels, CBD caused a subtle rise in [Ca2+]i, whereas CBD reduced [Ca2+]iand prevented Ca2+oscillations under high-excitability conditions (high K+or exposure to the K+channel antagonist 4AP). Regulation of [Ca2+]iwas not primarily mediated by interactions with ryanodine or IP3receptors of the endoplasmic reticulum. Instead, dual-calcium imaging experiments with a cytosolic (fura-2 AM) and a mitochondrial (Rhod-FF, AM) fluorophore implied that mitochondria act as sinks and sources for CBD's [Ca2+]iregulation. Application of carbonylcyanide-p-trifluoromethoxyphenylhydrazone (FCCP) and the mitochondrial Na+/Ca2+exchange inhibitor, CGP 37157, but not the mitochondrial permeability transition pore inhibitor cyclosporin A, prevented subsequent CBD-induced Ca2+responses. In established human neuroblastoma cell lines (SH-SY5Y) treated with mitochondrial toxins, CBD (0.1 and 1 μm) was neuroprotective against the uncoupler FCCP (53% protection), and modestly protective against hydrogen peroxide- (16%) and oligomycin- (15%) mediated cell death, a pattern also confirmed in cultured hippocampal neurons. Thus, under pathological conditions involving mitochondrial dysfunction and Ca2+dysregulation, CBD may prove beneficial in preventing apoptotic signaling via a restoration of Ca2+homeostasis.
Own-Song Recognition in the Songbird Auditory Pathway: Selectivity and Lateralization
Authors: Poirier Colline , Boumans Tiny , Verhoye Marleen , Balthazart Jacques , Van der Linden Annemie
Published: February 2009

The songbird brain is able to discriminate between the bird's own song and other conspecific songs. Determining where in the brain own- song selectivity emerges is of great importance because experience-dependent mechanisms are necessarily involved and because brain regions sensitive to self-generated vocalizations could mediate auditory feedback that is necessary for song learning and maintenance. Using functional MRI, here we show that this selectivity is present at the midbrain level. Surprisingly, the selectivity was found to be lateralized toward the right side, a finding reminiscent of the potential right lateralization of song production in zebra finches but also of own-face and own-voice recognition in human beings. These results indicate that a midbrain structure can process subtle information about the identity of a subject through experience-dependent mechanisms, challenging the classical perception of subcortical regions as primitive and nonplastic structures. They also open questions about the evolution of the cognitive skills and lateralization in vertebrates.
The Cochaperone BAG2 Sweeps Paired Helical Filament- Insoluble Tau from the Microtubule
Authors: Carrettiero Daniel C. , Hernandez Israel , Neveu Pierre , Papagiannakopoulos Thales , Kosik Kenneth S.
Published: February 2009

Tau inclusions are a prominent feature of many neurodegenerative diseases including Alzheimer's disease. Their accumulation in neurons as ubiquitinated filaments suggests a failure in the degradation limb of the Tau pathway. The components of a Tau protein triage system consisting of CHIP/Hsp70 and other chaperones have begun to emerge. However, the site of triage and the master regulatory elements are unknown. Here, we report an elegant mechanism of Tau degradation involving the cochaperone BAG2. The BAG2/Hsp70 complex is tethered to the microtubule and this complex can capture and deliver Tau to the proteasome for ubiquitin-independent degradation. This complex preferentially degrades Sarkosyl insoluble Tau and phosphorylated Tau. BAG2 levels in cells are under the physiological control of the microRNA miR-128a, which can tune paired helical filament Tau levels in neurons. Thus, we propose that ubiquitinated Tau inclusions arise due to shunting of Tau degradation toward a less efficient ubiquitin-dependent pathway.
Trophic Factor-Induced Intracellular Calcium Oscillations Are Required for the Expression of Postsynaptic Acetylcholine Receptors during Synapse Formation betweenLymnaeaNeurons
Authors: Xu Fenglian , Hennessy Deirdre A. , Lee Thomas K. M. , Syed Naweed I.
Published: February 2009

