bluuebunny/crossref_metadata_2025 huggingface dataset:
Short Sales and Fundamental Value: Explaining the REIT Premium to NAV
Authors: Brounen Dirk , Ling David C. , Prado Melissa Porras
Published: June 2013

This study explores the role of short sale constraints in explaining the variation in premiums to Net Asset Value (NAV) in REIT pricing. We use proprietary information on short sales between June 2006 and September 2008 to examine how short sales and short sale constraints affect the variation in monthly REIT NAV premiums using panel vector autoregression models. We find that variation in short sale activity across individual REITs can account for at least one‐third of the variation in NAV premiums. Short sale constraints tend to be binding when there is strong demand and limited supply of shares to short. Excess demand leads to overvaluation and the correction of the overvaluation explains the under‐performance of premium REITs.
Risk Segmentation of American Homes: Evidence from Denver
Authors: Peng Liang , Thibodeau Thomas
Published: June 2013

This article empirically examines the segmentation of house price risk across 99 ZIP‐code‐delineated neighborhoods in metropolitan Denver. The house price risk in each neighborhood is measured with the temporal variation of quarterly appreciation rates of the neighborhood house price index over the 2002–2007 period. Cross‐sectional regressions of neighborhood house price risk on the median household income and the percentage of population in poverty from the 2000 census data for the same neighborhoods provide strong evidence that the house price risk is significantly higher in low‐income/poor neighborhoods. Subperiod analyses further indicate that the risk segmentation exists in both a booming period (pre 2005:2) and a busting period (post 2005:3). The results indicate that homeownership can be a much riskier investment for low‐income/poor households.
Caught in the Same Frame? The Language of Evidence‐based Policy in Debates about the Australian Government ‘Intervention’ into Northern Territory Aboriginal Communities
Authors: Partridge Emma
Published: June 2013

This article examines ongoing contestation surrounding the policies of the Federal government's ‘Intervention’ in Indigenous communities in Australia's Northern Territory. It highlights how the paradigm of ‘evidence‐based policy’ has been used by both the government and its critics, suggesting this commonality of language is worthy of reflection. Cautioning against an over‐reliance on the rationalist framework of ‘evidence‐based policy’, it draws on literature that problematizes this idea and insists on the inherently contested and political nature of the relationship between knowledge, evidence and policy‐making. It concludes by pointing to alternative strategies for improving Indigenous policy that risk being overlooked by a focus on ‘evidence‐based policy’ as a prescriptive ideal.
Putting the Research Boot on the Policymakers' Foot: Can Participatory Approaches Change the Relationship between Policymakers and Evaluation?
Authors: Richardson Liz
Published: June 2013

Barriers to the full use of social science in public policy‐making are related to a separation of knowledge production from its consumption, and by a lack of mechanisms to accommodate the political nature of decision‐making processes. Policymakers can ignore evidence in favour of conventional wisdom or ideologically driven choices. Avoiding policy engagement is a denial of some core ambitions for applied social science, but attempts at policy engagement have sometimes resulted in academic regret or little impact. One implication is that more participatory and co‐productive approaches to evaluation could be used by researchers and policymakers, particularly politicians, working together. However, participatory approaches have tended to align with methodologies which de‐privilege the idea of objective evidence of policy effectiveness. A case study of self‐evaluation by local government politicians attempted to overcome an artificial separation of positivist and non‐positivist methods into non‐participatory and participatory approaches, and close the divide between evidence and politically situated policymakers. It finds interest by local councillors in outcome evaluation, and some efforts to temper ideological biases with evidence, although a bias towards positive results remained. Successful self‐evaluations used data on policy outcomes in mixed methods pre‐ and post‐intervention designs, but not all were successful. One conclusion from the case study is that the participation of policymakers in conducting research may simply replicate difficulties faced by academic researchers using more conventional methods. However, the example suggests that a belief in positivism and a commitment to participatory approaches do not need to be in conflict.
RHD*weak partial 4.0 is associated with an altered RHCE*ce(48C, 105T, 733G, 744C, 1025T) allele in the Tunisian population
Authors: Ouchari M. , Polin H. , Romdhane H. , Abdelkefi S. , Houissa B. , Chakroun T. , Gabriel C. , Hmida S. , Jemni Yacoub S.
Published: June 2013

Background and Objectives

D is the most immunogenic blood group antigen. About 1% of whites carry an altered RHD allele leading to quantitative or qualitative changes in the antigen D expression. T201R and F223V encoded by 602C>G and 667T>G are specific amino acid substitutions of the weak D type 4 cluster of African origin, comprising the alleles RHD*09.01, RHD*09.02, RHD*09.03, RHD*09.04 and RHD*09.05. The purpose of this study was to estimate the presence of these RHD genotypes in the Tunisian population.

Materials and Methods

Ethylenediaminetetraacetate blood samples from 907 D+ and 93 D− blood donors were tested for markers 602G and 667G by allele‐specific primer‐polymerase chain reaction (PCR‐ASP). Samples with positive reactions were re‐evaluated by DNA sequencing for RHD and RHCE exons 1–10 and adjacent intronic sequences.

Results

Among 907 D+ samples, 19 individuals were identified to harbour the RHD*weak partial 4.0 allele. RHCE sequencing post‐haplotype‐specific extraction (HSE) revealed an altered RHCE*ce(48C, 105T, 733G, 744C, 1025T) in those samples. The linkage of the RHCE polymorphisms to one haplotype was proven by DNA sequencing post‐HSE.

