bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of the effects of GaN buffer layer quality on the dc characteristics of AlGaN/GaN high electron mobility transistors
Authors: Ahn Shihyun , Zhu Weidi , Dong Chen , Le Lingcong , Hwang Ya-Hsi , Kim Byung-Jae , Ren Fan , Pearton Stephen J. , Lind Aaron G. , Jones Kevin S. , Kravchenko I. I. , Zhang Ming-Lan
Published: April 2015

The effect of buffer layer quality on dc characteristics of AlGaN/GaN high electron mobility (HEMTs) was studied. AlGaN/GaN HEMT structures with 2 and 5 μm GaN buffer layers on sapphire substrates from two different vendors with the same Al concentration of AlGaN were used. The defect densities of HEMT structures with 2 and 5 μm GaN buffer layer were 7 × 109 and 5 × 108 cm−2, respectively, as measured by transmission electron microscopy. There was little difference in drain saturation current or in transfer characteristics in HEMTs on these two types of buffer. However, there was no dispersion observed on the nonpassivated HEMTs with 5 μm GaN buffer layer for gate-lag pulsed measurement at 100 kHz, which was in sharp contrast to the 71% drain current reduction for the HEMT with 2 μm GaN buffer layer.
Interaction of a magnet and a point charge: Unrecognized internal electromagnetic momentum
Authors: Boyer Timothy H.
Published: April 2015

Whereas nonrelativistic mechanics always connects the total momentum of a system to the motion of the center of mass, relativistic systems, such as interacting electromagnetic charges, can have internal linear momentum in the absence of motion of the system's center of energy. This internal linear momentum of a system is related to the controversial concept of “hidden momentum.” We suggest that the term “hidden momentum” be abandoned. Here, we use the relativistic conservation law for the center of energy to give an unambiguous definition of the “internal momentum of a system,” and then we exhibit this internal momentum for the system of a magnet (modeled as a circular ring of moving charges) and a distant static point charge. The calculations provide clear illustrations of this system for three cases: (a) the moving charges of the magnet are assumed to continue in their unperturbed motion; (b) the moving charges of the magnet are free to accelerate but have no mutual interactions; and (c) the moving charges of the magnet are free to accelerate and also interact with each other. When the current-carrying charges of the magnet are allowed to interact, the magnet itself will contain internal electromagnetic linear momentum, something that has not been described clearly in the research and teaching literature.
Science Signaling
Podcast: 21 April 2015
Authors: Dorn Gerald W. , Song Moshi , VanHook Annalisa M.
Published: April 2015

Related isoforms of protein kinase C control growth of the heart in both developmental and pathological contexts.
Wasting away without insulin
Authors: VanHook Annalisa M.
Published: April 2015

Hyperproliferating cells secrete an insulin antagonist that induces a cachexia-like wasting syndrome in fruit flies.
Nonenzymatic lysine phosphorylation
Authors: Prabakaran Sudhakaran
Published: April 2015

Nonenzymatic polyP phosphorylation on lysines represents a previously unknown form of posttranslational modification.
Multiple
cyp51A
-Based Mechanisms Identified in Azole-Resistant Isolates of Aspergillus fumigatus from China
Authors: Liu Musang , Zeng Rong , Zhang Lili , Li Dongmei , Lv Guixia , Shen Yongnian , Zheng Hailin , Zhang Qiangqiang , Zhao Jingjun , Zheng Nan , Liu Weida
Published: April 2015

Seventy-two
A. fumigatus
clinical isolates from China were investigated for azole resistance based on mutations of
cyp51A
. We identified four azole-resistant strains, among which we found three strains highly resistant to itraconazole, two of which exhibit the TR34/L98H/S297T/F495I mutation, while one carries only the TR34/L98H mutation. To our knowledge, the latter has not been found previously in China. The fourth multiazole-resistant isolate (with only moderate itraconazole resistance) carries a new G432A mutation.
Fluconazole Population Pharmacokinetics and Dosing for Prevention and Treatment of Invasive Candidiasis in Children Supported with Extracorporeal Membrane Oxygenation
Authors: Watt Kevin M. , Gonzalez Daniel , Benjamin Daniel K. , Brouwer Kim L. R. , Wade Kelly C. , Capparelli Edmund , Barrett Jeffrey , Cohen-Wolkowiez Michael
Published: April 2015

Candidainfections are a leading cause of infectious disease-related death in children supported by extracorporeal membrane oxygenation (ECMO). The ECMO circuit can alter drug pharmacokinetics (PK); thus, standard fluconazole dosing may result in suboptimal drug exposures. The objective of our study was to determine the PK of fluconazole in children on ECMO. Forty children with 367 PK samples were included in the analysis. The PK data were analyzed using nonlinear mixed-effect modeling (NONMEM). A one-compartment model best described the data. Weight was included in the base model for clearance (CL) and volume of distribution (V). The final model included the effect of serum creatinine (SCR) level on CL and the effect of ECMO onVas follows: CL (in liters per hour) = 0.019 × weight × (SCR/0.4)−0.29× exp(ηCL) andV(in liters) = 0.93 × weight × 1.4ECMO× exp(ηV). The fluconazoleVwas increased in children supported by ECMO. Consequently, children on ECMO require a higher fluconazole loading dose for prophylaxis (12 mg/kg of body weight) and treatment (35 mg/kg) paired with standard maintenance doses to achieve exposures similar to those of children not on ECMO.
Activity of Antimicrobial Combinations against KPC-2-Producing Klebsiella pneumoniae in a Rat Model and Time-Kill Assay
Authors: Toledo Paula Virginia Michelon , Aranha Junior Ayrton Alves , Arend Lavinia Nery , Ribeiro Vanessa , Zavascki Alexandre Prehn , Tuon Felipe Francisco
Published: April 2015