Nervous system functions in all animals rely upon synaptic connectivity that is established during early development. Whereas cell–cell signaling plays a critical role in establishing synapse specificity, the involvement of extrinsic growth factors cannot, however, be undermined. We have previously demonstrated that trophic factors are required for excitatory but not inhibitory synapse formation betweenLymnaeaneurons. Moreover, in the absence of trophic factors, neurons from a number of species establish inappropriate inhibitory synapses, which can, however, be corrected by the addition of trophic factors. The precise site of trophic factor actions (presynaptic versus postsynaptic) and the underlying mechanisms remain, however, undefined. Here, we provide the first direct evidence that the trophic factor-mediated excitatory synapse formation involves activity-induced calcium (Ca2+) oscillations in the postsynaptic left pedal dorsal 1 (LPeD1) but not the presynaptic visceral dorsal 4 (VD4, cholinergic) neuron. These oscillations involved Ca2+influx through voltage-gated Ca2+channels and required receptor tyrosine kinase activity which was essential for the expression of excitatory, nicotinic acetylcholine receptors in the postsynaptic cell during synapse formation. We also demonstrate that selectively blocking the electrical activity presynaptically did not perturb trophic factor-induced synapse formation between the paired cells, whereas hyperpolarizing the postsynaptic cell prevented appropriate synaptogenesis between VD4 and LPeD1 cells. Together, our data underscore the importance of extrinsic trophic factors in regulating the electrical activity of the postsynaptic but not the presynaptic cell and that the resulting Ca2+oscillations are essential for the expression of postsynaptic receptors during specific synapse formation.
Involvement of the Cytoplasmic C-Terminal Domain of Connexin43 in Neuronal Migration
Authors: Cina Cima , Maass Karen , Theis Martin , Willecke Klaus , Bechberger John F. , Naus Christian C.
Published: February 2009

During brain development, young neurons closely associate with radial glial while migrating from the ventricular zone (VZ) to the cortical plate (CP) of the neocortex. It has been shown previously that gap junctions are needed for this migration to occur properly, but the precise mechanism responsible is still in question. Here, we used Cre recombinase, driven by the nestin promoter, to conditionally knock-out a floxed coding DNA of the connexin43 (Cx43) gene in mice. Radial glia in the VZ normally express connexin43. They undergo divisions that produce neurons and astrocytes and serve as migratory guides for the daughter cells that they produce. Based on histological analysis, we suggest that removing Cx43 from radial glia alters the normal lamination of the mouse neocortex. To monitor newborn neurons during development, we introduced a plasmid containing green fluorescent protein driven by a neuronal (Tα1 tubulin) promoter into the embryonic neocortex usingin uteroelectroporation. The transfected migrating neurons remain in the VZ/intermediate zone (IZ) of the Cx43 conditional knock-out (Cx43cKO) animals, whereas inCx43fl/flmice, neurons migrate through the IZ into the CP, indicating that deletion of Cx43 from nestin-positive cells disrupts neuronal migration. We were able to rescue migration ofCx43cKOneurons by electroporating a cytomegalovirus–Cx43 expression plasmid into the embryonic cortex. In contrast, a C-terminal truncated form of Cx43 failed to rescue neuronal migration. In addition,Cx43K258stopmice, in which Cx43 lacks the last 125 amino acid residues of the cytoplasmic C-terminal domain, gave results similar to those seen with theCx43cKOmice. This study illustrates that deletion of the C-terminal domain of Cx43 alters neuronal migration in the neocortex.
Bacterial Artificial Chromosome Transgenic Mice Expressing a Truncated Mutant Parkin Exhibit Age-Dependent Hypokinetic Motor Deficits, Dopaminergic Neuron Degeneration, and Accumulation of Proteinase K-Resistant α-Synuclein
Authors: Lu Xiao-Hong , Fleming Sheila M. , Meurers Bernhard , Ackerson Larry C. , Mortazavi Farzad , Lo Victor , Hernandez Daniela , Sulzer David , Jackson George R. , Maidment Nigel T. , Chesselet Marie-Francoise , Yang X. William
Published: February 2009

Recessive mutations in parkin are the most common cause of familial early-onset Parkinson's disease (PD). Recent studies suggest that certain parkin mutants may exert dominant toxic effects to cultured cells and such dominant toxicity can lead to progressive dopaminergic (DA) neuron degeneration inDrosophila. To explore whether mutant parkin could exert similar pathogenic effects to mammalian DA neuronsin vivo, we developed a BAC (bacterial artificial chromosome) transgenic mouse model expressing a C-terminal truncated human mutant parkin (Parkin-Q311X) in DA neurons driven by a dopamine transporter promoter. Parkin-Q311X mice exhibit multiple late-onset and progressive hypokinetic motor deficits. Stereological analyses reveal that the mutant mice develop age-dependent DA neuron degeneration in substantia nigra accompanied by a significant loss of DA neuron terminals in the striatum. Neurochemical analyses reveal a significant reduction of the striatal dopamine level in mutant mice, which is significantly correlated with their hypokinetic motor deficits. Finally, mutant Parkin-Q311X mice, but not wild-type controls, exhibit age-dependent accumulation of proteinase K-resistant endogenous α-synuclein in substantia nigra and colocalized with 3-nitrotyrosine, a marker for oxidative protein damage. Hence, our study provides the first mammalian genetic evidence that dominant toxicity of a parkin mutant is sufficient to elicit age-dependent hypokinetic motor deficits and DA neuron lossin vivo, and uncovers a causal relationship between dominant parkin toxicity and progressive α-synuclein accumulation in DA neurons. Our study underscores the need to further explore the putative link between parkin dominant toxicity and PD.
Ca2+–Calmodulin Feedback Mediates Sensory Adaptation and Inhibits Pheromone-Sensitive Ion Channels in the Vomeronasal Organ
Authors: Spehr Jennifer , Hagendorf Silke , Weiss Jan , Spehr Marc , Leinders-Zufall Trese , Zufall Frank
Published: February 2009