Conclusion

The RHD*weak partial 4.0 allele syn. RHD*09.03 was estimated to occur 1 in 47 among D+ Tunisians. There was no evidence for other RHD alleles included in the weak D type 4 cluster.
Evolutionary insight into thePeripatopsis balfourisensu lato species complex (Onychophora:Peripatopsidae) reveals novel lineages and zoogeographic patterning
Authors: Daniels Savel R. , McDonald Dane E. , Picker Mike D.
Published: June 2013

Evolutionary relationships in the widely distributed velvet wormPeripatopsis balfourisensu lato species complex were examined using DNA sequence data, gross andSEMmorphology. Sequence data were generated for theCOImtDNAand the18SrRNAloci and analysed using aBayesian inference approach, maximum likelihood and maximum parsimony. Phylogenetic analyses of the combinedDNAsequence data revealed thatPeripatopsis clavigeraspecimens from the southernCape (clade 1) was sister toP. balfourisensu lato specimens from theCederbergMountains (clade 2). Within the mainP. balfourisensu lato species complex, three addition clades could be discerned (clades 3, 4 and 5). The obligatory troglobitic speciesPeripatopsis albawas equidistant between theCapePeninsula and adjacent interior (clade 3) and the twoBoland andHottentotsHollandMountains (clades 4 and 5). On theCapePeninsula,P. stelliporataspecimens nested among the sympatricP. balfourisensu lato specimens. TheCapePeninsula specimens were sister to specimens from Jonkershoek site 1,Kogelberg andSimonsberg. TwoBoland clades were retrieved, comprisingDuToit'sKloof,Bain'sKloof andMitchell'sPass and sister (in clade 4) to specimens from theBoland and adjacentHottentotsHollandMountains in clade 5. These results revealed complex biogeographic patterning in theP. balfourisensu lato species complex. The presence of sympatric, yet genetically discrete species pairs at six of the sample localities (DuToit'sKloof,Simonsberg,Jonkershoek sites 1 and 2,Kogelberg andLandroskop) suggests that there is reproductive isolation between the lineages. Divergence time estimations suggest aMiocene/Pliocene/Pleistocene cladogenesis. A taxonomic revision of theP. balfourisensu lato species complex was undertaken to stabilize the taxonomy.P. clavigerais monophyletic and retained for the southernCape specimens,P. balfourisensu stricto is now confined to theCapePeninsula and adjacent interior, whileP. stelliporatais regarded as a junior synonym of the latter taxon,P. albais endemic to theWynbergCave systems on theCapePeninsula. Three novel species (Peripatopsis cederbergiensis,sp. n.,Peripatopsis bolandisp. n. andPeripatopsis purpureus,sp. n.) are described.
Ultrasonic Effect on the Startup of an Oscillating Heat Pipe
Authors: Zhao Nannan , Zhao Dianli , Ma H. B.
Published: June 2013

This paper investigates the ultrasonic sound effect on oscillating motion and heat transfer in an oscillating heat pipe (OHP). The ultrasonic sound produced by electrically controlled piezoelectric ceramics is used to generate and maintain the oscillating motion and thereby enhance heat transfer. The results demonstrate that when an ultrasonic sound with a total electric power of 4.48 mW is added, the input power needed to start the oscillating motion can be reduced from 30 W to 18 W and the effective thermal conductivity is increased from 672.8 W/mK to 1254.7 W/mK.
Nanoscale Atoms in Solid-State Chemistry
Authors: Roy Xavier , Lee Chul-Ho , Crowther Andrew C. , Schenck Christine L. , Besara Tiglet , Lalancette Roger A. , Siegrist Theo , Stephens Peter W. , Brus Louis E. , Kim Philip , Steigerwald Michael L. , Nuckolls Colin
Published: June 2013

Ionic Materials via Charged Clusters

The formation of salts from atomic and small molecular ions could in principle be replicated with larger inorganic clusters. However, many clusters are stabilized by organic ligands that create a barrier for charge transfer reactions to create ions.

Roy
et al.

(p.
157
, published online 6 June; see the Perspective by

Batail

) now report that chromium, cobalt, and nickel selenide and telluride clusters form materials by charge transfer with C
60
. The Co and Cr clusters formed a layered structure analogous to CdI
2
, while the Ni cluster formed a structure related to NaCl.
Interactions of Multisensory Components Perceptually Rescue Túngara Frog Mating Signals
Authors: Taylor R. C. , Ryan M. J.
Published: June 2013

Romancing the Frog

In túngara frogs, auditory and visual components of mate calling do not naturally occur together.
Taylor and Ryan
(p.
273
, published online 6 June) now show that two signals that are unattractive to female frogs when presented alone become highly attractive when presented together. In a kind of “perceptual rescue,” the unique combination of two signals increased the receiver's interest in the previously uninteresting signals.
Peri-implant galactocele following vacuum-assisted core biopsy of the breast: a cautionary tale
Authors: Taylor Donna , Kulawansa Sagarika Thushanthi , McCallum Dugald Dalziel , Saunders Christobel
Published: June 2013

A lactating woman in her early 40s with a strong family history of breast cancer presented with a markedly swollen breast days after having a vacuum-assisted core biopsy performed to sample indeterminate microcalcifications in her left breast. Ultrasound showed a large peri-implant fluid collection which yielded milky fluid on aspiration consistent with galactocele formation. Histology of the core specimens revealed a fragment of fibrous capsule suggesting that the core biopsy had created a fistula between the breast tissue and the peri-implant space. Bromocriptine was given and the galactocele slowly resolved.
An unusual presentation of MEN2A
Authors: Casey R , Bell M , Keane M , Smyth A
Published: June 2013