This study evaluated the efficacy of tigecycline (TIG), polymyxin B (PMB), and meropenem (MER) in 80 rats challenged with
Klebsiella pneumoniae
carbapenemase (KPC)-producing
K. pneumoniae
infection. A time-kill assay was performed with the same strain. Triple therapy and PMB+TIG were synergistic, promoted 100% survival, and produced negative peritoneal cultures, while MER+TIG showed lower survival and higher culture positivity than other regimens (
P
= 0.018) and was antagonistic.
In vivo
and
in vitro
studies showed that combined regimens, except MER+TIG, were more effective than monotherapies for this KPC-producing strain.
Pharmacokinetics of Ceftaroline in Normal Body Weight and Obese (Classes I, II, and III) Healthy Adult Subjects
Authors: Justo Julie Ann , Mayer Stockton M. , Pai Manjunath P. , Soriano Melinda M. , Danziger Larry H. , Novak Richard M. , Rodvold Keith A.
Published: April 2015

The pharmacokinetic profile of ceftaroline has not been well characterized in obese adults. The purpose of this study was to evaluate the pharmacokinetics of ceftaroline in 32 healthy adult volunteers aged 18 to 50 years in the normal, overweight, and obese body size ranges. Subjects were evenly assigned to 1 of 4 groups based on their body mass index (BMI) and total body weight (TBW) (ranges, 22.1 to 63.5 kg/m
2
and 50.1 to 179.5 kg, respectively). Subjects in the lower-TBW groups were matched by age, sex, race/ethnicity, and serum creatinine to the upper-BMI groups. Serial plasma and urine samples were collected over 12 h after the start of the infusion, and the concentrations of ceftaroline fosamil (prodrug), ceftaroline, and ceftaroline M-1 (inactive metabolite) were assayed. Noncompartmental and population pharmacokinetic analyses were used to evaluate the data. The mean plasma ceftaroline maximum concentration and area under the curve were ca. 30% lower in subjects with a BMI of ≥40 kg/m
2
compared to those <30 kg/m
2
. A five-compartment pharmacokinetic model with zero-order infusion and first-order elimination optimally described the plasma concentration-time profiles of the prodrug and ceftaroline. Estimated creatinine clearance (eCL
CR
) and TBW best explained ceftaroline clearance and volume of distribution, respectively. Although lower ceftaroline plasma concentrations were observed in obese subjects, Monte Carlo simulations suggest the probability of target attainment is ≥90% when the MIC is ≤1 μg/ml irrespective of TBW or eCL
CR
. No dosage adjustment for ceftaroline appears to be necessary based on TBW alone in adults with comparable eCL
CR
. Confirmation of these findings in infected obese patients is necessary to validate these findings in healthy volunteers. (This study has been registered at ClinicalTrials.gov under registration no. NCT01648127.)
Bioluminescence for Assessing Drug Potency against Nonreplicating Mycobacterium tuberculosis
Authors: Vocat Anthony , Hartkoorn Ruben C. , Lechartier Benoit , Zhang Ming , Dhar Neeraj , Cole Stewart T. , Sala Claudia
Published: April 2015

Targeting dormant
Mycobacterium tuberculosis
represents a challenge to antituberculosis drug discovery programs. We previously reported and validated the use of the streptomycin (STR)-dependent
M. tuberculosis
18b strain as a tool for assessing drug potency against nonreplicating bacteria both
in vitro
and
in vivo
. In this study, we generated a luminescent 18b strain, named 18b-Lux, by transforming the bacteria with a vector expressing the
luxCDABE
operon from
Photorhabdus luminescens
. Luciferase expression was demonstrated under replicating conditions, and, more importantly, luminescence levels significantly above background were detected following STR removal. The sensitivity of STR-starved 18b-Lux to approved and candidate antituberculosis therapeutic agents was evaluated by means of a luciferase assay in a 96-well format. Results mirrored the data obtained with the standard resazurin reduction microplate assay, and the luminescence readout allowed time course assessments of drug efficacy
in vitro
. Specifically, we proved that bedaquiline, the rifamycins, and sutezolid displayed time-dependent activity against dormant bacteria, while pyrazinamide and SQ109 showed bactericidal effects at the highest concentrations tested. Overall, we established the optimal conditions for an inexpensive, simple, and very sensitive assay with great potential for future applications.
Increasing Prevalence of a Novel Triple-Mutant Dihydropteroate Synthase Genotype in Plasmodium falciparum in Western Kenya
Authors: Lucchi Naomi W. , Okoth Sheila Akinyi , Komino Franklin , Onyona Philip , Goldman Ira F. , Ljolje Dragan , Shi Ya Ping , Barnwell John W. , Udhayakumar Venkatachalam , Kariuki Simon
Published: April 2015