The mammalian vomeronasal organ (VNO) mediates the regulation of social behaviors by complex chemical signals. These cues trigger transient elevations of intracellular Ca2+in vomeronasal sensory neurons (VSNs), but the functional role of such Ca2+elevations is unknown. We show that stimulus-induced Ca2+entry plays an essential role as a negative feedback regulator of VSN sensitivity. Electrophysiological VSN responses undergo effective sensory adaptation that requires the influx of Ca2+and is mediated by calmodulin (CaM). Removal of the Ca2+–CaM feedback eliminates this form of adaptation. A key target of this feedback module is the pheromone-sensitive TRPC2-dependent cation channel of VSNs, as its activation is strongly inhibited by Ca2+–CaM. Our results reveal a previously unrecognized CaM-signaling pathway that endows the VSNs with a mechanism for adjusting gain and sensitivity of chemosensory signaling in the VNO.
Restricted Cortical and Amygdaloid Removal of Vesicular Glutamate Transporter 2 in Preadolescent Mice Impacts Dopaminergic Activity and Neuronal Circuitry of Higher Brain Function
Authors: Wallén-Mackenzie Åsa , Nordenankar Karin , Fejgin Kim , Lagerström Malin C. , Emilsson Lina , Fredriksson Robert , Wass Caroline , Andersson Daniel , Egecioglu Emil , Andersson My , Strandberg Joakim , Lindhe Örjan , Schiöth Helgi B. , Chergui Karima , Hanse Eric , Långström Bengt , Fredriksson Anders , Svensson Lennart , Roman Erika , Kullander Klas
Published: February 2009

A major challenge in neuroscience is to resolve the connection between gene functionality, neuronal circuits, and behavior. Most, if not all, neuronal circuits of the adult brain contain a glutamatergic component, the nature of which has been difficult to assess because of the vast cellular abundance of glutamate. In this study, we wanted to determine the role of a restricted subpopulation of glutamatergic neurons within the forebrain, theVglut2-expressing neurons, in neuronal circuitry of higher brain function.Vglut2expression was selectively deleted in the cortex, hippocampus, and amygdala of preadolescent mice, which resulted in increased locomotor activity, altered social dominance and risk assessment, decreased sensorimotor gating, and impaired long-term spatial memory. Presynaptic VGLUT2-positive terminals were lost in the cortex, striatum, nucleus accumbens, and hippocampus, and a downstream effect on dopamine binding site availability in the striatum was evident. A connection between the induced late-onset, chronic reduction of glutamatergic neurotransmission and dopamine signaling within the circuitry was further substantiated by a partial attenuation of the deficits in sensorimotor gating by the dopamine-stabilizing antipsychotic drug aripiprazole and an increased sensitivity to amphetamine. Somewhat surprisingly, given the restricted expression ofVglut2in regions responsible for higher brain function, our analyses show that VGLUT2-mediated neurotransmission is required for certain aspects of cognitive, emotional, and social behavior. The present study provides support for the existence of a neurocircuitry that connects changes in VGLUT2-mediated neurotransmission to alterations in the dopaminergic system with schizophrenia-like behavioral deficits as a major outcome.
William Wordsworth and Photographic Subjectivity
Authors: Hess Scott
Published: February 2009

