Design of High Speed and Low Offset Dynamic Latch Comparator in 0.18 μm CMOS Process

The cross-coupled circuit mechanism based dynamic latch comparator is presented in this research. The comparator is designed using differential input stages with regenerative S-R latch to achieve lower offset, lower power, higher speed and higher resolution. In order to decrease circuit complexity, a comparator should maintain power, speed, resolution and offset-voltage properly. Simulations show that this novel dynamic latch comparator designed in 0.18 µm CMOS technology achieves 3.44 mV resolution with 8 bit precision at a frequency of 50 MHz while dissipating 158.5 µW from 1.8 V supply and 88.05 µA average current. Moreover, the proposed design propagates as fast as 4.2 nS with energy efficiency of 0.7 fJ/conversion-step. Additionally, the core circuit layout only occupies 0.008 mm².     

Sexual dimorphisms in the vocal control system of a teleost fish: morphology of physiologically identified neurons

In one species of vocalizing (sonic) fish, the midshipman (Porichthys notatus), there are two classes of sexually mature males--Types I and II--distinguished by a number of traits including body size, gonad size, and reproductive tactic. The larger Type-I males (unlike Type-II males and females) build nests, guard eggs, and generate several types of vocalizations. Sound production by Type-I males is paralleled by a proportionate increase of 600% in their sonic muscle mass. The motor volley from ventral occipital roots innervating the sonic muscles establishes their contraction rate and, in turn, the fundamental frequency of emitted sounds. Electrical stimulation of the midbrain in every male and female elicited a rhythmic sonic discharge as recorded in the occipital roots; however, the fundamental frequency was slightly, but significantly, higher (20%) in Type-I males. Intracellular recording from identified motoneurons and presumed presynaptic "pacemaker" neurons showed their synaptic and action potentials had the same frequency as that of the nerve volley in every male and female. Reconstructions of physiologically identified motoneurons and pacemaker neurons following intracellular horseradish-peroxidase (HRP) filling showed their somata and dendrites to be 100-300% larger in Type-I males. These data unambiguously show that the size of a target muscle is correlated with the size of both the respective motoneurons and their presynaptic afferent neurons. As discussed, this implies that the dramatic increase in neuron size in the sonic motor system of Type-I males is causally dependent upon expansion of the sonic muscle. It is further likely that the more modest sex difference in the rhythmic central discharge is established by the intrinsic membrane properties of sonic neurons. These results also corroborate, at a number of behavioral, morphological, and neurophysiological levels, that the sonic motor system of "sneak spawning" Type-II males is similar to that of females. Thus, unlike the vocalizing Type-I males, sexual differentiation of the reproductive system in Type-II males is not linked to concomitant changes in the neurophysiological and morphological features of the sonic motor circuit.     

Resource recovery from paddy field using plant microbial fuel cell

The plant microbial fuel cell (PMFC) is a recently developed energy-generating technology that supports sustainable agriculture. Design configuration is the key bottleneck in optimization and upscaling of paddy based PMFCs. In this study, two designs (Type-I (horizontal) and Type-II (vertical)) of terracotta based ceramic PMFCs (C-PMFC) are incorporated into the paddy field to recover nutrients, energy, and water (“NEW”) resources. The peak voltage generated in Type-I and Type-II C-PMFC was 292.1 mV and 321.7 mV respectively. The polarisation study in the ripening phase of paddy showed a maximum power density of 9.1 mW/m² (type-I) and 16.8 mW/m² (type-II). The volume of catholyte recovered is observed to be dependent on the C-PMFC performance and growth phases of the paddy. In the entire 10 weeks of the experimental period, a total of 451 mL and 943 mL of catholyte was collected at 100Ω load in type-I and type-II, respectively. The collected catholyte is alkaline in nature and maximum catholyte recovery is achieved at the active tillering phase and declined with the advancement of the development stages of the plant. Osmotic and electro-osmotic migration of various nutrients like ammonium from the paddy field to cathode chamber of C-PMFC is observed throughout the experiment.     

The adenosine triphosphatase-inhibitor content of bovine heart submitochondrial particles. Influence of the inhibitor on adenosine triphosphate-dependent reactions.

