bluuebunny/crossref_metadata_2025 huggingface dataset:
High‐dimensional robust inference for Cox regression models using desparsified Lasso
Authors: Kong Shengchun , Yu Zhuqing , Zhang Xianyang , Cheng Guang
Published: June 2021

We consider high‐dimensional inference for potentially misspecified Cox proportional hazard models based on low‐dimensional results by Lin and Wei (1989). A desparsified Lasso estimator is proposed based on the log partial likelihood function and shown to converge to a pseudo‐true parameter vector. Interestingly, the sparsity of the true parameter can be inferred from that of the above limiting parameter. Moreover, each component of the above (nonsparse) estimator is shown to be asymptotically normal with a variance that can be consistently estimated even under model misspecifications. In some cases, this asymptotic distribution leads to valid statistical inference procedures, whose empirical performances are illustrated through numerical examples.
Speculating on vacancy
Authors: Noterman Elsa
Published: June 2021

Property speculation has long served a role in the settler colonial appropriation of land and the racialised uneven development of contemporary cities. This future‐oriented approach to property acquisition and management is underpinned by notions of vacancy that erase past and present forms of possession and associate racialised spaces with lack and risk. Efforts to define, represent, and manage the speculative value of “vacant” properties through predictive mapping work to colonise the future in ways that erase the present and past. In this paper, I reflect on the role of speculative cartographies of property in both reifying and undermining normative urban property regimes. Specifically, I examine the city of Philadelphia’s use of cartographic tools to identify “likely” property vacancy and how they relate to ongoing racialised dispossession. I then turn to consider the potential of speculative (counter) cartographies of property to contribute to new political realities, not just prevailing geographies. To do so, I engage with the work of artists and activists who are using mapmaking grounded in Afrofuturism to reclaim and reimagine the space‐times of properties deemed by city officials and developers to be “empty” or “wasted.” I suggest that while speculative cartographies of property facilitate the consolidation of liberal property regimes, they also allow for their disruption by revealing their situatedness and contingency – and by facilitating alternative visions of urban futures.
Use of incisional preventive negative pressure wound therapy in open incisional hernia repair: Who benefits?
Authors: Leuchter Matthias , Hitzbleck Michael , Schafmayer Clemens , Philipp Mark
Published: June 2021

Complex surgery of abdominal wall hernia continues to bear the major concern of wound healing disorders. Technical modifications have not been able to sufficiently prevent wound healing impairments or infections, even in clean elective cases, especially when dealing with large‐scale hernia defects. Incisional negative pressure wound therapy (iNPWT) in its intentional use as a preventive tool has recently found its way from theoretical and experimental advantages to the clinical routine. Different indications have been defined but evidence is lacking. We performed a retrospective analysis (1/2014–5/2019) of all ventral hernia repairs (n = 386) done in our institution as open sublay mesh reinforcement, partially requiring component separation (CS), receiving iNPWT in selected cases based on single surgeon experience. Pre‐ and perioperative data included patient and hernia characteristics as well as the employed mesh sizes. Postoperative follow‐up (median 38.5 months [interquartile range: 23.4, 53.3]) extended beyond patient dismissal and included the rate of re‐admission due to wound healing disorders. The primary outcome was the incidence of surgical site occurrences (SSO). Secondary endpoints included wound‐related readmissions, reoperations and recurrences. Patients were matched based on propensity scores in a 1:1 ratio. Propensity scores were calculated based on five preoperative variables, including sex, body‐mass‐index, American Society of Anesthesiology classification, recurrent hernia repair and operation technique, to identify significant parameters. The rate of SSO was 12% (n = 46) for all operated cases, and the rate of surgical site infection (SSI) was 8.8% (n = 34). In the subgroup of CS (n = 40), the rate increased to 15% (n = 6). The usage of iNPWT (n = 54) led to an in‐hospital SSO rate of 14.8% (n = 8) but increased to 33.3% (n = 18) when including the re‐admission rate. The SSI rate for the iNPWT cohort was 14.8% (n = 8) with a consecutive need for reoperation (Clavien‐Dindo IIIb) in 87.5% (n = 7). In the matched‐pair analysis, the hernia‐size and mesh‐size were the main risk factors for SSO. The use of iNPWT significantly reduced this statistical effect (p = 0.405). In a large and representative patient cohort, we were able to demonstrate that the advantage of iNPWT used after complex abdominal wall repair does not come first hand. Especially in the follow‐up, we found a relevant increase in wound healing problems after dismissal. To proof the benefit of iNPWT in these heterogeneous patients, we could identify hernia size and mesh size as individual risk factors that were nihilated by the use of iNPWT. We found it to be favourable to use iNPWT when mesh‐size exceeded 450 cm2.
A New Method to Measure Prandtl Number and Thermal Conductivity of Fluids
Authors: Eckert E. R. G. , Irvine T. F.
Published: June 2021

