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A system is implemented that simulates a bond portfolio over the long-term of liabilities. It pays all liabilities and extracts continuously a fixed percentage of remaining liabilities to stakeholders while maintaining a strategic asset allocation. This fixed percentage is proposed as return measure in an ALM-context with risk derived from its distribution. Tabled inputs completed with simple coherent inductive models for interest rate changes and spread changes allow to map return and risk as function of market probability in a deterministic white-box approach. Aim is to provide insight in the dependency of return potential and risk drivers on the bond allocation, on assumptions and on market conditions in order to improve allocations, understand risk, specify risk-appetite, facilitate capital management and budgeting. Examples are based on an actual €10billion insurer portfolio. Current market conditions favor short bond duration, reducing government bonds and mixing in some high yield bonds. Duration matching now decreases return potential and increases risk so that Solvency 2 regulation is counterproductive from a quantitative risk perspective. Bond portfolios are less risky in an ALM-context than in an assets-context due to the mitigation of loss by a balance of opposing forces when bonds are reinvested. Their downside is resilient to increasing correlation. This system is the kernel of a system for all assets but first focus is exclusively on bonds for their weight in current allocations and their pricing characteristics.

A new return and risk measure is presented that captures the whole Assets -Liabilities Runoff for an insurance company. It shows: (1) that short duration allocations with higher yielding diversified assets are currently safer and more rewarding what refutes duration matching as a method to reduce risk, (2) that a high Solvency 2 ratio is counterproductive and (3) that the Solvency 2 framework falls short by being return agnostic.

STUDY DESIGN A descriptive quantitative evaluation was done of the transverse orientation of the lower lumbar facet joints as measured by computed tomography scanning. OBJECTIVES To evaluate a new parameter for facet joint angulation in the transverse plane (the "facet orientation circle") and to obtain reference values for this new parameter. SUMMARY OF BACKGROUND DATA In other studies, both in vitro and in vivo, the angulation of the facet joints has been measured in degrees relative to the frontal or sagittal plane. These methods have some limitations. The parameter used in the present study has not been described in the literature. METHODS Lower lumbar facet joint orientation was measured in 212 vertebral levels of 123 consecutive patients using the facet orientation circle parameter. Patients with degenerative or developmental abnormalities of the lumbar spine were excluded, as were those with technically inadequate computed tomography studies. RESULTS Mean facet orientation circle diameters (+/-SD) were: L3-L4, 43.7 +/- 10.5 mm; L4-L5, 63.8 +/- 26.4 mm; and L5-S1, 82.3 +/- 23.5 mm. Differences between right and left sides were: L3-L4, 6.3 +/- 7.1 mm; L4-L5, 13.9 +/- 25.3 mm; and L5-S1, 17.9 +/- 16.2 mm, intra-observer variability was 2.3%. CONCLUSIONS Measurement of facet joint angulation using the facet orientation circle is possible and reproducible. The morphometric data presented may be useful as a reference for biomechanical and clinical research of facet joint orientation and asymmetry.

The top quintile portfolio of a linear model that equally weighs value factors Book Value/Price, Cash Flow/Price, Dividend/Price, Earnings/Price and Sales/Price and one 9-month price momentum factor has outperformed the MSCI Developed World benchmark by 18% per year since 2001 and by 13% since 1996. Factors can be ranks or values scaled by their monthly standard deviation. This model performs for all regions and sectors, and especially well for small caps and emerging markets. Across universes the average annual outperformance of top to bottom quintile is of the order of 20% since 2001 with information ratios around 2.The bulk of the performance stems from the factors themselves. Performance improvement of the order of 10% is achieved by optimizing model architecture like dynamically adapting factor weights or ranking within sectors. Risk characteristics improve more and information ratios improve by up to 30%. Factors using analyst’s estimates underperform factors based on reported data in periods of crisis and have to be used with caution.Simple portfolio construction schemes that keep turnover below 10% monthly allow to implement these performances by feasible equal weight portfolios. As such this simple system draws a bottom line of performance that should be achieved by quantitative investment systems.

