bluuebunny/crossref_metadata_2025 huggingface dataset:
Biological impact of missing-value imputation on downstream analyses of gene expression profiles
Authors: Oh Sunghee , Kang Dongwan D. , Brock Guy N. , Tseng George C.
Published: November 2010

Motivation: Microarray experiments frequently produce multiple missing values (MVs) due to flaws such as dust, scratches, insufficient resolution or hybridization errors on the chips. Unfortunately, many downstream algorithms require a complete data matrix. The motivation of this work is to determine the impact of MV imputation on downstream analysis, and whether ranking of imputation methods by imputation accuracy correlates well with the biological impact of the imputation.

Methods: Using eight datasets for differential expression (DE) and classification analysis and eight datasets for gene clustering, we demonstrate the biological impact of missing-value imputation on statistical downstream analyses, including three commonly employed DE methods, four classifiers and three gene-clustering methods. Correlation between the rankings of imputation methods based on three root-mean squared error (RMSE) measures and the rankings based on the downstream analysis methods was used to investigate which RMSE measure was most consistent with the biological impact measures, and which downstream analysis methods were the most sensitive to the choice of imputation procedure.

Results: DE was the most sensitive to the choice of imputation procedure, while classification was the least sensitive and clustering was intermediate between the two. The logged RMSE (LRMSE) measure had the highest correlation with the imputation rankings based on the DE results, indicating that the LRMSE is the best representative surrogate among the three RMSE-based measures. Bayesian principal component analysis and least squares adaptive appeared to be the best performing methods in the empirical downstream evaluation.

Contact:  ctseng@pitt.edu; guy.brock@louisville.edu

Supplementary information:  Supplementary data are available at Bioinformatics online.
Gene expression profiling of human breast tissue samples using SAGE-Seq
Authors: Wu Zhenhua Jeremy , Meyer Clifford A. , Choudhury Sibgat , Shipitsin Michail , Maruyama Reo , Bessarabova Marina , Nikolskaya Tatiana , Sukumar Saraswati , Schwartzman Armin , Liu Jun S. , Polyak Kornelia , Liu X. Shirley
Published: November 2010

We present a powerful application of ultra high-throughput sequencing, SAGE-Seq, for the accurate quantification of normal and neoplastic mammary epithelial cell transcriptomes. We develop data analysis pipelines that allow the mapping of sense and antisense strands of mitochondrial and RefSeq genes, the normalization between libraries, and the identification of differentially expressed genes. We find that the diversity of cancer transcriptomes is significantly higher than that of normal cells. Our analysis indicates that transcript discovery plateaus at 10 million reads/sample, and suggests a minimum desired sequencing depth around five million reads. Comparison of SAGE-Seq and traditional SAGE on normal and cancerous breast tissues reveals higher sensitivity of SAGE-Seq to detect less-abundant genes, including those encoding for known breast cancer-related transcription factors and G protein–coupled receptors (GPCRs). SAGE-Seq is able to identify genes and pathways abnormally activated in breast cancer that traditional SAGE failed to call. SAGE-Seq is a powerful method for the identification of biomarkers and therapeutic targets in human disease.
Norwegian house mice (Mus musculus musculus/domesticus): distributions, routes of colonization and patterns of hybridization
Authors: JONES ELEANOR P. , Van Der KOOIJ JEROEN , SOLHEIM ROAR , SEARLE JEREMY B.
Published: November 2010

We investigated the distributions and routes of colonization of two commensal subspecies of house mouse in Norway: Mus musculus domesticus and M. m. musculus. Five nuclear markers (Abpa, D11 cenB2, Btk, SMCY and Zfy2) and a morphological feature (tail length) were used to differentiate the two subspecies and assess their distributions, and mitochondrial (mt) D‐loop sequences helped to elucidate their colonization history. M. m. domesticus is the more widespread of the two subspecies, occupying the western and southern coast of Norway, while M. m. musculus is found along Norway’s southeastern coast and east from there to Sweden. Two sections of the hybrid zone between the two subspecies were localized in Norway. However, hybrid forms also occur well away from that hybrid zone, the most prevalent of which are mice with a M. m. musculus‐type Y chromosome and an otherwise M. m. domesticus genome. MtDNA D‐loop sequences of the mice revealed a complex phylogeography within M. m. domesticus, reflecting passive human transport to Norway, probably during the Viking period. M. m. musculus may have colonized earlier. If so, that leaves open the possibility that M. m. domesticus replaced M. m. musculus from much of Norway, with the widely distributed hybrids a relict of this process. Overall, the effects of hybridization are evident in house mice throughout Norway.
The mTOR pathway affects proliferation and chemosensitivity of urothelial carcinoma cells and is upregulated in a subset of human bladder cancers
Authors: Makhlin Igor , Zhang Jiaru , Long Christopher J. , Devarajan Karthik , Zhou Yan , Klein‐Szanto Andres J. , Huang Min , Chernoff Jonathan , Boorjian Stephen A.
Published: November 2010

What’s known on the subject? and What does the study add?

