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Data sharing: The PHOSP-COVID study protocol, consent form, definition, and derivation of clinical characteristics and outcomes, training materials, regulatory documents, information about requests for data access, and other relevant study materials are available online. UK Biobank information can be released once necessary approvals have been obtained. Other data (eg, the R code and protocol) will be made available on reasonable request to the corresponding author. Copyright © 2023 The Author(s). Background: Sleep disturbance is common following hospital admission both for COVID-19 and other causes. The clinical associations of this for recovery after hospital admission are poorly understood despite sleep disturbance contributing to morbidity in other scenarios. We aimed to investigate the prevalence and nature of sleep disturbance after discharge following hospital admission for COVID-19 and to assess whether this was associated with dyspnoea. Methods: CircCOVID was a prospective multicentre cohort substudy designed to investigate the effects of circadian disruption and sleep disturbance on recovery after COVID-19 in a cohort of participants aged 18 years or older, admitted to hospital for COVID-19 in the UK, and discharged between March, 2020, and October, 2021. Participants were recruited from the Post-hospitalisation COVID-19 study (PHOSP-COVID). Follow-up data were collected at two timepoints: an early time point 2–7 months after hospital discharge and a later time point 10–14 months after hospital discharge. Sleep quality was assessed subjectively using the Pittsburgh Sleep Quality Index questionnaire and a numerical rating scale. Sleep quality was also assessed with an accelerometer worn on the wrist (actigraphy) for 14 days. Participants were also clinically phenotyped, including assessment of symptoms (ie, anxiety [Generalised Anxiety Disorder 7-item scale questionnaire], muscle function [SARC-F questionnaire], dyspnoea [Dyspnoea-12 questionnaire] and measurement of lung function), at the early timepoint after discharge. Actigraphy results were also compared to a matched UK Biobank cohort (non-hospitalised individuals and recently hospitalised individuals). Multivariable linear regression was used to define associations of sleep disturbance with the primary outcome of breathlessness and the other clinical symptoms. PHOSP-COVID is registered on the ISRCTN Registry (ISRCTN10980107). Findings: 2320 of 2468 participants in the PHOSP-COVID study attended an early timepoint research visit a median of 5 months (IQR 4–6) following discharge from 83 hospitals in the UK. Data for sleep quality were assessed by subjective measures (the Pittsburgh Sleep Quality Index questionnaire and the numerical rating scale) for 638 participants at the early time point. Sleep quality was also assessed using device-based measures (actigraphy) a median of 7 months (IQR 5–8 months) after discharge from hospital for 729 participants. After discharge from hospital, the majority (396 [62%] of 638) of participants who had been admitted to hospital for COVID-19 reported poor sleep quality in response to the Pittsburgh Sleep Quality Index questionnaire. A comparable proportion (338 [53%] of 638) of participants felt their sleep quality had deteriorated following discharge after COVID-19 admission, as assessed by the numerical rating scale. Device-based measurements were compared to an age-matched, sex-matched, BMI-matched, and time from discharge-matched UK Biobank cohort who had recently been admitted to hospital. Compared to the recently hospitalised matched UK Biobank cohort, participants in our study slept on average 65 min (95% CI 59 to 71) longer, had a lower sleep regularity index (–19%; 95% CI –20 to –16), and a lower sleep efficiency (3·83 percentage points; 95% CI 3·40 to 4·26). Similar results were obtained when comparisons were made with the non-hospitalised UK Biobank cohort. Overall sleep quality (unadjusted effect estimate 3·94; 95% CI 2·78 to 5·10), deterioration in sleep quality following hospital admission (3·00; 1·82 to 4·28), and sleep regularity (4·38; 2·10 to 6·65) were associated with higher dyspnoea scores. Poor sleep quality, deterioration in sleep quality, and sleep regularity were also associated with impaired lung function, as assessed by forced vital capacity. Depending on the sleep metric, anxiety mediated 18–39% of the effect of sleep disturbance on dyspnoea, while muscle weakness mediated 27–41% of this effect. Interpretation: Sleep disturbance following hospital admission for COVID-19 is associated with dyspnoea, anxiety, and muscle weakness. Due to the association with multiple symptoms, targeting sleep disturbance might be beneficial in treating the post-COVID-19 condition. Funding: UK Research and Innovation, National Institute for Health Research, and Engineering and Physical Sciences Research Council. UK Research and Innovation, National Institute for Health Research, and Engineering and Physical Sciences Research Council.