Noisy markets need extensive descriptions that are noisy themselves, such as deep regression trees that capture many data-local nonlinear anomalies and that do not require arbitrary weighting schemes like traditional linear multifactor models often do. Simple tools allow extraction of general and stock specific insightful information from such regression trees and facilitate factor selection. Large tree-models show excellent out-of-sample predictive power, that we measure and discuss extensively. The method is described by a seven-factor example model for the worldwide industrial sector that delivers 20% quintile-separation excess return out-of-sample and that reveals for instance how following price falls analysts react belatedly and investors overreact and thus create reversal outperformance opportunities.

Stock markets proved to be statistically predictable on an economically interesting scale over the past decade by fully data driven automatically constructed maps that associate to a set of new factor values a return prediction that is the average of historically observed returns for an area in factor space around the new values. Partitioning of the factor space in suitable areas is easily done by regression trees. Annual updating improves performance.Such an updated model with five value and two momentum factors on World Industrials showed out-of-sample over the past decade and after transaction costs more than 90% probability of best to worst quintile outperformance within six months, and 90% probability of more than 15% annual outperformance over ten years. Such models deliver excellent return/risk tradeoff and lower risk by internal diversification of alpha sources, exploiting linear as well as non-linear multifactor anomalies.The choice of factors requires economic expertise and insight, both enhanced by single factor maps and projections of regression tree models that allow to interpret the contents of the noisy and extensive tree models. Such maps as function of time show for instance that momentum factors ceased to work over the past decade while value factors proved reliable.

The evaluation of cell-material surface interactions is important for the design of novel biomaterials which are used in a variety of biomedical applications. While traditional in vitro test methods have routinely used samples of relatively large size, microarrays representing different biomaterials offer many advantages, including high throughput and reduced sample handling. Here, we describe the simultaneous cell-based testing of matrices of polymeric biomaterials, arrayed on glass slides with a low cell-attachment background coating. Arrays were constructed using a microarray robot at 6 fold redundancy with solid pins having a diameter of 375 µ m. Printed solutions contained at least one monomer, an initiator and a bifunctional crosslinker. After subsequent UV polymerisation, the arrays were washed and characterised by X-ray photoelectron spectroscopy. Cell cult ure experiments were carried out over 24 hours using HeLa cells. After labelling with CellTracker ® Green for the final hour of incubation and subsequent fixation, the arrays were scanned. In addition, individual spots were also viewed by fluorescence microscopy. The evaluation of cell-surface interactions in high-throughput assays as demonstrated here is a key enabling technology for the effective development of future biomaterials. Keywords: Microarrays, high-throughput, biomaterials, cell culture, in vitro

First, the author relates his memories of his first encounter with the new Editor-in-Chief of the Acta Neurochirurgica in 1957 and the reasons why it made such an unforgettable impression. Next, follows a discussion of the technical difficulties in the treatment of spinal aneurysmal bone cysts, which may produce extensive destruction of its bony elements. The relatively rare occurrence of these lesions and resulting limited experience provide insufficient grounds for developing rigid rules of surgical treatment. Their treatment must rather rely on experience by means of examples (paradigms). The present author's principles of surgical strategy are total removal of these cysts and repair by means of stabilizing bony autotransplants. A description is given of an unusual case of an aneurysmal bone cyst localized in the cervical-occipital transition area in which 3 D CT images give a better view on stabilization reached by osteoplastic repair of the destroyed structures than can be achieved with previous imaging methods.

