bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhanced near-infrared quantum cutting in GdBO3:Tb3+,Yb3+ phosphors by Ce3+ codoping
Authors: Huang X. Y. , Yu D. C. , Zhang Q. Y.
Published: December 2009

A near-infrared quantum cutting phosphor GdBO3:Tb3+,Yb3+ shows poor optical absorption in the ultraviolet-visible excitation spectral range and weak near-infrared luminescence in the 900–1100 nm range, which strongly limit its practical application in silicon-based solar cells, due to the inefficient excitation of the Tb3+ ions for their intra-4f forbidden transitions. Herein, Ce3+ ion has been codoped as a sensitizer in GdBO3:Tb3+,Yb3+, thus enlarging the absorption linewidth and increasing the absorption cross-sections in the ultraviolet-visible region. The presence of Ce3+ results in an enhancement in Yb3+ near-infrared emission intensity by a factor of ∼30, which makes these phosphors more attractive as luminescent downconversion materials for enhanced silicon-based solar cell performance. The relevant luminescence and energy transfer mechanisms involved have also been investigated. The present results demonstrate that the 4f−5d luminescence of Ce3+ may be used to sensitize the Tb3+–Yb3+ downconversion process.
Rotational relaxation in H2 gas observed with optical beating Brillouin spectroscopy
Authors: Minami Yasuo , Yogi Takeshi , Sakai Keiji
Published: December 2009

The optical beating Brillouin spectroscopy used in this study possesses quite high frequency resolution, up to 1 kHz, which enabled us to observe the Brillouin peak of hydrogen gas in the megahertz frequency region. In this study, we measured the sound velocity of hydrogen gas in the 10 MHz frequency region with optical beating Brillouin spectroscopy and observed rotation-translation relaxation. The obtained value of the relaxation frequency is reasonable. This method would enable us to observe rotation–translation relaxation of other gases in a nondestructive, noncontact manner.
High pressure transition in amorphous As2S3 studied by EXAFS
Authors: Vaccari M. , Garbarino G. , Yannopoulos S. N. , Andrikopoulos K. S. , Pascarelli S.
Published: December 2009

We report an in situ high pressure investigation of the structural change in vitreous As2S3 up to 60 GPa using the diamond anvil cell and energy dispersive x-ray absorption spectroscopy. The main finding of the present study is a gradual elongation of the average As–S bond length, which takes place in the pressure range of 15–50 GPa. This change is interpreted as a signature of the coordination number increase around As atoms. The negative shift of the As K absorption edge position confirms the progressive metallization of the glass at high pressure. The observed changes are reversible after pressure release.
Revisiting waterlike network-forming lattice models
Authors: Pretti M. , Buzano C. , De Stefanis E.
Published: December 2009

We revisit different three-dimensional network-forming lattice models proposed in the literature to investigate water anomalies. We perform a semianalytical calculation based on a cluster-variation technique, showing a quite good agreement with independent Monte Carlo results. The method allows us to clarify the structure of the phase diagrams, which turn out to exhibit different kinds of orientationally ordered phases. We point out that certain “waterlike” thermodynamic anomalies, claimed by previous studies, are indeed artifacts of a homogeneity assumption made in the analytical treatment. We argue that such a difficulty is common to a whole class of lattice models for water and suggest a possible way to overcome the problem in terms of “equivalent” models defined on random lattices.
Direct writing and characterization of poly(p-phenylene vinylene) nanostructures
Authors: Wang Debin , Kim Suenne , Underwood William D. , Giordano Anthony J. , Henderson Clifford L. , Dai Zhenting , King William P. , Marder Seth R. , Riedo Elisa
Published: December 2009

We report the use of thermochemical nanolithography to convert a precursor polymer film to poly(p-phenylene vinylene) with sub-100 nm spatial resolution, in ambient conditions. The local thermochemical conversion is verified by Raman spectroscopy, fluorescence imaging, and atomic force microscopy. This convenient direct writing of conjugated polymer nanostructures could be desirable for the design and fabrication of future nanoelectronic, nanophotonic, and biosensing devices.
On the stick-slip flow from slit and cylindrical dies of a Phan-Thien and Tanner fluid model. I. Steady state
Authors: Karapetsas George , Tsamopoulos John
Published: December 2009

The steady planar and cylindrical stick-slip flows for a viscoelastic fluid are computed using the Phan-Thien and Tanner (PTT) constitutive model. The mixed finite element method is used in combination with the elastic-viscous stress-splitting technique and the streamline upwind Petrov–Galerkin discretization for the constitutive equation. This combination of methods when applied to the PTT constitutive model allows us to compute steady state solutions up to high Weissenberg numbers; practically without an upper limit. Equally important, the global Jacobian matrix is generated in order to be able to perform a linear stability analysis of the computed steady state. The dependence of the steady solutions on all the problem parameters is examined. In the limit of a Newtonian fluid, the expansion coefficients near the singularity are computed with comparable accuracy to those from previous analytical and numerical studies, which include the singular finite element method. In the case of a viscoelastic liquid, it is shown that the computed solutions converge quadratically with mesh refinement even at the exit plane of the die and also locally very close to the singularity. The form of the converged solution near the singularity is examined as well as its dependence on various rheological parameters. It is shown that the singularity at the die exit is a logarithmic one and always integrable. Under such conditions our calculations can be extended to determine the linear stability of the herein computed steady states.
Enhanced spin injection and voltage bias in (Zn,Co)O/MgO/(Zn,Co)O magnetic tunnel junctions
Authors: Chen G. , Zeng F. , Pan F.
Published: December 2009