This essay argues that William Wordsworth's poetry constructs a subject position analogous to that of the photographic viewer: hence, a photographic subjectivity. Critics have often read Wordsworth's writing as opposing imagination against visibility and mimetic realism. Many of the visual structures of his poetry, however, continue the structures of the picturesque, whose desire to capture the landscape as framed image culminated in the technology of photography. These structures of perception include the stationed point of view of the observer, focusing the scene from a single location; the tendency to reduce the multisensory, ambient experience of lived environment to pure vision; the separation of the observer from the landscape; and the resulting general disembodiment of that observer. Much of Wordsworth's poetry positions the observer in these ways in order to capture images that can then be viewed in private isolation (as in the “spots of time”), like a series of internalized photographs. These structures of visuality construct what would emerge, after the invention of photography, as a photographic subjectivity, complementing (rather than opposing) the objectivity of the photographic image. They define the viewing subject, in the manner of photography, as a mobile, seemingly autonomous self in an appropriative relationship to landscape—the paradigm of the modern self, taking a “view from nowhere” on a world captured as image. The stability, unity, and autonomy of the Wordsworthian self ultimately depend on these photographic relationships.
Becoming A Fulfilled Jew: An Ethnographic Study of a British Messianic Jewish Congregation
Authors: Dein Simon
Published: February 2009

This paper discusses the findings of ethnographic fieldwork among a congregation of British Messianic Jews. After a description of the history and theology of the movement, it describes various themes expressed by informants who have come to accept Yeshua as the Messiah: An ethnic as opposed to a spiritual religious identity; dissatisfaction with Judaism; the influence of family and social networks outside the home; a religious search; a process of intellectual resolution; the importance of personal religious experience; dealing with crises; social support provided by members of the congregation; and the perceived importance of Messianic Judaism giving them a close relationship with God or Yeshua. The importance of religious experience and theological conflict are emphasized. The findings are discussed in relation to the conversion process described by Lewis Rambo.
Rapid effects of LH on gene expression in the mural granulosa cells of mouse periovulatory follicles
Authors: Carletti Martha Z , Christenson Lane K
Published: February 2009

LH acts on periovulatory granulosa cells by activating the PKA pathway as well as other cell signaling cascades to increase the transcription of specific genes necessary for ovulation and luteinization. Collectively, these cell signaling responses occur rapidly (within minutes); however, presently no high throughput studies have reported changes before 4 h after the LH surge. To identify early response genes that are likely critical for initiation of ovulation and luteinization, mouse granulosa cells were collected before and 1 h after hCG. Fifty-seven gene transcripts were significantly (P<0.05) upregulated and three downregulated following hCG. Twenty-four of these transcripts were known to be expressed after the LH/hCG surge at later time points, while 36 were unknown to be expressed by periovulatory granulosa cells. Temporal expression of several transcripts, including the transcription factorsNr4a1,Nr4a2,Egr1,Egr2,Btg1, andBtg2, and the epidermal growth factor (EGF)-like ligandsAregandEreg, were analyzed by quantitative RT-PCR, and their putative roles in granulosa cell function are discussed. Epigen (Epgn), another member of the family of EGF-like ligands was identified for the first time in granulosa cells as rapidly induced by LH/hCG. We demonstrate thatEpgninitiates cumulus expansion, similar to the other EGF-receptor ligandsAregandEreg. These studies illustrate that a number of changes in gene expression occurin vivoin response to LH, and that many of the differentially expressed genes are transcription factors that we would predict in turn modulate granulosa cell gene expression to ultimately impact the processes of ovulation and luteinization.
Immune response to bacteria in seminiferous epithelium
Authors: Nagaosa Kaz , Nakashima Chie , Kishimoto Atsushi , Nakanishi Yoshinobu
Published: February 2009

The luminal part of the seminiferous epithelium, a tissue compartment protected by the blood–testis barrier, has been considered a site of immune privilege. However, there are reports describing the production of anti-microbial peptides and the expression of Toll-like receptors in cells present in the seminiferous epithelium, evoking the possibility that this tissue compartment is immunologically active at least with regard to the innate immune response. To test this, we injectedEscherichia coliinto seminiferous tubules of live mice and examined the fate of bacteria, the production of chemokines and inflammatory cytokines, and the infiltration of neutrophils. The bacteria actively propagated and reached a maximal level in a day, but started to decrease after 5 days and completely disappeared in 2 months. The expression of macrophage inflammatory protein-2 and tumor necrosis factor-α became evident in macrophages present in the interstitial compartment of testes as early as 1–3 h after the inoculation of bacteria. Neutrophils first accumulated in the interstitial space at 9–12 h and entered the tubules after a day. On the other hand, impairment of spermatogenesis was observed a day after bacteria injection and seemed unrecoverable even after the bacteria were eliminated. By contrast, bacteria injected into the interstitial compartment were more rapidly cleared with no damage in the seminiferous epithelium. These results suggest the existence of immunity against invading microbes in the seminiferous epithelium although its effectiveness in maintaining tissue homeostasis remains equivocal.
The DAZL and PABP families: RNA-binding proteins with interrelated roles in translational control in oocytes
Authors: Brook Matthew , Smith Joel W S , Gray Nicola K
Published: February 2009