1. The activity of the ATPase (adenosine triphosphatase) of phosphorylating particles prepared by sonication of bovine heart mitochondria in the presence of MgCl2 and ATP is influenced by the isolation method for the mitochondria used in the preparation of particles. Type-I particles, made from mitochondria isolated in a medium lacking succinate, have a lower ATPase activity than to Type-II particles, which are prepared from mitochondria isolated in a medium containing succinate. 2. Centrifugation under appropriate energized conditions increases the ATPase activity of Type-I particles almost to that of the Type-II particles. The ATPase activity of Type-II particles was only slightly stimulated by this procedure. These data are interpreted as indicating a higher content of the ATPase-inhibitor protein in the Type-I particles. 3. A comparison was made of the ATP-driven enhancement of 8-anilinonaphthalene-1-sulphonate fluorescence and the exchange of the endogenous tightly bound nucleotides of the ATPase in Type-I and Type-II particles. The effect of exogenous inhibitor protein on both these reactions was also studied. 4. The time-scale on which the inhibitor protein can exchange between ATPase molecules is discussed.     

Morphology and location of dense-core vesicles in the stomatogastric ganglion of the lobster,Panulirus interruptus

The appearance and distribution of dense-core vesicles in the stomatogastric ganglion of the spiny lobster, Panulirus interruptus, were examined using transmission electron microscopy. Following five fixation techniques, three types of dense-core vesicles were identified on the basis of size and morphology. Type-I vesicles are found in a distinct neuronal fiber system that appears to be involved in chemical transmission within the ganglion. Type-II vesicles occur in nerve processes in the ganglion, in major nerve trunks and in the perineural sheath of the nerves and ganglion. Type-III vesicles are present in all neuronal somata of the ganglion. The distinct morphology and location of the three types of vesicles suggest that their functional roles differ. Furthermore, the histochemical, biochemical and physiological data available for the stomatogastric ganglion indicate that Type-I vesicles may store dopamine.     

Polarized distribution of γ interferon-stimulated MHC antigens and transferrin receptors in a clonal cell line isolated from Fisher rat thyroid (FRT cells)

Summary The fine structure of single identified muscle fibers and their nerve terminals in the limb closer muscle of the shore crab Eriphia spinifrons was examined, using a previous classification based on histochemical evidence which recognizes a slow (Type-I) fiber and three fast (Type-II, Type-III, Type-IV) fibers. All four fiber types have a fine structure characteristic of crustacean slow muscle, with 10–12 thin filaments surrounding each thick filament and sarcomere lengths of 6–13 m. Type-IV fibers have sarcomere lengths of 6 m while the other three types have substantially longer sarcomeres (10–13 m). Structural features of nerve terminals revealed excitatory innervation in all four fiber types but inhibitory innervation in Type-I, Type-II, and Type-III fibers only. Thus fibers with longer sarcomeres receive the inhibitor axon but those with shorter sarcomeres do not. Amongst the former, synaptic contact from an inhibitory nerve terminal onto an excitatory one, denoting presynaptic inhibition, was seen in Type-I and Type-II fibers but not in Type-III and Type-IV fibers. Inhibitory innervation of the walking leg closer muscle is therefore highly differentiated: some fibers lack inhibitory nerve terminals, some possess postsynaptic inhibition, and some possess both postsynaptic and presynaptic inhibition.     

Ligh- and electron-microscopic immunocytochemistry of somatotropes in the anterior pituitary gland of European ferret,Mustela putorius furo

Light-microscopic immunocytochemistry of ferret anterior pituitary revealed the localization of somatotropes in the pars distalis, but no immunoreactive cells were detected in the pars tuberalis. Ultrastructural studies by superimposition immunocytochemistry and immuno-electron microscopy, clucidated the morphological heterogeneity of these somatotropic cells. They were classified into 2 subtypes on the basis of size of the secretory granules. Type-I cells with small granules (mean diameter, 192 nm), were considered to be the immature somatotrop, while Type-II cells, with comparatively larger secretory granules (mean diameter, 257 nm), were considered to be the matured form of Type-I cells and the typical somatotropic cell-type, and were much more predominant than the Type-I cells. The fact that Type-II cells had a distinct Golgi zone and many mitochondria, while in Type-I cells the intracellular organelles were generally less developed, supports this suggestion. In addition to these two extreme subtypes, several intermediate forms were also encountered that may represent different transitional phases during the conversion of Type I to Type II. Protein A-gold immuno-electron microscopy illustrated the specific localization of growth hormone over the granules, with no labelling over any other cytoplasmic organelles of the 2 somatotrope subtypes.     