Eccentric cycling (ECC) may be an attractive exercise method in COPD because of both low cardiorespiratory demand and perception of effort compared with conventional concentric cycling (CON) at matched mechanical loads. However, it is unknown whether ECC can be performed by individuals with COPD at an intensity able to cause sufficient metabolic stress to improve aerobic capacity.What are the cardiopulmonary and metabolic responses to ECC in people with COPD and healthy volunteers when compared with CON at matched mechanical loads?Thirteen people with COPD (mean ± SD age, 64 ± 9 years; FEVAt matched mechanical loads, oxygen uptake, minute ventilation, heart rate, systolic BP, respiratory exchange ratio (all P .001), capillary lactate, perceived breathlessness, and leg fatigue (P .05) were lower in both groups during ECC than CON. Muscle lactate content increased (P = .008) and muscle phosphocreatine decreased (P = .012) during CON in COPD, which was not evident during ECC.Cardiopulmonary and blood lactate responses during submaximal ECC were less compared with during CON at equivalent mechanical workloads in healthy participants and COPD patients, and this was confirmed at a muscle level in COPD patients. Submaximal ECC was well tolerated and allowed greater mechanical work at lower ventilatory cost. However, in people with COPD, a training intervention based on ECC is unlikely to stimulate cardiovascular and metabolic adaptation to the same extent as CON.

Complex problems can often only be solved with a workflow of different applications whose progress depends also on the need of shared data. There are different challenges that developers must overcome when sharing data in a workflow; each application may have very different requirements in how they access and consume shared data. For example, data access can be online or offline, data sizes and types may vary as well as the frequency they are consumed and produced by applications in the workflow. Moreover, producers and consumers may not run at the same time scale, thus introducing possible latency. Also, the deployment system itself plays an important role, especially when considering low latency read/write operations and reliability in case of failures.To facilitate the communication of information within a workflow, in this paper we present the Data Broker, a programming model helping applications to share data in the form of named tuples, relying on the concept of namespaces providing software-based data isolation. The client API provides access to the namespaces through mainly put/get primitives, enriched also with namespace management functions and key browsing/querying. Our programming model can support different backends for storing/retrieving the data: in this paper, we will focus on the Redis implementation. By using Redis as backend, we enable the Data Broker with the reliability and infrastructure provided by it, which allows users to have access to a fast local or remote in-memory distributed key-value/object store configured as a set of independent instances or a coordinated cluster.On top of Redis, we implement data access function, namespace management, asynchronous call with client-side queues per server, and key-space browsing.

Despite the wide-ranging benefits of pulmonary rehabilitation, conflicting results remain regarding whether people with COPD can improve their peak oxygen uptake (V˙OThe goal of this study was to investigate the effect of aerobic training and exercise prescription on V˙OA systematic review was performed by using MEDLINE, Embase, Cumulative Index to Nursing and Allied Health Literature, and Cochrane databases for all studies measuring V˙OA total of 112 studies were included (participants, N = 3,484): 21 controlled trials (n = 489), of which 13 were randomized (n = 288) and 91 were uncontrolled (n = 2,995) studies. Meta-analysis found a moderate positive change in V˙OOverall, people with COPD achieved moderate improvements in V˙OPROSPERO; No.: CRD42018099300; URL: https://www.crd.york.ac.uk/prospero/.