The molecular basis of sulfadoxine-pyrimethamine (SP) resistance lies in a combination of single-nucleotide polymorphisms (SNPs) in two genes coding for
Plasmodium falciparum
dihydrofolate reductase (
Pfdhfr
) and
P. falciparum
dihydropteroate synthase (
Pfdhps
), targeted by pyrimethamine and sulfadoxine, respectively. The continued use of SP for intermittent preventive treatment in pregnant women in many African countries, despite SP's discontinuation as a first-line antimalarial treatment option due to high levels of drug resistance, may further increase the prevalence of SP-resistant parasites and/or lead to the selection of new mutations. An antimalarial drug resistance surveillance study was conducted in western Kenya between 2010 and 2013. A total of 203 clinical samples from children with uncomplicated malaria were genotyped for SNPs associated with SP resistance. The prevalence of the triple-mutant
Pfdhfr
C
50

I
51
R
59
N
108

I
164
genotype and the double-mutant
Pfdhps
S
436

G
437
E
540

A
581
A
613
genotype was high. Two triple-mutant
Pfdhps
genotypes, S
436

G
437
E
540
G
581

A
613
and

H
436
G
437
E
540

A
581
A
613
, were found, with the latter thus far being uniquely found in western Kenya. The prevalence of the S
436

G
437
E
540
G
581

A
613
genotype was low. However, a steady increase in the prevalence of the
Pfdhps
triple-mutant

H
436
G
437
E
540

A
581
A
613
genotype has been observed since its appearance in early 2000. Isolates with these genotypes shared substantial microsatellite haplotypes with the most common double-mutant allele, suggesting that this triple-mutant allele may have evolved locally. Overall, these findings show that the prevalence of the

H
436
G
437
E
540

A
581
A
613
triple mutant may be increasing in this population and could compromise the efficacy of SP for intermittent preventive treatment in pregnant women if it increases the resistance threshold further.
Optimization of Polyene-Azole Combination Therapy against Aspergillosis Using an
In Vitro
Pharmacokinetic-Pharmacodynamic Model
Authors: Siopi Maria , Siafakas Nikolaos , Vourli Sophia , Zerva Loukia , Meletiadis Joseph
Published: April 2015

Although amphotericin B-azole combination therapy has traditionally been questioned due to potential antagonistic interactions, it is often used successfully to treat refractory invasive aspergillosis. So far, pharmacodynamic (PD) interactions have been assessed with conventional
in vitro
tests, which do not mimic human serum concentrations and animal models using limited doses. We therefore simulated the human serum concentration profiles of amphotericin B and voriconazole in an
in vitro
dialysis/diffusion closed pharmacokinetic-pharmacodynamic (PK-PD) model and studied the pharmacodynamic interactions against an azole-resistant and an azole-susceptible
Aspergillus fumigatus
isolate, using Bliss independence and canonical mixture response surface analyses. Amphotericin B dosing regimens with the drug administered every 24 h (q24h) were combined with voriconazole q12h dosing regimens.
In vitro
PK-PD combination data were then combined with human PK data by using Monte Carlo analysis. The target attainment rate and the serum concentration/MIC ratio were calculated for isolates with different MICs. Synergy (20 to 31%) was observed at low amphotericin B-high voriconazole exposures, whereas antagonism (−6 to −16%) was found at high amphotericin B-low voriconazole exposures for both isolates. Combination therapy resulted in 17 to 48% higher target attainment rates than those of monotherapy regimens for isolates with voriconazole/amphotericin B MICs of 1 to 4 mg/liter. Optimal activity was found for combination regimens with a 1.1 total minimum concentration of drug in serum (
tC
min
)/MIC ratio for voriconazole and a 0.5 total maximum concentration of drug in serum (
tC
max
)/MIC ratio for amphotericin B, whereas the equally effective monotherapy regimens required a voriconazole
tC
min
/MIC ratio of 1.8 and an amphotericin B
tC
max
/MIC ratio of 2.8. Amphotericin B-voriconazole combination regimens were more effective than monotherapy regimens. Therapeutic drug monitoring can be employed to optimize antifungal combination therapy with low-dose (≤0.6 mg/kg) amphotericin B-based combination regimens against resistant isolates for minimal toxicity.
Replication of Salmonella enterica Serovar Typhimurium in Human Monocyte-Derived Macrophages
Authors: Lathrop Stephanie K. , Binder Kelsey A. , Starr Tregei , Cooper Kendal G. , Chong Audrey , Carmody Aaron B. , Steele-Mortimer Olivia
Published: April 2015

Salmonella enterica
serovar Typhimurium is a common cause of food-borne gastrointestinal illness, but additionally it causes potentially fatal bacteremia in some immunocompromised patients. In mice, systemic spread and replication of the bacteria depend upon infection of and replication within macrophages, but replication in human macrophages is not widely reported or well studied. In order to assess the ability of
Salmonella
Typhimurium to replicate in human macrophages, we infected primary monocyte-derived macrophages (MDM) that had been differentiated under conditions known to generate different phenotypes. We found that replication in MDM depends greatly upon the phenotype of the cells, as M1-skewed macrophages did not allow replication, while M2a macrophages and macrophages differentiated with macrophage colony-stimulating factor (M-CSF) alone (termed M0) did. We describe how additional conditions that alter the macrophage phenotype or the gene expression of the bacteria affect the outcome of infection. In M0 MDM, the temporal expression of representative genes from
Salmonella
pathogenicity islands 1 and 2 (SPI1 and SPI2) and the importance of the PhoP/Q two-component regulatory system are similar to what has been shown in mouse macrophages. However, in contrast to mouse macrophages, where replication is SPI2 dependent, we observed early SPI2-independent replication in addition to later SPI2-dependent replication in M0 macrophages. Only SPI2-dependent replication was associated with death of the host cell at later time points. Altogether, our results reveal a very nuanced interaction between
Salmonella
and human macrophages.
Abolishing Cell Wall Glycosylphosphatidylinositol-Anchored Proteins in Candida albicans Enhances Recognition by Host Dectin-1
Authors: Shen Hui , Chen Si Min , Liu Wei , Zhu Fang , He Li Juan , Zhang Jun Dong , Zhang Shi Qun , Yan Lan , Xu Zheng , Xu Guo Tong , An Mao Mao , Jiang Yuan Ying
Published: April 2015

