Rollover risk in commercial paper markets and firms' debt maturity choice

By using short-term direct finance firms of the highest credit quality expose themselves to rollover risk in the public debt markets. Firms insure themselves against this risk by securing backup lines of credit from banks that they may use should market liquidity dry up. In a first step, this paper explains why high quality firms introduce a maturity mismatch into their balance sheets and do not simply use long-term direct finance. It also highlights why banks may be willing to roll over a firm's debt while direct investors may not. In a second step, I extend the model to allow for different levels of firm's publicly observable credit quality. Under plausible assumptions about the cost of bank borrowing the model generates a maturity structure choice broadly consistent with observed financing patterns: Low quality firms issue short-term direct debt, medium quality firms issue long-term direct debt, and high quality firms use short-term direct debt in normal times and bank debt in adverse times. The paper suggests that better publicly available information about firm quality and the moderation of the business cycle over the past decade help to explain the decrease in nonfinancial commercial paper outstanding since the beginning of the decade. -- Kapitalmarktfähige Unternehmen können sich nur dann durch die Ausgabe von kurzfristigen Geldmarktpapieren (Commercial Paper - CP) refinanzieren, wenn sie eine vernachlässigbare Ausfallwahrscheinlichkeit aufweisen. Gleichwohl ist es diesen Firmen bisweilen nicht m¨oglich, eine Anschlussfinanzierung vorzunehmen. In solchen Situationen können CP-Emittenten auf Kreditlinien ausweichen, sofern sie diese zuvor mit Banken vereinbart haben und sich ihre Kreditqualität bei Inanspruchnahme der Kreditlinie nicht verschlechtert hat. In dem vorliegenden Papier werden zunächst zwei Fragenkomplexe näher untersucht. Erstens, warum bekommen Firmen von höchster Kreditqualität zu bestimmten Zeiten keinen Kredit, obwohl ihre tatsächliche Ausfallwahrscheinlichkeit nahe null liegt? Zweitens, warum wählen diese Firmen eine Finanzierungsform, bei der sie sich in guten Zeiten über die Ausgabe von Geldmarktpapieren finanzieren und in schlechten Zeiten einen Bankkredit in Anspruch nehmen? Warum nehmen sie eine Inkongruenz der Laufzeiten zwischen Aktiv- und Passivseite in Kauf, anstatt lang laufende Anleihen zu emittieren und sich somit keinem Refinanzierungsrisiko auszusetzen?Rollover risk,Liquidity,Asymmetric Information,Debt maturity

Wavelet-Based Angiographic Reconstruction of Computed Tomography Perfusion Data Diagnostic Value in Cerebral Venous Sinus Thrombosis

Objective: The aim of this study was to test the diagnostic value of wavelet-based angiographic reconstruction of CT perfusion data (waveletCTA) to detect cerebral venous sinus thrombosis (CVST) in patients who underwent whole-brain CT perfusion imaging (WB-CTP). Materials and Methods: Datasets were retrospectively selected from an initial cohort of 2863 consecutive patients who had undergone multiparametric CT including WB-CTP. WaveletCTA was reconstructed from WB-CTP: the angiographic signal was generated by voxel-based wavelet transform of time attenuation curves (TACs) from WB-CTP raw data. In a preliminary clinical evaluation, waveletCTA was analyzed by 2 readers with respect to presence and location of CVST. Venous CT and MR angiography (venCTA/venMRA) served as reference standard. Diagnostic confidence for CVST detection and the quality of depiction for venous sections were evaluated on 5-point Likert scales. Thrombus extent was assessed by length measurements. The mean CT attenuation and waveletCTA signal of the thrombus and of flowing blood were quantified. Results: Sixteen patients were included: 10 patients with venCTA-/venMRAconfirmed CVST and 6 patients with arterial single-phase CT angiography (artCTA)-suspected but follow-up-excluded CVST. The reconstruction of waveletCTA was successful in all patients. Among the patients with confirmed CVST, waveletCTA correctly demonstrated presence, location, and extent of the thrombosis in 10/10 cases. In 6 patients with artCTA-suspected but follow-up-excluded CVST, waveletCTA correctly ruled out CVST in 5 patients. Reading waveletCTA in addition to artCTA significantly increased the diagnostic confidence concerning CVST compared with reading artCTA alone (4.4 vs 3.6, P = 0.044). The mean flowing blood-to-thrombus ratio was highest in waveletCTA, followed by venCTA and artCTA (146.2 vs 5.9 vs 2.6, each with P < 0.001). In waveletCTA, the venous sections were depicted better compared with artCTA (4.2 vs 2.6, P < 0.001), and equally well compared with venCTA/venMRA (4.2 vs 4.1, P = 0.374). Conclusions: WaveletCTA was technically feasible in CVST patients and reliably identified CVST in a preliminary clinical evaluation. WaveletCTA might serve as an additional reconstruction to rule out or incidentally detect CVST in patients who undergo WB-CTP