A new method is described by which the Prandtl number and indirectly the thermal conductivity of fluids can be measured. The method is based on the fact that a well-established, unique relation exists between the Prandtl number and the recovery factor for laminar high-velocity boundary-layer flow. The test setup is described which has been devised for such measurements, and test results are presented for air at atmospheric pressure and temperatures between 60 and 350 F.
Forced Vibration of a Body on an Elastic Stratum
Authors: Warburton G. B.
Published: June 2021

The paper considers the forced vibration of a body with a circular base resting on a homogeneous elastic stratum of infinite surface area and constant depth. The body is subjected to a vertical disturbing force along the axis of symmetry. After evaluating an integral given by Arnold, Bycroft, and Warburton, curves are given showing the dependence of the resonant frequency on three parameters. Good agreement is obtained between theoretical values of the resonant frequency and experimental values taken from the previous paper.
A Theoretical Criterion for the Fracture of Metals Under Combined Alternating Stresses
Authors: Yokobori Takeo
Published: June 2021

A criterion for the fracture of metals under combined alternating stresses is developed on the basis of the present concepts of dislocations. These concepts are modified by taking into account the stress concentration by the inclusion itself against which dislocations pile up. The agreement is good with the experimental data in the literature.
Stresses and Displacements in an Elastic-Plastic Wedge
Authors: Naghdi P. M.
Published: June 2021

An elastic, perfectly plastic wedge of an incompressible isotropic material in the state of plane strain is considered, where the stress-strain relations of Prandtl-Reuss are employed in the plastic domain. For a wedge (with an included angle β) subjected to a uniform normal pressure on one boundary, the complete solution is obtained which is valid in the range 0 < β < π/2; this latter limitation is due to the character of the initial yield which depends on the magnitude of β. Numerical results for stresses and displacements are given in one case (β = π/4) for various positions of the elastic-plastic boundary.
On the Stress Distribution at the Base of a Stationary Crack
Authors: Williams M. L.
Published: June 2021

In an earlier paper it was suggested that a knowledge of the elastic-stress variation in the neighborhood of an angular corner of an infinite plate would perhaps be of value in analyzing the stress distribution at the base of a V-notch. As a part of a more general study, the specific case of a zero-angle notch, or crack, was carried out to supplement results obtained by other investigators. This paper includes remarks upon the antisymmetric, as well as symmetric, stress distribution, and the circumferential distribution of distortion strain-energy density. For the case of a symmetrical loading about the crack, it is shown that the energy density is not a maximum along the direction of the crack but is one third higher at an angle ± cos−1 (1/3); i.e., approximately ±70 deg. It is shown that at the base of the crack in the direction of its prolongation, the principal stresses are equal, thus tending toward a state of (two-dimensional) hydrostatic tension. As the distance from the point of the crack increases, the distortion strain energy increases, suggesting the possibility of yielding ahead of the crack as well as ±70 deg to the sides. The maximum principal tension stress occurs on ±60 deg rays. For the antisymmetrical stress distribution the distortion strain energy is a relative maximum along the crack and 60 per cent lower ± 85 deg to the sides.
Two-Dimensional, Steady, Cavity Flow About Slender Bodies in Channels of Finite Breadth
Authors: Cohen Hirsh , Gilbert Robert
Published: June 2021

The steady, cavitating flow past slender symmetrical bodies placed in a solid-wall channel is studied by means of the linearized theory of Tulin. The free-boundary condition is linearized and boundary conditions are applied on the line of symmetry of the flow in analogy with thin-air-foil theory. A singular integral equation formulation of the boundary-value problem is obtained and can be solved to yield expressions for cavity length, maximum cavity width, and drag coefficient as functions of the cavitation number and the channel breadth. These expressions are given for an arbitrary body and evaluated for the case of a wedge.
Corrections for the Oscillating-Disk Viscometer
Authors: Kestin J. , Wang H. E.
Published: June 2021