Prior to publication of our paper, evidence had suggested elevated activity of the mTOR pathway in urothelial carcinoma. Separate studies had in addition demonstrated that mTOR inhibition sensitized certain cancer cells to cisplatin therapy. We therefore evaluated the efficacy of mTOR inhibition using in vitro and in vivo models of bladder cancer, and investigated whether mTOR inhibition accentuates the response of bladder cancer cells to cisplatin, which is currently the most effective systemic treatment for metastatic bladder cancer.

We found that mTOR blockade inhibits urothelial carcinoma cell proliferation, and enhances the therapeutic efficacy of cisplatin. Our data support a functional relevance for the mTOR signaling pathway in bladder cancer, and provide evidence to suggest the potential for mTOR inhibitors to be used in combination with cisplatin‐based chemotherapy regimens.

OBJECTIVE

• To investigate whether mammalian target of rapamycin (mTOR) inhibition by rapamycin is therapeutically efficacious in combination with cisplatin for bladder cancer.

MATERIALS AND METHODS

• Using a panel of human urothelial carcinoma cell lines, we determined the effect of rapamycin on cell viability, cell‐cycle progression, signalling and apoptosis.

• The effect of mTOR inhibition on chemosensitivity was investigated by treating cells with rapamycin, alone, or with cisplatin.

• The effect of rapamycin or cisplatin treatment was assessed in xenograft mice inoculated with urothelial carcinoma cells.

• Expression of p‐mTOR in human bladder cancer specimens was assessed using a tissue microarray.

RESULTS

• Treatment with rapamycin significantly decreased cell viability in UMUC3 (P= 0.004) and 253J (P < 0.001) cells. It induced arrest in the G0‐G1 phase and decreased activation of p‐mTOR and its downstream effector, p‐S6K, in both cell lines.

• Treatment with rapamycin increased the ability of cisplatin to inhibit cell viability in UMUC3 (P= 0.002) and 253J (P= 0.03) cells. No evidence for apoptosis induction was noted after treatment with rapamycin alone.

• Mouse xenografts of UMUC3 cells revealed that rapamycin significantly prolonged survival and enhanced the therapeutic efficacy of cisplatin.

• In patient urothelial carcinoma specimens, p‐mTOR expression was increased in cancer vs non‐tumour bladder tissue in 65/203 (32.0%) tumours.

CONCLUSIONS

• mTOR blockade inhibits urothelial carcinoma cell proliferation and enhances the effectiveness of cisplatin.

• Suppression of the mTOR pathway has the potential to be a therapeutic target in bladder cancer for selected patients.
Spousal support decreases the negative impact of pain on mental quality of life in women with interstitial cystitis/painful bladder syndrome
Authors: Ginting Jessica V. , Tripp Dean A. , Nickel J. Curtis , Fitzgerald Mary Pat , Mayer Robert
Published: November 2010

Study Type – Symptom prevalence (case series)

Level of Evidence 4

What’s known on the subject? and What does the study add?

Research has demonstrated that significant others influence the course of pain experienced by individuals with chronic pain. Generally, spousal responses to pain behaviour are associated with higher levels of pain, disability, and depression.

The present research discusses novel findings regarding how spousal responses to patient pain behaviour influences the impact of pain on mental quality of life in women with IC/PBS. These findings go beyond correlations, and begin to untangle the circumstances under which pain influences mental quality of life. Women with IC/PBS would benefit from spouse‐led distraction as a way to help them cope with their pain.

OBJECTIVE

• To examine whether spousal responses to patient pain would alter the association between pain and patient health‐related quality of life (HRQL), depression and disability.

METHODS

• Ninety‐six women with IC/PBlS (mean age = 50.6 (13.8); mean time since diagnosis = 6.2 years) completed questionnaires on demographics, depressive symptoms (Center for Epidemiological Studies‐Depression Scale), disability (Pain Disability Index), HRQL (Medical Outcomes Study Short Form 12) and a measure of perceived spousal responses to their pain (Multidimensional Pain Inventory).

• A repeated measures multivariate analysis of variance examined association changes between pain and adjustment variables at high, moderate and low levels of negative, solicitous and distracting spousal responses.

RESULTS

• The association between pain and all outcome variables did not vary as a function of levels of solicitous and negative spousal responses.

• However, the association between pain and mental HRQL was stronger at lower levels (β=−1.25) of distracting responses than it was at moderate (β=−0.66) and higher (β=−0.06) levels.

CONCLUSION

• Distracting spousal responses act to ‘buffer’ the deleterious effects of pain on mental HRQL for women suffering from IC/PBlS. Spousal support training may be a useful HRQL intervention.
The learning curve for reducing complications of robotic‐assisted laparoscopic radical prostatectomy by a single surgeon
Authors: Ou Yen‐Chuan , Yang Chi‐Rei , Wang John , Yang Chun‐Kuang , Cheng Chen‐Li , Patel Vipul R. , Tewari Ashutosh K.
Published: November 2010

Study Type – Therapy (case series)

Level of Evidence 4

What’s known on the subject? and What does the study add?

Between December 2005 and January 2010, 200 consecutive patients with prostate cancer received RALP performed by a single surgeon. Only one case with Clavien grade II complication due to gouty arthritis. The complication rate was 1%. We suggested that patient with history of gouty arthritis need to prescribe preventive colchicine.

OBJECTIVE

To analyse the learning curve for reducing complications of robotic‐assisted laparoscopic radical prostatectomy (RALP) performed by a single surgeon in Taiwan.