The tunnel magnetoresistance (TMR) and voltage bias dependence of (Zn,Co)O/MgO/(Zn,Co)O magnetic tunnel junctions (MTJs) are investigated in this study. Using MgO as the tunnel barrier, a positive TMR of 46.8% is obtained at 2 T at 4 K with the applied current of 1 μA. The MTJs are found to show a high voltage bias with an ultrahigh V1/2, for which half of the TMR remains, exceeding 10 V compared with other conventional MTJs. These results are promising for further research on MgO as a tunnel barrier in the application of diluted magnetic semiconductor-based spintronic devices.
The effect of moisture on the photon-enhanced negative bias thermal instability in Ga–In–Zn–O thin film transistors
Authors: Lee Kwang-Hee , Jung Ji Sim , Son Kyoung Seok , Park Joon Seok , Kim Tae Sang , Choi Rino , Jeong Jae Kyeong , Kwon Jang-Yeon , Koo Bonwon , Lee Sangyun
Published: December 2009

We investigated the impact of photon irradiation on the stability of gallium-indium-zinc oxide (GIZO) thin film transistors. The application of light on the negative bias temperature stress (NBTS) accelerated the negative displacement of the threshold voltage (Vth). This phenomenon can be attributed to the trapping of the photon-induced carriers into the gate dielectric/channel interface or the gate dielectric bulk. Interestingly, the negative Vth shift under photon-enhanced NBTS condition worsened in relatively humid environments. It is suggested that moisture is a significant parameter that induces the degradation of bias-stressed GIZO transistors.
Analysis of vibrational resonance in a quintic oscillator
Authors: Jeyakumari S. , Chinnathambi V. , Rajasekar S. , Sanjuan M. A. F.
Published: December 2009

We consider a damped quintic oscillator with double-well and triple-well potentials driven by both low-frequency force f cos ωt and high-frequency force g cos Ωt with Ω⪢ω and analyze the occurrence of vibrational resonance. The response consists of a slow motion with frequency ω and a fast motion with frequency Ω. We obtain an approximate analytical expression for the response amplitude Q at the low-frequency ω. From the analytical expression of Q, we determine the values of ω and g (denoted as ωVR and gVR) at which vibrational resonance occurs. The theoretical predictions are found to be in good agreement with numerical results. We show that for fixed values of the parameters of the system, as ω varies, resonance occurs at most one value of ω. When the amplitude g is varied we found two and four resonances in the system with double-well and triple-well cases, respectively. We present examples of resonance (i) without cross-well motion and (ii) with cross-well orbit far before and far after it. ωVR depends on the damping strength d while gVR is independent of d. Moreover, the effect of d is found to decrease the response amplitude Q.
Near infrared long-persistent phosphorescence in SrAl2O4:Eu2+,Dy3+,Er3+ phosphors based on persistent energy transfer
Authors: Yu Naiyin , Liu Feng , Li Xufan , Pan Zhengwei
Published: December 2009

Eu 2 + , Dy3+, and Er3+ ions codoped SrAl2O4 phosphors with near infrared (NIR) (at 1530 nm) long-persistent phosphorescence were synthesized by a combustion method. The NIR phosphorescence emission was realized through a persistent energy transfer process from Eu2+ ions to Er3+ ions. Optimal Er3+ concentration for the maximum energy transfer efficiency was determined and NIR phosphorescence persisting for more than 10 min was achieved. A model of charge trapping and energy transfer process among Eu, Dy, and Er ions in SrAl2O4 host was proposed.
First-principles study on ferromagnetism in Mg-doped SnO2
Authors: Zhang Chang-wen , Yan Shi-shen
Published: December 2009

Using the full-potential linearized augmented plane wave method, we study the magnetism and electronic structures of Mg-doped SnO2 system. We find that the Sn23MgO48 supercell with an isolated Mg atom produces a total magnetic moment of 2.00μB and introduces spin-polarized 2p states in the band gap. The origin of the magnetic moments is the holes in MgO6 octahedron induced by Mg doping. The ferromagnetic interaction between Mg atoms can be attributed to the hole-mediated double exchange through the strong p-p interaction between Mg and neighboring oxygen.
Current-voltage spectroscopy of the subband structure of strongly pinched-off quantum point contacts
Authors: Song J. , Kawano Y. , Ishibashi K. , Mikalopas J. , Aizin G. R. , Aoki N. , Reno J. L. , Ochiai Y. , Bird J. P.
Published: December 2009

We demonstrate current-voltage spectroscopy of the one-dimensional subband structure of pinched-off quantum point contacts (QPCs). This technique yields the full subband structure and effective barrier of the QPC, without the need to perform an undesirable average over a range of gate voltage. Our measurements reveal strong asymmetry in the potential drop across the QPC, and a significantly enhanced subband spacing, in the pinch-off regime.
Non-Brownian particle gel
Authors: Yuan Chia-Nan , Sheng Yu-Jane , Tsao Heng-Kwong
Published: December 2009

Particle gels are usually formed by density matching or Brownian motion against gravity. However, the suspended state of non-Brownian particles is essential in applications, such as Si-wafer wire sawing. By the addition of alkyl amine, micron-sized SiC suspensions are shown to form particle gel in ethylene glycol. The ratio of storage to loss modulus is about 3, indicating a weak gel. The structure by particle-particle attraction is demonstrated through existing yield stress. With increasing surfactant concentration, the gel forms easier, the sediment layer swells more significantly, and the yield stress is greater accordingly. A gelling mechanism has been proposed and examined.
Electron-phonon coupling and intervalley splitting determine the linewidth of single-electron transport through PbSe nanocrystals
Authors: Overgaag K. , Vanmaekelbergh D. , Liljeroth P. , Mahieu G. , Grandidier B. , Delerue C. , Allan G.
Published: December 2009