Rachael Caera Ward (nee Darlison) was born in Haywards Heath, West Sussex. Her family moved to Winchester in 1997, and she attended the Westgate School and Peter Symonds Sixth Form College. Rachael decided on a medical career after work experience with her general practitioner aunt and went up to study medicine at Clare College, Cambridge, in 2010. While at Cambridge she met her future husband, Matthew, a PhD student in music. After Rachel graduated from her pre-clinical course, they married in 2013, and Rachael started clinical studies at Imperial College, London. Her daughter was born in 2015 and Rachael took substantial maternity leave out of her studies. She received her degree with distinction in 2017, five days after giving birth to her first …

While developing the protein folding application for the IBM Blue Gene®/L supercomputer, some frequently executed computational kernels were encountered. These were significantly more complex than the linear algebra kernels that are normally provided as tuned libraries with modern machines. Using regular library functions for these would have resulted in an application that exploited only 5-10% of the potential floating-point throughput of the machine. This paper is a tour of the functions encountered; they have been expressed in C++ (and could be expressed in other languages such as Fortran or C). With the help of a good optimizing compiler, floating-point efficiency is much closer to 100%. The protein folding application was initially run by the life science researchers on IBM POWER3™ machines while the computer science researchers were designing and bringing up the Blue Gene/L hardware. Some of the work discussed resulted in enhanced compiler optimizations, which now improve the performance of floating-point-intensive applications compiled by the IBM VisualAge® series of compilers for POWER3, POWER4™, POWER4+™, and POWER5™. The implementations are offered in the hope that they may help in other implementations of molecular dynamics or in other fields of endeavor, and in the hope that others may adapt the ideas presented here to deliver additional mathematical functions at high throughput.

This paper presents results on a communications-intensive kernel, the three-dimensional fast Fourier transform (3D FFT), running on the 2,048-node Blue Gene®/L (BG/L) prototype. Two implementations of the volumetric FFT algorithm were characterized, one built on the Message Passing Interface library and another built on an active packet Application Program Interface supported by the hardware bring-up environment, the BG/L advanced diagnostics environment. Preliminary performance experiments on the BG/L prototype indicate that both of our implementations scale well up to 1,024 nodes for 3D FFTs of size 128 × 128 × 128. The performance of the volumetric FFT is also compared with that of the Fastest Fourier Transform in the West (FFTW) library. In general, the volumetric FFT outperforms a port of the FFTW Version 2.1.5 library on large-node-count partitions.

Blue Matter is the application framework being developed in conjunction with the scientific portion of the IBM Blue Gene® project. We describe the parallel decomposition currently being used to target the Blue Gene/L machine and discuss the application-based trace tools used to analyze the performance of the application. We also present the results of early performance studies, including a comparison of the performance of the Ewald and the particle-particle particle-mesh (P3ME) methods, compare the measured performance of some key collective operations with the limitations imposed by the hardware, and discuss some future directions for research.

We describe the design of a dual-issue single-instruction, multiple-data-like (SIMD-like) extension of the IBM PowerPC® 440 floating-point unit (FPU) core and the compiler and algorithmic techniques to exploit it. This extended FPU is targeted at both the IBM massively parallel Blue Gene®/L machine and the more pervasive embedded platforms. We discuss the hardware and software codesign that was essential in order to fully realize the performance benefits of the FPU when constrained by the memory bandwidth limitations and high penalties for misaligned data access imposed by the memory hierarchy on a Blue Gene/L node. Using both hand-optimized and compiled code for key linear algebraic kernels, we validate the architectural design choices, evaluate the success of the compiler, and quantify the effectiveness of the novel algorithm design techniques. Our measurements show that the combination of algorithm, compiler, and hardware delivers a significant fraction of peak floating-point performance for compute-bound-kernels, such as matrix multiplication, and delivers a significant fraction of peak memory bandwidth for memorybound kernels, such as DAXPY, while remaining largely insensitive to data alignment.

