bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of nanosized carbon black on the morphology, transport, and mechanical properties of rubbery epoxy and silicone composites
Authors: Ali Raza Mohsin , Westwood Aidan , Stirling Chris , Brydson Rik , Hondow Nicole
Published: April 2012

Three different types of nanosized carbon black (CB), Printex XE2 (CBP), Vulcan XC72, and Printex 140 U (CBU), were dispersed by mechanical mixing in rubbery epoxy (RE) and silicone to produce composites. It was found that the maximum possible loading of CB in the polymers depended on the surface area of CB. For a given loading, all three CBs produced similar improvements in the thermal conductivity of the resulting composites, but their effects on the electrical conductivity varied and ranged from insulating composites with CBU to conducting composites with CBP. CBP produced a greater improvement in the electrical conductivity than the thermal conductivity of the polymers compared to the other CBs. This was attributed to the high structure of CBP, which led to the formation of a concatenated structure within the matrix. The CB/silicone composites had a similar thermal conductivity to that of the CB/RE composites, but only the CBP/silicone composite produced at 8 wt % loading was electrically conducting. The compression and hardness properties of RE were also significantly improved with the addition of CB. However, in the case of silicone, only CBP had a considerable effect on the compression properties. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Electrospun poly(lithium 2‐acrylamido‐2‐methylpropanesulfonic acid) fiber‐based polymer electrolytes for lithium‐ion batteries
Authors: Cui Wei‐Wei , Tang Dong‐Yan
Published: April 2012

Novel single‐ion conducting polymer electrolytes based on electrospun poly(lithium 2‐acrylamido‐2‐methylpropanesulfonic acid) (PAMPSLi) membranes were prepared for lithium‐ion batteries. The preparation started with the synthesis of polymeric lithium salt PAMPSLi by free‐radical polymerization of 2‐acrylamido‐2‐methylpropanesulfonic acid, followed by ion‐exchange of H+ with Li+. Then, the electrospun PAMPSLi membranes were prepared by electrospinning technology, and the resultant PAMPSLi fiber‐based polymer electrolytes were fabricated by immersing the electrospun membranes into a plasticizer composed of ethylene carbonate and dimethyl carbonate. PAMPSLi exhibited high thermal stability and its decomposition did not occur until 304°C. The specific surface area of the electrospun PAMPSLi membranes was raised from 9.9 m2/g to 19.5 m2/g by varying the solvent composition of polymer solutions. The ionic conductivity of the resultant PAMPSLi fiber‐based polymer electrolytes at 20°C increased from 0.815 × 10−5 S/cm to 2.12 × 10−5 S/cm with the increase of the specific surface area. The polymer electrolytes exhibited good dimensional stability and electrochemical stability up to 4.4 V vs. Li+/Li. These results show that the PAMPSLi fiber‐based polymer electrolytes are promising materials for lithium‐ion batteries. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Combined effect of isophthalic acid and polyethylene glycol in polyethylene terephthalate polymer on thermal, mechanical, and gas transport properties
Authors: Mohan T. P. , George A. Prem , Kanny K.
Published: April 2012

The objective of this article is to study the combined effect of isophthalic acid (IPA) and polyethylene glycol (PEG‐400) in PET polymer and film on thermal, mechanical, and gas transport properties. The purpose of developing this material is to reduce the melting point, improve mechanical, thermal, and gas barrier properties. The chosen raw materials, namely, IPA and PEG for copolyester synthesis will replace partially the acid and diol monomers of PET. The molar concentration of comonomers (IPA and PEG‐400) were varied from 2 to 50% and the result shows that the gas barrier properties (namely O2, CO2, N2, and water vapor transmission rate), mechanical, and thermal properties were lesser than that of PET polymer. On improving the crystallinity of PET‐isophthalate‐PEG (PET‐IP) copolymer, barrier properties are improved than that of PET polymer. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
The evolution of structure and properties of poly(p‐phenylene terephthalamide) during the hydrothermal aging
Authors: Li Chang‐Sheng , Zhan Mao‐Sheng , Huang Xian‐Cong , Zhou Hong
Published: April 2012

The evolution of structure and properties of poly(p‐phenylene terephthalamide) (PPTA) with different hydrothermal aging temperatures were systematically investigated. The cooperative change in tensile strength and reduced viscosity upon aging time indicated a direct chemical structure‐property correlation. The linear relationship between tensile strength and reduced viscosity was explored. Wide angle X‐ray diffraction measurements disclosed the crystal structure of aramid fibers was stable with aging time and temperature. Fiber exhibited skin and core structure in different ways. Cracks and microfilbrils were observed in the core after hydrothermal aging, while the structure was unchanged in the skin. Fourier transform infrared spectroscopy also proved that the chemical structure of the skin was not affected by degradation. The results elucidated the hydrolysis of amide function happened in amorphous or bundles between microfibrils in the core rather than in skin of the fiber. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
β‐Blockers in Heart Failure: Benefits of β‐Blockers According to Varying Male Proportions of Study Patients
Authors: He Yong‐Ming , Yang Xiang‐Jun , Zhao Xin , Cheng Xu‐Jie , Xu Hai‐Feng , Qian Yun‐Xia , Li Xun
Published: April 2012

Background:

In patients with heart failure (HF), b‐blockers reduce mortality. It's not known whether the beneficial effects of the b‐blockers were associated with the differing male proportions of study patients. It also remains to be clarified regarding the true beneficial effects of the 3 b‐blockers recommended by the guideline on mortality in the real world.