Fungi can shield surface pathogen-associated molecular patterns (PAMPs) for evading host immune attack. The most common and opportunistic human pathogen,Candida albicans, can shield β-(1 3)-glucan on the cell wall, one of the major PAMPs, to avoid host phagocyte Dectin-1 recognition. The way to interfere in the shielding process for more effective antifungal defense is not well established. In this study, we found that deletion of theC. albicansGPI7gene, which was responsible for adding ethanolaminephosphate to the second mannose in glycosylphosphatidylinositol (GPI) biosynthesis, could block the attachment of most GPI-anchored cell wall proteins (GPI-CWPs) to the cell wall and subsequently unmask the concealed β-(1,3)-glucan. Neutrophils could kill the uncloakedgpi7mutant more efficiently with an augmented respiratory burst. Thegpi7mutant also stimulated Dectin-1-dependent immune responses of macrophages, including activation of nuclear factor-κB (NF-κB) and mitogen-activated protein kinase (MAPK) pathways and secretion of specific cytokines, such as tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), and IL-12p40. Furthermore, thegpi7null mutant could induce an enhanced inflammatory response through promoting significant recruitment of neutrophils and monocytes and could stimulate stronger Th1 and Th17 cell responses to fungal infectionsin vivo. Thesein vivophenotypes also were Dectin-1 dependent. Thus, we assume that GPI-CWPs are involved in the immune mechanism ofC. albicansescaping from host recognition by Dectin-1. Our studies also indicate that the blockage of GPI anchor synthesis is a strategy to inhibitC. albicansevading host recognition.
Chronic alveolar haemorrhage in a paediatric patient: a diagnostic and treatment challenge
Authors: Freitas Ana , Senra Virgílio , Marinho António , Guedes Margarida
Published: April 2015

Pulmonary haemosiderosis is characterised by chronic alveolar haemorrhage, which can lead to serious cardiorespiratory complications. Although considered idiopathic in most patients, there are many possible aetiologies. We present a case of an 18-year-old woman with pulmonary haemosiderosis since 4 years of age, with an inconclusive initial study, who was treated with systemic corticosteroids and hydroxychloroquine until the age of 12 years, and azathioprine since then. Multiple exacerbations led to interstitial lung disease with restrictive functional pattern. Unilateral cochlear deafness was diagnosed at the age of 12 years and occasional polyarthralgias were recorded. When she was 16 years of age the study revealed an atypical myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA) pattern. Cyclophosphamide and rituximab were administered with resolution of respiratory insufficiency and functional disability, without new episodes of alveolar haemorrhage. This case of chronic pulmonary haemorrhage was revealed to be an ANCA vasculitis, the diagnosis of which was possible only after 12 years of symptoms, with clinical and functional improvement with the association of cyclophosphamide and rituximab.
Two-stage release in Streeter's dysplasia
Authors: Naqvi Zohaib Gulzar , Rao Irfan , Anwer Wahid , Yaseen Tahir
Published: April 2015

Streeter's dysplasia is a rare disorder of congenital constricting bands, occurring in 1–10 000 birth, with no sex predilection. In severe cases, it is associated with autoamputation of distal extremities such as fingers and toes. Recent advances have made it possible, in developed countries, to recognise this condition in the prenatal period and to initiate prompt intrauterine management, however, these, being uncommon procedures, need technical advances and experienced hands. In developing countries, recognition of the condition with timely management of primary and associated abnormalities required. We present a case of a 4-month-old child with type IV Streeter's dysplasia associated with right flexible clubfoot, who underwent successful two-stage release of symptomatic constricting bands from bilateral legs.
Congenital hernia of cord: an often misdiagnosed entity
Authors: Raju Rubin , Satti Mohamed , Lee Quoc , Vettraino Ivana
Published: April 2015

Congenital hernia of the cord, also known as umbilical cord hernia, is an often misdiagnosed and under-reported entity, easily confused with a small omphalocele. It is different from postnatally diagnosed umbilical hernias and is believed to arise from persistent physiological mid-gut herniation. Its incidence is estimated to be 1 in 5000. Unlike an omphalocele, it is considered benign and is not linked with chromosomal anomalies. It has been loosely associated with intestinal anomalies, suggesting the need for a complete fetal anatomical ultrasound evaluation. We present a case of a fetal umbilical cord hernia diagnosed in a 28-year-old woman at 21 weeks gestation. The antenatal and intrapartum courses were uncomplicated. It was misdiagnosed postnatally as a small omphalocele, causing unwarranted anxiety in the parents. Increased awareness and knowledge of such an entity among health professionals is important to prevent unwarranted anxiety from misdiagnosis, and inadvertent bowel injury during cord clamping at delivery.
Community-linked maternal death review (CLMDR) to measure and prevent maternal mortality: a pilot study in rural Malawi
Authors: Bayley Olivia , Chapota Hilda , Kainja Esther , Phiri Tambosi , Gondwe Chelmsford , King Carina , Nambiar Bejoy , Mwansambo Charles , Kazembe Peter , Costello Anthony , Rosato Mikey , Colbourn Tim
Published: April 2015

Background

In Malawi, maternal mortality remains high. Existing maternal death reviews fail to adequately review most deaths, or capture those that occur outside the health system. We assessed the value of community involvement to improve capture and response to community maternal deaths.