PATIENTS AND METHODS

Complication rates were prospectively assessed in 200 consecutive patients undergoing RALP (Group I: cases 1–50; Group II: cases 51–100; Group III: cases 101–150 and Group IV: cases 151–200).

Complications were classified using the Clavien system: grade I: deviation normal postoperative course without treatment; grade II: drug or bedside treatment; grade III: endoscopic or surgical intervention; grade IV: life‐threatening problem; and grade V: death.

Operative parameters and peri‐operative complications were evaluated, including operative and console time, blood loss and transfusion rate, Gleason scores, positive surgical margin (PSM) rate, specimen volume, tumour size, tumour percentage, node positive rate and intra‐ and postoperative complications.

RESULTS

RALP console time was gradually lowered from Group I to Group IV (P < 0.05). Significantly less blood loss occurred after every 50 cases of RALP (Group I 275 mL, Group II 179 mL, Group III 145 mL, Group IV 102 mL, P < 0.001).

Blood transfusion incidence was 8%, 4%, 2% and 0% in Groups I, II, III and IV, respectively.

Complication rates were 18%, 12%, 18% and 0% in Groups I, II, III and IV, respectively.

Major complications (grade III–IV) were 6%, 2%, 4% and 0% in Groups I, II, III and IV, respectively.

Bowel injury occurred in three cases (Group II: 1; Group III: 2); one received intra‐operative repair without sequelae and two received a transient colostomy and later colostomy closure.

CONCLUSIONS

The learning curve for every 50 cases of RALP showed significantly less blood loss and blood transfusion rate.

The learning curve for significantly decreasing complications is 150 cases.
Prognostic significance of lymphovascular invasion in radical prostatectomy specimens
Authors: Yee David S. , Shariat Shahrokh F. , Lowrance William T. , Maschino Alexandra C. , Savage Caroline J. , Cronin Angel M. , Scardino Peter T. , Eastham James A.
Published: November 2010

Study Type – Prognosis (case series)

Level of Evidence 4

What’s known on the subject? and What does the study add?

The reported incidence of lymphovascular invasion (LVI) in radical prostatectomy specimens ranges from 5% to 53%. Although LVI has a strong and significant association with adverse clinicopathologic features, it has almost uniformly not been found to be a predictor of biochemical recurrence (BR) on multivariate analysis.

This study confirms that LVI is associated with features of aggressive disease and is an independent predictor of BCR. Given that LVI may play a role in the metastatic process, it may be useful in clinical decision‐making regarding adjuvant therapy for patients treated with RP.

OBJECTIVES

To determine whether lymphovascular invasion (LVI) in radical prostatectomy (RP) specimens has prognostic significance.

The study examined whether LVI is associated with clinicopathological characteristics and biochemical recurrence (BCR).

PATIENTS AND METHODS

LVI was evaluated based on routine pathology reports on 1298 patients treated with RP for clinically localized prostate cancer between 2004 and 2007.

LVI was defined as the unequivocal presence of tumour cells within an endothelium‐lined space.

The association between LVI and clinicopathological features was assessed with univariate logistic regression. Cox regression was used to test the association between LVI and BCR.

RESULTS

LVI was identified in 10% (129/1298) of patients.

The presence of LVI increased with advancing pathological stage: 2% (20/820) in pT2N0 patients, 16% (58/363) in pT3N0 patients and 17% (2/12) in pT4N0 patients; and was highest in patients with pN1 disease (52%; 49/94).

Univariate analysis showed an association between LVI and higher preoperative prostate‐specific antigen levels and Gleason scores, and a greater likelihood of extraprostatic extension, seminal vesicle invasion, lymph node metastasis and positive surgical margins (all P < 0.001).

With a median follow‐up of 27 months, LVI was significantly associated with an increased risk of BCR after RP on univariate (P < 0.001) and multivariate analysis (hazard ratio, 1.77; 95% confidence interval, 1.11–2.82; P= 0.017).

As a result of the relatively short follow‐up, the predictive accuracy of the standard clinicopathological features was high (concordance index, 0.880), and inclusion of LVI only marginally improved the predictive accuracy (0.884).

CONCLUSIONS

Although associated with features of aggressive disease and BCR, LVI added minimally to established predictors on short follow‐up.

Further study of cohorts with longer follow‐up is warranted to help determine its prognostic significance.
MEASURING QUALITY IN SOCIAL CARE SERVICES: THEORY AND PRACTICE
Authors: Malley Juliette , Fernández José‐Luis
Published: November 2010

ABSTRACT**:  Measuring and assessing service quality in the social care sector presents distinct challenges. The ‘experience’ good properties of social care, for instance, and the large influence played by subjective judgements about the quality of personal relationships between carer and user and of process‐related service characteristics make it difficult to develop indicators of service quality, including those of service impact on final outcomes. Using some of the key features of the ‘Production of Welfare’ approach, the paper discusses recent developments in the UK of the theoretical and practical frameworks used for assessing quality in social care and for understanding the final impact of services on the wellbeing of their recipients. Key current and future challenges to the development of such frameworks include difficulties in disentangling the impact of social care services on final outcomes from the often dominating effects of other, non‐service related factors, and the generalization of consumer‐directed care models and of the ‘personalization’ of care services. These challenges are discussed in the context of the different possible applications of quality indicators, including their role as supporting the service commissioning process and their use for assessing the performance of service providers.
DOES THE MISSION OF PROVIDERS MATTER ON A QUASI‐MARKET? THE CASE OF THE BELGIAN ‘SERVICE VOUCHER’ SCHEME
Authors: Defourny Jacques , Henry Arnaud , Nassaut Stéphane , Nyssens Marthe
Published: November 2010