A 35-year-old woman presented with non-specific symptoms of fatigue and weight loss. Radiological investigations diagnosed a metastatic process and large bilateral adrenal masses. Histology from a liver biopsy and skin biopsy confirmed a diagnosis of metastatic medullary thyroid cancer. Further biochemical investigations revealed a positive 24-h urinary metanephrine collection and evidence of primary hyperparathyroidism. Genetic testing confirmed a mutant RET oncogene, confirming our clinical suspicion of multiple endocrine neoplasia type 2 (MEN2A) syndrome. The patient had no family history of endocrine disease and presented with widespread metastatic disease, making this an unusual presentation of MEN2A syndrome. Furthermore cutaneous metastases are rarely encountered in conjunction with metastatic medullary thyroid cancer. This case draws attention to the importance of genetic counselling in first-degree relatives of patients with confirmed MEN2A. This allows for timely diagnosis and reduced morbidity and mortality.
Self-inflicted long complex urethro-vesical foreign body: is open surgery always needed?
Authors: Garg Manish , Kumar Manoj , Sankhwar Satyanarayan , Singh Vishwajeet
Published: June 2013

In this case report, we describe our experience of a self-inflicted long complex urethrovesical foreign body managed suprapubically through the minimally invasive technique. A 21-year-old man with antipsychotic treatment for the past 10 years presented with a long electric cable wire in his bladder with the distal end in the penile urethra. He presented with symptoms of voiding difficulty and gross haematuria. An attempt of gentle retrieval of wire through the cystoscopic forceps was not successful due to a very complex knot of cable in the bladder. To avoid open surgery such as suprapubic cystotomy, the percutaneous minimally invasive approach was planned. Access to the bladder was achieved by the suprapubic puncture of the bladder, placement of a guide-wire and serial dilation of supra-pubic tract. With the help of nephroscope, through suprapubic tract, the cable wire was retrieved antegradely without causing undue trauma to the bladder or urethra.
The prolonged clotting time in two female patients with thromboangiitis obliterans
Authors: Dang Yiping , Xia Yin , Li Yiqing , Yu DannyCW
Published: June 2013

Thromboangiitis obliterans (TAO), also known as Buerger's disease, is segmental non-atherosclerotic inflammatory disease, which affects the small and medium-sized peripheral arteries, veins and nerves of young adult smokers. The paper reports two TAO female patients, 26-year-old and 42-year-old, with prolonged clotting time. We compared 13 male patients and 2 female patients with TAO. The prothrombin time (PT), activated partial thromboplastin time (APTT) and thrombin time (TT) were normal in the male patients, whereas the clotting times were prolonged in the female patients. Coagulation tests including PT, APTT and TT evaluation could be the potential markers to female patients with TAO.
Central nervous system relapse in a patient with acute promyelocytic leukaemia: does the risk stratification matter?
Authors: Sahin Deniz Goren , Gunduz Eren , Akay Olga Meltem , Gulbas Zafer
Published: June 2013

Extramedullary relapse is an uncommon complication of acute promyelocytic leukaemia (APL). The most common site of extramedullary relapse is the central nervous system (CNS), and the majority of CNS relapses occur in patients with high-risk disease in which white blood cell count at presentation is greater than 10×103/μL. The best management of such patients is still controversial. We describe a 47-year-old man with APL who developed two CNS relapses which were diagnosed through the presence of t(15;17)(q22;q21) on PCR of the cerebrospinal fluid (CSF), despite presenting initially with intermediate-risk disease. We conclude that the intermediate risk group is very heterogeneous and these patients sometimes may behave like high-risk patients. Also, clinicians should take into account symptoms that can be related to CNS relapse in patients with APL and consider lumbar puncture even if radiological imaging does not reveal anything.
l-2 Hydroxyglutaric aciduria presenting with anxiety symptoms
Authors: Gökçen Cem , Işikay Sedat , Yilmaz Kutluhan
Published: June 2013

l-2 Hydroxyglutaric aciduria is a rare autosomal recessively inherited metabolic disorder of organic acid metabolism. Cerebellar and pyramidal signs with progressive neurological syndromes, mental deterioration, tremors, seizures, epilepsy and rarely macrocephaly are clinical findings of the disease. The diagnosis depends on increased levels ofl-2 hydroxyglutaric acid in urine, plasma and cerebrospinal fluid. Brain MRI shows peripheral white matter abnormalities in cerebral hemispheres, bilateral symmetrically abnormal signal intensity in basal ganglia and dentate nuclei. In this case report, we present a 13-year-old patient who presented with tremors and anxiety symptoms and was diagnosed asl-2 hydroxyglutaric aciduria after consultation with the child neurology department. We present a patient suffering from psychiatric symptoms with a metabolic disorder.
Primary intraosseous squamous cell carcinoma: a devil in disguise
Authors: Pardhe Nilesh , Bhagalia Sanjay , Nayak Prathibha Anand , Sireesha Sundaragiri Krishna
Published: June 2013