Methods

We designed and piloted a community-linked maternal death review (CLMDR) process in Mchinji District, Malawi, which partnered community and health facility stakeholders to identify and review maternal deaths and generate actions to prevent future deaths. The CLMDR process involved five stages: community verbal autopsy, community and facility review meetings, a public meeting and bimonthly reviews involving both community and facility representatives.

Results

The CLMDR process was found to be comparable to a previous research-driven surveillance system at identifying deaths in Mchinji District (population 456 500 in 2008). 52 maternal deaths were identified between July 2011 and June 2012, 27 (52%) of which would not have been identified without community involvement. Based on district estimates of population (500 000) and crude birth rate (35 births per 1000 population), the maternal mortality ratio was around 300 maternal deaths per 100 000 live births. Of the 41 cases that started the CLMDR process, 28 (68%) completed all five stages. We found the CLMDR process to increase the quantity of information available and to involve a wider range of stakeholders in maternal death review (MDR). The process resulted in high rates of completion of community-planned actions (82%), and district hospital (67%) and health centre (65%) actions to prevent maternal deaths.

Conclusions

CLMDR is an important addition to the established forms of MDR. It shows potential as a maternal death surveillance system, and may be applicable to similar contexts with high maternal mortality.
Nutritional support and follow‐up of a puppy with chronic kidney disease
Authors: Dupont Sofie , Van de Maele Isabel , Lourenço Marta , Hesta Myriam
Published: April 2015

A five months old, Flat‐Coated Retriever puppy with poor body condition diagnosed with pyelonephritis and chronic kidney disease (CKD) was referred for a nutritional consult. The conflicting protein and phosphorus requirements for growth and poor body condition versus CKD were scrutinised. To maximise the quality of life (QoL) despite the poor prognosis, several diet plans were advised taking into account the different growth periods of this medium breed puppy. At 15 months of age, body condition was still below target and the creatinine level had increased consistently since the first consult. Despite the progressive decline in kidney function, serum urea concentration decreased compared with seven months before, whereas serum concentrations of total protein, albumin and phosphate remained normal at all times. With the different adjusted diet plans, the QoL of the puppy was improved, allowing for a normal and exceptionally energetic life until the age of nearly three years.
Nrf2 inducer and cncC overexpression attenuates neurodegeneration due to α-synuclein in Drosophila
Authors: Wang Bing , Liu Qingqing , Shan Hongyun , Xia Chunlin , Liu Zhaohui
Published: April 2015

The study of the genes that are related to the pathogenesis of Parkinson’s disease (PD) will improve our understanding of the mechanisms that underlie the development of PD. α-Synuclein is a major protein component of Lewy bodies, which are characteristic structures of PD pathology. Mutations in α-synuclein are closely related to the early onset of autosomal dominant PD. Transgenic flies with mutant α-synuclein (A53T) display neurodegenerative changes that include movement dysfunctions and a loss of dopaminergic neurons in the brain. In the present study, we measured reactive oxygen species (ROS) levels in α-synuclein transgenic flies by monitoring the fluorescence levels of redox-sensitive indicators based on GFP (roGFP) in flies co-expressing roGFP and mutant α-synuclein. We found that the ROS levels were significantly increased in the mutant α-synuclein flies. The elevations in ROS levels were also proportionate to the behavioral disorders and the losses of dopaminergic neurons. We also found that CDDO-Me inhibited the increases in ROS levels in the A53T flies and improved the neurodegenerative changes by activating the Nrf2/antioxidant response element signaling pathway. Selective expression of the Nrf2 homologous gene cncC in the dopaminergic neurons effectively protected against the neurodegenerative phenotype of the A53T α-synuclein flies, compared to the flies that expressed cncC in all neurons. These results indicate that the reductions in oxidative stress that are mediated by the activation of the antioxidant signaling pathway can effectively attenuate the neurotoxicity caused by mutations in α-synuclein.
Testing antifreeze protein from the longhorn beetle Rhagium mordax as a kinetic gas hydrate inhibitor using a high-pressure micro differential scanning calorimeter
Authors: Daraboina Nagu , Malmos Perfeldt Christine , von Solms Nicolas
Published: April 2015

Low dosage kinetic hydrate inhibitors are employed as alternatives to expensive thermodynamic inhibitors to manage the risk of hydrate formation inside oil and gas pipelines. These chemicals need to be tested at appropriate conditions in the laboratory before deployment in the field. A high pressure micro differential scanning calorimeter HP-μDSC VII (Setaram Inc.) containing two 50 cc high pressure cells (maximum operating pressure 40 MPa; temperature range –40 to 120 °C) was employed to observe methane hydrate formation and decomposition in the presence of hyperactive antifreeze protein from Rhagium mordax (RmAFP) and biodegradable synthetic kinetic inhibitor Luvicap Bio. A systematic capillary dispersion method was used, and this method enhanced the ability to detect the effect of various inhibitors on hydrate formation with small quantities. The presence of RmAFP and Luvicap Bio influence (inhibit) the hydrate formation phenomena significantly. Luvicap Bio (relative strength compared to buffer: 13.3 °C) is stronger than RmAFP (9.8 °C) as a nucleation inhibitor. However, the presence RmAFP not only delays hydrate nucleation but also reduces the amount of hydrate formed (20%–30%) after nucleation significantly. Unlike RmAFP, Luvicap Bio promoted the amount of hydrate formed after nucleation. The superior hydrate growth inhibition capability and predictable hydrate melting behavior compared to complex, heterogeneous hydrate melting with Luvicap Bio shows that RmAFP can be a potential natural green kinetic inhibitor for hydrate formation in pipelines.
Optimization of a Safranine O three-component photoinitiating system for use in holographic recording
Authors: Ibrahim Ahmad , Fouhaili Bandar El , Yong Aurélie Chan , Ley Christian , Allonas Xavier , Carré Christiane
Published: April 2015