Gametogenesis is a highly complex process that requires the exquisite temporal, spatial and amplitudinal regulation of gene expression at multiple levels. Translational regulation is important in a wide variety of cell types but may be even more prevalent in germ cells, where periods of transcriptional quiescence necessitate the use of post-transcriptional mechanisms to effect changes in gene expression. Consistent with this, studies in multiple animal models have revealed an essential role for mRNA translation in the establishment and maintenance of reproductive competence. While studies in humans are less advanced, emerging evidence suggests that translational regulation plays a similarly important role in human germ cells and fertility. This review highlights specific mechanisms of translational regulation that play critical roles in oogenesis by activating subsets of mRNAs. These mRNAs are activated in a strictly determined temporal manner via elements located within their 3′UTR, which serve as binding sites fortrans-acting factors. While we concentrate on oogenesis, these regulatory events also play important roles during spermatogenesis. In particular, we focus on the deleted in azoospermia-like (DAZL) family of proteins, recently implicated in the translational control of specific mRNAs in germ cells; their relationship with the general translation initiation factor poly(A)-binding protein (PABP) and the process of cytoplasmic mRNA polyadenylation.
A 12‐bit segmented resistor‐capacitor digital‐to‐analog converter for a display driver IC of a large TFT‐LCD panel system
Authors: Yoo Seongjong , Song Yongjoo , Jung Jiwoon , Lee Myunghee
Published: February 2009

Abstract— A 12‐bit segmented R‐C DAC to support a linear gamma curve has been proposed and fabricated in a 720‐channel LCD source driver with a 16‐V 1‐poly 3‐metal high‐voltage CMOS process. The proposed DAC has a global resistor string and sample‐and‐hold buffers. A MSB voltage selected by the upper 6 bits of input data and a LSB voltage selected by the lower 6 bits of input data are summed by using a sample‐and‐hold operation with offset cancellation in the proposed DAC. The measured DNL was less than 0.3 LSB, and the output voltage deviation was less than 3 mV in all gray levels. Although two sample‐and‐hold buffers were adopted to operate alternatively, the die size was as small as 24.9 mm2, which was only an 8.3% increase compared to that of a conventional 8‐bit 720‐channel source driver. Because of its good performance with small area, the proposed DAC can be a good low‐cost solution for a 10‐bit TV system.
Color‐breakup suppression and low‐power consumption by using the Stencil‐FSC method in field‐sequential LCDs
Authors: Lin Fang‐Cheng , Huang Yi‐Pai , Wei Ching‐Ming , Shieh Han‐Ping D.
Published: February 2009

Abstract— Field‐sequential color (FSC) is a potential technique for low‐power liquid‐crystal displays (LCDs). However, it still experiences a serious visual artifact, color break‐up (CBU), which degrades image quality. Consequently, the “Stencil Field‐Sequential‐Color (Stencil‐FSC)” method, which applies local color‐backlight‐dimming technology at a 240‐Hz field rate to FSC‐LCDs, is proposed. Using the Stencil‐FSC method not only suppressed CBU efficiently but also enhanced the image contrast ratio by using low average power consumption. After backlight signal optimization, the Stencil‐FSC method was demonstrated on a 32‐in. FSC‐LCD and effectively suppressed the CBU, which resulted in more than a 27,000:1 dynamic contrast ratio and less than 40‐W average power consumption.
Efficient and compact green laser for micro‐projector applications
Authors: Bhatia Vikram , Gregorski Steven J. , Pikula Dragan , Chaparala Satish C. , Loeber David A. S. , Gollier Jacques , Gregorski Joan D. , Hempstead Martin , Ozeki Yukihiro , Hata Yoshiaki , Shibatani Kazuhiro , Nagai Fumio , Mori Nobuyoshi , Nakabayashi Yukinobu , Mitsugi Naoki , Nakano Satoshi
Published: February 2009