Coping with aquatic hypoxia: how the plainfin midshipman (Porichthys notatus) tolerates the intertidal zone

Although plainfin midshipman (Porichthys notatus) are primarily known for their alternative reproductive tactics, and the dimorphic male subtypes, in which Type-I males demonstrate parental investment and mate attraction, and Type-II males ‘sneak’ fertilization and show no investment after fertilization, little is known about the physiology and tolerance to low aquatic oxygen while nesting in the intertidal zone. In May 2007, females and Type-I and Type-II males were collected, and in June 2009, only Type-I males were collected from nest sites on the coast of Vancouver Island, British Columbia. In the 2007 season, an initial assessment of hypoxia tolerance and nest parameters was recorded for the three subtypes of midshipman. Historical evidence indicates that Type-I males remain on the nest for prolonged periods, and our results suggest they can cope with repeated bouts of aquatic hypoxia by elevating their hematocrit and tolerating high lactate levels. The 2009 season was directed at examining the aquatic hypoxia tolerance of only the Type-I male. Hypoxic (~15 % air saturated water) Type-I males had oxygen consumption rates at ~12 % of the normoxic control (~100 % air saturated water) and a P_crit, the critical oxygen tension, when a fish switches from oxyregulator to oxyconformer, could not be determined; an indication that these fish are solely oxyconformers. With prolonged exposure to aquatic hypoxia, Type-I males displayed significant elevations in plasma and tissue lactate (heart), tissue glucose (liver), and a depression in gill Na⁺/K⁺ATPase and catalase activities. Results suggest that male Type-I midshipman survival in the intertidal zone is enhanced by metabolic depression and tolerance to anaerobic byproducts.     

Steady-state kinetics of low molecular weight (type-II) NADH dehydrogenase.

(1) The steady-state kinetics of the NADH dehydrogenase activity of Type-II (low molecular weight) NADH dehydrogenase with the acceptors ferricyanide, cytochrome c and 2,6-dichloroindophenol are consistent with the simultaneous operation of an ordered and a ping-pong mechanism. Thus, depending on the acceptor concentration, the reduced enzyme is preferentially oxidized before or after NAD+ disociates from it. (2) The acceptors are able to oxidize the reduced enzyme and its NAD+ complex equally well. In contrast to the kinetics of the Type-I (high molecular weight) enzyme, double substrate inhibition is not found, implying that the site of oxidation of the reduced enzyme by acceptors and the NADH-binding site are remote. (3) With the indophenol, in the concentration range measured, the ordered mechanism is mainly operative. At infinite NADH and acceptor concentrations the rate constant of the reduction of enzyme by bound NADH is measured. (4) With ferricyanide and cytochrome c, in the concentration range measured, erroneous conclusions may be drawn from extrapolations owing to the fact that extrapolated lines in double-reciprocal plots of turnover number against acceptor concentration, at different NADH concentrations, intersect in the third quadrant. A method is described that allows the extrapolation of these data to zero acceptor concentrations. (5) The relation between activity and NADH concentration is sigmoidal (h = 2.0) with ferricyanide or cytochrome c as acceptor, but hyperbolic with 2,6-dichloroindophenol. The latter is also an inhibitor, competitive with respect to NADH. It is concluded that this two-electron acceptor, like ubiquinone, acts as an allosteric effector. (6) Type II is isolated from Type I without gross changes in tertiary structure, as judged by the unaltered rate constants of dissociation of NADH (k-1) and NAD+ (k4) and association of NADH (k1). (7) Type II differs from Type I in two respects, (a) The accessibility of the acceptors is greater by at least two orders of magnitude (k3). (b) The redox potential of the prosthetic group FMN is 120 mV less, as judged by a drop in the value of k2 by four orders of magnitude. It is suggested that one or more of the iron-sulphur proteins present in Type-I but lacking in Type-II dehydrogenase functions as an effector, regulating the redox potential of the FMN.     