In this paper we describe the context, architecture, and challenges of Blue Matter, the application framework being developed in conjunction with the science effort within IBM's Blue Gene project. The study of the mechanisms behind protein folding and related topics can require long time simulations on systems with a wide range of sizes and the application supporting these studies must map efficiently onto a large range of parallel partition sizes to optimize scientific throughput for a particular study. The design goals for the Blue Matter architecture include separating the complexities of the parallel implementation on a particular machine from those of the scientific simulation as well as minimizing system environmental dependencies so that running an application within a low overhead kernel with minimal services is possible. We describe some of the parallel decompositions currently being explored that target the first member of the Blue Gene family, BG/L, and present simple performance models for these decompositions that we are using to prioritize our development work. Preliminary results indicate that the high-performance networks on BG/L will allow us to use FFT-based techniques for periodic electrostatics with reasonable speedups on 512-1024 node count partitions even for systems with as few as 5000 atoms.

Densfrakturen machen etwa 10 bis 15% der Frakturen der Halswirbelsaule aus. Als Verletzungsfolgen wird ein weites Spektrum zwischen fehlender klinischer Symptomatik und dem sofortigen Tod beschrieben. Eine neurologische Symptomatik wird in dieser Patientengruppe mit 6 bis 25% angegeben. Die Gesamtmortalitat betragt bei diesen Patienten 3 bis 8%. Densfrakturen mit primarer Myelopathie sind in der Literatur in geringer Anzahl beschrieben. Wir berichten uber eine traumatische Densfraktur Typ III mit primarer Myelopathie, die durchgefuhrte Therapie und den Verlauf.

Storage class memory is receiving increasing attention for use in HPC systems for the acceleration of intensive IO operations. We report a particular instance using SLC FLASH memory integrated with an IBM BlueGene/Q supercomputer at scale Blue Gene Active Storage, BGAS. We describe two principle modes of operation of the non-volatile memory: 1 block device; 2 direct storage access DSA. The block device layer, built on the DSA layer, provides compatibility with IO layers common to existing HPC IO systems POSIX, MPIO, HDF5 and is expected to provide high performance in bandwidth critical use cases. The novel DSA strategy enables a low-overhead, byte addressable, asynchronous, kernel by-pass access method for very high user space IOPs in multithreaded application environments. Here, we expose DSA through HDF5 using a custom file driver. Benchmark results for the different modes are presented and scale-out to full system size showcases the capabilities of this technology.

Hook-plate fixation is designed for posterior cervical stabilization from C2 to C7. Indications remain the same as for standard posterior fixations. The prime indications are discoligamentous injuries. The plates are hooked under the lower laminas and attached to the articular masses of the upper vertebra by oblique screws. An H-graft is placed between the spinous processes. The vertebrae are compressed together by the plates at three points, the facet joints, and graft. The resulting pre-stressed system is stable in all directions. A protocol for safe reduction of cervical dislocations is observed. Of 70 patients treated from 1979 to 1986, 51 were examined 12-54 months after surgery. All fusions consolidated. Two neurologic complications not attributable to the fixation occurred. Other major complications were not seen.

The neonatal progeroid syndrome (NPS), or Wiedemann-Rautenstrauch, is a rare autosomal recessive disorder comprised of generalized lipoatrophy except for fat pads in the suprabuttock areas, hypotrichosis of the scalp hair, eyebrows, and eyelashes, relative macrocephaly, triangular face, natal teeth, and micrognathia. We report on 5 new patients who demonstrate phenotypic variability and who represent the single largest series of NPS reported to date. Two of the patients are from an African-American kindred, an ethnic occurrence not reported previously. The fact that there are 2 pairs of sibs among the 5 patients further supports that NPS is an autosomal recessive condition. This report also includes a review of the previously reported 16 patients and compares them with the 5 new patients. Abnormalities in endocrine and lipid metabolism were found in 3 of 5 patients. Skeletal findings in 2 of our patients demonstrated some new findings as well as the typical radiological abnormalities previously noted in NPS. It is apparent, based on the 21 cases, that mild to moderate mental retardation is common in NPS. Long term follow-up of patients with NPS should provide more information relative to their ultimate psychomotor development. NPS is usually lethal by 7 months; however, on rare occasions, patients have survived into the teens. Our 3 surviving patients range in age from 16-23 months. Variability in the phenotype of NPS is clear; however, the phenotype remains distinct enough to allow a secure diagnosis.