Primary intraosseous squamous cell carcinoma (PIOSCC) is a rare central jaw carcinoma derived from odontogenic epithelial remnants. When the tumour arises in an existing cyst, it may be difficult to recognise early PIOSCC and carry out necessary treatment. We report a case diagnosed in a 50-year-old man where timely intervention was delayed and prognosis was affected and the case diagnosed eventually by comprehensive clinical, radiological and histopathological examination.
Caecal volvulus: a consequence of acute cholecystitis
Authors: Anjum Ghulam Ali , Jaberansari Sarah , Habeeb Kayode
Published: June 2013

Caecal volvulus is an uncommon cause of closed loop intestinal obstruction which can lead to caecal gangrene and high mortality. Delay in diagnosis is one of the causes of this high mortality. Caecal volvulus is reported to be associated with previous abdominal surgery in most cases. We present the first reported case of caecal volvulus following/associated with acute cholecystitis.
Splinting with diastema closure as an adjunct to periodontal therapy
Authors: Gandi Padma , Rajavasireddi Shravanthi Rajah , Gurram Sindhura Reddy
Published: June 2013

A variety of treatment modalities, from removable partial dentures, fixed prosthesis to implant placement can be used for replacement of missing teeth. Anterior diastema closure is one of the most challenging tasks; it is appreciable that restorative approach is the fastest, simplest and most predictable. This case report presents a successfully accomplished closure of diastema in mandibular anterior teeth, and splinting of the adjacent teeth which were grade II mobile. This present treatment modality offers a conservative, aesthetic and non-invasive treatment which can be considered as a long-lasting treatment.
Diagnosis and management of a ruptured rudimentary horn pregnancy in a low-resource setting
Authors: Nathan Hannah , Sornum Alvin
Published: June 2013

A 22-year-old woman presented with amenorrhoea, lower abdominal pain and brown vaginal discharge. She was noted to be in hypovolaemic shock with a distended and peritonitic abdomen. On bimanual examination, the uterus was not palpated, the posterior fornix was full and cervical excitation was present. A clinical diagnosis of a ruptured ectopic pregnancy was made. She was resuscitated and an emergency laparotomy was performed. Intraoperatively, a ruptured rudimentary horn with an ex utero pregnancy was discovered. The right horn and tube were removed, as was the non-viable fetus. There were no postoperative complications and the patient was discharged after 5 days of observation.
Stress urinary incontinence as a rare presentation of large prostatic stones in neurogenic bladder: implications and management
Authors: Goyal Neeraj Kumar , Goel Apul , Sankhwar Satyanarayan
Published: June 2013

We report a case of a 38-year-old man with a background of a neglected neurogenic bladder, who presented with a recent onset history of stress urinary incontinence. He was diagnosed as having large prostatic stones along with a low-compliance, small capacity bladder and bilateral hydronephrosis with deranged renal functions. As self-catheterisation was not possible due to obstructing prostatic stones, holmium-YAG laser lithotripsy of prostatic stones was performed as initial procedure that resulted in complete resolution of stress incontinence as well. Successful gastrocystoplasty was performed as a second step to deal with the underlying condition of neurogenic poorly compliant bladder. The present case describes the successful endoscopic management of prostatic calculi using holmium-laser lithotripsy and draws attention to other important issues that need to be addressed in certain special situations like neurogenic bladder.
Effect of a home-based end-of-life nursing service on hospital use at the end of life and place of death: a study using administrative data and matched controls
Authors: Chitnis X A , Georghiou T , Steventon A , Bardsley M J
Published: June 2013

Objective

To assess the effect of routinely delivered home-based end-of-life care on hospital use at the end of life and place of death.

Design

Retrospective analysis using matched controls and administrative data.

Setting

Community-based care in England.

Participants

29 538 people aged over 18 who received Marie Curie nursing support compared with 29 538 controls individually matched on variables including: age, socioeconomic deprivation, prior hospital use, number of chronic conditions and prior diagnostic history.

Intervention

Home-based end-of-life nursing care delivered by the Marie Curie Nursing Service (MCNS), compared with end-of-life care available to those who did not receive MCNS care.

Main outcome measures

Proportion of people who died at home; numbers of emergency and elective inpatient admissions, outpatient attendances and attendances at emergency departments in the period until death; and notional costs of hospital care.

Results

Intervention patients were significantly more likely to die at home and less likely to die in hospital than matched controls (unadjusted OR 6.16, 95% CI 5.94 to 6.38, p<0.001). Hospital activity was significantly lower among intervention than matched control patients (emergency admissions: 0.14 vs 0.44 admissions per person, p<0.001) and average costs across all hospital services were lower (unadjusted average costs per person, £610 (intervention patients) vs £1750 (matched controls), p<0.001). Greater activity and cost differences were seen in those patients who had been receiving home nursing for longer.

Conclusions

Home-based end-of-life care offers the potential to reduce demand for acute hospital care and increase the number of people able to die at home.
Comparison of the performance of STI Screening Services for gay and bisexual men across 40 European cities: results from the European MSM Internet Survey
Authors: Schmidt Axel J , Hickson Ford , Weatherburn Peter , Marcus Ulrich ,   The EMIS Network
Published: June 2013

Objectives

Sexually transmitted infections (STIs) such as anal/genital warts, syphilis and genital/rectal gonorrhoeal/chlamydial infections compromise the health of men who have sex with men (MSM). Rectal bacterial STIs increase the per-contact risk of HIV infection. Early detection of asymptomatic STIs requires regular screening including collection of clinical specimens (or, for warts: physical examinations) that allow for the detection of infections at sites common to men's same sex practices.