ABSTRACT**: In 2001, the Belgian government introduced a ‘service voucher’ scheme in the field of domestic (housework) services, following a quasi‐market mechanism which fosters competition between providers of different types as regards sector (for‐profit, public, third sector) and mission (seeking profits, home care provision to vulnerable groups and work integration of the unemployed). Empirical evidence suggests that third sector organizations focusing on a social mission recognized by a tutelary regulation are the best performing with regards to the quality of jobs and service organization, leading to a better ‘triangulation’ of the service relationship. On the other hand, for‐profit providers, especially temporary work agencies, seem to favour their capacity of adaptation to the desiderata of their clients and costs’ minimization to the detriment of the quality of jobs which are made as flexible as possible.
Forced Exits: Accounting for the Removal of Contemporary Party Leaders
Authors: McANULLA STUART
Published: November 2010

This article seeks to account for the remarkably high number of British party leaders who have been forced to leave office in recent years. In particular it seeks to explain why numerous leaders have felt compelled to resign following pressure from party colleagues. It is suggested that four general factors may be of importance: i) the increased importance of perceptions of leadership; ii) the rise of ‘celebrity’ politics; iii) erosion of traditional public–private divides, and; iv) increased professionalism amongst parliamentarians. The article refers to both the forced exit of leaders of all the major British political parties as well as the removal of leaders of parties within the devolved regions of the UK.
Climbing the Greasy Pole: Promotion in British Politics
Authors: JONES BILL
Published: November 2010

This article addresses the subject of ministerial promotion and is based on memoirs and interviews. It seeks to discern the essential qualities which motivate political ambition; for example extremes of energy, confidence, optimism and family support. The talent pool for office is held to be worryingly shallow though allowing wider access, via the Lords, has not so far proved a huge success. Deciding upon appointments is also analysed as is the means politicians use to advertise their suitability for office. It concludes that, natural ability notwithstanding, luck and courage are often the chief attributes of success.
Copines‐1, ‐2, ‐3, ‐6 and ‐7 show different calcium‐dependent intracellular membrane translocation and targeting
Authors: Perestenko Pavel V. , Pooler Amy M. , Noorbakhshnia Maryam , Gray Adrian , Bauccio Charlotte , Jeffrey McIlhinney Robert Andrew
Published: November 2010

The copines are a family of C2‐ and von Willebrand factor A‐domain‐containing proteins that have been proposed to respond to increases in intracellular calcium by translocating to the plasma membrane. The copines have been reported to interact with a range of cell signalling and cytoskeletal proteins, which may therefore be targeted to the membrane following increases in cellular calcium. However, neither the function of the copines, nor their actual movement to the plasma membrane, has been fully established in mammalian cells. Here, we show that copines‐1, ‐2, ‐3, ‐6 and ‐7 respond differently to a methacholine‐evoked intracellular increase in calcium in human embryonic kidney cell line‐293 cells, and that their membrane association requires different levels of intracellular calcium. We demonstrate that two of these copines associate with different intracellular vesicles following calcium entry into cells, and identify a novel conserved amino acid sequence that is required for their membrane translocation in living cells. Our data show that the von Willebrand factor A‐domain of the copines modulates their calcium sensitivity and intracellular targeting. Together, these findings suggest a different set of roles for the members of this protein family in mediating calcium‐dependent processes in mammalian cells.

Structured digital abstract

 MINT‐8049236: Copine‐6 (uniprotkb:Q9Z140) and transferrin (uniprotkb:P02787) colocalize (MI:0403) by fluorescence microscopy (MI:0416)

 MINT‐8049176: CD2 (uniprotkb:P06729) and Copine‐2 (uniprotkb:P59108) colocalize (MI:0403) by fluorescence microscopy (MI:0416)
Automatic Affective Appraisal of Sexual Penetration Stimuli in Women with Vaginismus or Dyspareunia
Authors: Huijding Jorg , Borg Charmaine , Weijmar-Schultz Willibrord , de Jong Peter J.
Published: November 2010

Introduction

Current psychological views are that negative appraisals of sexual stimuli lie at the core of sexual dysfunctions. It is important to differentiate between deliberate appraisals and more automatic appraisals, as research has shown that the former are most relevant to controllable behaviors, and the latter are most relevant to reflexive behaviors. Accordingly, it can be hypothesized that in women with vaginismus, the persistent difficulty to allow vaginal entry is due to global negative automatic affective appraisals that trigger reflexive pelvic floor muscle contraction at the prospect of penetration.

Aims

To test whether sexual penetration pictures elicited global negative automatic affective appraisals in women with vaginismus or dyspareunia and to examine whether deliberate appraisals and automatic appraisals differed between the two patient groups.