The linewidth of the resonances in the single-electron tunneling spectra has been investigated for PbSe semiconductor nanocrystals (NCs) with scanning tunneling spectroscopy at low temperature. The linewidth of the resonances corresponding to tunneling through the first conduction and valence levels is found to increase with decreasing size of the NCs. Based on theoretical calculations, this broadening is mainly induced by the coupling between the tunneling electrons and the longitudinal optical phonon mode of the NC, and by the splitting of the degenerate electronic levels between the different L-valleys in the Brillouin zone. For the smallest sizes, it is shown that the intervalley splitting is the major source of broadening.
Synthesis, Structure, and Photoluminescent Properties of Two New Microporous Eu(III) Coordination Polymers with 2,4,6-Pyridinetricarboxylate
Authors: Li Cui-Jin , Li Wei , Meng Zhao-Sha , Peng Meng-Xia , Yang Ming-Mei , Tong Ming-Liang
Published: December 2009

Two new three-dimensional (3D) microporous Eu(iii) coordination polymers, [Eu5(pyta)5(H2O)7]·3.5H2O (1) and [Eu2(ox)1.5(pyta)(H2O)4]·4.5H2O (2) (H3pyta = 2,4,6-pyridinetricarboxylic acid, ox2– = oxalate), have been synthesized under hydrothermal conditions. The oxalate ligand in 2, generated in situ from the cleavage and chemical rearrangement of the H3pyta ligand, is incorporated to construct two kinds of 1D hydrophilic channels in 2. Both 1 and 2 show the characteristic photoluminescent properties of Eu(iii) compounds. Desolvated 2 shows interesting solvent-dependent photoluminescent properties.
X-Ray Crystal Structure, Acid - Base Properties and Complexation Characteristics of a Methylenephosphonate Derivative of 1,4,7,10-Tetraazacyclododecane
Authors: Kreher Ute , Hearn Milton T. W. , Spiccia Leone
Published: December 2009

The X-ray crystal structures of 1,4,7-tris(methylenephosphonate)-1,4,7,10-tetraazacyclododecane (DO3P·3.5H2O) and 1,7-bis(methylenephosphonate)-1,4,7,10-tetraazacyclododecane dihydrochloride trihydrate (DO2P·2HCl·3H2O) reveal that two nitrogen atoms in the trans-annular positions are protonated. The macrocyclic ring adopts a (3,3,3,3)-B conformation stabilized by intramolecular hydrogen bonding involving oxygen atoms from the phosphonate groups and the protonated amines. The acid–base dissociation constants of DO3P and metal complex formation constants (for Ca2+, Mg2+, Zn2+, Fe3+) were determined using potentiometric measurements. The first two protonations of DO3P occur at quite high pH and, consequently, were determined by NMR measurements. The stability constants indicate that DO3P forms more stable complexes with the transition metal ions Zn2+ and Fe3+ (log K
[ML] = 21.23(4) and 22.74(5) respectively) than with the alkaline earth metal ions Ca2+ and Mg2+ (log K
[ML] = 10.96(6) and 8.72(6) respectively). For Fe3+, Ca2+ and Mg2+, the data support the formation of dinuclear species, presumably through the coordination of an additional metal ion to the phosphonate groups.
Rapid, Chemoenzymatic Syntheses of the Epoxyquinols ( - )-Bromoxone Acetate and ( - )-Tricholomenyn A
Authors: Pinkerton David M. , Banwell Martin G. , Willis Anthony C.
Published: December 2009

The epoxyquinol derivatives (–)-bromoxone acetate (ent-1) and (–)-tricholomenyn A (2) have been prepared from the cis-1,2-dihydrocatechols 3 and 4, respectively. Compounds 3 and 4 are themselves obtained in enantiomerically pure form through the whole-cell biotransformation of the corresponding halobenzene.
Evidence for abrupt speciation in a classic case of gradual evolution
Authors: Hull Pincelli M. , Norris Richard D.
Published: December 2009

In contrast with speciation in terrestrial organisms, marine plankton frequently display gradual morphological change without lineage division (e.g., phyletic gradualism or gradual evolution), which has raised the possibility that a different mode of evolution dominates within pelagic environments. Here, we reexamine a classic case of putative gradual evolution within the
Globorotalia plesiotumida–G. tumida
lineage of planktonic foraminifera, and find both compelling evidence for the existence of a third cryptic species during the speciation event and the abrupt evolution of the descendant
G. tumida
. The third morphotype, not recognized in previous analyses, differs in shape and coiling direction from its ancestor,
G. plesiotumida
. This species dominates the globorotaliid population for 414,000 years just before the appearance of
G. tumida
. The first population of the descendant,
G. tumida
, evolves abruptly within a 44,000-year interval. A combination of morphological data and biostratigraphic evidence suggests that
G. tumida
evolved by cladogenesis. Our findings provide an unexpected twist on one of the best-documented cases of within-lineage phyletic gradualism and, in doing so, revisit the limitations and promise of the study of speciation in the fossil record.
Using a functional enzyme model to understand the chemistry behind hydrogen sulfide induced hibernation
Authors: Collman James P. , Ghosh Somdatta , Dey Abhishek , Decréau Richard A.
Published: December 2009

