Concentrated Ground Plane Booster Antenna Technology for Multiband Operation in Handset Devices

The current demand in the handset antenna field requires multiband antennas due to the existence of multiple communication standards and the emergence of new ones. At the same time, antennas with reduced dimensions are strongly required in order to be easily integrated. In this sense, the paper proposes a compact radiating system that uses two non-resonant elements to properly excite the ground plane to solve the abovementioned shortcomings by minimizing the required Printed Circuit Board (PCB) area while ensuring a multiband performance. These non-resonant elements are called here ground plane boosters since they excite an efficient mode of the ground plane. The proposed radiating system comprises two ground plane boosters of small dimensions of 5 mm x 5 mm x 5 mm. One is in charge of the low frequency region (0.824-0.960 GHz) and the other is in charge of the high frequency region (1.710-2.170 GHz). With the aim of achieving a compact configuration, the two boosters are placed close to each other in a corner of the ground plane of a handset device (concentrated architecture). Several experiments related to the coupling between boosters have been carried out in two different platforms (barphone and smartphone), and the best position and the required matching network are presented. The novel proposal achieves multiband performance at GSM850/900/1800/1900 and UMTS

Hot electron cooling by acoustic phonons in graphene

We have investigated the energy loss of hot electrons in metallic graphene by means of GHz noise thermometry at liquid helium temperature. We observe the electronic temperature T / V at low bias in agreement with the heat diffusion to the leads described by the Wiedemann-Franz law. We report on $T\propto\sqrt{V}$ behavior at high bias, which corresponds to a T4 dependence of the cooling power. This is the signature of a 2D acoustic phonon cooling mechanism. From a heat equation analysis of the two regimes we extract accurate values of the electron-acoustic phonon coupling constant $\Sigma$ in monolayer graphene. Our measurements point to an important effect of lattice disorder in the reduction of $\Sigma$, not yet considered by theory. Moreover, our study provides a strong and firm support to the rising field of graphene bolometric detectors.Comment: 5 figure

Promiscuous mismatch extension by human DNA polymerase lambda

DNA polymerase lambda (Pol λ) is one of several DNA polymerases suggested to participate in base excision repair (BER), in repair of broken DNA ends and in translesion synthesis. It has been proposed that the nature of the DNA intermediates partly determines which polymerase is used for a particular repair reaction. To test this hypothesis, here we examine the ability of human Pol λ to extend mismatched primer-termini, either on ‘open’ template-primer substrates, or on its preferred substrate, a 1 nt gapped-DNA molecule having a 5′-phosphate. Interestingly, Pol λ extended mismatches with an average efficiency of ≈10−2 relative to matched base pairs. The match and mismatch extension catalytic efficiencies obtained on gapped molecules were ≈260-fold higher than on template-primer molecules. A crystal structure of Pol λ in complex with a single-nucleotide gap containing a dG·dGMP mismatch at the primer-terminus (2.40 Å) suggests that, at least for certain mispairs, Pol λ is unable to differentiate between matched and mismatched termini during the DNA binding step, thus accounting for the relatively high efficiency of mismatch extension. This property of Pol λ suggests a potential role as a ‘mismatch extender’ during non-homologous end joining (NHEJ), and possibly during translesion synthesis

Hair cells use active zones with different voltage dependence of Ca²⁺ influx to decompose sounds into complementary neural codes.

For sounds of a given frequency, spiral ganglion neurons (SGNs) with different thresholds and dynamic ranges collectively encode the wide range of audible sound pressures. Heterogeneity of synapses between inner hair cells (IHCs) and SGNs is an attractive candidate mechanism for generating complementary neural codes covering the entire dynamic range. Here, we quantified active zone (AZ) properties as a function of AZ position within mouse IHCs by combining patch clamp and imaging of presynaptic Ca2+ influx and by immunohistochemistry. We report substantial AZ heterogeneity whereby the voltage of half-maximal activation of Ca2+ influx ranged over ∼20 mV. Ca2+ influx at AZs facing away from the ganglion activated at weaker depolarizations. Estimates of AZ size and Ca2+ channel number were correlated and larger when AZs faced the ganglion. Disruption of the deafness gene GIPC3 in mice shifted the activation of presynaptic Ca2+ influx to more hyperpolarized potentials and increased the spontaneous SGN discharge. Moreover, Gipc3 disruption enhanced Ca2+ influx and exocytosis in IHCs, reversed the spatial gradient of maximal Ca2+ influx in IHCs, and increased the maximal firing rate of SGNs at sound onset. We propose that IHCs diversify Ca2+ channel properties among AZs and thereby contribute to decomposing auditory information into complementary representations in SGNs