Critical reflection on knowledge and narratives of conservation agriculture

In the context of contemporary concerns about climate change and food security, Conservation Agriculture (CA) has emerged as a well-supported and central component of the agricultural sector development strategy across sub-Saharan Africa, including in Zambia, which is the focus of this paper. A variety of narratives about the benefits of CA over conventional agricultural systems underpin endeavours towards ‘scaling up’ CA and increasing rates of adoption amongst smallholder farmers nationwide. However, there is a knowledge politics underlying the translation of a weak evidence base around CA into persuasive narratives and financial and political support. In this paper, we trace the evolution of five narratives around CA in Zambia in relation to changing political agendas and the involvement of new public and private sector actors, and review the development of evidence bases and knowledge that support and challenge each of these narratives. We discuss the potential to open up space within this knowledge politics to alternative narratives and the contestation of the pervasive CA scaling up agenda. Critical reflection is essential to ensure that national and local evidence is more effectively used to guide national climate and agricultural policy developments and international donor initiatives

Crossed cerebellar diaschisis in acute ischemic stroke: Impact on morphologic and functional outcome

Crossed cerebellar diaschisis (CCD) is the phenomenon of hypoperfusion and hypometabolism of the contralateral cerebellar hemisphere caused by dysfunction of the related supratentorial region. Our aim was to analyze its influence on morphologic and functional outcome in acute ischemic stroke. Subjects with stroke caused by a large vessel occlusion of the anterior circulation were selected from an initial cohort of 1644 consecutive patients who underwent multiparametric CT including whole-brain CT perfusion. Two experienced readers evaluated the posterior fossa in terms of CCD absence (CCD-) or presence (CCD+). A total of 156 patients formed the study cohort with 102 patients (65.4%) categorized as CCD- and 54 (34.6%) as CCD+. In linear and logistic regression analyses, no significant association between CCD and final infarction volume (beta = -0.440, p = 0.972), discharge mRS2 (OR = 1.897, p = 0.320), or 90-day mRS <= 2 (OR = 0.531, p = 0.492) was detected. CCD+ patients had larger supratentorial cerebral blood flow deficits (median: 164 ml vs. 115 ml;p = 0.001) compared to CCD-patients. Regarding complications, CCD was associated with a higher rate of parenchymal hematomas (OR = 4.793, p = 0.035). In conclusion, CCD is frequently encountered in acute ischemic stroke caused by large vessel occlusion of the anterior circulation. CCD was associated with the occurrence of parenchymal hematoma in the ipsilateral cerebral infarction but did not prove to significantly influence patient outcome

Penumbra Pattern Assessment in Acute Stroke Patients: Comparison of Quantitative and Non-Quantitative Methods in Whole Brain CT Perfusion

