bluuebunny/crossref_metadata_2025 huggingface dataset:
Do Expected Shifts in Inflation Affect Estimates of the Long‐Run Fisher Relation?
Authors: EVANS MARTIN D. D. , LEWIS KAREN K.
Published: April 2012

Recent empirical studies suggest that nominal interest rates and expected inflation do not move together one‐for‐one in the long run, a finding at odds with many theoretical models. This article shows that these results can be deceptive when the process followed by inflation shifts infrequently. We characterize the shifts in inflation by a Markov switching model. Based upon this model's forecasts, we reexamine the long‐run relationship between nominal interest rates and inflation. Interestingly, we are unable to reject the hypothesis that in the long run nominal interest rates reflect expected inflation one‐for‐one.
On Intraday Risk Premia
Authors: SPIEGEL MATTHEW , SUBRAHMANYAM AVANIDHAR
Published: April 2012

This article presents a framework for analyzing the dynamic effects of anticipated large demand pressures on asset risk premia. We show that large institutions who can time their entry into the market will trade either at the open, or during periods of unusual demand pressures. We show that if these institutions do enter later in the day, they trade in the same direction as institutions which provide liquidity continuously; institutions therefore appear to exhibit “herding” behavior. We also explore how changing the uncertainty of demand pressures late in the day affects trading costs throughout the day.
What Do We Know about Capital Structure? Some Evidence from International Data
Authors: RAJAN RAGHURAM G. , ZINGALES LUIGI
Published: April 2012

We investigate the determinants of capital structure choice by analyzing the financing decisions of public firms in the major industrialized countries. At an aggregate level, firm leverage is fairly similar across the G‐7 countries. We find that factors identified by previous studies as correlated in the cross‐section with firm leverage in the United States, are similarly correlated in other countries as well. However, a deeper examination of the U.S. and foreign evidence suggests that the theoretical underpinnings of the observed correlations are still largely unresolved.
Optimal Investment, Monitoring, and the Staging of Venture Capital
Authors: GOMPERS PAUL A.
Published: April 2012

This paper examines the structure of staged venture capital investments when agency and monitoring costs exist. Expected agency costs increase as assets become less tangible, growth options increase, and asset specificity rises. Data from a random sample of 794 venture capital‐backed firms support the predictions. Venture capitalists concentrate investments in early stage and high technology companies where informational asymmetries are highest. Decreases in industry ratios of tangible assets to total assets, higher market‐to‐book ratios, and greater R&D intensities lead to more frequent monitoring. Venture capitalists periodically gather information and maintain the option to discontinue funding projects with little probability of going public.
Fairly Priced Deposit Insurance and Bank Charter Policy
Authors: CRAINE ROGER
Published: April 2012

The thrust of current deposit insurance reform—risk‐based insurance premiums and capital requirements—is an effort to price deposit insurance more fairly. Fairly pricing deposit insurance eliminates inequitable wealth transfers, but it does not lead to an efficient equilibrium. This paper shows that an alternative charter policy results in an efficient separating equilibrium.
Transparency and Liquidity: A Comparison of Auction and Dealer Markets with Informed Trading
Authors: PAGANO MARCO , RÖELL AILSA
Published: April 2012

Trading systems differ in their degree of transparency, here defined as the extent to which market makers can observe the size and direction of the current order flow. We investigate whether greater transparency enhances market liquidity by reducing the opportunities for taking advantage of uninformed participants. We compare the price formation process in several stylized trading systems with different degrees of transparency: various types of auction markets and a stylized dealer market. We find that greater transparency generates lower trading costs for uninformed traders on average, although not necessarily for every size of trade.
Investment Policy and Exit‐Exchange Offers Within Financially Distressed Firms
Authors: BERNARDO ANTONIO E. , TALLEY ERIC L.
Published: April 2012

This article examines the conflict of interest between shareholders and bondholders in a setting in which firms can renegotiate the terms of existing debt with public debtholders. In particular, we consider one of the most common types of debt restructuring: the exit‐exchange offer. Our analysis explores the relation between exit‐exchange offers and investment choice by the manager, and it concludes that managers, acting strategically on behalf of shareholders, may select inefficient investment projects in order to enhance their bargaining position vis‐a‐vis creditors. Holding the upside potential of an investment project fixed, managers/shareholders prefer projects with lower payoffs in states of bankruptcy because it induces individual bondholders to accept poorer terms in a debt‐for‐debt exit‐exchange offer, thus generating a greater residual for shareholders in states of solvency. Additionally, we show how the investment inefficiencies in our analysis depend on (i) the inability of bondholders to coordinate their actions; (ii) the ability of managers to commit to suboptimal investment projects; and (iii) the coupling of an individual bondholder's decision to tender and her decision to consent to allow the firm to strip fiduciary covenants. We suggest conditions under which a ban on coupled exit‐exchange offers—or alternatively, constraints on “debt‐for‐debt” exchanges—would be efficiency‐enhancing.
Delayed Reaction to Good News and the Cross‐Autocorrelation of Portfolio Returns
Authors: MCQUEEN GRANT , PINEGAR MICHAEL , THORLEY STEVEN
Published: April 2012