Hypothesis:

The benefits of b‐blockers in HF patients were sex‐related different.

Methods:

Randomized, placebo controlled clinical trials were included if they evaluated the beneficial effects of the three b‐blockers on mortality and on hospital admissions on an intention‐to‐treat basis, and lasted at least 3 months.

Results:

Twenty‐eighty trials with 14,829 patients were included. The b‐blockers significantly reduced all cause mortality by 29.6%, cardiac death by 29.8%, sudden death by 49.4%, respectively. The magnitude of benefits of b‐blockers in HF patients was increased with the increased male proportion. A similar magnitude of reduction in all cause mortality was observed among the three b blockers. A trend toward to reduced cardiac death was observed among the three b blockers, but only in bisoprolol was this statistically different (RR, 0.72; 95%CI, [0.59–0.87]). Metoprolol was significantly superior to carvedilol (P = 0.008) or bisoprolol (P = 0.034) in reduced sudden death.

Conclusions:

In patients with HF, the 3 commonly used b‐blockers significantly reduced mortality. Greater benefits of b‐blockers were observed in the higher male proportion studies. The metoprolol was significantly superior to carvedilol or bisoprolol in reduced sudden death. Additional trials are required to determine whether the benefits of b‐blockers will be observed in female HF patients. Clin. Cardiol. 2012 DOI: 10.1002/clc.21985

The authors have no funding, financial relationships, or conflicts of interest to disclose.
Clinical Characteristics, Sex Hormones, and Long‐Term Follow‐Up in Swiss Postmenopausal Women Presenting With Takotsubo Cardiomyopathy
Authors: Brenner Roman , Weilenmann Daniel , Maeder Micha T. , Jörg Lucas , Bluzaite Ina , Rickli Hans , De Pasquale Gabriella , Ammann Peter
Published: April 2012

Background:

The overwhelming majority of patients with stress cardiomyopathy (SC) are postmenopausal women, suggesting an important pathophysiologic role of the female sex hormones. Preliminary data suggest that myocardial stunning might be provoked by estrogen deficiency.

Hypothesis:

We hypothesized that, compared with age‐ and gender‐matched patients with myocardial infarction (MI) or patients with normal coronary arteries, patients with SC would exhibit altered levels of sex hormones. Furthermore, we aimed to describe the clinical course and the pattern of sex hormones of the SC patients during long‐term follow‐up.

Methods:

Blood samples obtained on hospital admission were analyzed for estradiol (E2), progesterone (P), luteinizing hormone (LH), and follicle‐stimulating hormone (FSH) in women with SC (n = 17), age‐matched women with acute MI (n = 16), and women with normal coronary arteries (n = 15). Six years after the initial event, SC patients underwent a clinical and echocardiographic follow‐up and reassessment of sex hormones.

Results:

Estrogen concentrations at hospital admission were significantly higher in the SC group compared with the MI and the control groups, with no difference in P, FSH, and LH concentrations. Follow‐up E2 after 6 years in SC patients was lower than during the acute SC episode. Follow‐up P in these patients was lower than P in the MI and control groups during the acute event, with a similar trend for E2. After a median follow‐up of 6.4 years, 1 sudden cardiac death occurred and 2 patients suffered from SC recurrence.

Conclusions:

During the acute event, E2 concentrations are elevated in postmenopausal SC patients compared with women with acute MI or with normal coronary arteries. The higher E2 concentrations might have exerted atheroprotective effects and thus diverted the stress response to SC rather than MI. Recurrence and/or sudden cardiac death remains a potential risk of SC. Clin. Cardiol. 2012 DOI: 10.1002/clc.21986

Roman Brenner, MD, and Daniel Weilenmann, MD, contributed equally to this work and should be considered first authors.

The authors have no funding, financial relationships, or conflicts of interest to disclose.
Inhaled Low‐Dose Iloprost for Pulmonary Hypertension: A Prospective, Multicenter, Open‐Label Study
Authors: Sun Yun‐Juan , Xiong Chang‐Ming , Shan Guang‐Liang , Gu Qing , Zeng Wei‐Jie , Lu Xian‐Ling , Zhu Feng , Liu Zhi‐Hong , Ni Xin‐Hai , He Jian‐Guo ,   on behalf of the Iloprost Therapy on Pulmonary Hypertension Study Group
Published: April 2012

Background:

Inhaled iloprost (average >30 µg/d) has been considered an effective treatment for severe pulmonary hypertension (PH). Further evidence also showed that low‐dose iloprost given intravenously was equally effective as high‐dose iloprost in the therapy of systemic sclerosis.

Hypothesis:

Patients with pulmonary hypertension will benefit from inhalation of low‐dose iloprost.

Methods:

Sixty‐two patients with PH were enrolled and initiated with neubulizedlow‐dose iloprost (2.5 µg per inhalation, 6× daily) for 24 weeks in 13 medical centers in China. Efficacy endpoints included changes in 6‐minute walk distance (6MWD), World Health Organization functional class (WHO‐FC), and hemodynamic parameters.

Results:

Fourteen patients (22.6%) prematurely discontinued the study: 8 due to clinical worsening (6 in WHO‐FCIII–IV at baseline), 4 because of protocol change, and 2 patients lost during follow‐up. In the remaining 48 patients, 6MWD was increased from 356 ± 98 meters to 414 ± 99 meters (P < 0.001) and WHO‐FC improved significantly (P = 0.006) after 24‐week inhalation therapy. Cardiac output, cardiac index, and mixed venous oxygen saturation improved significantly compared with baseline (n = 34, P < 0.05). Most of the hemodynamic parameters improved significantly in patients in WHO‐FC II (P < 0.05) but not in patients in WHO‐FCIII–IV.