The coupling between a holographic resin, combining multiple monomers and additives, with photoinitiating systems (PIS) is not straightforward. In this paper, a classic PIS based on Safranine O (SFH+) as dye, an amine (ethyl-4-(dimethylamino)benzoate) as electron donor, and a triazine derivative (2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine) as electron acceptor for holographic recording was studied using time-resolved spectroscopic experiments. By taking into account the viscosity of the matrix, a method to evaluate the overall quantum yield of radicals released is proposed and the contribution of singlet and triplet excited states of SFH+ in the formation of radicals is evaluated. Then the corresponding photopolymerization efficiencies of the PIS, studied by real-time FTIR, are compared with holographic recording experiments: this system allows the formation of a hologram with high diffraction efficiency (0.9) in 3 s of irradiation time. It is shown that besides holographic resin formulation, the photochemistry of PIS also impacts the hologram formation.
Black hole corrections due to minimal length and modified dispersion relation
Authors: Nasser Tawfik Abdel , Magied Diab Abdel
Published: April 2015

The generalized uncertainty principles (GUP) and modified dispersion relations (MDR) are much like two faces for one coin in research for the phenomenology of quantum gravity which apparently plays an important role in estimating the possible modifications of the black hole thermodynamics and the Friedmann equations. We first reproduce the horizon area for different types of black holes and investigate the quantum corrections to Bekenstein–Hawking entropy (entropy-area law). Based on this, we study further thermodynamical quantities and accordingly the modified Friedmann equation in four-dimensional de Sitter–Schwarzschild, Reissner–Nördstrom and Garfinkle–Horowitz–Strominger black holes. In doing this, we applied various quantum gravity approaches. The MDR parameter relative to the GUP one is computed and the properties of the black holes are predicted. This should play an important role in estimating response of quantum gravity to the various metric-types of black holes. We found a considerable change in the thermodynamics quantities. We find that the modified entropy of de Sitter–Schwarzshild and Reissner–Nördstrom black holes starts to exist at a finite standard entropy. The Garfinkle–Horowitz–Strominger black hole shows a different entropic property. The modified specific heat due to GUP and MDR approaches vanishes at large standard specific heat, while the corrections due to GUP result in different behaviors. The specific heat of modified de Sitter–Schwarzshild and Reissner–Nördstrom black holes seems to increase, especially at large standard specific heat. In the early case, the black hole cannot exchange heat with the surrounding space. Accordingly, we would predict black hole remnants which may be considered as candidates for dark matter.
Magnetic susceptibility at zero and nonzero chemical potential in QCD and QED
Authors: Orlovsky V. D. , Simonov Yu. A.
Published: April 2015

Magnetic susceptibility of the quark and electron gas is calculated in a closed form for any chemical potential μ summing the whole Matsubara series. For the quark gas and small μ≪T a strong rise with T is found due to Polyakov loop factors L(T), in good agreement with lattice data. For the electron gas the lowest Matsubara term (n = 1) contributes 40% larger than the exact answer. In the case of small T, [Formula: see text], the oscillations as functions of eB occur, characteristic of the de Haas–van Alphen effect. Results are compared with available lattice data and with the case of relativistic electron gas, which obtains putting L(T)≡1.
How important is iϵ in QFT?
Authors: Fariborz Amir H. , Jora Renata , Schechter Joseph
Published: April 2015

We discuss the role of iϵ in quantum field theories and suggest that it can be identified with the dimensional regularization parameter iϵ = 4-d thus clarifying and simplifying issues related to the infrared divergences without altering any of the present knowledge in QFT. We further present the relevance of this assumption for the optical theorem.
Effects of vanadium impurity on TiO2 properties
Authors: Stashans Arvids , Escobar Jairo
Published: April 2015

Our present work is based on the density functional theory (DFT) studies of TiO 2 crystals doped with V impurities. Both rutile and anatase structures have been considered within the present research and different defect concentrations have been used as well. Our calculations reveal equilibrium geometry of the system showing atomic rearrangement around the point defect being mainly inward with respect to the impurity. Magnetism and electronic structure based on the density of states (DOS) patterns for both rutile and anatase crystals have been obtained and discussed in detail. It is shown that local magnetic moments arise mainly from the 3d states of the impurity atom with some admixture of 2p states from the vanadium-nearest O atoms.
Measurement-induced nonlocality in the two-qubit Heisenberg XY model
Authors: Chen Wen-Xue , Xie Yu-Xia , Xi Xiao-Qiang
Published: April 2015