Methods

Women with persistent vaginismus (N = 24), dyspareunia (N = 23), or no sexual complaints (N = 30) completed a pictorial Extrinsic Affective Simon Task (EAST), and then made a global affective assessment of the EAST stimuli using visual analogue scales (VAS).

Main Outcome Measures

The EAST assessed global automatic affective appraisals of sexual penetration stimuli, while the VAS assessed global deliberate affective appraisals of these stimuli.

Results

Automatic affective appraisals of sexual penetration stimuli tended to be positive, independent of the presence of sexual complaints. Deliberate appraisals of the same stimuli were significantly more negative in the women with vaginismus than in the dyspareunia group and control group, while the latter two groups did not differ in their appraisals.

Conclusion

Unexpectedly, deliberate appraisals seemed to be most important in vaginismus, whereas dyspareunia did not seem to implicate negative deliberate or automatic affective appraisals. These findings dispute the view that global automatic affect lies at the core of vaginismus and indicate that a useful element in therapeutic interventions may be the modification of deliberate global affective appraisals of sexual penetration (e.g., via counter-conditioning).
Genome‐wide gene expression changes in an industrial clavulanic acid overproduction strain of Streptomyces clavuligerus
Authors: Medema Marnix H. , Alam Mohammad T. , Heijne Wilbert H. M. , van den Berg Marco A. , Müller Ulrike , Trefzer Axel , Bovenberg Roel A. L. , Breitling Rainer , Takano Eriko
Published: November 2010

To increase production of the important pharmaceutical compound clavulanic acid, a β‐lactamase inhibitor, both random mutagenesis approaches and rational engineering of Streptomyces clavuligerus strains have been extensively applied. Here, for the first time, we compared genome‐wide gene expression of an industrial S. clavuligerus strain, obtained through iterative mutagenesis, with that of the wild‐type strain. Intriguingly, we found that the majority of the changes contributed not to a complex rewiring of primary metabolism but consisted of a simple upregulation of various antibiotic biosynthesis gene clusters. A few additional transcriptional changes in primary metabolism at key points seem to divert metabolic fluxes to the biosynthetic precursors for clavulanic acid. In general, the observed changes largely coincide with genes that have been targeted by rational engineering in recent years, yet the presence of a number of previously unexplored genes clearly demonstrates that functional genomic analysis can provide new leads for strain improvement in biotechnology.
Postoperative Pain Control using a Comprehensive Programme for Day-Case Shoulder Surgery
Authors: Neilson Sam , Hallam Linda , Hundle Bhagwant , Funk Lennard
Published: November 2010

Background

To assess the effectiveness of a peri-operative pain control regimen for day-case shoulder surgery, including open and complex procedures.

Methods

A prospective cohort study of all patients undergoing day-case shoulder surgery in a single hospital over a 1-year period, using a comprehensive pain control regimen. The regimen included patient education, interscalene block, analgesics, nonsteroidal anti-inflammatory medications and a cold compression shoulder wrap. All patients were followed up with a telephone call 24 hours after surgery to assess their pain levels, compliance and any ill effects.

Results

There were 187 patients in the time period, with 90.4% reporting that their pain was well controlled. Twenty-eight patients (15%) experienced moderate and severe pain 24 hours postoperatively. These were limited to five common procedures, with arthroscopic rotator cuff repair and arthroscopic stabilization being the most common, comprising 75% of the reported painful procedures. Only four patients reported severe pain (2%). Two of these took no medication at all. Three of these four patients had 360° labral repairs and the other a massive, revision arthroscopic rotator cuff repair.

Conclusion

Postoperative pain after day-case shoulder surgery can be effectively managed with a comprehensive analgesic regimen. This includes open shoulder surgery and complex arthroscopic procedures.
Terrestrial ages of meteorites from the Nullarbor region, Australia, based on 14C and 14C–10Be measurements
Authors: JULL A. J. Timothy , McHARGUE Lanny R. , BLAND Philip A. , GREENWOOD Richard C. , BEVAN Alexander W. R. , KIM Kyeong J. , LaMOTTA Sarah E. , JOHNSON Jeffrey A.
Published: November 2010

Abstract– We have investigated the terrestrial ages, or residence times, of 78 meteorites (representing 73 discrete falls) recovered in Western Australia, and one from South Australia, using both 14C measurements and also 14C/10Be. The samples studied included two ureilites, one CK and one EL chondrite. We have included 10Be measurements from 30 meteorites, including some meteorites for which the 14C terrestrial age was previously determined. We find that the 14C/10Be terrestrial ages are more precise than 14C alone, as we can correct for shielding effects. In general, the two different age determinations age by 14C–10Be are precise to 0.5–1 ka and 14C alone within 1–2 ka. However, measurement of the 14C age alone gives good agreement with the 14C–10Be for most samples. The study of the terrestrial ages of meteorites gives us useful information concerning the storage and weathering of meteorites and the study of fall times and terrestrial age. We have compared the terrestrial ages to weathering, degree of oxidation (estimated from Mössbauer studies) and Δ17O. In this study, we found that weathering is not well correlated with terrestrial age for Nullarbor meteorites. However, there is a good correlation between degree of oxidation and Δ17O. The implications for the study of terrestrial ages and weathering from other desert environments will be discussed.
Stress Distribution Around a Circular Bar, With Flat and Spherical Ends, Embedded in a Matrix in a Triaxial Stress Field
Authors: Parks V. J. , Durelli A. J. , Chandrashekhara K. , Chen T. L.
Published: November 2010