A new type of spinous process deviation is described. This variant may cause confusion in the interpretation of anteroposterior (AP) radiographs of the lumbar spine. In the literature, two types of lumbar spinous process deviation (SPD) have been described: 1) SPD due to rotation of the entire vertebra (as in rotatory scoliosis and degenerative arthritis), and 2) SPD as a consequence of developmental asymmetries of the neural arch. The present study demonstrates that spinous process deviation in the AP radiograph is not a reliable diagnostic guide. The authors' quantitative morphologic analysis of computed tomographic (CT) sections of over 200 lower lumbar vertebrae in vivo revealed a third type of SPD, namely isolated deviation of the spinous process, ie, deviation without any associated rotation or asymmetry of the vertebral body or arch. Since the oval shadow cast by the spinous process in AP radiographs is caused by its tip, rather than by its base (as was demonstrated by in vitro tests), it is concluded that the position of the spinous process shadow in AP radiographs cannot be used as a reliable landmark to differentiate between the three types of SPD. This is only possible by means of a CT examination.

Transaxial computed tomographic (CT) sections represent a new approach to vertebral morphometry, allowing certain measurements to be made in vivo for the first time. The cross-sectional morphology of the bodies and pedicles of L3, L4, and L5 was studied in a series of 213 vertebrae. This revealed that the pedicles of L5 arise more laterally from the body of L5 than from L3. Further, the lateral surfaces of the L5 body are inclined obliquely, unlike those of L3. L4 is transitional in form between L3 and L5, more closely resembling the former. This morphology explains the fact, hitherto unnoticed, that the lateral outlines of the pedicles and the lateral borders of the body of L5 are not normally imaged on plain anteroposterior radiographs. It is evident that pathologic changes of the lateral borders of the body of L5 may be invisible also. In cases of transitional vertebrae in the lumbosacral region the presence or absence of the lateral outlines of the pedicles and of the lateral borders of the vertebral body may be of help in identifying the vertebrae on conventional projections.

Le langage medical, la reconnaissance des images, la connaissance. Influence des paradigmes, des ideologies et des normes. Exemple illustrant ces considerations: la premiere description par l'auteur du canal rachidien etroit

1. Five cases of involvement of vertebrae by growths classified as giant-cell tumours, and two cases of involvement by tumours classified as aneurysmal bone cysts are described. 2. The periods of observation after operation in the benign cases were in three cases six years, in one ten years and in one twenty-one years. 3. In one case malignant transformation developed four and a half years after operation and one patient, in whom a sacral tumour was already malignant at the time of operation, died five months later. 4. Four patients showed significant involvement of vertebral bodies. 5. The problems related to the removal of a vertebral body and the measures taken to stabilise the spine are discussed.

In a case material of 254 space-occupying chronic or subacute processes, with one exception, preoperative dyshydration only occurred in processes involving the cerebral hemispheres, the cerebellum and 4th ventricle and tumors developing within the pons.

A method of cisternal fractional encephalography of the posterior fossa fluid spaces is described. This method can be applied in patients who cannot stand lumbar encephalography in the sitting position for one reason or another. Furthermore, a method is described which, in case it has been attempted to obtain filling of the fourth ventricle during ventriculography by means of special positioning or movements of the head, while the air has escaped to the spinal fluid space, to move this spinal air again to the posterior fossa. A spirit level is used to indicate on the encephalograms the posture of the head in relation to gravity.

The cause of hydrocephalus in patients with theArnold-Chiari malformation is not constant and uniform, but is different and varies in every individual case. Decompression of the malformation should be performed when air studies have revealed, that the cerebro-spinal fluid pathways are impeded in the area of malformation. But even so surgical decompression may be ineffective because of the concomitant obstruction of the fluid pathways in other areas. Two cases withArnold-Chiari malformation showing progressive hydrocephalus following surgical decompression are described. In the first case with obstructive hydrocephalus surgical decompression resulted in communicating hydrocephalus with obstruction of the cerebro-spinal fluid circulation in the anterior part of the basal cisterns. In the second case communicating hydrocephalus was found preoperatively. Surgical decompression resulted in obstructive hydrocephalus.