Conclusions:

Low‐dose iloprost inhalation significantly improved exercise capacity and functional status in patients with PH. It was well tolerated. The improvement of hemodynamics was confirmed in patients with WHO‐FCI–II but not in patients with WHO‐FCIII–IV, suggesting the importance of early treatment in patients with advanced disease stages. Clin. Cardiol. 2012 DOI: 10.1002/clc.21987

This study was supported by National Grant from the Ministry of Science and Technology (Beijing, China, project number 2006BAI01A07) and the Capital Development Scientific Fund (Beijing, China, project number 2005‐1018). The authors have no other funding, financial relationships, or conflicts of interest to disclose.
Maternal depression and infant daytime cortisol
Authors: Azak Schale , Murison Robert , Wentzel‐Larsen Tore , Smith Lars , Gunnar Megan R.
Published: April 2012

The effect of maternal depressive disorder on infant daytime cortisol production was studied in three groups of infants; one group with mothers with comorbid depression and anxiety (n = 19), a second group with mothers with depression only (n = 7), and a third group with non‐depressed mothers (n = 24). The infants' cortisol production pattern was measured when they were 6, 12, and 18 months old in combination with repeated measures of parenting stress and depression symptoms. Multilevel modeling analyses showed that infants of mothers with comorbid depression and anxiety had relatively higher cortisol production from morning to bedtime and higher bedtime values as compared to infants of non‐depressed mothers and infants of depressed only mothers when they were 6 and 12 months old, but not when 18 months old. The results were interpreted in light of possible changes in the infants' stress regulatory capacities or changes in maternal coping strategies at infant age 18 months. © 2012 Wiley Periodicals, Inc. Dev Psychobiol 55: 334–351, 2013
Development of active controlled retrieval during middle childhood
Authors: Dionne Joannie , Cadoret Geneviève
Published: April 2012

The aim of this study was to examine the development of active controlled memory retrieval in children. Active retrieval is an effortful retrieval required to disambiguate information stored in memory. Brain imaging studies and monkey experiments have shown that the ventrolateral prefrontal cortex (VLPFC) is specifically engaged in this retrieval in both adult humans and monkeys. Three groups of 6‐, 8‐, and 11‐year‐old children and adults were tested on an active retrieval task. Results showed a marked difference in performance between 6‐year olds, who made more errors and had longer response time, and 8‐ and 11‐year olds, who had performance similar to adults. These results provide evidence that the VLPFC and the network supporting its top–down modulation undergo substantial maturational changes between 6 and 8 years old, giving children better active control of visual memory. © 2012 Wiley Periodicals, Inc. Dev Psychobiol 55: 443–449, 2013
Sex, horizontal transmission, and multiple hosts prevent local adaptation of Crithidia bombi, a parasite of bumblebees (Bombus spp.)
Authors: Erler Silvio , Popp Mario , Wolf Stephan , Lattorff H. Michael G.
Published: April 2012

Local adaptation within host‐parasite systems can evolve by several non‐exclusive drivers (e.g., host species‐genetic adaptation; ecological conditions‐ecological adaptation, and time‐temporal adaptation). Social insects, especially bumblebees, with an annual colony life history not only provide an ideal system to test parasite transmission within and between different host colonies, but also parasite adaptation to specific host species and environments. Here, we study local adaptation in a multiple‐host parasite characterized by high levels of horizontal transmission. Crithidia bombi occurs as a gut parasite in several bumblebee species. Parasites were sampled from five different host species in two subsequent years. Population genetic tools were used to test for the several types of adaptation. Although we found no evidence for local adaptation of the parasite toward host species, there was a slight temporal differentiation of the parasite populations, which might have resulted from severe bottlenecks during queen hibernation. Parasite populations were in Hardy‐Weinberg equilibrium and showed no signs of linkage disequilibrium suggesting that sexual reproduction is an alternative strategy in this otherwise clonal parasite. Moreover, high levels of multiple infections were found, which might facilitate sexual genetic exchange. The detection of identical clones in different host species suggested that horizontal transmission occurs between host species and underpins the lack of host‐specific adaptation.
Transforming growth factor‐α mediates estrogen‐induced upregulation of glutamate transporter GLT‐1 in rat primary astrocytes
Authors: Lee Eunsook , Sidoryk‐Wegrzynowicz Marta , Yin Zhaobao , Webb Anton , Son Deok‐Soo , Aschner Michael
Published: April 2012