This paper deals with the stress and strain distribution around a circular bar embedded in a matrix and subjected to a mechanically applied triaxial load. The three-dimensional “freezing” technique of photoelasticity was used. The results obtained correspond to the case of a rigid circular bar embedded in a homogeneous, elastic matrix. Two models were analyzed; in one, the axis of the circular bar was parallel to the direction of the loading and, in the other, the axis of the circular bar was normal to the direction of loading. By combining the results obtained independently for these two cases, stress and strain distribution around the circular bar for various ratios of triaxial load can be obtained.
Slope Discontinuities in Pressure Vessels
Authors: Steele C. R. , Skogh J.
Published: November 2010

A closed-form solution is obtained for the problem of a shell of revolution with a meridional slope discontinuity, which might occur at a weld seam in a pressure vessel. The effect of significant variation in the slope occurring within the usual “edge zone” and the nonlinear pressurization effect are taken into consideration. Graphs are presented from which maximum stresses can be easily computed for a wide variation of the parameters. The theoretical results agree with numerical values obtained from a computer program, even for shells that are relatively thick, for slope discontinuities that are relatively severe, and for high pressurization.
Some General Orthogonality Relations
Authors: Herman H.
Published: November 2010

General orthogonality relations which are valid for all linear elastic systems are derived, one relation for systems without damping and another for systems with viscous damping. A general orthogonality relation is also derived for linear viscoelastic systems, but the proof of its validity does not extend to approximate theories with indeterminacies in the stress-strain relations. The method of utilizing the orthogonality relations to determine the coefficients in series expansions is demonstrated.
Effect of Central Clamping on Transverse Vibrations of Spinning Membrane Disks
Authors: Krauter A. I. , Bulkeley P. Z.
Published: November 2010

Free transverse vibrations of a centrally clamped spinning membrane disk are experimentally observed. The axisymmetric and asymmetric frequencies found are compared with theoretical predictions. Agreement is good when central clamping effects are included in the theory.
Parametric Self-Excitation of a Belt Into Transverse Vibration
Authors: Rhodes J. E.
Published: November 2010

As a belt is taken up on a pulley, a varying tension will be laid down, or “recorded,” as a strain pattern. As the belt pays off, the pattern “plays back” creating a corresponding varying tension on the next span. If the delay is proper, the oscillating tension associated with transverse vibration of a belt span can feed around the belt circuit and parametrically drive the vibration. A belt span may be self-excited into vibration by this mechanism without imperfections in either the belt or pulleys.
Applications of Holography to Dynamics: High-Frequency Vibrations of Plates
Authors: Aprahamian R. , Evensen D. A.
Published: November 2010

The techniques of holographic interferometry are applied to study the high-frequency transverse vibrations of a simply supported rectangular plate. Over 110 vibration modes were identified using stored beam holography, at frequencies ranging from 162 cps to 20,000 cps. In addition, three very high modes were identified at frequencies up to 76.8 kcps. The corresponding modal numbers were m = 17, n = 31, for the highest mode identified. Time average holograms were made of these and other modes, and photographs made from the holograms are included herein. The experimental mode shapes and frequencies were generally in agreement with classical plate theory, except for the three highest modes. The latter agreed with Mindlin’s plate theory, which includes rotary inertia and shear effects. Other applications of holography to dynamics are briefly discussed.
Optimum Damping and Stiffness in a Nonlinear Four-Degree-of-Freedom System Subject to Shock Load
Authors: Kemper J. D. , Ayre R. S.
Published: November 2010

A nonlinear four-degree-of-freedom system representing an articulated off-road vehicle is analyzed for ground shock response. The assumed shock is a versed-sine pulse, which results as one front wheel passes over a ground surface bump. Families of exponential functions are used to represent the nonlinear stiffness and nonlinear damping. Digital computer solutions to the nonlinear differential equations of the system are obtained for combinations of different members of these families. Certain combinations are then selected which produce optimum responses; these responses are then compared to the optimum responses for linear systems.
A First-Passage Approximation in Random Vibration
Authors: Racicot Ronald L. , Moses Fred
Published: November 2010

A numerical technique is described for computing approximate first-passage probabilities for single-degree-of-freedom systems. It is applicable to cases where the joint probability distribution of response at two times can be found. From these distributions, the average size of a clump of consecutive failure crossings is computed. Results are compared to previously published simulation first-passage probabilities and good agreement is found. Examples illustrate applications to Gaussian and filtered Poisson processes.
On Certain Approximations in the Finite-Element Method
Authors: McLay R. W.
Published: November 2010

Approximations made outside of the variational principle used in the finite-element method are examined for a restricted problem in elasticity. They are shown to be rigorous from the standpoint of a generalized variational principle in which Lagrange multipliers are utilized. The convergence of the Ritz solution to the exact solution is demonstrated. The bound is shown to be a function of the quality of both the displacement functions and other approximate functions in the analysis.
Propagation of Longitudinal Waves in Circularly Cylindrical Bone Elements
Authors: Nowinski J. L. , Davis C. F.
Published: November 2010