Fractures of the odontoid are reported to contribute in 15% to cervical spine fractures. The clinical findings range between no symptoms at all and sudden death. Neurological deficits are seen in 6 to 25% of these patients. The overall mortality in this group is 3 to 8%. Fractures of the odontoid process combined with primary myelopathy has been reported seldom. We describe a traumatic fracture of the odontoid process with primary myelopathy, the chosen therapy and the follow-up.

Restriction endonuclease mapping demonstrates a 3' end deletion of one erythropoietin receptor (EpoR) gene in TF-1 cells, a human erythroleukemia cell line that overexpresses the EpoR and proliferates in response to erythropoietin (Epo). EpoR mRNA transcripts are highly abundant and normal in size. These findings raise interesting questions about the possible role of this EpoR gene abnormality in the pathogenesis of the erythroleukemia from which this cell line was derived. This is the first report of an abnormal human erythropoietin receptor gene.

In acute cervical spine trauma, skull traction is used to reduce a dislocation or fracture dislocation, to immobilize an unstable lesion until definitive treatment (operative or conservative) is possible or, more rarely, as a definitive treatment until healing occurs. This method may be dangerous when an unstable lesion is accidentally overdistracted. A few cases have been reported in the literature, some with neurological complications. We report five cases in which overdistraction was seen. Two hangman's fractures were overdistracted. One of the two patients developed a Cheyne-Stokes breathing pattern during traction which resolved after the weight was reduced. Furthermore, two hyperextension/distraction injuries (C4/5 and C6/7) and one bilateral C5/6 fracture dislocation were overdistracted without neurological deterioration. Occipitocervical dislocations, fractures of the odontoid process, hangman's fractures, hyperextension/distraction injuries and bilateral dislocations or fracture dislocations may present disruption of both the anterior and posterior elements. Therefore, these injuries are specially vulnerable to overdistraction when skull traction is used. To prevent accidental overdistraction during skull traction, we recommend the use of less weight than is generally proposed in the literature. To reduce a dislocation, we start traction weight at 2 kg and slowly increase it under continuous neurological and radiological monitoring until reduction is completed. Traction of 5–7 kg is usually sufficient; however, heavier traction may occasionally be necessary. After reduction is completed, traction is reduced to 2 kg. This weight is sufficient to immobilize a lesion until definitive treatment is possible. Inadvertent rotation may be prevented by placing sandbags on both sides of the head.

N-body simulations present some of the most interesting challenges in the area of massively parallel computing, especially when the object is to improve the time to solution for a fixed-size problem. The Blue Matter molecular simulation framework was developed specifically to address these challenges, to explore programming models for massively parallel machine architectures in a concrete context, and to support the scientific goals of the IBM Blue Gene® Project. This paper reviews the key issues involved in achieving ultrastrong scaling of methodologically correct biomolecular simulations, particularly the treatment of the long-range electrostatic forces present in simulations of proteins in water and membranes. Blue Matter computes these forces using the particle-particle particle-mesh Ewald (P3ME) method, which breaks the problem up into two pieces, one that requires the use of three-dimensional fast Fourier transforms with global data dependencies and another that involves computing interactions between pairs of particles within a cutoff distance. We summarize our exploration of the parallel decompositions used to compute these finite-ranged interactions, describe some of the implementation details involved in these decompositions, and present the evolution of strong-scaling performance achieved over the course of this exploration, along with evidence for the quality of simulation achieved.

Calcaneal fractures in young children are rare. Bilateral calcaneal fractures in this age group are exceptional. In the literature only 4 cases of bilateral calcaneal fractures have been reported, and the youngest patient was 6 years old (range 6-17 years). Jonasch estimated that calcaneal fractures accounted for 0.005% of all fractures before the age of 15, in contrast to 1%-2% in adults. This is confirmed by other studies. It is not unlikely that the incidence is indeed higher because the joint involvement in childhood injuries is often subtle, and the fracture can easily be overlooked on initial X-ray examination. We survey the literature and report the case of a 5-year-old boy who sustained bilateral calcaneal fractures and an additional fracture of the neck of the talus on one side, a combination which to our knowledge has never been described before.