The toxic gas H
2
S is produced by enzymes in the body. At moderate concentrations, H
2
S elicits physiological effects similar to hibernation. Herein, we describe experiments that imply that the phenomenon probably results from reversible inhibition of the enzyme cytochrome
c
oxidase (CcO), which reduces oxygen during respiration. A functional model of the oxygen-reducing site in CcO was used to explore the effects of H
2
S during respiration. Spectroscopic analyses showed that the model binds two molecules of H2S. The electro-catalytic reduction of oxygen is reversibly inhibited by H
2
S concentrations similar to those that induce hibernation. This phenomenon derives from a weak, reversible binding of H
2
S to the Fe
II
porphyrin, which mimics heme a
3
in CcO's active site. No inhibition of CcO is detected at lower H
2
S concentrations. Nevertheless, at lower concentrations, H
2
S could have other biological effects on CcO. For example, H
2
S rapidly reduces Fe
III
and Cu
II
in both the oxidized form of this functional model and in CcO itself. H
2
S also reduces CcO's biological reductant, cytochrome
c
, which normally derives its reducing equivalents from food metabolism. Consequently, it is speculated that H
2
S might also serve as a source of electrons during periods of hibernation when food supplies are low.
The impact of long-distance horizontal gene transfer on prokaryotic genome size
Authors: Cordero Otto X. , Hogeweg Paulien
Published: December 2009

Horizontal gene transfer (HGT) is one of the most dominant forces molding prokaryotic gene repertoires. These repertoires can be as small as ≈200 genes in intracellular organisms or as large as ≈9,000 genes in large, free-living bacteria. In this article we ask what is the impact of HGT from phylogenetically distant sources, relative to the size of the gene repertoire. Using different approaches for HGT detection and focusing on both cumulative and recent evolutionary histories, we find a surprising pattern of nonlinear enrichment of long-distance transfers in large genomes. Moreover, we find a strong positive correlation between the sizes of the donor and recipient genomes. Our results also show that distant horizontal transfers are biased toward those functional groups that are enriched in large genomes, showing that the trends in functional gene content and the impact of distant transfers are interdependent. These results highlight the intimate relationship between environmental and genomic complexity in microbes and suggest that an ecological, as opposed to phylogenetic, signal in gene content gains relative importance in large-genomed bacteria.
Human Langerhans cells induce distinct IL-22-producing CD4
+
T cells lacking IL-17 production
Authors: Fujita Hideki , Nograles Kristine E. , Kikuchi Toyoko , Gonzalez Juana , Carucci John A. , Krueger James G.
Published: December 2009

IL-22 is a cytokine that acts mainly on epithelial cells. In the skin, it mediates keratinocyte proliferation and epidermal hyperplasia and is thought to play a central role in inflammatory diseases with marked epidermal acanthosis, such as psoriasis. Although IL-22 was initially considered a Th17 cytokine, increasing evidence suggests that T helper cells can produce IL-22 even without IL-17 expression. In addition, we have shown the existence of this unique IL-22-producing T cell in normal skin and in the skin of psoriasis and atopic dermatitis patients. In the present study, we investigated the ability of cutaneous resident dendritic cells (DCs) to differentiate IL-22-producing cells. Using FACS, we isolated Langerhans cells (LCs; HLA-DR
+
CD207
+
cells) and dermal DCs (HLA-DR
hi
CD11c
+
BDCA-1
+
cells) from normal human epidermis and dermis, respectively. Both LCs and dermal DCs significantly induced IL-22-producing CD4
+
and CD8
+
T cells from peripheral blood T cells and naive CD4
+
T cells in mixed leukocyte reactions. LCs were more powerful in the induction of IL-22-producing cells than dermal DCs. Moreover, in vitro-generated LC-type DCs induced IL-22-producing cells more efficiently than monocyte-derived DCs. The induced IL-22 production was more correlated with IFN-γ than IL-17. Surprisingly, the majority of IL-22-producing cells induced by LCs and dermal DCs lacked the expression of IL-17, IFN-γ, and IL-4. Thus, LCs and dermal DCs preferentially induced helper T cells to produce only IL-22, possibly “Th22” cells. Our data indicate that cutaneous DCs, especially LCs, may control the generation of distinct IL-22 producing Th22 cells infiltrating into the skin.
La categoría ‘adjetivo’ en el Arte del idioma zapoteco (1578) y el Vocabulario en lengua çapoteca (1578) de Juan de Córdova
Authors: Torres Rosa María Rojas
Published: December 2009

Este artículo es un acercamiento a la descripción de la categoría lingüística Adjetivo en dos fuentes coloniales: el Arte del idioma zapoteco y el Vocabulario en lengua çapoteca ambas escritas por Fray Juan de Córdova, O.P. (1501–1595) en 1578. A partir de la descripción lingüística de esta categoría propuesta por Juan de Córdova y de la situación de las lenguas zapotecas actuales, sobre todo el zapoteco de Santa Ana del Valle (lengua hablada en el estado de Oaxaca, México), la autora mostrará que la categoría adjetivo que Juan de Córdova describe en su obra, aún no estaba conformada. Del mismo modo, se mostrará que en dos textos coloniales (el testamento de Gabriel Luis de1610 y el de Juan López de 1618), las palabras que Córdova llama adjetivos son poco frecuentes y su uso como tales se debe a una traducción literal del español y no propiamente a las características gramaticales del zapoteco de la época. Al final del texto, la autora compara los adjetivos del zapoteco contemporáneo con las entradas del Vocabulario de Córdova para mostrar que, en la mayoría de los casos, los adjetivos actuales tienen un verbo correspondiente en el zapoteco colonial.
Value of multidetector computed tomography in assessing blunt multitrauma patients
Authors: Ahvenjärvi L. , Mattila L. , Ojala R. , Tervonen O.
Published: December 2009

Purpose: To find out if multidetector computed tomography (MDCT), using a dedicated trauma protocol, provides sufficient diagnostic information of the injuries of blunt multitrauma patients to enable the planning of treatment for all body compartments.