Graves' disease developed in a 45 years old male patient suffering from long standing diabetes mellitus with mild retinopathy. During a period of overtreatment with antithyroid drugs and following psychological stress, progressive oedematous exophthalmos developed which caused an unusual and very alarming ophthalmological picture. Initially there was a good response to 131I and corticosteroid therapy, but later on pituitary stalk section had to be done, after which the condition of the eyes improved. The clinical picture was interpreted as the result of Graves' disease in a patient whose vessels were already damaged by diabetic retinopathy. Serum EPS activity was elevated before the operation and could not be demonstrated postoperatively.

1. A measuring instrument is described which enables the surgeon to determine the anteroposterior diameter of the vertebral canal during operation. 2. Developmental narrowness of the lumbar vertebral canal is shown to exist and to be caused by an abnormally short antero-posterior diameter. 3. In patients with a narrow, although not abnormally narrow, lumbar vertebral canal, slight deformities such as posterior spur formation or small disc protrusions may produce particular symptoms, which are interesting from a clinical as well as from a medico-legal point of view.

A follow-up study of forty-seven patients treated for traumatic lesions of the cervical spine with and without associated neural deficits is presented. Operation was performed six hours to eight months after injury. The objectives of these procedures were to remove any causes of compression of the cord or nerve roots, especially anterior compression, to reduce the dislocation and kyphosis, and to stabilize the cervical spine by interbody fusion. Preoperative and postoperative care is described as well as the exposure used for different levels of the spine and the three types of bone-grafting procedures that were developed to correct and stabilize the deformities associated with the various fractures and fracture-dislocations encountered. Normal or satisfactory alignment was regained in all but three of the forty-one surviving patients, and solid fusion occurred in the forty-one surviving patients who were followed long enough to determine the results of fusion. There was no evidence that the operation had aggravated any neural deficits, although in two of the six patients who died after acute complete transverse cord lesions it was thought that early operation within twelve hours of injury may have contributed to the fatal outcome. The functional results of operation in terms of relief of neck pain and recovery of cord and nerve-root function were encouraging. The prompt recovery of function of a few patients who had not improved after as long as 3.5 months of non-operative treatment suggested that reduction of the dislocation and correction of the kyphosis, combined with removal of the posteriorly extruded disc material in nine patients, had corrected a vascular insufficiency. It was concluded that anterolateral operations may be harmful for patients with acute complete transverse lesions of the cord but that traumatic abnormalities causing compression of the anterior part of the cord or traction and consequent anterior pressure on the cord (the result of angulation of the cervical spine) can be eliminated or corrected under direct vision in a way not possible by laminectomy. It was further concluded that fusion is easily effected through the anterolateral approach, whereas after laminectomy posterior fusion may be difficult or impossible.

Description of 6 patients with A. V. A. of the posterior fossa. Case I showed a combination of congenital kyphoscoliosis of the thoracic spinal column with spastic paresis of both legs; also an extensive animal skin naevus, hemangioma of the skin, sarcoma and angioma of left occipital lobe, meningeal sarcomatosis and an A. V. A. of the right cerebellar lobe and left cerebellar tonsil. Rupture of the A. V. A. caused a subdural hematoma of the posterior fossa. Patient operated upon when already dying. Removal of subdural hematoma and A. V. A. The patient did not improve and died 2 days later.

Portal [22] hat als Erster 1803 uber eine durch eine Wirbelsaulenverkrummung verursachte Verengung des Wirbelkanals berichtet. Er unterschied zwischen uni- und multisegmentalen Einengungen des Kanals. In seinem Material waren Rachitis und Lues die Hauptursachen. In einem seiner Falle war der Wirbelkanal auf die Halfte seines normalen Durchmessers eingeengt. Einige seiner Patienten hatten Schwache in den Beinen entwickelt. Er hatte aber auch Verengung des Wirbelkanals ohne Lahmungserscheinungen, Schwachen oder Muskelatrophien der Beine beobachtet. Auch Ollivier [21] berichtete uber rachitische Verengung des Wirbelkanals. Die nachste Veroffentlichung erfolgte erst etwa ein Jahrhundert spater, als Sumita [30] eine Enge des Wirbelkanals bei Achondroplasie beschrieb. Sarpyener [25, 26] veroffentlichte Falle von engem Wirbelkanal als ein Teil angeborener Misbildungen wie Spina bifida und Diastematomyelie. Das Auftreten von Verengungen wurde bis dahin immer mit Erkrankungen oder Misbildungen der Wirbelsaule in Zusammenhang gebracht.