We document a directional asymmetry in the small stock concurrent and lagged response to large stock movements. When returns on large stocks are negative, the concurrent beta for small stocks is high, but the lagged beta is insignificant. When returns on large stocks are positive, small stocks have small concurrent betas and very significant lagged betas. That is, the cross‐autocorrelation puzzle documented by Lo and MacKinlay (1990a) is associated with a slow response by some small stocks to good, but not to bad, common news. Time series portfolio tests and cross‐sectional tests of the delay for individual securities suggest that existing explanations of the cross‐autocorrelation puzzle based on data mismeasurement, minor market imperfections, or time‐varying risk premiums fail to capture the directional asymmetry in the data.
Who Manages Risk? An Empirical Examination of Risk Management Practices in the Gold Mining Industry
Authors: TUFANO PETER
Published: April 2012

This article examines a new database that details corporate risk management activity in the North American gold mining industry. I find little empirical support for the predictive power of theories that view risk management as a means to maximize shareholder value. However, firms whose managers hold more options manage less gold price risk, and firms whose managers hold more stock manage more gold price risk, suggesting that managerial risk aversion may affect corporate risk management policy. Further, risk management is negatively associated with the tenure of firms' CFOs, perhaps reflecting managerial interests, skills, or preferences.
The Method of Payment in Corporate Acquisitions, Investment Opportunities, and Management Ownership
Authors: MARTIN KENNETH J.
Published: April 2012

This article examines the motives underlying the payment method in corporate acquisitions. The findings support the notion that the higher the acquirer's growth opportunities, the more likely the acquirer is to use stock to finance an acquisition. Acquirer managerial ownership is not related to the probability of stock financing over small and large ranges of ownership, but is negatively related over a middle range. In addition, the likelihood of stock financing increases with higher pre‐acquisition market and acquiring firm stock returns. It decreases with an acquirer's higher cash availability, higher institutional shareholdings and blockholdings, and in tender offers.
Tax‐Exempt Debt and the Capital Structure of Nonprofit Organizations: An Application to Hospitals
Authors: WEDIG GERARD J. , HASSAN MAHMUD , MORRISEY MICHAEL A.
Published: April 2012

The availability of tax‐exempt financing provides nonprofit (NP) organizations with their own tax‐based incentives to issue debt. In this article, we develop a theoretical model in which NPs gain an indirect arbitrage from tax‐exempt debt issuance, constrained by: 1) the requirement that fixed investment exceed tax‐exempt debt flows (the project financing constraint), and 2) the constraint against share issuance. These constraints cause them to impute tax benefits to projects that afford access to the tax‐exempt bond market. Empirical tests indicate that NP hospitals behave as if they have target levels of tax‐exempt debt. Debt targeting is constrained by the availability of capital projects, while excess debt capacity stimulates investment.
Evidence of Bank Market Discipline in Subordinated Debenture Yields: 1983–1991
Authors: FLANNERY MARK J. , SORESCU SORIN M.
Published: April 2012

We examine debenture yields over the period 1983–1991 to evaluate the market's sensitivity to bank‐specific risks, and conclude that investors have rationally reflected changes in the government's policy toward absorbing private losses in the event of a bank failure. Although this evidence does not establish that market discipline can effectively control banking firms, it soundly rejects the hypothesis that investors cannot rationally differentiate among the risks undertaken by the major U.S. banking firms.
Decision Frequency and Synchronization Across Agents: Implications for Aggregate Consumption and Equity Return
Authors: LYNCH ANTHONY W.
Published: April 2012

This article examines a model in which decisions are made at fixed intervals and are unsynchronized across agents. Agents choose nondurable consumption and portfolio composition, and either or both can be chosen infrequently. A small utility cost is associated with both decisions being made infrequently. Calibrating returns to the U.S. economy, less frequent and unsynchronized decision‐making delivers the low volatility of aggregate consumption growth and its low correlation with equity return found in U.S. data. Allowing portfolio rebalancing to occur every period has a negligible impact on the joint behavior of aggregate consumption and returns.
Evidence of Discrimination in Lending: An Extension
Authors: SHAFFER SHERRILL
Published: April 2012

We generalize the model of Ferguson and Peters (1995) to allow for unequal recovery rates in the event of default by majority borrowers versus minority borrowers. This simple extension has two direct implications: (i) a uniform credit policy, as defined by Ferguson and Peters, entails cross‐subsidization across groups; and (ii) it is possible for a profit‐maximizing (and therefore economically nondiscriminatory) lending policy to generate lower average default rates among minority borrowers than among majority borrowers.
Do Brokerage Analysts' Recommendations Have Investment Value?
Authors: WOMACK KENT L.
Published: April 2012

An analysis of new buy and sell recommendations of stocks by security analysts at major U.S. brokerage firms shows significant, systematic discrepancies between prerecommendation prices and eventual values. The initial return at the time of the recommendations is large, even though few recommendations coincide with new public news or provide previously unavailable facts. However, these initial price reactions are incomplete. For buy recommendations, the mean postevent drift is modest (+2.4%) and short‐lived, but for sell recommendations, the drift is larger (−9.1%) and extends for six months. Analysts appear to have market timing and stock picking abilities.
Volatility in Wheat Spot and Futures Markets, 1950–1993: Government Farm Programs, Seasonality, and Causality
Authors: CRAIN SUSAN J. , LEE JAE HA
Published: April 2012