Methods

From June to August 2010, the European MSM Internet Survey recruited 174 209 men from 38 European countries to an anonymous online questionnaire in 25 languages. As sexual healthcare for MSM in most countries is organised locally, we chose cities for comparison. Multivariable regression models were used to compare accessibility of services and applied diagnostic procedures across 40 cities.

Results

The proportion of respondents tested for STIs in the last 12 months in the absence of symptoms ranged from 8.9% in Istanbul to 48.0% in Amsterdam. At city level, low STI screening correlated with inaccessible services (R2=44.1%). At individual level, anal/penile inspection and anal swabbing was most common in UK cities, Amsterdam, Dublin and Stockholm. Compared to London, MSM in 30 cities had an adjusted OR (AOR) of (0.02 to 0.18) for anal swabbing; and (0.06 to 0.25) for anal/penile inspection (p<0.001).

Conclusions

Anal/genital warts and rectal infections are likely to be profoundly underdiagnosed among MSM in most European cities. This has implications for the sexual health of MSM, HIV prevention and comparing national surveillance data. There is an urgent need to improve sexual healthcare tailored to MSM at risk for STIs.
Sequence variation of the feline immunodeficiency virus genome and its clinical relevance
Authors: Stickney A. L. , Dunowska M. , Cave N. J.
Published: June 2013

The ongoing evolution of feline immunodeficiency virus (FIV) has resulted in the existence of a diverse continuum of viruses. FIV isolates differ with regards to their mutation and replication rates, plasma viral loads, cell tropism and the ability to induce apoptosis. Clinical disease in FIV‐infected cats is also inconsistent. Genomic sequence variation of FIV is likely to be responsible for some of the variation in viral behaviour. The specific genetic sequences that influence these key viral properties remain to be determined. With knowledge of the specific key determinants of pathogenicity, there is the potential for veterinarians in the future to apply this information for prognostic purposes. Genomic sequence variation of FIV also presents an obstacle to effective vaccine development. Most challenge studies demonstrate acceptable efficacy of a dual‐subtype FIV vaccine (Fel‐O‐Vax FIV) against FIV infection under experimental settings; however, vaccine efficacy in the field still remains to be proven. It is important that we discover the key determinants of immunity induced by this vaccine; such data would compliment vaccine field efficacy studies and provide the basis to make informed recommendations on its use.
ROLE OF THREE-PHONON AND FOUR-PHONON PROCESSES IN THERMAL TRANSPORT OF SINGLE-WALLED CARBON NANOTUBES
Authors: SAPNA P. , SINGH T. J.
Published: June 2013

Thermal conductivity of single-walled carbon nanotubes has been calculated considering the three-phonon and four-phonon processes. The contribution of the acoustic modes and optical modes in the relaxation rate of the phonon–phonon interaction and hence to the thermal conductivity have been considered. The thermal conductivity has been calculated for the (8, 0), (10, 0), (11, 0) and (13, 0) zigzag semiconducting nanotubes having different radii. It is found that the thermal conductivity increases linearly at low temperatures which is nearly T2 below 30 K and after reaching a peak, it decreases as aT-1 - bT-2 where a and b are constants and b > a at higher temperatures. It is also found that the thermal conductivity increases with increasing radius of the tube due to the independent effect of three-phonon process and four-phonon process. The thermal conductivity is also found to decrease with increasing tube length due to four-phonon process.
DECOHERENCE STUDY OF ELECTRON SPIN STATES IN QUANTUM DOTS USING A SIMPLISTIC MODEL
Authors: MATHEW AGILE , NANDY MALAY K.
Published: June 2013

Using a simple model of central spin interacting with a spin bath, we study the decoherence of single electron spin states in quantum dots within one-, two- and three-dimensional nanostructure geometries. We consider a one-component hyperfine interaction term and express its strength as a smooth function of position vector. Decoherence measures are evaluated and plotted for various initial states, and we notice a decrease in decoherence time with the reduction of spin-bath dimension.
A GALLERY OF CHAOTIC OSCILLATORS BASED ON HP MEMRISTOR
Authors: BUSCARINO ARTURO , FORTUNA LUIGI , FRASCA MATTIA , GAMBUZZA LUCIA VALENTINA
Published: June 2013

This work deals with the design of chaotic circuits based on memristors modeled as in [Strukov et al., 2008]. This physical model has the capability of capturing the behavior of the TiO2 memristor fabricated in the HP laboratories and, thus, is representative of real devices. We propose a configuration based on two such memristors in antiparallel as the nonlinear element for chaotic oscillators and discuss a series of nonlinear circuits derived from Chua's oscillators by replacing Chua's diodes with such element.
STABILITY SWITCH BOUNDARIES IN AN INTERNET CONGESTION CONTROL MODEL WITH DIVERSE TIME DELAYS
Authors: ZHANG SHU , CHUNG KWOK-WAI , XU JIAN
Published: June 2013

For a two-dimensional congestion control model with diverse time delays, this paper provides a detailed study on the geometrical properties of stability switch boundaries in the plane of time delays. Conditions for stability switch boundaries to arise as vertical spiral-like curves, horizontal spiral-like curves, diagonal spiral-like curves and closed-loops are obtained on the system parameters other than time delays. The boundary curves may self-intersect or intersect with one another. Some of these intersections are identified as tangent double Hopf bifurcation with codimension three. It is found that double Hopf bifurcation point exists in the plane of time delays regardless of the values of the other system parameters.
CENTER PROBLEM FOR THIRD-ORDER ODEs
Authors: MAHDI ADAM
Published: June 2013