Objective. —To determine whether a program incorporating smoking intervention and use of an inhaled bronchodilator can slow the rate of decline in forced expiratory volume in 1 second (FEV1) in smokers aged 35 to 60 years who have mild obstructive pulmonary disease. Design. —Randomized clinical trial. Participants randomized with equal probability to one of the following groups: (1) smoking intervention plus bronchodilator, (2) smoking intervention plus placebo, or (3) no intervention. Setting. —Ten clinical centers in the United States and Canada. Participants. —A total of 5887 male and female smokers, aged 35 to 60 years, with spirometric signs of early chronic obstructive pulmonary disease. Interventions. —Smoking intervention: intensive 12-session smoking cessation program combining behavior modification and use of nicotine gum, with continuing 5-year maintenance program to minimize relapse. Bronchodilator: ipratropium bromide prescribed three times daily (two puffs per time) from a metered-dose inhaler. Main Outcome Measures. —Rate of change and cumulative change in FEV1over a 5-year period. Results. —Participants in the two smoking intervention groups showed significantly smaller declines in FEV1than did those in the control group. Most of this difference occurred during the first year following entry into the study and was attributable to smoking cessation, with those who achieved sustained smoking cessation experiencing the largest benefit. The small noncumulative benefit associated with use of the active bronchodilator vanished after the bronchodilator was discontinued at the end of the study. Conclusions. —An aggressive smoking intervention program significantly reduces the age-related decline in FEV1in middle-aged smokers with mild airways obstruction. Use of an inhaled anticholinergic bronchodilator results in a relatively small improvement in FEV1that appears to be reversed after the drug is discontinued. Use of the bronchodilator did not influence the long-term decline of FEV1. (JAMA. 1994;272:1497-1505)

The great expansion in monasticism in Normandy and England in the eleventh and twelfth centuries is a commonplace of medieval history, as is the marked diminution in monastic grants after c. 1200. Far more attention, however, has been paid to the religious houses than to their founders, and it is only by looking at a baronial family over a long period that one can discern the fashions which undoubtedly existed in monastic benefaction and the changes in attitude of successive generations. The Clare family were both long-lasting and prolific, and, because of the numerous changes in the landed position of various members of the family, it is possible to see how closely in the eleventh and twelfth centuries the acquisition of new territories and the endowment of monasteries went together. Moreover, we are able to trace the changing preferences for different monastic orders and, to some extent, the reasons for this, and, in addition, to see this in the context not only of Normandy and England, but of Wales and Ireland as well. Whereas in the eleventh and early twelfth century, the Clares' gifts passed to Benedictine houses, many of them Norman or with Norman connections, they became more interested later in the new orders of the Augustinian canons and Cistercians which were spreading rapidly over Europe. At the same time they made grants to the military orders of the Hospitallers and Templars which, by giving knights the opportunity to combine fighting with a monastic life, fused two ideals of the twelfth-century world. In contrast to the variety and amount of these monastic benefactions, the Clares were content in the thirteenth century to make only the occasional grant, but they were insistent on maintaining their rights of patronage. In addition, their interest turned to the new orders of friars. There is, however, no indication here of continuous family interest from one generation to the next as would have been the case in the early twelfth century.

SUMMARYFixation of atmospheric dinitrogen by bacteria associated with contextual tissues of sporophores of Fomitopsis pinicola, Fomes fomentarius, and Echinodontium tinctorium is reported. Since ni...