Abstract— Efficient and compact green lasers are keystone components for micro‐projector applications in mobile devices. An architecture that consists of an infrared‐producing DBR (distributed Bragg reflector) laser with a frequency‐doubling crystal is used to synthesize a green laser that has high electrical‐to‐optical conversion efficiency and can be modulated at speeds required for scanner‐based projectors. The design and performance of a green‐laser package that uses adaptive optics to overcome the challenge of maintaining alignment between the waveguides of the DBR laser and the frequency‐doubling crystal over temperature and lifetime is described. The adaptive optics technology that is employed uses the piezo‐based smooth impact drive mechanism (SIDM) actuators that offer a very small step size and a range of travel adequate for the alignment operation. The laser is shown to be compact (0.7 cm3 in volume) and capable of a wall‐plug efficiency approaching 10% (at 100‐mW green power). It was demonstrated that the adaptive optics enables operation over a wide temperature range (10–60°C) and provides the capability for low‐cost assembly of the device.
Effect of geometrical characteristics of a scribing wheel on the bending strength of LCD glass substrates
Authors: Liao Y. S. , Yang G. M. , Hsu Y. S.
Published: February 2009

Abstract— Scribing followed by a breaking method has often been applied to separate the individual liquid‐crystal‐display (LCD) glass panels from the mother cells. In some special occasions, especially for compact mobile devices, the bending strength of the glass substrates after breakage is the most important concern. In this study, the effect of the geometrical characteristics of the scribing wheel on the bending strength of LCD glass substrates was investigated. A volume‐crack effective coefficient was defined to estimate the effect of different geometrical characteristics of the scribing wheels. It was found that there is a strong correlation between the bending strength and the coefficient before chipping appears as the scribing load is increased. Thus, the coefficient can be used for the assessment of the geometrical effect of scribing wheels on the bending strength of glass substrates.
Following the fish: penguins and productivity in the South Atlantic
Authors: Boersma P. Dee , Rebstock Ginger A. , Frere Esteban , Moore Sue E.
Published: February 2009

We tested four predictions for central‐place foragers provisioning offspring along a gradient in primary production spanning 1000 km of coastline in Argentina, using male Magellanic Penguins (Spheniscus magellanicus). Three of the predictions were supported. (1) Foraging trip distances corresponded with the production gradient; penguins swam shorter distances (mean maximum distance: 60–110 km) at the southern colonies where production is higher and prey species aggregate nearshore, and longer distances (143–242 km) at the northern colonies where production is lower and prey species aggregate at offshore fronts. Within these broad regions, foraging locations coincided with tidal mixing fronts or high chlorophyll concentrations. (2) Foraging trips followed a pattern of intermediate speed and meandering when outbound (32% of locations at sea), slow meandering movements within the foraging areas (45%), and very fast and direct returns to the colony (23%). Regardless of how far they went, penguins spent the most time at the outer limits of their trips, and travel speed slowed there, consistent with foraging. In 54% of trips, penguins left foraging patches between 15:00 and 21:00 hours, presumably with full loads for chicks. Returning penguins swam up to 173 km/d (2 m/s), swimming day and night and arriving at all hours to feed chicks. (3) Penguins stayed longer in more distant than closer foraging areas, presumably to feed themselves to recover the increased cost of swimming. One prediction was not supported. (4) Following a long trip, penguins did not meander more on their next outbound trip. Most penguins returned repeatedly to the same area to forage or alternated between two areas. Overall, penguin foraging patterns reflected patterns of oceanographic production, making them important sentinels of environmental variation.
Impacts of insect herbivory on cactus population dynamics: experimental demography across an environmental gradient
Authors: Miller Tom E. X. , Louda Svata M. , Rose Karen A. , Eckberg James O.
Published: February 2009

Understanding the role of consumers in plant population dynamics is important, both conceptually and practically. Yet, while the negative effects of herbivory on plant performance have been well documented, we know much less about how individual‐level damage translates to impacts on population growth or whether spatial variation in herbivory affects patterns of plant distribution. We studied the role of insect herbivory in the dynamics and distribution of the tree cholla cactus (Opuntia imbricata), a long‐lived perennial plant, across an elevational gradient in central New Mexico, USA, from low‐elevation grassland (1670 m) to a grassland–mountain transition zone (1720 m) to the rocky slopes of the Los Pinos Mountains (1790 m). Tree cholla density increased significantly with elevation, while abundance of and damage by a suite of native, cactus‐feeding insects decreased. We combined field experiments and demographic models to test the hypothesis that systematic spatial variation in chronic insect herbivory limits the tree cholla distribution to a subset of suitable habitat across the gradient. Our results support this hypothesis.