Background and Purpose: While penumbra assessment has become an important part of the clinical decision making for acute stroke patients, there is a lack of studies measuring the reliability and reproducibility of defined assessment techniques in the clinical setting. Our aim was to determine reliability and reproducibility of different types of three-dimensional penumbra assessment methods in stroke patients who underwent whole brain CT perfusion imaging (WB-CTP). Materials and Methods: We included 29 patients with a confirmed MCA infarction who underwent initial WB-CTP with a scan coverage of 100 mm in the z-axis. Two blinded and experienced readers assessed the flow-volume-mismatch twice and in two quantitative ways: Performing a volumetric mismatch analysis using OsiriX imaging software (MMVOL) and visual estimation of mismatch (MMEST). Complementarily, the semiquantitative Alberta Stroke Programme Early CT Score for CT perfusion was used to define mismatch (MMASPECTS). A favorable penumbral pattern was defined by a mismatch of >= 30% in combination with a cerebral blood flow deficit of = 1, respectively. Inter-and intrareader agreement was determined by Kappa-values and ICCs. Results: Overall, MMVOL showed considerably higher inter-/intrareader agreement (ICCs: 0.751/0.843) compared to MMEST (0.292/0.749). In the subgroup of large (>= 50 mL) perfusion deficits, inter-and intrareader agreement of MMVOL was excellent (ICCs: 0.961/0.942), while MMEST interreader agreement was poor (0.415) and intrareader agreement was good (0.919). With respect to penumbra classification, MMVOL showed the highest agreement (interreader agreement: 25 agreements/4 non-agreements/kappa: 0.595;intrareader agreement 27/2/0.833), followed by MMEST (22/7/0.471;23/6/0.577), and MMASPECTS (18/11/0.133;21/8/0.340). Conclusion: The evaluated approach of volumetric mismatch assessment is superior to pure visual and ASPECTS penumbra pattern assessment in WB-CTP and helps to precisely judge the extent of 3-dimensional mismatch in acute stroke patients

Early Imaging Prediction of Malignant Cerebellar Edema Development in Acute Ischemic Stroke

Background and Purpose-Malignant cerebellar edema (MCE) is a life-threatening complication of acute ischemic stroke that requires timely diagnosis and management. Aim of this study was to identify imaging predictors in initial multiparametric computed tomography (CT), including whole-brain CT perfusion (WB-CTP). Methods-We consecutively selected all subjects with cerebellar ischemic WB-CTP deficits and follow-up-confirmed cerebellar infarction from an initial cohort of 2635 patients who had undergone multiparametric CT because of suspected stroke. Follow-up imaging was assessed for the presence of MCE, measured using an established 10-point scale, of which scores >= 4 are considered malignant. Posterior circulation-Acute Stroke Prognosis Early CT Score (pc-ASPECTS) was determined to assess ischemic changes on noncontrast CT, CT angiography (CTA), and parametric WB-CTP maps (cerebellar blood flow [CBF];cerebellar blood volume;mean transit time;time to drain). Fisher's exact tests, Mann-Whitney U tests, and receiver operating characteristics analyses were performed for statistical analyses. Results-Out of a total of 51 patients who matched the inclusion criteria, 42 patients (82.4%) were categorized as MCE-and 9 (17.6%) as MCE+. MCE+ patients had larger CBF, cerebellar blood volume, mean transit time, and time to drain deficit volumes (all with P0.05). Receiver operating characteristics analyses yielded the largest area under the curve values for the prediction of MCE development for CBF (0.979) and cerebellar blood volume deficit volumes (0.956) and pc-ASPECTS on CBF (0.935), whereas pc-ASPECTS on noncontrast CT (0.648) and CTA (0.684) had less diagnostic value. The optimal cutoff value for CBF deficit volume was 22 mL, yielding 100% sensitivity and 90% specificity for MCE classification. Conclusions-WB-CTP provides added diagnostic value for the early identification of patients at risk for MCE development in acute cerebellar stroke

Molecular characterisation of sporadic endolymphatic sac tumours and comparison to von Hippel–Lindau disease‐related tumours