As this paper forms part of a “cours de perfectionment neuroradiologique”, the emphasis has been laid on Sect. 12.3. The problems in nomenclature are of commom interest to all specialist involved in some aspects of stenosis. The linguistic symbols in scientific communication are intended to be noniconical. The choice of scientific terminology is therefore essentially arbitrary. Unfortunately, many clinical terms are failing in explicitness in their definition because they are the result of tacit convention. But even outspoken agreements reached through the activities of committees for nomenclature are too often an outcome of compromise and neglect of linguistic implements or implications, the latter representing a science in itself.

There is ever-increasing literature pointing out that gene expression in tumour cells is different from that in normal cells from which or in which the tumour originates. In general, neoplasia is characterized by misprogramming of protein synthesis (16).

Pyruvate kinase isozyme distribution was studied in 101 intracranial tumours of various nature and origin, and in normal human brain (both foetal and adult). In foetal brain, five different forms could be detected by electrophoresis (K4, K3M, K2M2, KM3, and M4). In adult brain, the M4 type, K3M hybrid, and K4 are present; the M type is largely predominant. Alanine inhibition of pyruvate kinase can be used to discriminate between M and K-type pyruvate kinase. The results obtained in an alanine inhibition test are in agreement with the electrophoretic pattern. Pyruvate kinase from foetal brain and brain of a newborn is more inhibited compared with pyruvate kinase from adult brain. In adult brain a high residual activity of pyruvate kinase is found in the presence of alanine. Well differentiated neuroepithelial tumours,i.e., astrocytomas, oligodendrogliomas, and ependymomas showed also relatively high residual activities, though less than in normal adult brain. On the contrary, in poorly differentiated gliomas low residual activity was found. Alanine inhibition of pyruvate kinase correlates well with degree of differentiation of these tumours. There is also a strong correlationship between alanine inhibition of pyruvate kinase and one year survival after “total or subtotal” resection of gliomas in adults. When in gliomas the residual activity is determined not in the centre of the tumour but more towards the periphery, much higher residual activity is found. It is suggested that brain biopsies in which a residual activity higher than 70% is found probably contain no tumour in the paraffin slides. Poorly differentiated gliomas were characterized by the presence of type K, and the hybrids K3M. In well differentiated gliomas, besides K4 and K3M, M4 was also present. Alanine inhibition was in agreement with the electrophoretic pattern in all tumours. In children (age 1–11 years) gliomas showed no correlation between the distribution of pyruvate kinase isozymes and the histological classification and grading. Of the non-neuro-epithelial tumours studied relatively high residual activities were found for pyruvate kinase in haemangioblastomas, chromophobe adenomas, and craniopharyngiomas. This was also found in an arteriovenous malformation. Other non-neuroepithelial tumours showed much less residual activity. These included benign tumours, meningiomas, neurilemmomas, malignant metastatic tumours, and fibrosarcomas. It was also found in cavernomas. The determination of pyruvate kinase activity in the presence of alanine may be useful for the diagnosis and treatment of intracerebral tumours, in particular gliomas of adults. The alanine inhibition test is a reliable quantitative procedure. It can be performed in 10 minutes, and may well fit in the scope of a surgical procedure.