We found that key demographic functions (survival, growth, fecundity) and the responses of these functions to experimental reductions in insect herbivory varied across the gradient. The effects of insect exclusion on plant growth and seed production were strongest in the low‐elevation grassland and decreased in magnitude with increasing elevation. We used the experimental data to parameterize integral projection models (IPM), which predict the asymptotic rate of population increase (λ). The modeling results showed that insect herbivory depressed λ and that the magnitude of this effect was context‐dependent. The effect of insect herbivory on population growth was strongest at low elevation (Δλlow = 0.095), intermediate at mid elevation (Δλmid = 0.046), and weakest at high elevation (Δλhigh = −0.0089). The total effect of insects on λ was due to a combination of reductions in growth and in fecundity and their combination; the relative contribution of each of these effects varied spatially. Our results, generated by experimental demography across a heterogeneous landscape, provide new insights into the role of native consumers in the population dynamics and distribution of abundance of long‐lived native plants.
Predicting 21st‐century polar bear habitat distribution from global climate models
Authors: Durner George M. , Douglas David C. , Nielson Ryan M. , Amstrup Steven C. , McDonald Trent L. , Stirling Ian , Mauritzen Mette , Born Erik W. , Wiig Øystein , DeWeaver Eric , Serreze Mark C. , Belikov Stanislav E. , Holland Marika M. , Maslanik James , Aars Jon , Bailey David A. , Derocher Andrew E.
Published: February 2009

Projections of polar bear (Ursus maritimus) sea ice habitat distribution in the polar basin during the 21st century were developed to understand the consequences of anticipated sea ice reductions on polar bear populations. We used location data from satellite‐collared polar bears and environmental data (e.g., bathymetry, distance to coastlines, and sea ice) collected from 1985 to 1995 to build resource selection functions (RSFs). RSFs described habitats that polar bears preferred in summer, autumn, winter, and spring. When applied to independent data from 1996 to 2006, the RSFs consistently identified habitats most frequently used by polar bears. We applied the RSFs to monthly maps of 21st‐century sea ice concentration projected by 10 general circulation models (GCMs) used in the Intergovernmental Panel of Climate Change Fourth Assessment Report, under the A1B greenhouse gas forcing scenario. Despite variation in their projections, all GCMs indicated habitat losses in the polar basin during the 21st century. Losses in the highest‐valued RSF habitat (optimal habitat) were greatest in the southern seas of the polar basin, especially the Chukchi and Barents seas, and least along the Arctic Ocean shores of Banks Island to northern Greenland. Mean loss of optimal polar bear habitat was greatest during summer; from an observed 1.0 million km2 in 1985–1995 (baseline) to a projected multi‐model mean of 0.32 million km2 in 2090–2099 (−68% change). Projected winter losses of polar bear habitat were less: from 1.7 million km2 in 1985–1995 to 1.4 million km2 in 2090–2099 (−17% change). Habitat losses based on GCM multi‐model means may be conservative; simulated rates of habitat loss during 1985–2006 from many GCMs were less than the actual observed rates of loss. Although a reduction in the total amount of optimal habitat will likely reduce polar bear populations, exact relationships between habitat losses and population demographics remain unknown. Density and energetic effects may become important as polar bears make long‐distance annual migrations from traditional winter ranges to remnant high‐latitude summer sea ice. These impacts will likely affect specific sex and age groups differently and may ultimately preclude bears from seasonally returning to their traditional ranges.
Like a rolling stone: the mobility of maerl (Corallinaceae) and the neutrality of the associated assemblages
Authors: Hinojosa-Arango Gustavo , Maggs Christine A. , Johnson Mark P.
Published: February 2009

Beds of nonattached coralline algae (maerl or rhodoliths) are widespread and considered relatively species rich. This habitat is generally found in areas where there is chronic physical disturbance such that maerl thalli are frequently moved. Little is known, however, about how natural disturbance regimes affect the species associated with maerl. This study compared the richness, animal abundance, and algal biomass of maerl‐associated species over a two‐year period in a wave‐disturbed bed and a sheltered maerl bed. Changes in associated species over time were assessed for departures from a neutral model in which the dissimilarity between samples reflects random sampling from a common species pool. Algal biomass and species richness at the wave‐exposed site and on stabilized maerl at the sheltered site were reduced at times of higher wind speeds. The changes in species richness were not distinguishable from a neutral model, implying that algal species were added at random to the assemblage as the level of disturbance lessened. Results for animal species were more mixed. Although mobile species were less abundant during windy periods at the exposed site, both neutral and non‐neutral patterns were evident in the assemblages. Artificial stabilization of maerl had inconsistent effects on the richness of animals but always resulted in more attached algal species. While the results show that the response of a community to disturbance can be neutral, the domain of neutral changes in communities may be relatively small. Alongside non‐neutral responses to natural disturbance, artificial stabilization always resulted in an assemblage that was more distinct than would be expected under random sampling from a common pool. Community responses to stabilization treatments did not consistently follow the predictions of the dynamic equilibrium model, the intermediate disturbance model, or a facilitation model. These inconsistencies may reflect site‐specific variation in both the disturbance regime and the adjacent habitats that provide source populations for many of the species found associated with maerl.
A boom–bust phylum? Ecological and evolutionary consequences of density variations in echinoderms
Authors: Uthicke Sven , Schaffelke Britta , Byrne Maria
Published: February 2009