Material and Methods: One‐hundred‐and‐thirty‐three patients exposed to high‐energy trauma were referred and scanned with the standardized MDCT multitrauma protocol. The imaging protocol consisted of axial scanning of the head and helical scanning of the facial bones, cervical spine, thorax, abdomen, and pelvis. The scanning times were 12 s for the head, 19–21 s for the facial bones and cervical spine (1 mm collimation), and 32–50 s for the thorax, abdomen, and pelvis (2 mm collimation). One‐hundred‐and‐forty milliliters of non‐iodinated contrast material (300 mg I/ml) was administered intravenously at 3 ml/s.

Results: Ninety‐nine of the patients (74%) had at least one finding consistent with trauma. The most frequent findings were in the thorax in 58 patients (44%). Nineteen false‐negative findings and two false‐positive findings were made. The overall sensitivity of MDCT was 94%, specificity 100%, and accuracy 97%.

Conclusion: MDCT is accurate in the assessment of blunt multitrauma patients. The decision to treat the patient can be made on the basis of MDCT with a reasonable level of certainty.
Compliance with european guidelines for diagnostic mammography in a decentralized health‐care setting
Authors: Jensen A. , Mikkelsen G. J. , Vestergaard M. , Lynge E. , Vejborg I.
Published: December 2009

Purpose: To evaluate the compliance of Danish mammography clinics with requirements concerning organization, activity volume, and assessment procedures from two European guidelines for quality assurance in diagnostic mammography (EUSOMA and EUREF).

Material and Methods: We used individual records on all diagnostic mammographies performed in Denmark in 2000, and questionnaires given to Danish mammography clinics in 2000, 2002, and 2004.

Results: The study showed a marked centralization of the diagnostic activity from 2000 to 2004 to a smaller number of public breast assessment centers with full multidisciplinary breast assessment. However, a relatively large number of these centers did not comply with the activity volume requirement of 2000 mammograms per clinic per year. The number of private diagnostic mammography clinics performing basic diagnostic mammography has remained fairly stable in the period 2000 to 2004. Compared with public breast assessment centers, the private diagnostic mammography clinics had a lower compliance with activity volume requirements.

Conclusion: A marked proportion of Danish public breast assessment centers operate with less than optimal activity volume, suggesting that further centralization would be appropriate. The situation in private diagnostic mammography clinics may cause concern, as our study showed that the majority of these clinics did not meet the activity volume requirements.
Prevalence study of proximal vertebral artery stenosis using high‐resolution contrast‐enhanced magnetic resonance angiography
Authors: Kim S. H. , Lee J. S. , Kwon O. K. , Han M. K. , Kim J. H.
Published: December 2009

Purpose: To evaluate the prevalence of proximal vertebral artery stenosis, compared with those of the distal vertebral/basilar artery and extracranial internal carotid artery, in a large population of stroke and non‐stroke patients.

Material and Methods: Nine‐hundred‐and‐thirty‐five patients who underwent high‐resolution contrast‐enhanced magnetic resonance angiography in a regional general hospital were categorized into six groups based on neurological symptoms and disease: an asymptomatic group ( n = 182), a minor symptom group with headache or dizziness ( n = 519), a cardiac group with coronary artery steno‐occlusive disease ( n = 15), a hemorrhagic group with old cerebral hemorrhage ( n = 26), an anterior circulation infarct group ( n = 121), and posterior circulation infarct group ( n = 72). Prevalence of stenosis of the proximal vertebral artery, distal vertebral/basilar artery, and internal carotid artery was analyzed.

Results: The prevalence of stenosis of the proximal vertebral artery, distal vertebral/basilar artery, and internal carotid artery was 12.9%, 5.5%, and 7.2%, respectively, in the study population, and rose as the age increased ( P<0.0001 for all arteries). The prevalence of stenosis of the proximal vertebral artery, distal vertebral/basilar artery, and internal carotid artery was 3.3%, 0.5%, and 1.1%, respectively, in the asymptomatic group; 8.3%, 2.1%, and 3.7%, respectively, in the minor symptom group; 13.3%, 6.7%, and 6.7%, respectively, in the cardiac group; 19.2%, 7.7%, and 7.7%, respectively, in the hemorrhagic group; 27.3%, 8.3%, and 25.6%, respectively, in the anterior circulation infarct group; and 44.4%, 36.1%, and 16.7%, respectively, in the posterior circulation infarct group. This increasing tendency of stenosis accordingly was statistically significant ( P<0.0001 for all arteries).

Conclusion: The prevalence of proximal vertebral artery stenosis was highest, compared with those of the distal vertebral/basilar artery and internal carotid artery, although the clinical significance of proximal vertebral artery stenosis should be investigated in further studies.
Posterior “nutcracker” phenomenon: hemodynamic relevant aorto‐retroaortal renal vein fistula leading to fatal right heart failure
Authors: Breitwieser C. , Asbach P. , Sachs M. , Rogalla P. , Rodenwaldt J.
Published: December 2009

A rare complication of an aneurysm of the abdominal aorta is the so‐called “posterior nutcracker phenomenon”, which describes compression of a retroaortal renal vein between the abdominal aorta and the vertebral column. The clinical presentation is flank pain and hematuria, which are usually caused by a renal (respectively ureteral) calculus or neoplasia.