X-ray structural study of noncrystalline regenerated Bombyx mori silk fibroin

X-ray diffraction measurements of regenerated Bombyx mori silk fibroin were carried out to determine its structural characteristic from an analysis of differential radial distribution functions (DRDFs). The temperature dependence of X-ray diffraction patterns from noncrystalline and crystal structures of regenerated silk fibroin was investigated using a high temperature furnace. Time resolved X-ray diffraction profiles were also obtained to construct kinematical models of structural changes caused by the addition of water. DRDFs, calculated from the experimental data, were compared with the DRDFs simulated on the basis of the Monte Carlo method. In order to model the noncrystalline structures, structural units were assumed to be parts of the crystalline structure of silk and those with appropriate structural defects reported previously. From the comparison of experimental and simulated DRDFs, it was determined that noncrystalline regenerated silk consisted of locally ordered atomic sheets similar to the atomic arrangement in the silk I crystal (Type-I sheets), and the final state of the structural change was noncrystalline, consisting of small crystallites, the structure of which is similar to that of silk II (Type-II crystallites). Time resolved DRDFs were also qualitatively interpreted by both the ordering of Type-I sheets and structural changes from Type-I to Type-II. The formation of the small Type-II crystallites obtained in this study was consistent with the nucleation of silk II by birefringence measurements of silk glands and the spinneret of Bombyx mori silkworm reported previously. X-ray diffraction should be a useful technique to understand the structural characteristics of noncrystalline organic materials.     

A two dimensional model for saccade generation

A model for the generation of oblique saccades is constructed by extending and modifying the one dimensional local feedback model. It is proposed that the visual system stores target location in inertial coordinates, but that the feedback loop which guides saccades works in retinotopic coordinates. To achieve straight trajectories for centripetal and centrifugal saccades in all meridians, a comparator computes motor error as a vector and uses the vectorial error signal to drive two orthogonally-acting burst generators. The generation of straight saccade trajectories when the extraocular muscles are of unequal strengths requires the introduction of a burst-tonic cell input to motor neurons. The model accounts for the results of two-site stimulation of the superior colliculus and frontal eye fields by allowing simultaneous activation of more than one comparator. The postulated existence of multiple comparators suggests that motor error may be computed topographically.     

X-ray structural study of noncrystalline regenerated Bombyx mori silk fibroin

X-ray diffraction measurements of regenerated Bombyx mori silk fibroin were carried out to determine its structural characteristic from an analysis of differential radial distribution functions (DRDFs). The temperature dependence of X-ray diffraction patterns from noncrystalline and crystal structures of regenerated silk fibroin was investigated using a high temperature furnace. Time resolved X-ray diffraction profiles were also obtained to construct kinematical models of structural changes caused by the addition of water. DRDFs, calculated from the experimental data, were compared with the DRDFs simulated on the basis of the Monte Carlo method. In order to model the noncrystalline structures, structural units were assumed to be parts of the crystalline structure of silk and those with appropriate structural defects reported previously. From the comparison of experimental and simulated DRDFs, it was determined that noncrystalline regenerated silk consisted of locally ordered atomic sheets similar to the atomic arrangement in the silk I crystal (Type-I sheets), and the final state of the structural change was noncrystalline, consisting of small crystallites, the structure of which is similar to that of silk II (Type-II crystallites). Time resolved DRDFs were also qualitatively interpreted by both the ordering of Type-I sheets and structural changes from Type-I to Type-II. The formation of the small Type-II crystallites obtained in this study was consistent with the nucleation of silk II by birefringence measurements of silk glands and the spinneret of Bombyx mori silkworm reported previously. X-ray diffraction should be a useful technique to understand the structural characteristics of noncrystalline organic materials.     