Two-phase poroelastic material is taken as a model of the living bone in the sense that the osseous tissue is treated as a linear isotropic perfectly elastic solid, and the fluid substances filling the pores as a perfect fluid. Using Biot’s equations, derived in his consolidation theory, four coupled governing differential equations for the propagation of harmonic longitudinal waves in circularly cylindrical bars of poroelastic material are derived. A longer manipulation reduces the task of solution to a single ordinary differential equation with variable coefficients and a regular singular point. The equation is solved by Frobenius’ method. Three boundary conditions on the curved surface of the bar, expressing the absence of external loading and the permeability of the surface, supply a system of three linear equations in three unknown coefficients. A nontrivial solution of the system gives two phase velocities of propagation of longitudinal waves in agreement with the finding of Biot for an infinite medium. A simplification to the purely elastic case yields the elementary classical result for the longitudinal waves.
Timoshenko Beam Dynamics
Authors: Anderson G. M.
Published: November 2010

The general problem of Timoshenko beam analysis is solved using the Laplace transform method. Time-dependent boundary and normal loads are considered. It is established that the integrands of the inversion integrals are always single-valued for beams of finite length and modal solutions can always be obtained using the residue theorem.
Lubrication Theory for Micropolar Fluids
Authors: Allen S. J. , Kline K. A.
Published: November 2010

The equations governing the flow of a fluid with rigid, spherical substructure are summarized. A two-dimensional flow field is considered and applied to the geometry of a slider bearing. Order-of-magnitude arguments are used which reduce the governing equations to a system of coupled, linear, ordinary differential equations. The equations are solved subject to appropriate boundary conditions and the effects of substructure discussed with the help of a specific numerical example.
Elastic-Plastic Plane Waves With Combined Compressive and Two Shear Stresses in a Half Space
Authors: Goel R. P. , Malvern L. E.
Published: November 2010

The simple wave solutions with one compression and two shear impact loadings on the boundary of a half space of isotropic hardening material are obtained. Both the fast simple wave and slow simple wave solutions imply a radial loading projection in the τ2, τ3 plane; i.e., in the plane of shear stress components. But the radial loading τ3/τ2 ratio for the fast wave may be different from the ratio for the slow wave. The transition is accompanied by jumps both in τ2 and τ3 traveling at the elastic shear wave speed c2.
Two-Dimensional Flow of Liquid During the Late Stage of Solidification of Alloys
Authors: Tien R. H.
Published: November 2010

This is a mathematical analysis of the two-dimensional interdendritic liquid flow occurring during late stages of solidification, i.e., when the liquidus front reaches the center of the slab. The liquid flow considered is that caused by density change accompanying freezing. The liquid-solid region is considered a porous medium where the liquid permeability is a function of the solid fraction. Analytical solution for the two-dimensional velocity and pressure fields in solidifying Al-4.5 percent Cu alloy is obtained from a mathematical model which includes the concept of conservation of mass and Darcy’s law to correlate the pressure and velocity. Assuming that there is no gas-bubble formation and that the solidified metal in the mushy zone remains rigid, the liquid moving with a creeping velocity in the interdendritic regions is under tension (when no external pressure is applied). The magnitude of this tension increases with increasing depth of the solidifying ingot and is a strong function of the cooling rate. For example, a negative pressure of the order of 100 atm in the interdendritic liquid of solidifying Al-4.5 percent Cu alloy is estimated at ∼90 percent solidification. On the basis of the present analysis, an estimate can be made of pressures required to suppress blow-hole formation during the later stages of freezing arising from the solidification shrinkage.
Calculation of Correlation Matrices for Linear Systems Subjected to Nonwhite Excitation
Authors: Yang I-Min , Iwan W. D.
Published: November 2010

This paper presents an approach which provides a particularly simple and direct way of determining the instantaneous correlation matrices for the stationary random response of multidegree-of-freedom linear systems subjected to excitations of nearly arbitrary spectral density. In the special case of white excitation, the instantaneous correlation matrices are determined directly from a set of linear algebraic equations. When the excitation is nonwhite, some integrals must be evaluated before solving a system of linear algebraic equations. However, the form of these integrals is considerably simpler than that encountered in other common approaches.
Shear-Layer Flow Regimes and Wave Instabilities and Reattachment Lengths Downstream of an Abrupt Circular Channel Expansion
Authors: Back L. H. , Roschke E. J.
Published: November 2010

An experimental investigation of water flow through an abrupt circular-channel expansion is described over a Reynolds number range between 20 and 4200. The shear layer between the central jet and the reverse flow region along the wall downstream behaved differently in the various flow regimes that were observed. With increasing Reynolds number these regimes changed progressively from a laminar flow to an unstable vortex sheetlike flow and then to a more random fluctuating flow. The distance between the step and the reattachment location downstream correspondingly increased, reached a maximum, and then decreased. Of particular significance are the shear layer wave instabilities observed in the shear flow and their relationship to rettachment which apparently has not received much attention previously. Visual observations aided in understanding the results.
Pretwisted Curved Beams of Thin-Walled Open Section
Authors: Soler A. I.
Published: November 2010