We explore how wheat spot and futures market volatility has been impacted by government farm programs during the 1950–1993 period. We find that changing volatility in both markets is highly associated with changing farm programs. The mandatory allotment programs of the 1950s and early 1960s (1/3/50–4/10/64) were associated with low volatility, while the voluntary programs initiated in the mid 1960s seem to have induced high volatility (4/11/64–12/22/85). Both market‐driven loan rates and conservation reserve programs appear to have helped volatility revert to lower levels since the mid 1980s (12/23/85–12/30/93). We also examine seasonality and causality in conjunction with the farm programs.
Momentum Strategies
Authors: CHAN LOUIS K. C. , JEGADEESH NARASIMHAN , LAKONISHOK JOSEF
Published: April 2012

We examine whether the predictability of future returns from past returns is due to the market's underreaction to information, in particular to past earnings news. Past return and past earnings surprise each predict large drifts in future returns after controlling for the other. Market risk, size, and book–to–market effects do not explain the drifts. There is little evidence of subsequent reversals in the returns of stocks with high price and earnings momentum. Security analysts' earnings forecasts also respond sluggishly to past news, especially in the case of stocks with the worst past performance. The results suggest a market that responds only gradually to new information.
Limit Order Trading
Authors: HANDA PUNEET , SCHWARTZ ROBERT A.
Published: April 2012

We analyze the rationale for limit order trading. Use of limit orders involves two risks: 1) an adverse information event can trigger an undesirable execution, and 2) favorable news can result in a desirable execution not being obtained. On the other hand, a paucity of limit orders can result in accentuated short‐term price fluctuations that compensate a limit order trader. Our empirical tests suggest that trading via limit orders dominates trading via market orders for market participants with relatively well balanced portfolios, and that placing a network of buy and sell limit orders as a pure trading strategy is profitable.
Bank Information Monopolies and the Mix of Private and Public Debt Claims
Authors: HOUSTON JOEL , JAMES CHRISTOPHER
Published: April 2012

This article examines the determinants of the mix of private and public debt using detailed information on the debt structure of 250 publicly traded corporations from 1980 through 1990. We find that the relationship between bank borrowing and the importance of growth opportunities depends on the number of banks the firm uses and whether the firm has public debt outstanding. For firms with a single bank relationship, the reliance on bank debt is negatively related to the importance of growth opportunities. In contrast, among firms borrowing from multiple banks, the relationship is positive.
An Anatomy of the “S&P Game”: The Effects of Changing the Rules
Authors: BENEISH MESSOD D. , WHALEY ROBERT E.
Published: April 2012

This study analyzes the effects of changes in S&P 500 index composition from January 1986 through June 1994, a period during which Standard and Poor's began its practice of preannouncing changes five days beforehand. The new announcement practice has given rise to the “S&P game” and has altered the way stock prices react. We find that prices increase abnormally from the close on the announcement day to the close on the effective day. The overall increase is greater than under the old announcement policy although part of the increase reverses after the stock is included in the index.
The CAPM is Wanted, Dead or Alive
Authors: FAMA EUGENE F. , FRENCH KENNETH R.
Published: April 2012

Kothari, Shanken, and Sloan (1995) claim that βs from annual returns produce a stronger positive relation between β and average return than βs from monthly returns. They also contend that the relation between average return and book‐to‐market equity (BE/ME) is seriously exaggerated by survivor bias. We argue that survivor bias does not explain the relation between BE/ME and average return. We also show that annual and monthly βs produce the same inferences about the β premium. Our main point on the β premium is, however, more basic. It cannot save the Capital asset pricing model (CAPM), given the evidence that β alone cannot explain expected return.
N‐acetylcysteine may improve residual renal function in hemodialysis patients: A pilot study
Authors: Feldman Leonid , Shani Michal , Sinuani Inna , Beberashvili Ilia , Weissgarten Joshua
Published: April 2012

Clinical outcomes in chronic dialysis patients are highly dependent on preservation of residual renal function (RRF). N‐acetylcysteine (NAC) may have a positive effect on renal function in the setting of nephrotoxic contrast media administration. In our recent study, we showed that NAC may improve RRF in peritoneal dialysis patients. The aim of the present study was to investigate the effect of NAC on RRF in patients treated with chronic hemodialysis. Prevalent chronic hemodialysis patients with a residual urine output of at least 100 mL/24 hours were included. The patients were administered oral NAC 1200 mg twice daily for 2 weeks. Residual renal function was assessed at baseline and at the end of treatment using a midweek interdialytic urine collection for measurement of urine output and calculation of residual renal Kt/V and glomerular filtration rate (GFR). Residual GFR was measured as the mean of urea and creatinine residual renal clearance. Each patient served as his own control. Twenty patients were prospectively enrolled in the study. Administration of NAC 1200 mg twice daily for 2 weeks resulted in significant improvement in RRF: urine volume increased from 320 ± 199 to 430 ± 232 mL/24 hours (P < 0.01), residual renal Kt/V increased from 0.19 ± 0.12 to 0.29 ± 0.14 (P < 0.01), and residual GFR increased from 1.6 ± 1.6 to 2.4 ± 2.3 mL/minute/1.73 m2 (P < 0.01). N‐acetylcysteine may improve RRF in patients treated with chronic hemodialysis.
Monitoring Failure Rates of Commercial Implant Brands; Substantial Equivalence in Question?
Authors: Hujoel Philippe , Becker William , Becker Burton
Published: April 2012

Objective

The aim of this study was to report on the failure rates of two distinct dental implant systems in a clinical practice setting.