Quantum correlations are essential for quantum information processing (QIP). Measurement-induced nonlocality (MIN) is a good measure of quantum correlation, and is favored for its conceptual implication and potential application. We investigated here the particular behaviors of the geometric and entropic measures of MIN in the two-qubit Heisenberg XY model and revealed the effects of anisotropic parameter γ and the external magnetic field B on them. Our results showed that both γ and B can serve as efficient controlling parameters for tuning MIN in the XY model.
Deposit heterogeneity and the dynamics of the organic semiconductors P3HT and PCBM solution under evaporation
Authors: Yu H. P. , Luo H. , Liu T. T. , Jing G. Y.
Published: April 2015

The formation of organic semiconductor layer is the key procedure in the manufacture of organic photovoltaic solar cell, in which the natural evaporation of the solvent from the polymer solution plays the essential role for the conversion efficiency. Here, poly(3-hexylthiophene) ( P3HT ) and fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester ( PCBM ), as two types of semiconductor polymers, were selected as the active layer to form the deposit by drying the blend solution drops on the substrate. We explored the influences of droplet size and solute concentration on the homogeneity of the deposit. Additionally, the spatial distribution of molecular chains and grains and the instability of the droplet morphology during the drying were investigated. The results showed that the "coffee-ring" phenomenon occurred forming an annular deposit at the outermost edge and the width of the annular ring increased linearly with the concentration of the P3HT solution, until a saturation plateau is approached. On the other hand, the PCBM deposition presented a circular disk at low concentration, but displayed a sudden instability for an irregular perimeter at a critical concentration and there existed a second critical concentration above which the deposit exhibited the return of the stable circular shape. The results have an instructive impact on the performance of the device and the formation of fine structures during the process of printing, film preparation and painting.
Floating and flying ferrofluid bridges induced by external magnetic fields
Authors: Ma Rongchao , Zhou Yixin , Liu Jing
Published: April 2015

A ferrofluid is a mixture that exhibits both magnetism and fluidity. This merit enables the ferrofluid to be used in a wide variety of areas. Here we show that a floating ferrofluid bridge can be induced between two separated boards under a balanced external magnetic field generated by two magnets, while a flying ferrofluid bridge can be induced under an unbalanced external magnetic field generated by only one magnet. The mechanisms of the ferrofluid bridges were discussed and the corresponding mathematical equations were also established to describe the interacting magnetic force between the ferro particles inside the ferrofluid. This work answered a basic question that, except for the well-known floating water bridges that are related to electricity, one can also build up a liquid bridge that is related to magnetism.
Secure identity-based encryption in the quantum random oracle model
Authors: Zhandry Mark
Published: April 2015

We give the first proof of security for an identity-based encryption (IBE) scheme in the quantum random oracle model. This is the first proof of security for any scheme in this model that does not rely on the assumed existence of so-called quantum-secure pseudorandom functions (PRFs). Our techniques are quite general and we use them to obtain security proofs for two random oracle hierarchical IBE schemes and a random oracle signature scheme, all of which have previously resisted quantum security proofs, even assuming quantum-secure PRFs. We also explain how to remove quantum-secure PRFs from prior quantum random oracle model proofs. We accomplish these results by developing new tools for arguing that quantum algorithms cannot distinguish between two oracle distributions. Using a particular class of oracle distributions that we call semi-constant distributions, we argue that the aforementioned cryptosystems are secure against quantum adversaries.
On some features of possible torsion effects on observables at Hadron colliders
Authors: Syromyatnikov A. G.
Published: April 2015

I give a geometrical description of conformal gauge gravitational theory (CGTG) from the viewpoint of symmetries and affine structure. In the frames of the CGTG incorporating gravitation with torsion space-time into Standard Model of electro-weak interaction (EWI) the multi-muon events produced at the Fermilab Tevatron collider were studied. The CGTG gives the value of the torsion pseudotrace–spinor (muon) universal coupling fT = 4.388 ⋅ 10-17 GF, and with limits from known experiments — torsion mass mT = 0.4700 ⋅ 10-7 eV or mT = 0.445 ⋅ 10-15 muon mass. So the value of the constant of effective four-fermions interaction fT/mT = 0.988, indeed may lead to multi-muon events production. The model of interaction of quantum oscillator with the tensor potential Wμν of traceless part of the torsion lead to 2 cm displacement of quark–lepton system as a whole in the magnetic field of collider in accordance with a significant sample of events related to [Formula: see text] production and decay in which at least one of the muon candidates is produced outside of the beam pipe of radius 1.5 cm. A traceless part of the torsion in CGTG does not vanish in the Newtonian limit of nonzero mass. Torsion gravity potential Wμν gives conservation of a special conformal current and may be produced in the condition of a spontaneous breaking of gauge symmetry where the gravitation mass MX defect is 1–3 Tev ⋅ c-2 or 10-13MX. This effect may be possible at known effects on top pair asymmetries at the Tevatron and LHC and takes place as the known energy dissipation above 3 TeV of the Galaxy gamma-ray and neutrino spectrum from two bubbles outside the Galaxy plane.
Symplectic structures related with higher order variational problems
Authors: Kijowski Jerzy , Moreno Giovanni
Published: April 2015

In this paper, we derive the symplectic framework for field theories defined by higher order Lagrangians. The construction is based on the symplectic reduction of suitable spaces of iterated jets. The possibility of reducing a higher order system of partial differential equations to a constrained first-order one, the symplectic structures naturally arising in the dynamics of a first-order Lagrangian theory, and the importance of the Poincaré–Cartan form for variational problems, are all well-established facts. However, their adequate combination corresponding to higher order theories is missing in the literature. Here we obtain a consistent and truly finite-dimensional canonical formalism, as well as a higher order version of the Poincaré–Cartan form. In our exposition, the rigorous global proofs of the main results are always accompanied by their local coordinate descriptions, indispensable to work out practical examples.
Quaternionic Heisenberg groups as naturally reductive homogeneous spaces
Authors: Agricola Ilka , Ferreira Ana Cristina , Storm Reinier
Published: April 2015