We obtain necessary and sufficient conditions for the existence of a center on a local center manifold for three 4-parameter families of quadratic systems on ℝ3. We also give a positive answer to an open question posed in [Dias & Mello, 2010] related to similar systems.
NONAUTONOMOUS SADDLE-NODE BIFURCATION IN A CANONICAL ELECTROSTATIC MEMS
Authors: GUTIÉRREZ ALEXANDER , TORRES PEDRO J.
Published: June 2013

We study the existence and stability of periodic solutions of a canonical mass-spring model of electrostatically actuated Micro-Electro-Mechanical System (MEMS) by means of classical topological techniques like a priori bounds, Leray–Schauder degree and topological index. A saddle-node bifurcation is revealed, in analogy with the autonomous case. A quantitative estimation of the bifurcation value in terms of realistic values of the involved parameters can be made.
FRACTIONAL DUFFING'S EQUATION AND GEOMETRICAL RESONANCE
Authors: JIMÉNEZ S. , GONZÁLEZ J. A. , VÁZQUEZ L.
Published: June 2013

We investigate the Fractional Duffing equation in the presence of nonharmonic external perturbations. We have applied the concept of Geometrical Resonance to this equation. We have obtained the conditions that should be satisfied by the external driving forces in order to produce high-amplitude periodic oscillations avoiding chaos. We also show that, for Duffing's equation with fractional damping, the perturbations that satisfy the Geometrical Resonance conditions are nonperiodic functions.
STABILITY OF PERIODIC TRAVELING WAVES FOR THE QUADRATIC AND CUBIC NONLINEAR SCHRÖDINGER EQUATIONS
Authors: HAKKAEV SEVDZHAN , ILIEV ILIYA D. , KIRCHEV KIRIL
Published: June 2013

We study the existence and stability of periodic traveling-wave solutions for the quadratic and cubic nonlinear Schrödinger equations in one space dimension.
NOISE-INDUCED CHAOS AND BACKWARD STOCHASTIC BIFURCATIONS IN THE LORENZ MODEL
Authors: BASHKIRTSEVA IRINA , RYASHKO LEV , STIKHIN PAVEL
Published: June 2013

We study the phenomena of stochastic D- and P-bifurcations of randomly forced limit cycles for the Lorenz model. As noise intensity increases, regular multiple limit cycles of this model in a period-doubling bifurcations zone are deformed to be stochastic attractors that look chaotic (D-bifurcation) and their multiplicity is reduced (P-bifurcation). In this paper for the comparative investigation of these bifurcations, the analysis of Lyapunov exponents and stochastic sensitivity function technique are used. A probabilistic mechanism of backward stochastic bifurcations for cycles of high multiplicity is analyzed in detail. We show that for a limit cycle with multiplicity two and higher, a threshold value of the noise intensity which marks the onset of chaos agrees with the first backward stochastic bifurcation.
COEXISTENCE OF POINT, PERIODIC AND STRANGE ATTRACTORS
Authors: SPROTT JULIEN CLINTON , WANG XIONG , CHEN GUANRONG
Published: June 2013

For a dynamical system described by a set of autonomous ordinary differential equations, an attractor can be a point, a periodic cycle, or even a strange attractor. Recently, a new chaotic system with only one stable equilibrium was described, which locally converges to the stable equilibrium but is globally chaotic. This paper further shows that for certain parameters, besides the point attractor and chaotic attractor, this system also has a coexisting stable limit cycle, demonstrating that this new system is truly complicated and interesting.
Hydrogen Tunneling Links Protein Dynamics to Enzyme Catalysis
Authors: Klinman Judith P. , Kohen Amnon
Published: June 2013

The relationship between protein dynamics and function is a subject of considerable contemporary interest. Although protein motions are frequently observed during ligand binding and release steps, the contribution of protein motions to the catalysis of bond making/breaking processes is more difficult to probe and verify. Here, we show how the quantum mechanical hydrogen tunneling associated with enzymatic C-H bond cleavage provides a unique window into the necessity of protein dynamics for achieving optimal catalysis. Experimental findings support a hierarchy of thermodynamically equilibrated motions that control the H-donor and -acceptor distance and active-site electrostatics, creating an ensemble of conformations suitable for H-tunneling. A possible extension of this view to methyl transfer and other catalyzed reactions is also presented. The impact of understanding these dynamics on the conceptual framework for enzyme activity, inhibitor/drug design, and biomimetic catalyst design is likely to be substantial.
Mechanisms for Initiating Cellular DNA Replication
Authors: Costa Alessandro , Hood Iris V. , Berger James M.
Published: June 2013

The initiation of DNA replication represents a committing step to cell proliferation. Appropriate replication onset depends on multiprotein complexes that help properly distinguish origin regions, generate nascent replication bubbles, and promote replisome formation. This review describes initiation systems employed by bacteria, archaea, and eukaryotes, with a focus on comparing and contrasting molecular mechanisms among organisms. Although commonalities can be found in the functional domains and strategies used to carry out and regulate initiation, many key participants have markedly different activities and appear to have evolved convergently. Despite significant advances in the field, major questions still persist in understanding how initiation programs are executed at the molecular level.
Molecular Chaperone Functions in Protein Folding and Proteostasis
Authors: Kim Yujin E. , Hipp Mark S. , Bracher Andreas , Hayer-Hartl Manajit , Ulrich Hartl F.
Published: June 2013