Materials and methods

Date of implant placement and loss were entered prospectively in a data registry system. Failure rates of two commercially pure titanium implants, one with a porous oxydized surface (POS) and the other with a chemically altered surface (CAS), were assessed using a quality control chart and survival analyses.

Results

A total of 860 POS and 759 CAS implants were placed. A warning of an increased failure rate of the CAS implant was identified by means of the quality control chart. Survival analyses indicated that the CAS implant failure rate was twice that of the POS implant (Hazard Ratio: 2.08; 95% CI: 1.33–3.28, P‐value < 0.0012). After adjusting for alternative explanations, the CAS implant remained associated with a 95% increased failure rate (95% CI: 1.14–3.35; P‐value = 0.0146). Abandoning the CAS implant and returning to a POS implant was associated with a non‐significant 64% drop in the implant failure rate within less than a year (HR: 0.36; 95% CI: 0.12–1.14; P‐value < 0.0826).

Conclusion

The difference between a 4% failure rate with the POS implant and an 8% failure with the CAS implant appears inconsistent with the assumption of substantial equivalence.
Is micro‐computed tomography reliable to determine the microstructure of the maxillary alveolar bone?
Authors: González‐García Raúl , Monje Florencio
Published: April 2012

Objectives

To analyze the reliability of micro‐computed tomography (micro‐CT) to assess bone density and the microstructure of the maxillary bones at the alveolar process in human clinics by direct comparison with conventional stereologic‐based histomorphometry.

Materials and methods

Analysis of osseous microstructural variables including bone volumetric density (BV/TV) of 39 biopsies from the maxillary alveolar bone was performed by micro‐CT. Conventional stereologic‐based histomorphometry of 10 bone biopsies was performed by optic microscopy (OM) and low‐vacuum surface electronic microscopy (SEM). Percentages of bone between micro‐CT and conventional stereologic‐based histomorphometry were compared.

Results

Significant positive correlations were observed between BV/TV and the percentage of bone (%Bone) analyzed by SEM (r = 0.933, P < 0.001), by toluidine blue staining OM (r = 0.950, P < 0.001) and by dark field OM (r = 0.667, P = 0.05). The high positive correlation coefficient between BV/TV and trabecular thickness illustrates that a value of BV/TV upper than 50% squares with a bone presenting most of their trabecules thicker than 0.2 mm. The high negative correlation between BV/TV and trabecular separation shows that values of BV/TV upper than 50% squares with a bone presenting most of their trabecules separated less than 0.3 mm each other.

Conclusion

BV/TV assessed by micro‐CT correlates with the percentage of bone assessed by conventional stereologic‐based histomorphometry. Micro‐CT is a reliable technique to determine the bone density and the microstructure of the maxillary alveolar bone at the site of dental implant insertion.
Activation of mitochondrial apoptosis pathways in cutaneous squamous cell carcinoma cells by diclofenac/hyaluronic acid is related to upregulation of Bad as well as downregulation of Mcl‐1 and Bcl‐w
Authors: Rodust Paul M. , Fecker Lothar F. , Stockfleth Eggert , Eberle Jürgen
Published: April 2012

Actinic keratosis (AK) is characterized by high prevalence and the risk to proceed to squamous cell carcinoma (SCC). Cyclooxygenase‐2 (COX‐2)‐mediated prostaglandin E2 (PGE
2) synthesis has been reported in AK and SCC, and the COX inhibitor diclofenac in hyaluronic acid (diclofenac/HA) was approved for AK therapy. Its mode of action, however, remained to be unravelled. In the present study, diclofenac resulted in reduced PGE
2 levels in apoptosis‐sensitive cutaneous SCC cell lines (SCL‐II, SCC‐12, SCC‐13) whereas no PGE
2 and no COX‐2 expression was detectable in a SCC cell line resistant to apoptosis induction (SCL‐I). Activation of mitochondrial apoptosis pathways was evident in SCC cells owing to loss of the mitochondrial membrane potential and release of the mitochondrial factors cytochrome c and apoptosis‐inducing factor. Characteristic proapoptotic changes at the level of Bcl‐2 proteins occurred in sensitive cells, as upregulation of Bad and downregulation of Mcl‐1 and Bcl‐w. In contrast, Bad was already high, and Mcl‐1 and Bcl‐w were already low in resistant SCL‐I, even without treatment, which may be explained by the lack of PGE
2. An antiapoptotic downregulation of proapoptotic Bcl‐2 proteins Noxa and Puma was, however, also seen in SCL‐I, suggesting here pathways independent of COX‐2. The regulations of Mcl‐1 and Bad were also reproduced in SCC cells by the more selective COX‐2 inhibitor celecoxib, thus further underlining the specific role of COX‐2. The findings illuminate the mode of action of diclofenac/HA in SCC cells as well as principles of their resistance, which may allow further adaptation and improvement of the new therapy.
Hailey–Hailey disease and tight junctions: Claudins 1 and 4 are regulated by ATP2C1 gene encoding Ca2+/Mn2+ATPase SPCA1 in cultured keratinocytes
Authors: Raiko Laura , Siljamäki Elina , Mahoney Mỹ G. , Putaala Heli , Suominen Erkki , Peltonen Juha , Peltonen Sirkku
Published: April 2012