An empirical equation has been found that appears to closely fit the annual variation of temperature in a stress. This equation is a modified sine curve and gives the temperature of the stream water as a function of the day of the water year and the average annual temperature of the stream. The applicability of the equation was verified using field data for 37 different stream stations. This data was analyzed by the method of least squares, and the average index of correlation obtained was 0.979. It was observed that the annual average temperature of the streams studied did not vary appreciably from year to year. In addition, the empirical coefficients of the temperature sine curve also did not change materially from year to year. Analysis of only 12 monthly average temperatures was observed to yield almost identical results as an analysis of 365 daily temperature readings. Although all of the calculations were performed on an IBM 650 computer, this means that the required calculations can be made by hand within a reasonable time.

Tanks in the form of a surface of revolution are sometimes employed for carrying fuel. The purpose of this paper is to show how the stresses, due to the internal hydrostatic pressure, in a shell of this kind can be calculated when the equation of the generating curve is given. The acceleration imposed on the shell and its contents will be assumed to be at right angles to the axis of revolution, hence shear as well as direct stresses are set up. It will be supposed that no longitudinal bulkheads are fitted, and the shell will be taken as very thin so that the bending stresses in it are negligible. No attempt will be made to examine the stress distribution in the neighbourhood of a relatively rigid supporting ring; as shown by Timoshenko these ‘ end effects ’ are appreciable only in the immediate vicinity of the support. Nor will the stability be considered of those portions of the shell which are subjected to compression. Thus attention will be confined to what are commonly described as the membrane stresses.

Some recent observations on the behavior of radicals in solid and near-solid media are reviewed. Polymerization in a matrix of swollen polymer molecules is first discussed, and this is followed by a consideration of the photochemical polymerization of crystalline methacrylic acid as studied by electron spin resonance, optical microscopy, and kinetics methods. The behavior of radicals produced on crystal faces was also investigated, and it is suggested that their behavior may be explained by assuming that their energies of interaction with the surface cover a wide range and that, on raising the temperature, propagation and termination reactions occur. Two types of polymer were produced by bulk polymerization of the crystals, one clear and glassy, the other fibrous or granular; both were amorphous and not oriented, and it was concluded that the crystal lattice exerted no influence on the configuration of the polymer produced from it. The reaction seems to proceed by a phase boundary process rather than by propagation through the lattice.

The paper describes the appearance, properties, and ultrastructure of red oak heartwood containing dark discolorations. The possible cause and origin of discoloration are discussed, although the etiology of the stain is not explicit. It was found that the heartwood stain moves from ray parenchyma to adjoining vessels, fibers, and tracheids by the pit membranes and plasmodesmata. It appears that there may be extended openings in the pit membrane which may facilitate the movement of materials through such a specialized filamentous structure. Internal checking or honeycomb as an indirect result of the discoloring material is mentioned.

An equation applicable for both laminar and turbulent flow in porous media has been developed and experimentally verified. This equation expresses the pressure drop per unit length as a function of the absolute viscosity and mass density of the fluid and the macroscopic velocity. Because this equation is dimensionally homogeneous, any consistent set of units (cgs, etc.) may be used. All of the experimental data are represented on a plot of the Fanning friction factor for porous media versus the Reynolds number for porous media, in which the characteristic length, in both cases, is the square root of the permeability. The analogy between this plot and similar plots for circular pipes is noted together with the differences. The relationship between filtration and sedimentation is also shown. Water was the fluid used in all of the experimental runs. Glass beads, ion exchange resin, sand, gravel, anthracite coal, and granular activated carbon were the porous media used; all of these media are commercially available. Some of the glass beads media were approximately uniform in size.

Percutaneous angioplasty catheter balloons may rupture if over-inflated. Balloon inflation pressures are not always measured. We describe a simple and inexpensive method for limiting balloon inflation pressures, using no additional equipment.

The subtraction procedure of Dyson is modified in order to eliminate a certain difficulty in the renormalization programme, namely the so-called `b' divergencies. The conclusions of Dyson concerning the finiteness of the renormalized S matrix are confirmed.

An electron bombardment oven is described which operates at temperatures of about 2500 K. A calculation of the power requirement is given together with a calculation of the (unstable) current-voltage characteristic. Measurements are in good agreement with these calculations.