Ca2+-binding protein 2 inhibits Ca2+-channel inactivation in mouse inner hair cells

Ca2+ channels mediate excitation-secretion coupling and show little inactivation at sensory ribbon synapses, enabling reliable synaptic information transfer during sustained stimulation. Studies of Ca2+-channel complexes in HEK293 cells indicated that Ca2+-binding proteins (CaBPs) antagonize their calmodulin-dependent inactivation. Although human mutations affecting CABP2 were shown to cause hearing impairment, the role of CaBP2 in auditory function and the precise disease mechanism remained enigmatic. Here, we disrupted CaBP2 in mice and showed that CaBP2 is required for sound encoding at inner hair cell synapses, likely by suppressing Ca2+-channel inactivation. We propose that the number of activatable Ca2+ channels at the active zone is reduced when CaBP2 is lacking, as is likely the case with the newly described human CABP2 mutation

E-NTPDases in human airways: Regulation and relevance for chronic lung diseases

Chronic obstructive lung diseases are characterized by the inability to prevent bacterial infection and a gradual loss of lung function caused by recurrent inflammatory responses. In the past decade, numerous studies have demonstrated the importance of nucleotide-mediated bacterial clearance. Their interaction with P2 receptors on airway epithelia provides a rapid ‘on-and-off’ signal stimulating mucus secretion, cilia beating activity and surface hydration. On the other hand, abnormally high ATP levels resulting from damaged epithelia and bacterial lysis may cause lung edema and exacerbate inflammatory responses. Airway ATP concentrations are regulated by ecto nucleoside triphosphate diphosphohydrolases (E-NTPDases) which are expressed on the mucosal surface and catalyze the sequential dephosphorylation of nucleoside triphosphates to nucleoside monophosphates (ATP → ADP → AMP). The common bacterial product, Pseudomonas aeruginosa lipopolysaccharide (LPS), induces an acute reduction in azide-sensitive E-NTPDase activities, followed by a sustained increase in activity as well as NTPDase 1 and NTPDase 3 expression. Accordingly, chronic lung diseases, including cystic fibrosis (CF) and primary ciliary dyskinesia, are characterized by higher rates of nucleotide elimination, azide-sensitive E-NTPDase activities and expression. This review integrates the biphasic regulation of airway E-NTPDases with the function of purine signaling in lung diseases. During acute insults, a transient reduction in E-NTPDase activities may be beneficial to stimulate ATP-mediated bacterial clearance. In chronic lung diseases, elevating E-NTPDase activities may represent an attempt to prevent P2 receptor desensitization and nucleotide-mediated lung damage

DNA polymerase λ, a novel DNA repair enzyme in human cells

DNA polymerase lambda (pol λ) is a novel family X DNA polymerase that has been suggested to play a role in meiotic recombination and DNA repair. The recent demonstration of an intrinsic 5′-deoxyribose-5-phosphate lyase activity in pol λ supports a function of this enzyme in base excision repair. However, the biochemical properties of the polymerization activity of this enzyme are still largely unknown. We have cloned and purified human pol λ to homogeneity in a soluble and active form, and we present here a biochemical description of its polymerization features. In support of a role in DNA repair, pol λ inserts nucleotides in a DNA template-dependent manner and is processive in small gaps containing a 5′-phosphate group. These properties, together with its nucleotide insertion fidelity parameters and lack of proofreading activity, indicate that pol λ is a novel β-like DNA polymerase. However, the high affinity of pol λ for dNTPs (37-fold over pol β) is consistent with its possible involvement in DNA transactions occurring under low cellular levels of dNTPs. This suggests that, despite their similarities, pol β and pol λ have nonredundant in vivo functions.This work was supported by Ministerio de Ciencia y Tecnologı´a Grant BMC2000-1138, Comunidad Auto´noma de Madrid Grant 08.5/0063/2000 (to L. B.) and by an institutional grant from Fundacio´n Ramo´n Areces