Equations of motion are derived for coupled extension, flexure, and torsion of pretwisted curved bars of thin-walled, open section. The derivation is based on energy principles and includes inertia terms. The major effect of initial pretwist is to allow coupling of all possible beam deformation modes; however, if the bar is straight and has two axes of symmetry, pretwist causes coupling only between the two bending modes, and between extension and torsion. The governing equations are presented in first-order form, and a numerical technique is suggested for the case of space varying pretwist. It is suggested that these equations may form the basis for a simplified study of the effect of superelevation on the static and dynamic response of curved highway bridges. Finally, a simple straight beam with uniform pretwist is studied to compare effects of pretwist and restrained torsion in a thin-walled beam of open section.
On Moire´ Method Applied to the Determination of Two-Dimensional Dynamic Strain Distributions
Authors: Chiang Fu-Pen
Published: November 2010

A technique is proposed whereby the moire´ methods are extended to general two-dimensional dynamic problems.
Structural Analysis of Pressure Hulls: Rib-Stiffened Cylindrical Shell With Reinforced Circular Penetration
Authors: Maye R. F. , Euler J. A. , Habip L. M.
Published: November 2010

A solution for the stresses in a rib-stiffened cylindrical shell with a reinforced circular penetration under hydrostatic pressure valid for a penetration radius to shell radius ratio less than or equal to 1/3 is presented. Numerical results for the unstiffened as well as the stiffened case are compared graphically with experimental data available from certain photoelastic model tests.
Recirculation Patterns in the Initial Region of Coaxial Jets
Authors: Rozenman T. , Weinstein H.
Published: November 2010

This experimental study is concerned with the mixing in the initial region of turbulent coaxial streams. The investigation is limited to the low-speed incompressible case with the inner stream of lower velocity than the outer stream. Velocity ratios ranged from infinity to one. The inner to outer stream density ratio was either 4 or 1. Experimental measurements were made with a hot-wire anemometer system, static pressure probes, and shadowgraphy. The data show that a backflow region is formed in this particular apparatus at outer to inner stream velocity ratio of 13 for the homogeneous case and at outer to inner stream velocity ratio of 26 for the heterogeneous case. For higher velocity ratio, a circulating toroidal vortex is established which enhances mixing between the inner and outer streams. This vortex pattern exhibits similarity of velocity with velocity ratio variations.
Elastoplastic Bending of Rectangular Plates With Large Deflection
Authors: Lin T. H. , Lin S. R. , Mazelsky B.
Published: November 2010

An analytical method for predicting the elastoplastic bending of rectangular plates with large deflection is studied. The effects of plastic strain and large deflection on plate deformation are shown to be the same as a set of applied external forces on the plate in the classical elastic small deflection theory. The calculated deflection for purely elastic plates compares well with previous existing solutions. For the plates considered, the deflection is increased only slightly by plastic strain; however, the maximum extreme fiber stress is considerably relieved by plastic yielding.
Nonlinear Vibrations of a Hinged Beam Including Nonlinear Inertia Effects
Authors: Atluri S.
Published: November 2010

This investigation treats the large amplitude transverse vibration of a hinged beam with no axial restraints and which has arbitrary initial conditions of motion. Nonlinear elasticity terms arising from moderately large curvatures, and nonlinear inertia terms arising from longitudinal and rotary inertia of the beam are included in the nonlinear equation of motion. Using a Galerkin variational method and a modal expansion, the problem is reduced to a system of coupled nonlinear ordinary differential equations which are solved for arbitrary initial conditions, using the perturbation procedure of multiple-time scales. The general response and frequency-amplitude relations are derived theoretically. Comparison with previously published results is made.
Steady-State Response of a Multidegree System With an Impact Damper
Authors: Masri S. F.
Published: November 2010

An exact solution is presented for the steady-state motion of a sinusoidally excited n-degree-of-freedom system that is provided with an impact damper. Both the excitation and the damper may be independently applied to any point in the system. Experimental studies with an analog computer and with a mechanical model corroborate the theoretical results. Results of the analysis are applied to the lumped parameter representation of a modern 10 story building, and the effects of various system parameters, including mode shape, excitation frequency, damper location, and force location are determined. It is found that the impact damper is an efficient device for reducing the vibrations of multidegree-of-freedom systems, particularly in structures such as tall buildings.
Forced Diffusion Through an Elastic Gel Membrane
Authors: Jasper M. T. , Kumar B. , Bryan W. M.
Published: November 2010

The objectives of the experiment were (a) to establish general empirical and theoretical techniques for the in vitro analysis of diffusion through biological membranes, and (b) to provide characteristic data on gel membranes for possible application as biological filtering septa. Experimental procedures are described for the manufacture of molded Agarose gel membranes of 0.025 cm uniform thickness and 113.2 sq cm area. Flow rates through the gel membranes were determined and reported for various values of temperature and impressed pressure and for gel concentrations of both six percent and eight percent. Water was the permeant for all tests. The gel membranes were treated as elastic structures, and it was determined that the flow was described by Darcy’s law. A simple capillaric model was postulated for the elastic structure and used for the correlation of the flow rate data. For vanishing rates of flow, permeabilities were reported as 11.60 × 10−14 sq cm for the six percent gel and 8.68 × 10−14 sq cm for the eight percent gel. Characteristic diameters of the gel pores were reported as 207 Angstroms for the six percent and 183.3 Angstroms for the eight percent gel. Void volume and pore density were also reported for each.