The biological functions of proteins are governed by their three-dimensional fold. Protein folding, maintenance of proteome integrity, and protein homeostasis (proteostasis) critically depend on a complex network of molecular chaperones. Disruption of proteostasis is implicated in aging and the pathogenesis of numerous degenerative diseases. In the cytosol, different classes of molecular chaperones cooperate in evolutionarily conserved folding pathways. Nascent polypeptides interact cotranslationally with a first set of chaperones, including trigger factor and the Hsp70 system, which prevent premature (mis)folding. Folding occurs upon controlled release of newly synthesized proteins from these factors or after transfer to downstream chaperones such as the chaperonins. Chaperonins are large, cylindrical complexes that provide a central compartment for a single protein chain to fold unimpaired by aggregation. This review focuses on recent advances in understanding the mechanisms of chaperone action in promoting and regulating protein folding and on the pathological consequences of protein misfolding and aggregation.
Arrest Peptides: Cis-Acting Modulators of Translation
Authors: Ito Koreaki , Chiba Shinobu
Published: June 2013

Each peptide bond of a protein is generated at the peptidyl transferase center (PTC) of the ribosome and then moves through the exit tunnel, which accommodates ever-changing segments of ∼40 amino acids of newly translated polypeptide. A class of proteins, called ribosome arrest peptides, contains specific sequences of amino acids (arrest sequences) that interact with distinct components of the PTC–exit tunnel region of the ribosome and arrest their own translation continuation, often in a manner regulated by environmental cues. Thus, the ribosome that has translated an arrest sequence is inactivated for peptidyl transfer, translocation, or termination. The stalled ribosome then changes the configuration or localization of mRNA, resulting in specific biological outputs, including regulation of the target gene expression and downstream events of mRNA/polypeptide maturation or localization. Living organisms thus seem to have integrated potentially harmful arrest sequences into elaborate regulatory mechanisms to express genetic information in productive directions.
Structural Basis of the Translational Elongation Cycle
Authors: Voorhees Rebecca M. , Ramakrishnan V.
Published: June 2013

The sequential addition of amino acids to a growing polypeptide chain is carried out by the ribosome in a complicated multistep process called the elongation cycle. It involves accurate selection of each aminoacyl tRNA as dictated by the mRNA codon, catalysis of peptide bond formation, and movement of the tRNAs and mRNA through the ribosome. The process requires the GTPase factors elongation factor Tu (EF-Tu) and EF-G. Not surprisingly, large conformational changes in both the ribosome and its tRNA substrates occur throughout protein elongation. Major advances in our understanding of the elongation cycle have been made in the past few years as a result of high-resolution crystal structures that capture various states of the process, as well as biochemical and computational studies.
Biocidal Packaging for Pharmaceuticals, Foods, and Other Perishables
Authors: Larson Alyssa M. , Klibanov Alexander M.
Published: June 2013

Many consumer goods must be protected from bacterial and fungal colonization to ensure their integrity and safety. By making these items' packaging biocidal, the interior environment can be preserved from microbial spoilage without altering the products themselves. Herein we briefly review this concept, referred to as active packaging, and discuss existing methods for constructing active packaging systems. They are based on either packaging materials that release biocides or those that are themselves intrinsically biocidal (or biostatic), with numerous variations within each category.
CTRP3 attenuates diet-induced hepatic steatosis by regulating triglyceride metabolism
Authors: Peterson Jonathan M. , Seldin Marcus M. , Wei Zhikui , Aja Susan , Wong G. William
Published: June 2013

CTRP3 is a secreted plasma protein of the C1q family that helps regulate hepatic gluconeogenesis and is downregulated in a diet-induced obese state. However, the role of CTRP3 in regulating lipid metabolism has not been established. Here, we used a transgenic mouse model to address the potential function of CTRP3 in ameliorating high-fat diet-induced metabolic stress. Both transgenic and wild-type mice fed a high-fat diet showed similar body weight gain, food intake, and energy expenditure. Despite similar adiposity to wild-type mice upon diet-induced obesity (DIO), CTRP3 transgenic mice were strikingly resistant to the development of hepatic steatosis, had reduced serum TNF-α levels, and demonstrated a modest improvement in systemic insulin sensitivity. Additionally, reduced hepatic triglyceride levels were due to decreased expression of enzymes (GPAT, AGPAT, and DGAT) involved in triglyceride synthesis. Importantly, short-term daily administration of recombinant CTRP3 to DIO mice for 5 days was sufficient to improve the fatty liver phenotype, evident as reduced hepatic triglyceride content and expression of triglyceride synthesis genes. Consistent with a direct effect on liver cells, recombinant CTRP3 treatment reduced fatty acid synthesis and neutral lipid accumulation in cultured rat H4IIE hepatocytes. Together, these results establish a novel role for CTRP3 hormone in regulating hepatic lipid metabolism and highlight its protective function and therapeutic potential in attenuating hepatic steatosis.
Activating the Nrf2-mediated antioxidant response element restores barrier function in the alveolar epithelium of HIV-1 transgenic rats
Authors: Fan Xian , Staitieh Bashar S. , Jensen J. Spencer , Mould Kara J. , Greenberg Jared A. , Joshi Pratibha C. , Koval Michael , Guidot David M.
Published: June 2013