Mutations in the ATP2C1 gene encoding Ca2+/Mn2+ ATPase SPCA1 cause Hailey–Hailey disease (HHD, OMIM 16960). HHD is characterized by epidermal acantholysis. We attempted to model HHD using normal keratinocytes, in which the SPCA1 mRNA was down‐regulated with the small inhibitory RNA (siRNA) method. SiRNA inhibition significantly down‐regulated the SPCA1 mRNA, as demonstrated by qPCR, and decreased the SPCA1 protein beyond detectable level, as shown by Western analysis. The expression of selected desmosomal, adherens and tight junction (TJ) proteins was then studied in the SPCA1‐deficient and control keratinocytes cultured in low (0.06 mm) or high (1.2 mm) calcium concentration. The mRNA and protein levels of most TJ components were up‐regulated in non‐treated control keratinocyte cultures upon switch from low to high calcium concentration. In contrast, SPCA1‐deficient keratinocytes displayed high levels of TJ proteins claudins 1 and 4 even in low calcium. ZO‐1 did not, however, follow similar expression patterns. Protein levels of occludin, beta‐catenin, E‐cadherin, desmoplakin, desmogleins 1–3, desmocollin 2/desmocollin 3 and plakoglobin did not show marked changes in SPCA1‐deficient keratinocytes. Indirect immunofluorescence labelling revealed delayed translocation of desmoplakin and desmoglein 3 in desmosomes and increased intracellular pools of TJ and desmosomal components in SPCA1‐inhibited keratinocytes. The results show that SPCA1 regulates the levels of claudins 1 and 4, but does not affect desmosomal protein levels, indicating that TJ proteins are differently regulated. The results also suggest a potential role for claudins in HHD.
Biometric ratio in estimating widths of maxillary anterior teeth derived after correlating anthropometric measurements with dental measurements
Authors: Kini Ashwini Y. , Angadi Gangadhar S.
Published: April 2012

doi: 10.1111/j.1741‐2358.2012.00648.x

Biometric ratio in estimating widths of maxillary anterior teeth derived after correlating anthropometric measurements with dental measurements

Objective:  To correlate dental measurements i.e. combined mesiodistal width of six maxillary anterior teeth with facial measurements i.e. inner canthal distance, interpupillary distance and intercommissural width and acquire a biometric ratio to serve as a preliminary guide in selection of the maxillary anterior teeth.

Background:  In the absence of pre‐extraction records, the resultant denture can lead to patient dissatisfaction towards the aesthetic appeal of their dentures. The maxillary anterior teeth play a pivotal role in denture aesthetics. Various techniques and biometric ratios have been described in literature for selection of the maxillary anteriors. This study derives a biometric ratio for the same, obtained after correlating anthropometric measurements with dental measurements.

Materials and methods:  Two standardized digital photographs of the face were generated; one, when the facial muscles were relaxed and the other, when the subject was smiling; thereby, revealing the maxillary anterior teeth upto the canine tip. Inner canthal distance, interpupillary distance, intercommissural distance, distance between the tips of the maxillary canines and distance between the distal surfaces of the canines were measured. On the cast, the distance between tips of maxillary canines and distance between distal surfaces of maxillary canines were noted. The data was analysed using Spearman’s rank correlation coefficient.

Results:  A high correlation was found between the intercommissural measurement with distance between the tips of the canines on the photograph and between the tips of the canines on the cast with the interpupillary distance, giving a biometric ratio of 1:1.35 and 1:1.41 respectively. The least correlation was between the inner canthal distance and the tips of the canines measured on the photograph.

Conclusions:  Extra oral anthropometric measurements of the interpupillary distances and the intercommissural distances with the help of standardised photographs can help us determine the combined widths of the anterior teeth accurately, thus aiding their selection in the absence of pre‐extraction records.
Frequency of iridocyclitis in patients with early psoriatic arthritis: a prospective, follow up study
Authors: Niccoli Laura , Nannini Carlotta , Cassarà Emanuele , Kaloudi Olga , Susini Massimo , Lenzetti Ivo , Cantini Fabrizio
Published: April 2012

Objective

The occurrence of iridocyclitis (IC) in early psoriatic arthritis (PsA) has been rarely assessed. The primary end‐point of this study was to evaluate the frequency of IC at onset in patients with early PsA.

Methods

We evaluated the frequency of IC in a clinical series of consecutive, new outpatients with early PsA observed between January 2000 and December 2009. All patients met the Classification Criteria for Psoriatic Arthritis (CASPAR) criteria for PsA and had a disease duration ≤12 months. The following clinical patterns were considered: peripheral PsA (oligoarthritis ≤4 and polyarthritis ≥5 involved joints), axial PsA and mixed. IC diagnosis was made by the ophthalmologist. Follow‐up visits were scheduled at baseline and every 4 months with interval shortening in the case of urgent clinical problems.