Glutamate transporter‐1 (GLT‐1) plays a central role in preventing excitotoxicity by removing excess glutamate from the synaptic clefts. 17β‐Estradiol (E2) and tamoxifen (TX), a selective estrogen receptor (ER) modulator, afford neuroprotection in a range of experimental models. However, the mechanisms that mediate E2 and TX neuroprotection have yet to be elucidated. We tested the hypothesis that E2 and TX enhance GLT‐1 function by increasing transforming growth factor (TGF)‐α expression and, thus, attenuate manganese (Mn)‐induced impairment in astrocytic GLT‐1 expression and glutamate uptake in rat neonatal primary astrocytes. The results showed that E2 (10 nM) and TX (1 μM) increased GLT‐1 expression and reversed the Mn‐induced reduction in GLT‐1, both at the mRNA and protein levels. E2/TX also concomitantly reversed the Mn‐induced inhibition of astrocytic glutamate uptake. E2/TX activated the GLT‐1 promoter and attenuated the Mn‐induced repression of the GLT‐1 promoter in astrocytes. TGF‐α knockdown (siRNA) abolished the E2/TX effect on GLT‐1 expression, and inhibition of epidermal growth factor receptor (TGF‐α receptor) suppressed the effect of E2/TX on GLT‐1 expression and GLT‐1 promoter activity. E2/TX also increased TGF‐α mRNA and protein levels with a concomitant increase in astrocytic glutamate uptake. All ERs (ER‐α, ER‐β, and G protein‐coupled receptor 30) were involved in mediating E2 effects on the regulation of TGF‐α, GLT‐1, and glutamate uptake. These results indicate that E2/TX increases GLT‐1 expression in astrocytes via TGF‐α signaling, thus offering an important putative target for the development of novel therapeutics for neurological disorders. © 2012 Wiley Periodicals, Inc.
Training Ethnic Minority Graduate Students in a White Man's Program: Don't Get Bucked Off!
Authors: Barcus Carolyn G. , Crowley Susan L.
Published: April 2012

This is a narrative journey of a Blackfeet woman as she learned to help ethnic minority students navigate graduate training. The talk reflects the holistic, contextual, and interdependent characteristics of Native American culture blended with the culture of the West. Insights from working with horses are included because they have much to teach people.

Esta es la narración de la trayectoria de una mujer de la tribu Pies Negros que aprendió a ayudar a los estudiantes de minorías étnicas a desenvolverse en sus estudios universitarios. El discurso refleja las características holísticas, contextuales e interdependientes de la cultura de los Nativos Americanos mezclada con la cultura occidental. Se incluyen observaciones obtenidas a partir del trabajo con caballos, porque tienen mucho que enseñar a los humanos.
Cultural Adaptation for Therapy With American Indians and Alaska Natives
Authors: Gray Jacqueline S. , Rose WanmdiWi J.
Published: April 2012

Because of the paucity of research on evidence‐based treatments with American Indian/Alaska Native (AI/AN) clients, this article addresses barriers to that research and how to adapt treatment to make it more culturally appropriate and acceptable to AI/AN clients so they might benefit from and remain in treatment.

Debido a la escasez de investigación sobre tratamientos basados en la evidencia con clientes Indoamericanos/Nativos de Alaska (AI/AN, por sus siglas en inglés), este artículo trata las barreras para ese tipo de investigación y cómo adaptar el tratamiento para hacerlo más apropiado culturalmente y aceptable para los clientes AI/AN, para que puedan beneficiarse del mismo y permanecer en tratamiento.
A curative cryosurgical technique for advanced cancer of sacrococcygeal pilonidal sinuses
Authors: Almeida‐Gonçalves José Carlos
Published: April 2012

Background and Objective

Malignant degeneration of pilonidal sinuses of the sacrococcygeal region is rare but quite serious, as the tumor soon perforates the sacral fascia and becomes adherent to the irregular posterior aspect of the sacrum, making it very difficult, if not impossible, to remove all neoplastic tissue by conventional surgery, hence the high recurrence rate and poor prognosis. A new cryosurgical technique to treat advanced sacrococcygeal pilonidal cancer is herein presented.

Materials and Methods

Seven men aged 30–75 (mean: 54.4 years) with advanced squamous‐cell carcinomas (four primary, three recurrent) arising in sacrococcygeal pilonidal sinuses were treated with open and thick liquid nitrogen spray—two freeze‐thaw cycles. Temperature monitoring was made by thermocouples.

Results

Local eradication was achieved in all cases; one patient, however, died of metastatic disease 10 months after treatment, without local recurrence. One patient had a recurrence, or a new tumor, 8 years after treatment and was again submitted to aggressive cryosurgery followed by plastic surgery. He was followed for 14 years without recurrence. The follow‐up of the remaining six patients ranges between 7 and 18 years.

Conclusion

To the author's knowledge, this is the first series of carcinomas of sacrococcygeal pilonidal sinuses successfully treated by cryosurgery. J. Surg. Oncol. 2012; 106:504–508. © 2012 Wiley Periodicals, Inc.
Proposal of new classification for stage III breast cancer on the number and ratio of metastatic lymph nodes
Authors: Zhu Cong , Wu Xiong‐Zhi
Published: April 2012

Background

The objective of the retrospective study was to confirm whether the current staging system of stage III was appropriate for breast cancer.

Methods

Four hundred fifteen patients with breast cancer in stage III were analyzed. The survival analysis was performed by Kaplan–Meier.

Results

Survival time of the patients with T1N3M0 was significantly better than the patients with other subgroups of stage IIIC (T2,3,4N3M0) and similar that of patients with T4N0,1,2M0 who formed the stage IIIB group based on pN stage. Tumor size, number of positive lymph nodes and lymph node ratio (LNR) were associated with overall survival (OS). The greatest survival difference was found when 0.60 as the cutoff point of LNR for the patients with current stage IIIC (pN3). rN1 included the patients in pN3 with LNR ≤0.60 and rN2 included the patients in pN3 with LNR >0.60. Survival time of the patients with T1,2,3,4N3(rN1)M0 and T1N3(rN2)M0 was differently better than the patients with T2,3,4N3(rN2)M0 and similar that of patients with T4N0,1,2M0.