The master transcription factor nuclear factor (erythroid-derived 2)-like 2 (Nrf2) regulates the expression of antioxidant and phase II-metabolizing enzymes by activating the antioxidant response element (ARE) and thereby protects cells and tissues from oxidative stress. Pulmonary complications remain the leading cause of death in human immunodeficiency virus (HIV)-1-infected individuals, who display systemic oxidative stress and glutathione deficiency that can be modeled in transgenic rats where HIV-1-related viral proteins decrease glutathione levels and cause epithelial barrier dysfunction within the alveolar space by as yet unknown mechanisms. We hypothesized that HIV-1-related proteins inhibit Nrf2-mediated antioxidant defenses and thereby disrupt the normally tight alveolar epithelial barrier. Nrf2 RNA silencing dampened Nrf2/ARE activity, decreased the expression of the tight junction proteins zonula occludens-1, occludin, and claudin-18, increased paracellular permeability of alveolar epithelial monolayers derived from wild-type rats, and therefore reproduced the effects of HIV-1 transgene expression on the epithelial barrier that we had previously described. In contrast, upregulating Nrf2 activity, either by plasmid-mediated overexpression or treatment with the Nrf2 activator sulforaphane, increased the expression of ARE-dependent antioxidants, including NAD(P)H dehydrogenase, quinone 1 and glutathione, improved the expression of tight junction proteins, and restored the ability to form tight barriers in alveolar epithelial cells from HIV-1 transgenic rats. Taken together, these new findings argue that HIV-1-related proteins downregulate Nrf2 expression and/or activity within the alveolar epithelium, which in turn impairs antioxidant defenses and barrier function, thereby rendering the lung susceptible to oxidative stress and injury. Furthermore, this study suggests that activating the Nrf2/ARE pathway with the dietary supplement sulforaphane could augment antioxidant defenses and lung health in HIV-1-infected individuals.
Short-term acetaminophen consumption enhances the exercise-induced increase in Achilles peritendinous IL-6 in humans
Authors: Gump Brian S. , McMullan David R. , Cauthon David J. , Whitt Jamie A. , Del Mundo Jonathon D. , Letham Tanya , Kim Paul J. , Friedlander Gary N. , Pingel Jessica , Langberg Henning , Carroll Chad C.
Published: June 2013

Through an unknown mechanism, the cyclooxygenase inhibitor and antipyretic acetaminophen (APAP) alters tendon mechanical properties in humans when consumed during exercise. Interleukin-6 (IL-6) is produced by tendon during exercise and is a potent stimulator of collagen synthesis. In nontendon tissue, IL-6 is upregulated in the presence of cyclooxygenase inhibitors and may contribute to alterations in extracellular matrix turnover, possibly due to inhibition of prostaglandin E2(PGE2). We evaluated the effects of APAP on IL-6 and PGE2in human Achilles peritendinous tissue after 1 h of treadmill exercise. Subjects were randomly assigned to a placebo ( n = 8, 26 ± 1 yr) or APAP ( n = 8, 25 ± 1 yr) group. Each subject completed a nonexercise and exercise experiment consisting of 6 h of microdialysis. Drug (APAP, 1,000 mg) or placebo was administered in a double-blind manner during both experiments. PGE2and IL-6 were determined via enzyme immunoassay and APAP via high-performance liquid chromatography. In subjects given APAP, peritendinous APAP levels increased to 4.08 ± 0.65 μg/ml ( P < 0.05). PGE2did not increase with exercise in either group ( P > 0.05), nor was PGE2significantly reduced in the APAP group. IL-6 levels increased with exercise in both groups ( P < 0.05), but this increase was greater in the APAP group ( P < 0.05). Our findings suggest that APAP enhances tendon IL-6 production after exercise. Peak levels of APAP obtained in the peritendinous space were twofold lower than values reported in plasma or skeletal muscle. These findings provide insight into the effects of APAP on tendon and provide novel information on the kinetics of APAP in tendon tissue after oral APAP consumption.
Contrasting effects of fatigue on multifinger coordination in young and older adults
Authors: Singh Tarkeshwar , Zatsiorsky Vladimir M. , Latash Mark L.
Published: June 2013

We investigated the effects of fatigue produced by timed maximal voluntary contraction (MVC) of the index finger of the right hand on performance in MVC and accurate cyclic force production tasks in right-handed young (Young group) and strength-matched elderly (Elderly group) participants. We hypothesized that, before fatigue, the Elderly group would show weaker force-stabilizing synergies and smaller adaptive changes in the synergy index during fatigue. Synergies were defined as covaried adjustments of neural commands to fingers (finger modes) across trials that stabilize total force. Fatigue caused a significant reduction in the MVC, which was larger in the Young group compared with the Elderly group for both fatigued finger (index finger) and four fingers (index, middle, ring, and little fingers pressing together). Indexes of finger enslaving (lack of individuation) increased with fatigue in both groups. The index of force-stabilizing synergies was similar for the two groups before fatigue, while its increase with fatigue was significantly larger in the Elderly group compared with the Young group. We infer that changes in the indexes of finger interaction (enslaving) and coordination (synergy) with age seem to be correlated with changes in muscle strength. This correlation may be causally related to the progressive death of neurons at different levels of the neuromotor hierarchy. The surprisingly large changes in the synergy index with fatigue in older adults suggest that, by itself, aging does not necessarily lead to impairment in synergic control. Strength training may be a method to avoid age-related decrement in finger interaction and coordination.