Results

Two hundred and forty‐two patients, 137 (57%) women and 105 (43%) men (mean age 50.33 ± 11.7 years; mean symptom duration 9.38 ± 3.1 months) were studied. One hundred and thirty‐two (51%) patients had peripheral PsA, 41 (17%) axial and 69 (28%) mixed. Twenty‐six episodes of IC were recorded at diagnosis in 22 (9%) patients, 17 (77.3%) female and five (22.7%) male; 11 (50%) patients had peripheral PsA, two (9.1%) axial, and nine (40.9%) mixed; 5/22 (22.7%) patients were B27‐positive. IC recurred in 2/22 (9%) patients over the follow‐up period. Mean follow‐up duration was 51 ± 23.2 months. Dactylitis was significantly more frequent in patients with IC compared to those without this feature (P = 0.032).

Conclusion

IC occurred in 9% of 242 patients with early PsA with no association with the clinical pattern and B27 positivity. This frequency is higher than previously reported.
Effect of Inlet Velocity Profiles on Patient-Specific Computational Fluid Dynamics Simulations of the Carotid Bifurcation
Authors: Campbell Ian C. , Ries Jared , Dhawan Saurabh S. , Quyyumi Arshed A. , Taylor W. Robert , Oshinski John N.
Published: April 2012

Patient-specific computational fluid dynamics (CFD) is a powerful tool for researching the role of blood flow in disease processes. Modern clinical imaging technology such as MRI and CT can provide high resolution information about vessel geometry, but in many situations, patient-specific inlet velocity information is not available. In these situations, a simplified velocity profile must be selected. We studied how idealized inlet velocity profiles (blunt, parabolic, and Womersley flow) affect patient-specific CFD results when compared to simulations employing a “reference standard” of the patient’s own measured velocity profile in the carotid bifurcation. To place the magnitude of these effects in context, we also investigated the effect of geometry and the use of subject-specific flow waveform on the CFD results. We quantified these differences by examining the pointwise percent error of the mean wall shear stress (WSS) and the oscillatory shear index (OSI) and by computing the intra-class correlation coefficient (ICC) between axial profiles of the mean WSS and OSI in the internal carotid artery bulb. The parabolic inlet velocity profile produced the most similar mean WSS and OSI to simulations employing the real patient-specific inlet velocity profile. However, anatomic variation in vessel geometry and the use of a nonpatient-specific flow waveform both affected the WSS and OSI results more than did the choice of inlet velocity profile. Although careful selection of boundary conditions is essential for all CFD analysis, accurate patient-specific geometry reconstruction and measurement of vessel flow rate waveform are more important than the choice of velocity profile. A parabolic velocity profile provided results most similar to the patient-specific velocity profile.
A Porous Elastic Model for Bacterial Biofilms: Application to the Simulation of Deformation of Bacterial Biofilms Under Microfluidic Jet Impingement
Authors: Zheng Leo Y. , Farnam Dylan S. , Homentcovschi Dorel , Sammakia Bahgat G.
Published: April 2012

The presence of bacterial biofilms is detrimental in a wide range of healthcare situations especially wound healing. Physical debridement of biofilms is a method widely used to remove them. This study evaluates the use of microfluidic jet impingement to debride biofilms. In this case, a biofilm is treated as a saturated porous medium also having linear elastic properties. A numerical modeling approach is used to calculate the von Mises stress distribution within a porous medium under fluid-structure interaction (FSI) loading to determine the initial rupture of the biofilm structure. The segregated model first simulates the flow field to obtain the FSI interface loading along the fluid-solid interface and body force loading within the porous medium. A stress-strain model is consequently used to calculate the von Mises stress distribution to obtain the biofilm deformation. Under a vertical jet, 60% of the deformation of the porous medium can be accounted for by treating the medium as if it was an impermeable solid. However, the maximum deformation in the porous medium corresponds to the point of maximum shear stress which is a different position in the porous medium than that of the maximum normal stress in an impermeable solid. The study shows that a jet nozzle of 500 μm internal diameter (ID) with flow of Reynolds number (Re) of 200 can remove the majority of biofilm species.
A New Catheter for Tumor-Targeting With Radioactive Microspheres in Representative Hepatic Artery Systems—Part II: Solid Tumor-Targeting in a Patient-Inspired Hepatic Artery System
Authors: Childress E. M. , Kleinstreuer C. , Kennedy A. S.
Published: April 2012

In this second part, the methodology for optimal tumor-targeting is further explored, employing a patient-inspired hepatic artery system which differs significantly from the idealized configuration discussed in Part I. Furthermore, the fluid dynamics of a microsphere supply apparatus is also analyzed. The best radial catheter positions and particle-release intervals for tumor targeting were determined for both the idealized and patient-inspired configurations. This was accomplished by numerically analyzing generated particle release maps (PRMs) for ten equally spaced intervals throughout the pulse. As in Part I, the effects of introducing a catheter were also investigated. In addition to the determination of micro-catheter positioning and, hence, optimal microsphere release, a microsphere-supply apparatus (MSA) was analyzed, which transports the particles to the catheter-nozzle, considering different axial particle injection functions, i.e., step, ramp, and S-curve. A refined targeting methodology was developed which demonstrates how the optimal injection region and interval can be determined with the presence of a catheter for any geometric configuration. Additionally, the less abrupt injection functions (i.e., ramp and S-curve) were shown to provide a more compact particle stream, making them better choices for targeting. The results of this study aid in designing the smart micro-catheter (SMC) in conjunction with the MSA, bringing this innovative treatment procedure one step closer to implementation in clinical practice.
Validation of a Pressure Diameter Method for Determining Modulus and Strain of Collagen Engagement for Long Branches of Bovine Pulmonary Arteries
Authors: Reusser Mark , Hunter Kendall S. , Lammers Steven R. , Stenmark Kurt R.
Published: April 2012