In this paper, we describe the geometry of the quaternionic Heisenberg groups from a Riemannian viewpoint. We show, in all dimensions, that they carry an almost 3-contact metric structure which allows us to define the metric connection that equips these groups with the structure of a naturally reductive homogeneous space. It turns out that this connection, which we shall call the canonical connection because of its analogy to the 3-Sasaki case, preserves the horizontal and vertical distributions and even the quaternionic contact (qc) structure of the quaternionic Heisenberg groups. We focus on the 7-dimensional case and prove that the canonical connection can also be obtained by means of a cocalibrated G2 structure. We then study the spinorial properties of this group and present the noteworthy fact that it is the only known example of a manifold which carries generalized Killing spinors with three different eigenvalues.
A perspective on non-commutative quantum gravity
Authors: Martins Rachel A. D.
Published: April 2015

In this paper, we present some of the concepts underlying a program of non-commutative quantum gravity and recall some of the results. This program includes a novel approach to spectral triple categorification and also a precise connection between Fell bundles and Connes' non-commutative geometry. Motivated by topics in quantization of the non-commutative standard model and introduction of algebraic techniques and concepts into quantum gravity (following for example Crane, Baez and Barrett), we define spectral C*-categories, which are deformed spectral triples in a sense made precise. This definition gives to representations of a C*-category on a small category of Hilbert spaces and bounded linear maps, the interpretation of a topological quantum field theory. The construction passes two mandatory tests: (i) there is a classical limit theorem reproducing a Riemannian spin manifold manifesting Connes' and Schücker's non-commutative counterpart of Einstein's equivalence principle, and (ii) there is consistency with the experimental fermion mass matrix. We also present an algebra invariant taking the form of a partition function arising from a C*-bundle dynamical system in connection with C*-subalgebra theory.
Magnetic Nanoparticles with High Specific Absorption Rate at Low Alternating Magnetic Field
Authors: Kekalo K. , Baker I. , Meyers R. , Shyong J.
Published: April 2015

This paper describes the synthesis and properties of a new type of magnetic nanoparticle (MNP) for use in the hyperthermia treatment of tumors. These particles consist of 2–4 nm crystals of gamma- Fe 2 O 3 gathered in 20–40 nm aggregates with a coating of carboxymethyl-dextran, producing a zetasize of 110–120 nm. Despite their very low saturation magnetization (1.5–6.5 emu/g), the specific absorption rate (SAR) of the nanoparticles is 22–200 W/g at applied alternating magnetic field (AMF) with strengths of 100–500 Oe at a frequency of 160 kHz.
Polarization insensitive metamaterial absorber based on E-shaped all-dielectric structure
Authors: Li Liyang , Wang Jun , Ma Hua , Wang Jiafu , Du Hongliang , Qu Shaobo
Published: April 2015

In this paper, we designed a metamaterial absorber performed in microwave frequency band. This absorber is composed of E-shaped dielectrics which are arranged along different directions. The E-shaped all-dielectric structure is made of microwave ceramics with high permittivity and low loss. Within about 1 GHz frequency band, more than 86% absorption efficiency was observed for this metamaterial absorber. This absorber is polarization insensitive and is stable for incident angles. It is figured out that the polarization insensitive absorption is caused by the nearly located varied resonant modes which are excited by the E-shaped all-dielectric resonators with the same size but in the different direction. The E-shaped dielectric absorber contains intensive resonant points. Our research work paves a way for designing all-dielectric absorber.
Dielectric properties of amorphous Zr–Al–O and Zr-Si-O thin films
Authors: Naoi T. A. , Paik Hanjong , Green M. L. , van Dover R. B.
Published: April 2015

We have systematically studied the composition dependence of the dielectric properties of Zr 1-x Al x O 2-x/2 and Zr 1-x Si x O 2. An essentially linear variation of the static dielectric constant, εs, was observed as a function of composition, x, for compositions rich in the p-block element, i.e., x > 0.4, for both chemical systems. However an abrupt change in εs is found near x ≈ 0.35, associated with the onset of crystallinity in as-deposited films. Breakdown fields do not show a comparable composition dependence. Measurements of the index of refraction at optical frequencies, combined with a simple Clausius–Mossotti interpretation, indicates that low-frequency (ionic) contributions to the polarizability exhibit systematic deviation with respect to values linearly interpolated from the endmembers. These trends are not consistently affected by the presence of crystalline order, but are related to changes associated with heterogeneous local oxygen coordination and bonding.
Hypervelocity Stars
Authors: Brown Warren R.
Published: April 2015

Hypervelocity stars (HVSs) travel with such extreme velocities that dynamical ejection via gravitational interaction with a massive black hole (MBH) is their most likely origin. Observers have discovered dozens of unbound main-sequence stars since the first in 2005, and the velocities, stellar nature, spatial distribution, and overall numbers of unbound B stars in the Milky Way halo all fit an MBH origin. Theorists have proposed various mechanisms for ejecting unbound stars, and these mechanisms can be tested with larger and more complete samples. HVSs' properties are linked to the nature and environment of the Milky Way's MBH, and, with future proper motion measurements, their trajectories may provide unique probes of the dark matter halo that surrounds the Milky Way.