Conclusion

We suggested current staging system should be modified combining pN with rN. We presumed the patients with T1N3M0 and T2,3,4N3(rN1)M0 disease were excluded from the current stage IIIC and included in stage IIIB group. J. Surg. Oncol. 2012; 106:696–702. © 2012 Wiley Periodicals, Inc.
Urticaria induced by laser epilation: A clinical and histopathological study with extended follow‐up in 36 patients
Authors: Landa Nerea , Corrons Natalia , Zabalza Iñaki , Azpiazu Jose L.
Published: April 2012

Background

Laser epilation is the most common dermatologic light‐based procedure in the world. We describe a unique side effect of the procedure: a delayed persistent urticarial rash.

Patients and methods

We conducted a retrospective study involving 13,284 patients who received laser epilation at our clinics from January 2006 through March 2010 with 755 nm alexandrite laser (MiniGentleLase, Gentlelase, and GentleMax, Candela). Using patient clinical data and photos that were recorded on a standard side‐effect report chart, we identified patients with suspected urticaria. Those patients were then followed for a period that ranged from 12 to 63 months. Only patients who could be diagnosed, treated, and followed by the dermatologist at our clinics were included in the study. Patients diagnosed or treated by other physicians or nurses and those without clinical photos or insufficient follow‐up data were not included.

Results

We identified 36 patients who developed a severe, itchy, persistent hive rash on the treated area 6–72 hours after treatment. Eruption occurred most often on the legs (31 cases), followed by the groin (11 cases), axillae (eight cases), forearms (one case), and upper lip (one case). The eruption consisted of a hive rash with multiple pruritic perifollicular papules and confluent plaques on the treated area. Most patients required oral corticosteroids to control the symptoms. Lesions resolved in 7–30 days. The urticaria occurred mostly after the first treatment (26 cases), and was recurrent in subsequent treatments. Pretreating with oral corticosteroids prevented or limited the eruption. Thirty‐three of the 36 patients reported a history of allergic rhinitis or some other allergy. Skin biopsies on four patients showed edema and a deep, dense dermal infiltrate consistent with lymphocytes mixed with eosinophils in a perivascular and occasionally perifollicular pattern in the mid and lower dermis.

Conclusions

Persistent urticaria is a rare side effect of laser epilation. Rupture of the hair follicle by laser heat may trigger a delayed hypersensitivity reaction in a subset of predisposed allergic patients. An antigen from the disrupted hair follicle may be the triggering factor. To prevent this side effect, we recommend that laser epilation in allergic patients be preceded by an extended laser patch test, which should be evaluated 24–48 hours later. Preventive prednisone should be prescribed to patients who develop an urticarial rash on the test area. Lasers Surg. Med. 44: 384–389, 2012. © 2012 Wiley Periodicals, Inc.
Pre‐existing fas ligand (FasL) in cancer cells elicits tumor‐specific protective immunity, but delayed induction of FasL expression after inoculation facilitates tumor formation
Authors: Chiu Hsiao‐Ying , Sun Guang‐Huan , Chen Shiow‐Yi , Wang Hsiao‐Hsien , Ho Ming‐Yi , Chu Chia‐Yi , Wu Wan‐Lin , Jhou Ren‐Shiang , Tsai Yi‐Lin , Huang Rui‐Ting , Sun Kuang‐Hui , Tang Shye‐Jye
Published: April 2012

Overexpression of Fas ligand (FasL) in cancer cells elicits potential antitumor effects via recruitment of neutrophils. Conversely, FasL‐expressing tumors may counterattack tumor‐infiltrating lymphocytes by delivering apoptotic death signals via Fas/FasL interactions, which may lead to tumor escape. In order to distinguish the role of FasL in antitumor activity and tumor progression, Lewis lung carcinoma cells (LLC‐1) were used to establish the cell line LLC‐FasL, in which FasL expression was repressed by doxycycline (Dox) treatment and induced in the absence of Dox. LLC‐FasL cells promote tumor regression when expressing FasL, whereas tumor outgrowth is observed by depletion of FasL expression. To investigate whether initial expression of FasL during tumor formation is critical for FasL‐mediated tumor regression, Dox‐treated LLC‐FasL cells were inoculated into Dox‐treated mice, but Dox treatment was stopped 5 days after inoculation. When low cell numbers were inoculated, we observed 80% survival and no tumor formation, whereas no mice survived inoculation with high cell numbers, despite the delayed induction of FasL by Dox withdrawal. The inoculation of a high density of cells may establish a favorable tumor microenvironment before the expression of FasL. Our findings demonstrate that FasL may elicit antitumor activity when it is initially present on injected cancer cells and thus can act prior to tumor microenvironment formation. Furthermore, a well‐established tumor microenvironment abrogates FasL‐mediated antitumor activity. © 2012 Wiley Periodicals, Inc.
Pseudo‐continuous arterial spin labeling at 7 T for human brain: Estimation and correction for off‐resonance effects using a Prescan
Authors: Luh Wen‐Ming , Talagala S. Lalith , Li Tie‐Qiang , Bandettini Peter A.
Published: April 2012

Pseudo‐continuous arterial spin labeling (ASL) can provide best signal‐to‐noise ratio efficiency with a sufficiently long tag at high fields such as 7 T, but it is very sensitive to off‐resonance fields at the tagging location. Here, a robust Prescan procedure is demonstrated to estimate the pseudo‐continuous ASL radiofrequency phase and gradients parameters required to compensate the off‐resonance effects at each vessel location. The Prescan is completed in 1–2 min and is based on acquisition of label/control pair‐wise ASL data as a function of the radiofrequency phase increment applied to the pseudo‐continuous ASL train. It is shown that this approach can be used to acquire high quality whole‐brain pseudo‐continuous ASL perfusion data of the human brain at 7 T. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
Coil compression for accelerated imaging with Cartesian sampling
Authors: Zhang Tao , Pauly John M. , Vasanawala Shreyas S. , Lustig Michael
Published: April 2012