Computational study of EGFR inhibition: molecular dynamics studies on the active and inactive protein conformations

The structural diversity observed across protein kinases, resulting in subtly different active site cavities, is highly desirable in the pursuit of selective inhibitors, yet it can also be a hindrance from a structure-based design perspective. An important challenge in structure-based design is to better understand the dynamic nature of protein kinases and the underlying reasons for specific conformational preferences in the presence of different inhibitors. To investigate this issue, we performed molecular dynamics simulation on both the active and inactive wild type epidermal growth factor receptor (EGFR) protein with both type-I and type-II inhibitors. Our goal is to better understand the origin of the two distinct EGFR protein conformations, their dynamic differences, and their relative preference for Type-I inhibitors such as gefitinib and Type-II inhibitors such as lapatinib. We discuss the implications of protein dynamics from a structure-based design perspective.     

Cloning and functional characterization of a fatty acid transport protein (FATP) from the pheromone gland of a lichen moth, Eilema japonica, which secretes an alkenyl sex pheromone

Sex pheromones of moths are largely classified into two types based on the presence (Type I) or absence (Type II) of a terminal functional group. While Type-I sex pheromones are synthesized from common fatty acids in the pheromone gland (PG), Type-II sex pheromones are derived from hydrocarbons produced presumably in the oenocytes and transported to the PG via the hemolymph. Recently, a fatty acid transport protein (BmFATP) was identified from the PG of the silkworm Bombyx mori, which produces a Type-I sex pheromone (bombykol). BmFATP was shown to facilitate the uptake of extracellular fatty acids into PG cells for the synthesis of bombykol. To elucidate the presence and function of FATP in the PG of moths that produce Type-II sex pheromones, we explored fatp homologues expressed in the PG of a lichen moth, Eilema japonica, which secretes an alkenyl sex pheromone (Type II). A fatp homologue cloned from E. japonica (Ejfatp) was predominantly expressed in the PG, and its expression is upregulated shortly after eclosion. Functional expression of EjFATP in Escherichia coli enhanced the uptake of long chain fatty acids (C₁₈ and C₂₀), but not pheromone precursor hydrocarbons. To the best of our knowledge, this is the first report of the cloning and functional characterization of a FATP in the PG of a moth producing a Type-II sex pheromone. Although EjFATP is not likely to be involved in the uptake of pheromone precursors in E. japonica, the expression pattern of Ejfatp suggests a role for EjFATP in the PG not directly linked to pheromone biosynthesis.     

Functional divergence after gene duplication and sequence-structure relationship: a case study of G-protein alpha subunits

In this article, we use animal G-protein alpha subunit family as an example to illustrate a comprehensive analytical pipeline for detecting different types of functional divergence of protein families, which is phylogeny-dependent, combined with ancestral sequence inference and available protein structure information. In particular, we focus on (i) Type-I functional divergence, or site-specific rate shift, as typically exemplified by amino acid residue highly conserved in a subset of homologous genes but highly variable in a different subset of homologous genes, and (ii) Type-II functional divergence, or the shift of cluster-specific amino acid property, as exemplified by a radical shift of amino acid property between duplicate genes, which is otherwise evolutionally conserved. We utilized the software DIVERGE2 to carry out these analyses. In the case of G-protein alpha subunit gene family, we have predicted amino acid residues that are related to either Type-I or Type-II functional divergence. The inferred ancestral sequences for these sites are helpful to explore the trends of functional divergence. Finally, these predicted residues are mapped to the protein structures to test whether these residues may have 3D structure or solvent accessibility preference.     

Phylogenetic analysis of different breeds of domestic chickens in selected area of Peninsular Malaysia inferred from partial cytochrome b gene information and RAPD markers

The present investigation was carried out in an attempt to study the phylogenetic analysis of different breeds of domestic chickens in Peninsular Malaysia inferred from partial cytochrome b gene information and random amplified polymorphic DNA (RAPD) markers. Phylogenetic analysis using both neighbor-joining (NJ) and maximum parsimony (MP) methods produced three clusters that encompassed Type-I village chickens, the red jungle fowl subspecies and the Japanese Chunky broilers. The phylogenetic analysis also revealed that majority of the Malaysian commercial chickens were randomly assembled with the Type-II village chickens. In RAPD assay, phylogenetic analysis using neighbor-joining produced six clusters that were completely distinguished based on the locality of chickens. High levels of genetic variations were observed among the village chickens, the commercial broilers, and between the commercial broilers and layer chickens. In this study, it was found that Type-I village chickens could be distinguished from the commercial chickens and Type-II village chickens at the position of the 27th nucleotide of the 351?bp cytochrome b gene. This study also revealed that RAPD markers were unable to differentiate the type of chickens, but it showed the effectiveness of RAPD in evaluating the genetic variation and the genetic relationships between chicken lines and populations.     