Recent studies have shown that capacitance measurements of large arteries provide better prognosis and diagnosis than tests of resistance alone in pulmonary hypertension (Mahapatra et al., 2006, “Relationship of Pulmonary Arterial Capacitance and Mortality in Idiopathic Pulmonary Arterial Hypertension,” J. Am. Coll. Cardiol., 47(4), pp. 799–803; Reuben, 1971, “Compliance of the Human Pulmonary Arterial System in Disease,” Circ. Res., 29, pp. 40–50]. Decreased arterial capacitance causes increased load to the heart and is the direct result of increased stiffness and elastic modulus of the arterial wall. Here, we validate a pressure-diameter (PD) method for comparing the elastic modulus and collagen engagement for post-hilar pulmonary arteries with a large range of arterial diameter. The tissue mechanics of the post-hilar arteries are not well-characterized in pulmonary hypertension. It is believed that future studies with this method will provide useful insight into the role of passive tissue mechanics of these arteries in the pathophysiology of pulmonary hypertension, eventually improving clinical diagnosis, prognosis, and treatment. Post-hilar pulmonary arteries, excised from healthy and hypertensive calves and healthy cows, were inflated over a range of 0 [mm Hg] to 110 [mm Hg] in an isolated tissue bath. Internal pressure was recorded with an electric pressure catheter. Artery diameter and longitudinal stretch were recorded photographically. Stress-strain data curves were extracted using Lame’s law of thick-walled tubes. Radial strips were removed from each section and tested in a uniaxial (MTS) tester for validation. Both the elastic modulus and collagen engagement strain were similar to results obtained by more traditional means. The average difference between measured values of the two methods for collagen engagement strain was 3.3% of the average value of the engagement strain. The average difference between the measured values of the two methods for modulus of elasticity was 7.4% of the average value of the modulus. The maximum, theoretical, relative error for the stress determined with the PD method was calculated at 20.3%. The PD method proved to be a suitable replacement for uniaxial strain tests in comparing collagen engagement strains. The method allowed faster testing of tissues of multiple diameters, while removing the effect of end conditions. The PD method will be of further utility in continued study of tissue mechanics in pulmonary hypertension studies.
A Patient-Specific Computer Tomography-Based Finite Element Methodology to Calculate the Six Dimensional Stiffness Matrix of Human Vertebral Bodies
Authors: Chevalier Yan , Zysset Philippe K.
Published: April 2012

In most finite element (FE) studies of vertebral bodies, axial compression is the loading mode of choice to investigate structural properties, but this might not adequately reflect the various loads to which the spine is subjected during daily activities or the increased fracture risk associated with shearing or bending loads. This work aims at proposing a patient-specific computer tomography (CT)-based methodology, using the currently most advanced, clinically applicable finite element approach to perform a structural investigation of the vertebral body by calculation of its full six dimensional (6D) stiffness matrix. FE models were created from voxel images after smoothing of the peripheral voxels and extrusion of a cortical shell, with material laws describing heterogeneous, anisotropic elasticity for trabecular bone, isotropic elasticity for the cortex based on experimental data. Validated against experimental axial stiffness, these models were loaded in the six canonical modes and their 6D stiffness matrix calculated. Results show that, on average, the major vertebral rigidities correlated well or excellently with the axial rigidity but that weaker correlations were observed for the minor coupling rigidities and for the image-based density measurements. This suggests that axial rigidity is representative of the overall stiffness of the vertebral body and that finite element analysis brings more insight in vertebral fragility than densitometric approaches. Finally, this extended patient-specific FE methodology provides a more complete quantification of structural properties for clinical studies at the spine.
Multimodal μCT/μMR based semiautomated segmentation of rat vertebrae affected by mixed osteolytic/osteoblastic metastases
Authors: Hojjat Seyed‐Parsa , Foltz Warren , Wise‐Milestone Lisa , Whyne Cari M.
Published: April 2012

Purpose:

Multimodal microimaging in preclinical models is used to examine the effect of spinal metastases on bony structure; however, the evaluation of tumor burden and its effect on microstructure has thus far been mainly qualitative or semiquantitative. Quantitative analysis of multimodality imaging is a time consuming task, motivating automated methods. As such, this study aimed to develop a low complexity semiautomated multimodal μCT/μMR based approach to segment rat vertebral structure affected by mixed osteolytic/osteoblastic destruction.

Methods:

Mixed vertebral metastases were developed via intracardiac injection of Ace‐1 canine prostate cancer cells in three 4‐week‐old rnu/rnu rats. μCT imaging (for high resolution bone visualization), T1‐weighted μMR imaging (for bone registration), and T2‐weighted μMR imaging (for osteolytic tumor visualization) were conducted on one L1, three L2, and one L3 vertebrae (excised). One sample (L1–L3) was processed for undecalcified histology and stained with Goldner's trichome. The μCT and μMR images were registered using a 3D rigid registration algorithm with a mutual information metric. The vertebral microarchitecture was segmented from the μCT images using atlas‐based demons deformable registration, levelset curvature evolution, and intensity‐based thresholding techniques. The μCT based segmentation contours of the whole vertebrae were used to mask the T2‐weighted μMR images, from which the osteolytic tumor tissue was segmented (intensity‐based thresholding).