DNA polymerase λ, a novel DNA repair enzyme in human cells

DNA polymerase lambda (pol λ) is a novel family X DNA polymerase that has been suggested to play a role in meiotic recombination and DNA repair. The recent demonstration of an intrinsic 5′-deoxyribose-5-phosphate lyase activity in pol A supports a function of this enzyme in base excision repair. However, the biochemical properties of the polymerization activity of this enzyme are still largely unknown. We have cloned and purified human pol A to homogeneity in a soluble and active form, and we present here a biochemical description of its polymerization features. In support of a role in DNA repair, pol λ inserts nucleotides in a DNA template-dependent manner and is processive in small gaps containing a 5′-phosphate group. These properties, together with its nucleotide insertion fidelity parameters and lack of proofreading activity, indicate that pol A is a novel β-like DNA polymerase. However, the high affinity of pol λ for dNTPs (37-fold over pol β) is consistent with its possible involvement in DNA transactions occurring under low cellular levels of dNTPs. This suggests that, despite their similarities, pol β and pol λ have nonredundant in vivo function

Tolerance for 8-oxoguanine but not thymine glycol in alignment-based gap filling of partially complementary double-strand break ends by DNA polymerase λ in human nuclear extracts

Ionizing radiation induces various clustered DNA lesions, including double-strand breaks (DSBs) accompanied by nearby oxidative base damage. Previous work showed that, in HeLa nuclear extracts, DSBs with partially complementary 3′ overhangs and a one-base gap in each strand are accurately rejoined, with the gaps being filled by DNA polymerase λ. To determine the possible effect of oxidative base damage on this process, plasmid substrates were constructed containing overhangs with 8-oxoguanine or thymine glycol in base-pairing positions of 3-base (-ACG or -GTA) 3′ overhangs. In this context, 8-oxoguanine was well tolerated by the end-joining machinery when present at one end of the break, but not when present at both ends. Thymine glycol was less well tolerated than 8-oxoguanine, reducing gap filling and accurate rejoining by at least 10-fold. The results suggest that complex DSBs can be accurately rejoined despite the presence of accompanying base damage, but that nonplanar bases constitute a major barrier to this process and promote error-prone joining. A chimeric DNA polymerase, in which the catalytic domain of polymerase λ was replaced with that of polymerase β, could not substitute for polymerase λ in these assays, suggesting that this domain is specifically adapted for gap filling on aligned DSB ends

Clinical pharmacology of exogenously administered alkaline phosphatase

Purpose: To evaluate the clinical pharmacology of exogenous alkaline phosphatase (AP). Methods: Randomized, double-blind, placebo-controlled sequential protocols of (1) ascending doses and infusion duration (volunteers) and (2) fixed dose and duration (patients) were conducted at clinical pharmacology and intensive care units. A total of 103 subjects (67 male volunteers and 36 patients with severe sepsis) were administered exogenous, 10-min IV infusions (three ascending doses) or 24-72 h continuous (132.5-200 U kg-124 h-1) IV infusion with/without preceding loading dose and experimental endotoxemia for evaluations of pharmacokinetics, pharmacodynamics, safety parameters, antigenicity, inflammatory markers, and outcomes. Results: Linearity and dose-proportionality were shown during 10-min infusions. The relatively short elimination half-life necessitated a loading dose to achieve stable enzyme levels. Pharmacokinetic parameters in volunteers and patients were similar. Innate immunity response was not significantly influenced by AP, while renal function significantly improved in sepsis patients. Conclusions: The pharmacokinetics of exogenous AP is linear, dose-proportional, exhibit a short half-life, and are not influenced by renal impairment or dialysis