Phylogenetic Analysis of Different Breeds of Domestic Chickens in Selected Area of Peninsular Malaysia Inferred from Partial Cytochrome b Gene Information and RAPD Markers

The present investigation was carried out in an attempt to study the phylogenetic analysis of different breeds of domestic chickens in Peninsular Malaysia inferred from partial cytochrome b gene information and random amplified polymorphic DNA (RAPD) markers. Phylogenetic analysis using both neighbor-joining (NJ) and maximum parsimony (MP) methods produced three clusters that encompassed Type-I village chickens, the red jungle fowl subspecies and the Japanese Chunky broilers. The phylogenetic analysis also revealed that majority of the Malaysian commercial chickens were randomly assembled with the Type-II village chickens. In RAPD assay, phylogenetic analysis using neighbor-joining produced six clusters that were completely distinguished based on the locality of chickens. High levels of genetic variations were observed among the village chickens, the commercial broilers, and between the commercial broilers and layer chickens. In this study, it was found that Type-I village chickens could be distinguished from the commercial chickens and Type-II village chickens at the position of the 27th nucleotide of the 351 bp cytochrome b gene. This study also revealed that RAPD markers were unable to differentiate the type of chickens, but it showed the effectiveness of RAPD in evaluating the genetic variation and the genetic relationships between chicken lines and populations.     

The Drosophila Activin-like ligand Dawdle signals preferentially through one isoform of the Type-I receptor Baboon

How TGF-β-type ligands achieve signaling specificity during development is only partially understood. Here, we show that Dawdle, one of four Activin-type ligands in Drosophila, preferentially signals through Babo_c, one of three isoforms of the Activin Type-I receptor that are expressed during development. In cell culture, Dawdle signaling is active in the presence of the Type-II receptor Punt but not Wit, demonstrating that the Type-II receptor also contributes to the specificity of the signaling complex. During development, different larval tissues express unique combinations of these receptors, and ectopic expression of Babo_c in a tissue where it is not normally expressed at high levels can make that tissue sensitive to Dawdle signaling. These results reveal a mechanism by which distinct cell types can discriminate between different Activin-type signals during development as a result of differential expression of Type-I receptor isoforms.     

Immunocytochemical study of the GH cells in the anterior pituitary gland of human fetus II. Anencephalic fetus

In order to elucidate the effects of hypothalamic regulation on the morphology of GH cells, light and electron microscopic immunocytochemical examinations were carried out comparing GH cells in the anterior pituitary gland of anencephalic fetus with those of normal fetuses. Three types of GH cells were identified in the anterior pituitary gland of anencephalic fetus as well as in the normal fetus. Type-I is a small, round cell containing a few small secretory granules. Type-III is a large, polygonal cell with numerous large secretory granules. Type-II is a polygonal cell with medium-sized secretory granules. The Type-II GH cell was predominant in both anencephalic and normal fetuses. The most striking difference between anencephalic and normal fetuses was the presence of atypical forms of the Type II cell. These were polygonal cells containing secretory granules, which were either immunopositive or immunonegative to anti-human GH (anti-hGH) serum. Furthermore, two other types of GH cells were identified. The somatomammotroph (SM cell) contained GH and PRL in different granules within the same cell. Also, a different type of the GH cell was noted containing two varieties of secretory granules; one was immunolabeled only with anti-hGH and the other was not immunolabeled to either anti-hGH or anti-human PRL (anti-hPRL). From these results, we suggest that an absence of hypothalamic regulation in the anencehpalic does not seriously modify GH cell morphology but induces an altered GH storage pattern in some of the cells.