MRI using receiver arrays with many coil elements can provide high signal‐to‐noise ratio and increase parallel imaging acceleration. At the same time, the growing number of elements results in larger datasets and more computation in the reconstruction. This is of particular concern in 3D acquisitions and in iterative reconstructions. Coil compression algorithms are effective in mitigating this problem by compressing data from many channels into fewer virtual coils. In Cartesian sampling there often are fully sampled k‐space dimensions. In this work, a new coil compression technique for Cartesian sampling is presented that exploits the spatially varying coil sensitivities in these nonsubsampled dimensions for better compression and computation reduction. Instead of directly compressing in k‐space, coil compression is performed separately for each spatial location along the fully sampled directions, followed by an additional alignment process that guarantees the smoothness of the virtual coil sensitivities. This important step provides compatibility with autocalibrating parallel imaging techniques. Its performance is not susceptible to artifacts caused by a tight imaging field‐of‐view. High quality compression of in vivo 3D data from a 32 channel pediatric coil into six virtual coils is demonstrated. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
Nonlinear formulation of the magnetic field to source relationship for robust quantitative susceptibility mapping
Authors: Liu Tian , Wisnieff Cynthia , Lou Min , Chen Weiwei , Spincemaille Pascal , Wang Yi
Published: April 2012

Quantitative susceptibility mapping (QSM) opens the door for measuring tissue magnetic susceptibility properties that may be important biomarkers, and QSM is becoming an increasingly active area of scientific and clinical investigations. In practical applications, there are sources of errors for QSM including noise, phase unwrapping failures, and signal model inaccuracy. To improve the robustness of QSM quality, we propose a nonlinear data fidelity term for frequency map estimation and dipole inversion to reduce noise and effects of phase unwrapping failures, and a method for model error reduction through iterative tuning. Compared with the previous phase based linear QSM method, this nonlinear QSM method reduced salt and pepper noise or checkerboard pattern in high susceptibility regions in healthy subjects and markedly reduced artifacts in patients with intracerebral hemorrhages. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
Intravoxel incoherent motion MR imaging for prostate cancer: An evaluation of perfusion fraction and diffusion coefficient derived from different b‐value combinations
Authors: Pang Yuxi , Turkbey Baris , Bernardo Marcelino , Kruecker Jochen , Kadoury Samuel , Merino Maria J. , Wood Bradford J. , Pinto Peter A. , Choyke Peter L.
Published: April 2012

There has been a resurgent interest in intravoxel incoherent motion (IVIM) MR imaging to obtain perfusion as well as diffusion information on lesions, in which the diffusion was modeled as Gaussian diffusion. However, it was observed that this diffusion deviated from expected monoexponential decay at high b‐values and the reported perfusion in prostate is contrary to the findings in dynamic contrast‐enhanced (DCE) MRI studies and angiogenesis. Thus, this work is to evaluate the effect of different b‐values on IVIM perfusion fractions (f) and diffusion coefficients (D) for prostate cancer detection. The results show that both parameters depended heavily on the b‐values, and those derived without the highest b‐value correlated best with the results from DCE‐MRI studies; specifically, f was significantly elevated (7.2% vs. 3.7%) in tumors when compared with normal tissues, in accordance with the volume transfer constant (Ktrans; 0.39 vs. 0.18 min−1) and plasma fractional volume (vp; 8.4% vs. 3.4%). In conclusion, it is critical to choose an appropriate range of b‐values in studies or include the non‐Gaussian diffusion contribution to obtain unbiased IVIM measurements. These measurements could eliminate the need for DCE‐MRI, which is especially relevant in patients who cannot receive intravenous gadolinium‐based contrast media. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
Preparation and characterization of monodisperse porous silica microspheres with controllable morphology and structure
Authors: He Jie , Yang Chengli , Xiong Xiaohui , Jiang Biwang
Published: April 2012

A novel method for the preparation of monodisperse porous silica microspheres with controllable morphology and structure is reported. The starting porous polymer microspheres were first functionalized with ethylenediamine (EDA) to generate amino groups. Subsequently, silica nanoparticles were deposited in the porous polymer microsphere to form polymer/silica hybrid microspheres via a modified sol‐gel process in the presence of tetra‐n‐butylammonium bromide (TBAB) or tetramethyl ammonium hydroxide (TMAH). Upon calcination of the polymer/silica hybrid microspheres, the porous silica microspheres were obtained. The morphology, inner structure, and properties of the porous silica microspheres were studied by field emission scanning electron microscope, Fourier transform infrared spectroscopy, thermogravimetric analysis, and mercury intrusion method. The results show that the presence of TBAB or TMAH in the process not only prevents the agglomeration of the hybrid microspheres, but also governs the controllable morphology from a porous inner structure to a hollow‐cage structure. The obtained porous silica microspheres exhibit no shrinkage from the polymer microspheres with a yield of around 98%. These porous silica microspheres have potential applications in the fields of chromatography, catalyst, and biology. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Interacting nanoparticles with functional surface groups
Authors: Popov Konstantin I. , Nap Rikkert J. , Szleifer Igal , de la Cruz Monica Olvera
Published: April 2012