Another rare differential diagnosis for these very common clinical symptoms is an aorto‐left renal vein fistula (ALRVF), which is a spontaneous vascular fistula, usually also associated with an aortic aneurysm, infrequently a result of abdominal trauma.
Metacarpophalangeal pattern profile analysis in leri‐weill dyschondrosteosis
Authors: Laurencikas E. , Söderman E. , Grigelioniene G. , Hagenäs L. , Jorulf H.
Published: December 2009

Purpose: To analyze the metacarpophalangeal profile (MCPP) in individuals with Leri‐Weill dyschondrosteosis (LWD) and to assess its value as a possible contributor to early diagnosis.

Material and Methods: Hand profiles of 39 individuals with a diagnosis of LWD were calculated and analyzed. Discriminant analysis was applied to differentiate between LWD and normal individuals.

Results: There was a distinct pattern profile in LWD. Mean pattern profile showed two bone‐shortening gradients, with increasing shortening from distal to proximal and from medial to lateral. Distal phalanx 2 was disproportionately long and second metacarpal was disproportionately short. Discriminant analysis yielded correct classification in 72% of analyzed cases.

Conclusion: MCPP is not age‐related and the analysis can be applied at any age, facilitating early diagnosis of LWD. In view of its availability, low costs, and diagnostic value, MCPP analysis should be considered as a routine method in the patients of short stature where LWD is suspected.
Detection of mild emphysema by computed tomography density measurements
Authors: Vikgren J. , Friman O. , Borga M. , Boijsen M. , Gustavsson S. , Ekberg‐Jansson A. , Bake B. , Tylén U.
Published: December 2009

Purpose: To assess the ability of a conventional density mask method to detect mild emphysema by high‐resolution computed tomography (HRCT); to analyze factors influencing quantification of mild emphysema; and to validate a new algorithm for detection of mild emphysema.

Material and Methods: Fifty‐five healthy male smokers and 34 never‐smokers, 61–62 years of age, were examined. Emphysema was evaluated visually, by the conventional density mask method, and by a new algorithm compensating for the effects of gravity and artifacts due to motion and the reconstruction algorithm. Effects of the reconstruction algorithm, slice thickness, and various threshold levels on the outcome of the density mask area were evaluated.

Results: Forty‐nine percent of the smokers had mild emphysema. The density mask area was higher the thinner the slice irrespective of the reconstruction algorithm and threshold level. The sharp algorithm resulted in increased density mask area. The new reconstruction algorithm could discriminate between smokers with and those without mild emphysema, whereas the density mask method could not. The diagnostic ability of the new algorithm was dependent on lung level. At about 90% specificity, sensitivity was 65–100% in the apical levels, but low in the rest of the lung.

Conclusion: The conventional density mask method is inadequate for detecting mild emphysema, while the new algorithm improves the diagnostic ability but is nevertheless still imperfect.
Learning curve for add-on stereotactic core needle breast biopsy
Authors: Koskela A. , Berg M. , Sudah M. , Malinen A. , Kärjä V. , Mustonen P. , Kataja V. , Soimakallio S. , Vanninen R.
Published: December 2009

Purpose: To evaluate the learning curve for an add-on 14 G stereotactic core needle biopsy (SCNB).

Material and Methods: A total of 231 non-palpable breast lesions that had undergone add-on SCNB were evaluated in this prospective study. Five radiologists performed their first three biopsies under supervision. Subsequent, independently performed, biopsies were also evaluated. The samples were collected in three different containers: the first sample in container A, the second and third samples in container B, and subsequent samples in container C (available for four radiologists from the first biopsy on). Technically successful biopsies and false-negative rate in three container combinations (A, A+B, A+B+C) were reported as a function of operator experience.

Results: Technically unsuccessful biopsies occurred significantly more often in microcalcifications than in masses (14.9% versus 3.8%; P = 0.04). For microcalcifications, the rate of successful biopsies was 75% (18/24) for the first 5 biopsies and 87.8% (79/90) for the subsequent biopsies ( P = 0.335); rates for the masses were 95.7% (22/23) and 96.3% (79/82) ( P = 1.0), respectively. A tendency was noted for the false-negative rate to be higher for the first five biopsies in three container combinations than in subsequent cases.

Conclusion: Our results support the existence of a learning curve, especially in the biopsy of microcalcifications. More than three mentor-guided biopsies are needed.
Diagnostic efficacy in knee MRI comparing conventional technique and multiplanar reconstruction with one-millimeter FSE PDW images
Authors: Yoon Y. C. , Kim S. S. , Chung H. W. , Choe B-K. , Ahn J. H.
Published: December 2009

Background: Magnetic resonance (MR) imaging has proved to be an excellent tool in diagnosing injuries of the cruciate ligaments and menisci. However, multiple planes and sometimes optimal oblique or double-oblique scan planes are needed due to the variability in the positioning of important structures, which means there is a lower throughput and longer scanning time.

Purpose: To compare the performance of a 1-mm-thickness fast spin-echo (FSE) proton-density-weighted (PDW) MR imaging technique with multiplanar reconstruction (MPR) in diagnosing tears of the menisci and cruciate ligaments with that of conventional MR imaging.

Material and Methods: Twenty-five consecutive patients underwent preoperative conventional and 1-mm-thickness FSE PDW MR imaging with subsequent knee arthroscopic surgery. Two musculoskeletal radiologists evaluated the status of the cruciate ligaments and menisci using two sets of MR images (method A: conventional images including seven sequences, taking 26 min; method B: 1-mm-thickness FSE PDW images with MPR, taking 7 min 20 s). The diagnostic efficacies of both methods for tears of the cruciate ligament and menisci were calculated and compared.

Results: Arthroscopic surgery revealed 10 anterior cruciate ligament (ACL) tears, one posterior cruciate ligament (PCL) tear, and 26 meniscal tears. The diagnostic values of both methods were 100% for a cruciate ligament tear. The diagnostic values (sensitivity, specificity, accuracy, positive predictive value, and negative predictive value) for meniscal tears were 90%, 100%, 96%, 100%, and 94% for method A, and 95%, 100%, 98%, 100%, and 97% for method B, respectively. There were no significant differences in the diagnostic values between methods A and B.