Echinoderms play a key role in structuring many marine ecosystems and are notorious for large population density variations in so‐called “outbreak” or “dieoff” events. In a review of this phenomenon, we assess the causal factors and ecological and evolutionary consequences. We identified 28 species (6 Asteroidea, 8 Echinoidea, 10 Holothuroidea, 4 Ophiuroidea) that exhibit large (more than two population doublings or halvings) population density changes. Three generalized patterns were identified and named for exemplary species: (1) rapid decreases followed by no or slow recovery (Diadema–Paracentrotus Model), (2), rapid increase and apparent stability at a new population density (Amperima–Amphiura Model), and (3) population density fluctuations (Acanthaster–Asterias Model). Echinoderms identified were distributed from the shallow intertidal to the deep sea, and from tropical to temperate regions. In most cases, significant impacts on the respective ecosystems were observed. The most striking similarity among all species identified was possession of the ancestral‐type planktotrophic larva. This larval type was significantly overrepresented in species identified within the Asteroidea, Echinoidea, Holothuroidea, and for the combined data set. We suggest three main factors that render a life history with planktotrophic larvae a high‐risk–high‐gain strategy: (1) a strong nonlinear dependency of larval production on adult densities (Allee effects), (2) a low potential for compensatory feedback mechanisms, and (3) an uncoupling of larval and adult ecology. The alternative (derived) lecithotrophic larva occurs in 68% of recent echinoderm species, suggesting an evolutionary trend toward this larval type. Lecithotrophic development represents a more buffered life history because compensatory feedback between adult densities and larval output is likely to be more efficient. For lecithotrophic developers, direct nutritive coupling from adult to larva to the early benthic juvenile provides a buffer against starvation. Lecithotrophic larvae are independent of the vagaries of planktonic food supply, and their short planktonic duration may promote local recruitment. Anthropogenic influences contributed to the population density variations in most cases, including increased primary productivity through eutrophication or global change, disease, overfishing, and species introductions. We suggest that anthropogenic disturbance, through its influence on the frequency and/or amplitude of echinoderm population density changes, may go beyond present ecosystem impacts and alter future evolutionary trends.
Neighborhood effects and size‐asymmetric competition in a tree plantation varying in diversity
Authors: Potvin Catherine , Dutilleul Pierre
Published: February 2009

A plantation of native trees was established in Panama in 2001 to study the relationship between biodiversity and ecosystem functioning. Five years later, mixed‐species plots had experienced enhanced tree growth compared with monocultures. Searching for underlying mechanisms, we developed a neighborhood model isolating size and identity effects. We found that the size of neighbors is, by far, the largest source of variation in individual‐tree diameter and height. Size‐asymmetric competition appears as a structuring factor in the plantation. The relative growth rate of small trees was significantly lower than that of large trees, and their height and basal diameter were most variable. The 50 smallest trees of the plantation suffered a disproportionate amount of death, and the proportion of small trees was highest in monoculture. Increased biomass allocation to branches for trees growing in three‐species plots suggests that competition for light might be taking place. Clearly, local neighborhood plays a central role in determining productivity, suggesting that scale needs to be incorporated in the theoretical development and analysis of biodiversity and ecosystem functioning.
Hierarchical demography: a general approach with an application to honey bees
Authors: Al-Khafaji Karim , Tuljapurkar Shripad , Carey James R. , Page Robert E.
Published: February 2009

Hierarchical population structure, where individuals are aggregated into colonies or similar groups that themselves grow, survive or perish, and potentially produce offspring groups, is an important feature of many biological systems, most notably eusocial organisms such as the honey bee,Apis mellifera. Despite this hierarchical structure, there is a paucity of analytical models and theory linking the dynamics of individuals within colonies to the dynamics of a population of colonies. We present an analytical framework that provides a simple, robust, and predictive theory for the population dynamics of hierarchical organisms. Our framework explicitly describes and links demographic dynamics for the different levels in the hierarchy (individuals, groups, population). We illustrate the application of the framework by developing a model for honey bees and analyzing the effects of life history traits such as worker life span and size at swarming on the growth rate of populations. We conclude by discussing possible extensions of the model that increase its realism and expand its usefulness beyond swarm‐founding, monogynous, eusocial insects.