Results:

Accurate registration of μCT and μMRI modalities yielded precise segmentation of whole vertebrae, trabecular centrums, individual trabeculae, and osteolytic tumor tissue. While the algorithm identified the osteoblastic tumor attached to the vertebral pereosteal surfaces, it was limited in segmenting osteoblastic tissue located within the trabecular centrums.

Conclusions:

This semiautomated segmentation method yielded accurate registration of μCT and μMRI modalities with application to the development of mathematical models analyzing the mechanical stability of metastatically involved vertebrae and in preclinical applications evaluating new and existing treatment effects on tumor burden and skeletal microstructure.
Stochastic region competition algorithm for Doppler sonography segmentation
Authors: Yeh Fang‐Cheng , Cheng Jie‐Zhi , Chou Yi‐Hong , Tiu Chui‐Mei , Chang Yeun‐Chung , Huang Chiun‐Sheng , Chen Chung‐Ming
Published: April 2012

Purpose:

A probabilistic image segmentation algorithm called stochastic region competition is proposed for performing Doppler sonography segmentation.

Methods:

The image segmentation is conducted by maximizinga posteriori that models histogram likelihood, gradient likelihood, and a spatial prior. The optimization is done by a modified expectation and maximization (EM) method that aims to improve computation efficiency and avoid local optima.

Results:

The algorithm was tested on 155 color Doppler sonograms and compared with manual delineations. The qualitative assessment shows that our algorithm is able to segment mass lesions under the condition of low image quality and the interference of the color‐encoded Doppler information. The quantitative assessment analysis shows that the average distance between the algorithm‐generated boundaries and manual delineations is statistically comparable to the variability of manual delineations. The ratio of the overlapping area between the algorithm‐generated boundaries and manual delineations is also comparable to that between different sets of manual delineations. A reproductivity test was conducted to confirm that the result is statistically reproducible.

Conclusions:

The algorithm can be used to perform Doppler sonography segmentation and to replace the tedious manual delineation task in clinical application.
Three-dimensional strength-reduction finite element analysis of slopes: geometric effects
Authors: Nian T.-K. , Huang R.-Q. , Wan S.-S. , Chen G.-Q.
Published: April 2012

The vast majority of slopes, both natural and constructed, exhibit a complex geometric configuration and three-dimensional (3D) state, whereas slopes satisfying the assumption of plane strain (infinite length) are seldom encountered. Existing research mainly emphasizes the 3D dimensions and boundary effect in slope stability analysis; however, the effect of complex geometric ground configuration on 3D slope stability is rarely reported. In this paper, an elastoplastic finite-element method using strength-reduction techniques is used to analyze the stability of special 3D geometric slopes. A typical 3D slope underlain by a weak layer with groundwater is described to validate the numerical modeling, safety factor values, and critical slip surface for the 3D slope. Furthermore, a series of special 3D slopes with various geometric configurations are analyzed numerically, and the effects of turning corners, slope gradient, turning arcs, and convex- and concave-shaped surface geometry on the stability and failure characteristics of slopes under various boundary conditions are discussed in detail.
CALCULATING THE FUNDAMENTAL BIQUANDLES OF SURFACE LINKS FROM THEIR CH–DIAGRAMS
Authors: ASHIHARA SOSUKE
Published: April 2012

The fundamental biquandle is an invariant of an oriented surface link, which is defined by a presentation obtained from a surface diagram of the surface link: The generating set consists of labels of the semi-sheets and the relator set consists of relations defined at the double point curves. Any surface link can be presented by a link diagram with some markers which is called a ch-diagram. Using this fact, we give a method for calculating the fundamental biquandle of a surface link from its ch-diagram directly.
STRING NUMBERS OF ABELIAN GROUPS
Authors: BRUNO ANNA GIORDANO , VIRILI SIMONE
Published: April 2012

The string number of self-maps arose in the context of algebraic entropy and it can be viewed as a kind of combinatorial entropy function. Later on, its values for endomorphisms of abelian groups were calculated in full generality. We study its global version for abelian groups, providing several examples involving also Hopfian abelian groups. Moreover, we characterize the class of all abelian groups with string number zero in many cases and discuss its stability properties.
TOPOLOGICAL K-THEORY OF THE GROUP C*-ALGEBRA OF A SEMI-DIRECT PRODUCT ℤn ⋊ ℤ/m FOR A FREE CONJUGATION ACTION
Authors: LANGER MARTIN , LÜCK WOLFGANG
Published: April 2012

We compute the topological K-theory of the group C*-algebra [Formula: see text] for a group extension 1 → ℤn → Γ → ℤ/m → 1 provided that the conjugation action of ℤ/m on ℤn is free outside the origin.
MEAN-VARIANCE APPROXIMATIONS TO THE GEOMETRIC MEAN
Authors: MARKOWITZ HARRY
Published: April 2012

This paper uses two databases to test the ability of six functions of arithmetic mean and variance to approximate geometric mean return or, equivalently, Bernoulli's expected log utility. The two databases are: (1) a database of returns on frequently used asset classes, and (2) that of real returns on the equity markets of sixteen countries, 1900–2000. Three of the functions of arithmetic mean and variance do quite well, even for return series with large losses. The other three do less well.