Aims: Although inactivation of the von Hippel-Lindau gene (VHL) on chromosome 3p25 is considered to be the major cause of hereditary endolymphatic sac tumours (ELSTs), the genetic background of sporadic ELST is largely unknown. The aim of this study was to determine the prevalence of VHL mutations in sporadic ELSTs and compare their characteristics to VHL-disease-related tumours. Methods: Genetic and epigenetic alterations were compared between 11 sporadic and 11 VHL-disease-related ELSTs by targeted sequencing and DNA methylation analysis. Results: VHL mutations and small deletions detected by targeted deep sequencing were identified in 9/11 sporadic ELSTs (82%). No other cancer-related genetic pathway was altered except for TERT promoter mutations in two sporadic ELST and one VHL-disease-related ELST (15%). Loss of heterozygosity of chromosome 3 was found in 6/10 (60%) VHL-disease-related and 10/11 (91%) sporadic ELSTs resulting in biallelic VHL inactivation in 8/10 (73%) sporadic ELSTs. DNA methylation profiling did not reveal differences between sporadic and VHL-disease-related ELSTs but reliably distinguished ELST from morphological mimics of the cerebellopontine angle. VHL patients were significantly younger at disease onset compared to sporadic ELSTs (29 vs. 52 years, p < 0.0001, Fisher's exact test). VHL-disease status was not associated with an increased risk of recurrence, but the presence of clear cells was found to be associated with shorter progression-free survival (p = 0.0002, log-rank test). Conclusion: Biallelic inactivation of VHL is the main mechanism underlying ELSTs, but unknown mechanisms beyond VHL may rarely be involved in the pathogenesis of sporadic ELSTs

TERT promoter mutation and chromosome 6 loss define a high-risk subtype of ependymoma evolving from posterior fossa subependymoma

Subependymomas are benign tumors characteristically encountered in the posterior fossa of adults that show distinct epigenetic profiles assigned to the molecular group "subependymoma, posterior fossa" (PFSE) of the recently established DNA methylation-based classification of central nervous system tumors. In contrast, most posterior fossa ependymomas exhibit a more aggressive biological behavior and are allocated to the molecular subgroups PFA or PFB. A subset of ependymomas shows epigenetic similarities with subependymomas, but the precise biology of these tumors and their potential relationships remain unknown. We therefore set out to characterize epigenetic traits, mutational profiles, and clinical outcomes of 50 posterior fossa ependymal tumors of the PFSE group. On histo-morphology, these tumors comprised 12 ependymomas, 14 subependymomas and 24 tumors with mixed ependymoma-subependymoma morphology. Mixed ependymoma-subependymoma tumors varied in their extent of ependymoma differentiation (2-95%) but consistently exhibited global epigenetic profiles of the PFSE group. Selective methylome analysis of microdissected tumor components revealed CpG signatures in mixed tumors that coalesce with their pure counterparts. Loss of chr6 (20/50 cases), as well as TERT mutations (21/50 cases), were frequent events enriched in tumors with pure ependymoma morphology (p < 0.001) and confined to areas with ependymoma differentiation in mixed tumors. Clinically, pure ependymoma phenotype, chr6 loss, and TERT mutations were associated with shorter progression-free survival (each p < 0.001). In conclusion, our results suggest that subependymomas may acquire genetic and epigenetic changes throughout tumor evolution giving rise to subclones with ependymoma morphology (resulting in mixed tumors) that eventually overpopulate the subependymoma component (pure PFSE ependymomas)

Diagnostic yield and accuracy of coronary CT angiography after abnormal nuclear myocardial perfusion imaging

We aimed to determine the diagnostic yield and accuracy of coronary CT angiography (CCTA) in patients referred for invasive coronary angiography (ICA) based on clinical concern for coronary artery disease (CAD) and an abnormal nuclear stress myocardial perfusion imaging (MPI) study. We enrolled 100 patients (84 male, mean age 59.6 +/- 8.9 years) with an abnormal MPI study and subsequent referral for ICA. Each patient underwent CCTA prior to ICA. We analyzed the prevalence of potentially obstructive CAD (>= 50% stenosis) on CCTA and calculated the diagnostic accuracy of >= 50% stenosis on CCTA for the detection of clinically significant CAD on ICA (defined as any >= 70% stenosis or >= 50% left main stenosis). On CCTA, 54 patients had at least one >= 50% stenosis. With ICA, 45 patients demonstrated clinically significant CAD. A positive CCTA had 100% sensitivity and 84% specificity with a 100% negative predictive value and 83% positive predictive value for clinically significant CAD on a per patient basis in MPI positive symptomatic patients. In conclusion, almost half (48%) of patients with suspected CAD and an abnormal MPI study demonstrate no obstructive CAD on CCTA