Functionalized nanoparticles with ionizable groups have generated a large variety of structures with important potential applications in technology. The nature of their interactions is crucial to determining their solubility and to exploring assemblies with diverse symmetries. Here, we use a molecular theory to describe the interactions between two nanoparticles coated with short polymer chains that contain ionizable (functional) end‐groups immersed in aqueous salt solution. It is shown here that the fraction of ionized functional groups in the system depends on factors such as the ionic strength and pH of solution, grafting density of polymer chains, the chain length, as well as the separation distance between the nanoparticles. The interactions between two neighboring nanoparticles influence the charge regulation of the end‐groups, which consequently induces an asymmetric distribution of these charged end‐groups on the nanoparticles, and thus confers a preferred directionality in nanoparticle–nanoparticle interactions. We show that the charge regulating system is less repulsive than an equivalent system with a fixed charge distribution. This is due to a decrease in the charge density of the weak acid end‐groups, to avoid a local increase in counterion confinement (condensation) in the region between neighboring nanoparticles, when their separation decreases. The anisotropic degree of ionization found in our results can be used to design aggregates of nanoparticles with reduced symmetries. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012
Multifunctional elastomer nanocomposites with functionalized graphene single sheets
Authors: Ozbas Bulent , O'Neill Christopher D. , Register Richard A. , Aksay Ilhan A. , Prud'homme Robert K. , Adamson Douglas H.
Published: April 2012

We demonstrate the use of functionalized graphene sheets (FGSs) as multifunctional nanofillers to improve mechanical properties, lower gas permeability, and impart electrical conductivity for several distinct elastomers. FGS consists mainly of single sheets of crumbled graphene containing oxygen functional groups and is produced by the thermal exfoliation of oxidized graphite (GO). The present investigation includes composites of FGS and three elastomers: natural rubber (NR), styrene–butadiene rubber, and polydimethylsiloxane (PDMS). All of these elastomers show similar and significant improvements in mechanical properties with FGS, indicating that the mechanism of property improvement is inherent to the FGS and not simply a function of chemical crosslinking. The decrease in gas permeability is attributed to the high aspect ratio of the FGS sheets. This creates a tortuous path mechanism of gas diffusion; fitting the permeability data to the Nielsen model yields an aspect ratio of ∼1000 for the FGS. Electrical conductivity is demonstrated at FGS loadings as low as 0.08% in PDMS and reaches 0.3 S/m at 4 wt % loading in NR. This combination of functionalities imparted by FGS is shown to result from its high aspect ratio and carbon‐based structure. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012
Study of simulation method of time evolution in rigged QED
Authors: Ichikawa Kazuhide , Fukuda Masahiro , Tachibana Akitomo
Published: April 2012

We discuss how we formulate time evolution of physical quantities in the framework of the Rigged quantum electrodynamics (QED). The Rigged QED is a theory which has been proposed to treat dynamics of electrons, photons, and atomic nuclei in atomic and molecular systems in a quantum field theoretic way. To solve the dynamics in the Rigged QED, we need different techniques from those developed for the conventional QED. As a first step toward this issue, we propose a procedure to expand the Dirac field operator, which represents electrons, by the electron annihilation/creation operators and solutions of the Dirac equation for electrons in nuclear potential. Similarly, the Schrödinger field operators, which represent atomic nuclei, are expanded by nucleus annihilation/creation operators. Then, we derive time evolution equations for these annihilation and creation operators and discuss how time evolution of the operators for physical quantities can be calculated. In the end, we propose a method to approximate the evolution equations of the operators by the evolution equations for the density matrices of electrons and atomic nuclei. Under this approximation, we carry out numerical simulation of the time evolution of electron charge density of a hydrogen atom. © 2012 Wiley Periodicals, Inc.
Does the H+5 hydrogen cluster exist in dense interstellar clouds?
Authors: Barbatti Mario , Nascimento Marco Antonio Chaer
Published: April 2012

The clustering of hydrogen molecules around a cation in dense interstellar clouds is examined taking into account recent accurate information about the structure and thermochemistry of these clusters. In general, these clustering processes are not important due to the small probability of occurrence of radiative association at low densities. However, the long lived metastable complex (H)* makes the concentration of the H clusters to be of the same order of the concentration of H in these media. This result may have considerable implications for the chemistry of dense interstellar clouds. © 2012 Wiley Periodicals, Inc.
Vibrational enhancement of positron affinities for nonpolar carbon dioxide and carbon disulfide molecules: Multi‐component molecular orbital study for vibrational excited states
Authors: Koyanagi Katsuhiko , Kita Yukiumi , Tachikawa Masanori
Published: April 2012

To demonstrate the binding of a positron to nonpolar CX2 (X = O and S) molecules, we have estimated the vibrational averaged positron affinity (PA) values for the harmonic asymmetric stretching vibrational coordinate with the multi‐component molecular orbital method. A positron can be attached at higher vibrational excitation levels, and vibrational averaged PA values become greater as the number of vibrational quantum number increases. The resultant PA values of carbon disulfide (CS2) molecule are greater than those of CO2, which is consistent with the corresponding property such as infrared (IR) intensity and polarizability of the parent species. © 2012 Wiley Periodicals, Inc.
Inverse sandwich complexes based on low‐valent group 13 elements and cyclobutadiene: A theoretical investigation on E‐C4H4‐E (E = Al, Ga, In, Tl)
Authors: Liu Nan‐Nan , Xu Jing , Ding Yi‐Hong
Published: April 2012