Conclusion: 1-mm-slice-thickness FSE PDW imaging with MPR showed comparable performance in diagnosing tears of the cruciate ligaments and menisci to conventional sequences but the scan time was much shorter. Therefore, this technique (method B) might improve the throughput of a 3T MR imaging system.
Magnetic resonance perfusion imaging in malformations of cortical development
Authors: Widjaja E. , Wilkinson I. D. , Griffiths P. D.
Published: December 2009

Background: Malformations of cortical development vary in neuronal maturity and level of functioning.

Purpose: To characterize regional relative cerebral blood volume (rCBV) and difference in first moment transit time (TTfm) in polymicrogyria and cortical tubers using magnetic resonance (MR) perfusion imaging.

Material and Methods: MR imaging and dynamic T2*-weighted MR perfusion imaging were performed in 13 patients with tuberous sclerosis complex, 10 with polymicrogyria, and 18 controls with developmental delay but no macroscopic brain abnormality. Regions of interest were placed in cortical tubers or polymicrogyric cortex and in the contralateral normal-appearing side in patients with malformations. In “control” subjects, regions of interest were placed in the frontal and parietal lobes in both hemispheres. The rCBV and TTfm of the tuber/contralateral side (rCBVRTSC and ΔTTFMTSC) as well as those of the polymicrogyria/contralateral side (rCBVRPMG and ΔTTFMPMG) were assessed. The right-to-left asymmetry of rCBV and TTfm in the control group was also assessed (rCBVRControls and ΔTTFMControls).

Results: There was no significant asymmetry between right and left rCBV or TTfm ( P>0.05) in controls. There was significant reduction in rCBVRTSC compared to rCBVRControls ( P<0.05), but no significant difference in ΔTTFMTSC compared to ΔTTFMControls ( P>0.05). There were no significant differences between rCBVRPMG and rCBVRControls ( P>0.05) or ΔTTFMPMG and ΔTTFMControls ( P>0.05).

Conclusion: Our findings imply that cerebral blood volume of polymicrogyria is similar to normal cortex, but there is reduced cerebral blood volume in cortical tubers. The lower rCBV ratio of cortical tubers may be related to known differences in pathogenetic timing of the underlying abnormalities during brain development or the presence of gliosis.
Intraarterial infusion chemotherapy and conformal radiotherapy for cancer of the mouth: prediction of the histological response to therapy with magnetic resonance imaging
Authors: Ishii A. , Korogi Y. , Hirai T. , Nishimura R. , Murakami R. , Ikushima I. , Kawanaka K. , Shinohara M. , Yamashita Y.
Published: December 2009

Background: Although intraarterial chemotherapy has been used to treat head and neck cancers, some cases have shown poor response. If we can predict the response to this therapy on MRI, individual treatment plans may be altered to the most appropriate form of treatment.

Purpose: To evaluate whether MRI can predict the histological response to preoperative chemoirradiation in patients with cancer of the mouth.

Material and Methods: This study comprised of 29 consecutive patients with 30 oral cancers. All patients underwent tumor resection after intraarterial infusion chemotherapy and conformal radiotherapy. We compared the margin of the tumor, the presence of bone invasion, tumor area, and volume on pre- and post-treatment MRI with histological responses.

Results: Eighteen lesions showed an excellent response, nine exhibited a good response, and three a poor response. Only the tumor area on pretreatment T1-weighted images and the tumor area and volume on pretreatment enhanced T1-weighted images were significantly correlated with the histological response ( P = 0.039, 0.008, and 0.016, respectively); smaller cancers showed better responses. The other factors were not significantly correlated with the histological responses.

Conclusion: MRI parameters, excluding initial tumor area and volume, were not predictive of the histological response of oral tumors to preoperative treatment.
Vaginal masses: magnetic resonance imaging features with pathologic correlation
Authors: Elsayes K. M. , Narra V. R. , Dillman J. R. , Velcheti V. , Hameed O. , Tongdee R. , Menias C. O.
Published: December 2009

The detection of vaginal lesions has increased with the expanding use of cross-sectional imaging. Magnetic resonance imaging (MRI)—with its high-contrast resolution and multiplanar capabilities—is often useful for characterizing vaginal masses. Vaginal masses can be classified as congenital, inflammatory, cystic (benign), and neoplastic (benign or malignant) in etiology. Recognition of the typical MR imaging features of such lesions is important because it often determines the treatment approach and may obviate surgery. Finally, vaginal MR imaging can be used to evaluate post-treatment changes related to previous surgery and radiation therapy. In this article, we will review pertinent vaginal anatomy, vaginal and pelvic MRI technique, and the MRI features of a variety of vaginal lesions with pathological correlation.
Burmese Days
Authors: Lin Htein
Published: December 2009

Artist and former political prisoner Htein Lin reports on a year of censorship in Burma — and reveals the unpredictable tactics of the regime
Web Tactics
Authors: Faris Robert , Zittrain Jonathan
Published: December 2009

Robert Faris and Jonathan Zittrain chart the highs and lows for free expression online in 2009: from the triumph over Green Dam to cyber attacks
Evaluation of a Mental Health Literacy Training Program for Junior Sporting Clubs
Authors: Bapat Swagata , Jorm Anthony , Lawrence Katherine
Published: December 2009

Objective: The aim of this study was to describe and evaluate a training program designed to improve mental health literacy in junior sporting club coaches and leaders. It was anticipated that participants would demonstrate an improvement in knowledge, confidence, and attitudes in relation to mental disorders and help seeking.