Pyruvate kinase isozymes were studied in normal brain tissue (both fetal and adult) and in meningiomas and malignant gliomas. In fetal brain five different forms could be detected by electrophoresis (K4, K3M, K2M2, KM3, and M4). In adult brain the M4-type, K3M hybrid, and K4-type are present; the M isozyme is largely predominant. Alanine inhibition of pyruvate kinase is in agreement with the electrophoretic pattern. Pyruvate kinase from fetal brain and brain of a newborn is more inhibited compared with pyruvate kinase from adult brain. The Lineweaver-Burk plots for pyruvate kinase from fetal brain and brain of the newborn are nonlinear due to the presence of hybrids. Pyruvate kinase from meningiomas and malignant gliomas is strongly inhibited by alanine. Electrophoresis proved the presence of mainly K4 type and the hybrid K3M, which is in agreement with the alanine inhibition. Determination of the Km's for phosphoenolpyruvate supports this conclusion. The determination of the alanine inhibition of pyruvate kinase may be a diagnostic tool in surgery for gliomas.

Zwischen den Foramina intervertebralia bzw. dem Verlauf der Spinalnervenwurzeln oberhalb und unterhalb des 1. Thorakalwirbels bestehen erhebliche Unterschiede. Zwischen dem 1. Brustwirbel und dem Kreuzbein liegen die Bogenwurzeln und die Wirbelgelenke ziemlich genau hinter den Wirbelkorpern, es besteht daher kein Kontakt zwischen den Querfortsatzen und den Processus articulares posteriores. Zwischen 2. Hals- und 1. Brustwirbel projezieren sich die Bogenwurzeln nach hinten und ausen, die Processus articulares posteriores grenzen seitlich und hinten an die Wirbelkorper an. Ein groser Teil dieser Processus geht sogar gleichmasig aus den Querfortsatzen hervor. Der zervikale intervertebrale Kanal ist deutlich groser als das Foramen intervertebrale. Fur rontgenologische Zwecke unterschied Pichler (1955) am zervikalen intervertebralen Kanal zwei Teile, ohne allerdings deren exakte Grenzen zu beschreiben: Der Winkel zwischen beiden Teilen erfordert unterschiedliche Lagerung des Patienten bei Schichtaufnahmen der einzelnen Abschnitte.

Man kann die Entwicklung einer Wissenschaft aus verschiedenen historischen Blickwinkeln betrachten. Es ist unmoglich, in so kurzer Zeit eine Geschichte aller Errungenschaften zu prasentieren und weil es der Wunsch war, das ich eine Ubersicht der Vergangenheit als Ausgangspunkt fur die Betrachtung von moglichen zukunftigen Entwicklungen benutzen sollte, schien mir eine formale Analyse von „Trends“ ein geeigneter Weg. Dem folgend werde ich geschichtliche Ereignisse nicht systematisch, sondern nur beispielhaft zur Kennzeichnung bestimmter Trends anfuhren.

Stenosis of the vertebral canal is a form of compressive stenosis in contrast to transport stenosis of vessels or other channels. The concept, definition and pathomorphological properties are discussed. As it is a form of compressive stenosis, the diagnosis is based on measurements of diameters rather than of cross-sectional surfaces. The biomechanical action of compressive stenosis is compression of the fixed living content at two opposite sites or at all sites. The special properties of sciatica in stenosis are described and presented in tabular form. Some properties of neurogenic intermittent claudication (I. Cl.) in the presence of stenosis are discussed. There is a predominance of sciatica at rest and of motor weakness during walking. The mechanism of neurogenic I. Cl. is obscure. Stenosis of the lumbar vertebral canal is one of the conditional determinants of I. Cl. The data presented in this paper demonstrate, however, that stenosis is not an absolute determinant of I. Cl. and that its production depends on the combination with other determinants. The theory is advanced that other determinants may be related to changes in the caudal nerve roots due to either constitutional properties or to subclinical changes induced by ageing and chronic wear and tear, and compression and traction in the area of stenosis during various bodily activities. Suppression of sciatica during I. Cl. is a phenomenon which is particularly difficult to explain.