The chemistry of the low‐valent Group 13 elements (E = B, Al, Ga, In, Tl) has formed the recent hot topic. Recently, a series of low‐valent Group 13‐based compounds have been synthesized, i.e., [E‐Cp*‐E]+ (E = Al, Ga, In, Tl) cations, which have been termed as the interesting “inverse sandwich” complexes. To enrich the family of inverse sandwiches, we report our theoretical design of a new type of inverse sandwiches E‐C4H4‐E (E = Al, Ga, In, Tl) for stabilizing the low‐valent Group 13 elements. The calculated dissociation energies indicate that unlike [E‐Cp‐E]+ that dissociates via loss of the charged atom E+, E‐C4H4‐E dissociates via loss of the neutral atom E with the bond strengths of Al > Ga > In > Tl. Moreover, E‐C4H4‐E are more stable in dissociation than [E‐Cp‐E]+ cations. By comparing with other various isomers, we found that the inverted E‐C4H4‐E should be kinetically quite stable with the least conversion barriers of 33.5, 33.5, 35.2, and 36.9 kcal/mol for E = Al, Ga, In, and Tl, respectively. Furthermore, replacement of cyclobutadiene‐H atoms by the highly electron‐positive groups such as SiH3 and Si(CH3)3 could significantly stabilize the inverted form in thermodynamics. Possible synthetic routes are proposed for E‐C4H4‐E. With no need of counterions, the newly designed neutral complexes E‐C4H4‐E welcome future synthesis. © 2012 Wiley Periodicals, Inc.
Nonharmonic vibrational effects in HgClOH: An MP2 Born–Oppenheimer molecular dynamics study
Authors: Ramírez‐Solís Alejandro , Maron Laurent
Published: April 2012

We report a Born–Oppenheimer molecular dynamics study of HgClOH to address the nonharmonic (NH) effects which are important in the development of classical interaction potentials. The electronic structure calculations were performed with the second order Möller–Plesset version of perturbation theory. For the Hg and Cl atoms, the Stuttgart–Dresden relativistic effective core potentials were used with extended‐optimized valence basis, while for O and H the aug‐cc‐pVnZ (n = D,T,Q) basis sets were used. Dynamic effects introduce non‐negligible changes to the equilibrium HgO distance and the ClHgO angle which shows rather large (but still harmonic) variations. The largest NH effects appear for the in‐molecular‐plane HOHg bending and the OH stretching modes. The results for the isolated molecule are relevant to compare the geometrical parameters with the water‐solvated species, both through cluster models or through condensed liquid phase studies. © 2012 Wiley Periodicals, Inc.
The Drosophila midgut: a model for stem cell driven tissue regeneration
Authors: Lucchetta Elena M. , Ohlstein Benjamin
Published: April 2012

The Drosophila and mammalian digestive systems bear striking similarities in genetic control and cellular composition, and the Drosophila midgut has emerged as an amenable model for dissecting the mechanisms of tissue homeostasis. The Drosophila midgut is maintained by multipotent intestinal stem cells (ISCs) that give rise to all cell types in the intestinal epithelium and are required for long‐term tissue homeostasis. ISC proliferation rate increases in response to a myriad of chemical and bacterial insults through the release of JAK‐STAT and EGFR ligands from dying enterocytes that activate the JAK‐STAT and EGFR pathways in ISCs. The Hippo and JNK pathways converge upon JAK‐STAT and EGFR signaling, presumably in response to specific stresses, and JNK and insulin signaling have been shown to be critical in response to age‐related stresses. This review details these emerging mechanisms of tissue homeostasis and the proliferative response of ISCs to epithelial damage, environmental stresses, and aging. WIREs Dev Biol 2012 doi: 10.1002/wdev.51

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DataDesk: an interactive package for data exploration, display, model building, and data analysis
Authors: Velleman Paul F.
Published: April 2012

DataDesk is an interactive package for exploration, display, and analysis of data that runs on a variety of desktop computers. Because it has been designed from the ground up for the purpose of data exploration, it incorporates several global design principles not found together in other data analysis software. This article discusses those design principles and illustrates how they lead to innovative approaches to regression model building. WIREs Comput Stat 2012. doi: 10.1002/wics.1208

This article is categorized under:

Software for Computational Statistics > Software/Statistical Software

Statistical and Graphical Methods of Data Analysis > Statistical Graphics and Visualization

Statistical and Graphical Methods of Data Analysis > Analysis of High Dimensional Data
The effective field theory of multifield inflation
Authors: Senatore Leonardo , Zaldarriaga Matias
Published: April 2012

Abstract

We generalize the Effective Field Theory of Inflation to include additional light scalar degrees of freedom that are in their vacuum at the time the modes of interest are crossing the horizon. In order to make the scalars light in a natural way we consider the case where they are the Goldstone bosons of a global symmetry group or are partially protected by an approximate supersymmetry. We write the most general Lagrangian that couples the scalar mode associated to the breaking of time translation during inflation to the additional light scalar fields. This Lagrangian is constrained by diffeomorphism invariance and the additional symmetries that keep the new scalars light. This Lagrangian describes the fluctuations around the time of horizon crossing and it is supplemented with a general parameterization describing how the additional fluctuating fields can affect cosmological perturbations. We find that multifield inflation can reproduce the non-Gaussianities that can be generated in single field inflation but can also give rise to new kinds of non-Gaussianities. We find several new three-point function shapes. We show that in multifield inflation it is possible to naturally suppress the three-point function making the four-point function the leading source of detectable non-Gaussianities. We find that under certain circumstances, i.e. if specific shapes of non-Gaussianities are detected in the data, one could distinguish between single and multifield inflation and sometimes even among the various mechanisms that kept the additional fields light.