Methods: A training program called Read the Play was delivered to 40 participants from junior AFL football and netball leagues in the Barwon region of Victoria. The effects of the training were evaluated using pre- and post-questionnaires.

Results: The course led to significant improvement in knowledge about mental disorders, increased confidence in helping someone with a mental disorder and more positive attitudes towards people with mental disorders.

Conclusions: Training programs delivered within sporting settings may be effective in improving mental health literacy. Future evaluations would benefit from assessing whether these changes are sustained over time and whether trainees subsequently assist young club members to seek appropriate professional help.
Two Models of Suicide
Authors: Pridmore Saxby , Jamil Mohammed Yaacob
Published: December 2009

Objective: The aim of this paper is to present two models of separate but related aspects of suicide, developed with a view to improving understanding and management of this behaviour.

Conclusions: First, the predicament model of suicide posits that all suicide represents an escape from a predicament and associated distress. Predicaments are composed of either external (environmental) or internal (mental disorders) factors, or both. Suicide occurs when a threshold is exceeded on a suicide risk ladder, and the degree of movement toward the threshold in response to a particular stressor depends on a range of factors. Second, the suicide pathways model integrates medical and sociological concepts, with distress as the central component, and three run-offs: mental disorder, medicalized and a non-mental disorder (egoistic/anomic; reaction) suicide.
Delayed diffusion-weighted MR abnormality in a patient with an extensive acute cerebral hypoxic injury: A case report
Authors: Hald J. K. , Brunberg J. A. , Dublin A. B. , Wootton-Gorges S. L.
Published: December 2009

Diffusion-weighted (DW) MR imaging usually identifies acute cerebral infarction injury in symptomatic patients. We report a patient with severe hypoxic brain injury following suicide attempt by hanging, but with normal DW MR imaging 5–6 h after the event. Follow-up DW MR imaging 3 days after the event, and subsequent autopsy, revealed extensive cerebral anoxic injury.
MR imaging of uncommon recurrence of fibrolipomatous hamartoma of the ulnar nerve: A case report
Authors: Kakitsubata Y. , Theodorou S. J. , Theodorou D. J. , Shibata M. , Yuge M. , Yuki Y. , Hatakeyama K. , Yokouchi T.
Published: December 2009

We present the MR and histopathologic findings of fibrolipomatous hamartoma (FLH) of the ulnar nerve in a 54-year-old woman, a lipomatous process that rarely affects the ulnar nerve. The case illustrated is further unusual as a local soft tissue recurrent mass developed over a remarkably long course of the disease.
New intravascular contrast agent applied to dynamic contrast enhanced MR imaging of human breast cancer
Authors: Rydland J. , Bjørnerud A. , Haugen O. , Torheim G. , Torres C. , Kvistad K. A. , Haraldseth O.
Published: December 2009

Purpose: To evaluate the feasibility of using dynamic contrast-enhanced MR imaging with a new intravascular contrast agent in grading human breast cancer.

Material and Methods: 23 patients with 27 breast tumors (21 carcinomas and 6 fibroadenomas) were examined with dynamic MR imaging after administration of Clariscan, an iron oxide nanoparticle with large T1 relaxivity and a long plasma half life. A 3D T1-weighted gradient echo sequence with an acquisition time of 60 s was repeated at regular intervals of 3–5 min before and up to 1 h after injection of 2 mg/kg b.w. of Clariscan. The endothelial transfer constant, Kps, which reflects overall vascular permeability, and the fractional plasma volume, fPV, were estimated from time-intensity curves acquired from three separate regions of interest (ROIs): whole tumor, a permeability hot spot, and a blood volume hot spot. Kps and fPV were compared to the results of histologic tumor grading (Scarff-Bloom-Richardson, SBR) and microvascular density, MVD.

Results: A statistically significant correlation between the MR-derived Kps parameters and the SBR score was obtained for the whole tumor ROI ( R = 0.70), and for the permeability hot spot ROIs ( R = 0.67). A correlation between fPV and SBR was detected for the blood volume hot spot ROIs ( R = 0.48). There was no statistically significant correlation between Kps or fPV with MVD.

Conclusion: The results support the hypothesis that dynamic MR with the intravascular contrast agent Clariscan may be used for non-invasive tumor grading.
Model studies on acetabular component migration in total hip arthroplasty using CT and a semiautomated program for volume merging
Authors: Olivecrona L. , Olivecrona H. , Weidenhielm L. , Noz M. E. , Maguire G. Q. , Zeleznik M. P.
Published: December 2009

Purpose: Validation of a non-invasive CT method for detection of acetabular cup migration after total hip arthroplasty in a phantom study.

Material and Methods: 26 CT examinations were obtained of a pelvic model while altering the position of the acetabular cup. Using a previously described program for volume merging, the pelvi in different examinations were fused and the 3D alterations of the position of the acetabular cup were evaluated visually and numerically and correlated to direct measurements on the model.

Results: Visually, two independent examiners differentiated between 0, 1 and 2 to 3 mm migration with 100% specificity and sensitivity. Numerically, the mean error over all cases between model and CT measurements was 0.04 mm (SD ± 0.33). The mean absolute error between model and CT data was 0.26 mm (SD ± 0.19). Intra- and interobserver 95% accuracy and repeatability limits were below 0.5/0.7 mm, respectively. No significant interobserver difference occurred. The data were normally distributed and not dependent on observer.

Conclusion: The accuracy of this non-invasive method out-performs routine plain radiography. The method gives both visual and numerical correlates to migration and can be used in clinical practice.