The paper reviews existing theories of the oscillating-disk viscometer and demonstrates their inadequacy. Using the results obtained previously by Kestin and Persen together with an empirical assumption that the edge-correction factor is proportional to the ideal viscous torque pieced together from the infinite-disk and infinite-cylinder solutions, the authors are able to develop working formulas which, in addition to the edge effect, include the effect of wire damping and unequal separation. The effect of a stem is discussed separately and shown to be negligible. Some remarks are made about the decrement-period relationship. The assumptions are compared with experimental results which demonstrate that for a given suspension system the edge-correction factor C depends on the dimensionless ratio x0 = δ/R (δ = √[ν/ω0] is the average boundary-layer thickness and R is the external radius of the disk) in a unique way. This shows that the use of the authors’ equations together with a suitable calibration procedure should lead to reliable values of viscosity.
The Propagation of Compressional Waves in a Dispersive Elastic Rod: Part I—Results From the Theory
Authors: Miklowitz Julius
Published: June 2021

Information on the propagation of compressional waves in a rod, in accord with the Mindlin-Herrmann approximate theory, is presented. The information stems from two sources: (a) A numerical evaluation of a previously derived integral solution, for the problem of a semi-infinite rod subjected to a step axial pressure, and (b) application of Kelvin’s stationary-phase method to the classical problem of the infinite rod subjected initially to an infinite axial pressure at the origin.
The Propagation of Compressional Waves in a Dispersive Elastic Rod: Part II—Experimental Results and Comparison With Theory
Authors: Miklowitz Julius , Nisewanger C. R.
Published: June 2021

Experimental results, obtained by employing an aerodynamic shock tube for rod excitation, are presented. Comparison of these results with the theoretical information presented in Part I is made. It is shown that the Mindlin-Herrmann theory, through its upper mode (radial), offers a good approximate representation of the moderately short waves that predominate at the later times at a random station of the rod. The very short waves of this same radial mode, however, govern the early disturbance, thus precluding the possibility of representing this portion of the disturbance, which the experiment shows to be composed of relatively long waves, by the longitudinal mode of the theory.
Stress Distributions in Rotating Disks Subjected to Creep at Elevated Temperature
Authors: Wahl A. M.
Published: June 2021

Assuming a creep rate proportional to a power function of the stress, curves of stress distribution as a function of the radius have been calculated for several cases of rotating disks subject to steady-state creep at elevated temperature. The disks are assumed to have central holes and to be uniformly loaded at the periphery (to simulate blade loading in turbine disks). It is also postulated that the Tresca (maximum-shear) criterion and the associated flow rule govern. The following cases are treated: (1) Disk of constant temperature and thickness with various ratios of outside to inside diameter and with various values of the exponent n in the assumed power function stress-creep rate relation. (2) Disk of constant temperature and variable thickness, the thickness at the periphery being equal to half that at the hub, for various n-values. (3) Disk with variable temperature such that the creep rate at the outside diameter is ten times that at the inside diameter for the same stress, various n-values being assumed. Limits of radial peripheral loading beyond which the derived stress-distribution curves are not valid are also determined. The results indicate that a considerable nonuniformity in stress distribution under creep conditions may exist, particularly for the lower n-values; thus creep-rupture strengths of such disks for long-time loading conditions may be lower than would be expected if based on average stress values, particularly for materials having limited ductility in long-time creep-rupture tests.
A Type of Flame-Excited Oscillation in a Tube
Authors: Bailey J. J.
Published: June 2021

Propane-air mixtures were burned in an effectively open-ended tube containing a screen flameholder. Two types of instability were observed. Of these, one is described in some detail. A driving mechanism is proposed and examined in the light of Rayleigh’s criterion. Finally, a linear, one-dimensional theory is presented, taking into account both the driving and damping effects in the system. The predictions of this theory are shown to be in good agreement with the experimental results.
A Photoelastic Study of Strain Waves Caused by Cavitation
Authors: Sutton G. W.
Published: June 2021

Ultra-high-speed photoelastic techniques have been applied to a study of the transient stresses and strains in a photoelastic plastic when subject to cavitation. A photocell, used to detect the transient strains, indicated that the time duration of the strains was about 2 microsec. Using an ultra-high-speed motion-picture camera, ultrasonic cavitation bubbles have been photographed collapsing on the surface of a photoelastic specimen, and the resulting strain wave in the solid has been photographed. The dynamic properties of a photoelastic material have been obtained in order to permit quantitative interpretation of the transients. This has indicated that the stresses due to cavitation may be as high as 2 × 105 psi. The photoelastic plastic, CR-39, was found to exhibit strain birefringence, and its strain-optic constant was found to be independent of the rate of loading.
Photothermoelasticity: An Exploratory Study
Authors: Gerard George , Gilbert A. C.
Published: June 2021

This paper summarizes the optical and physical properties of the photoelastic model material Paraplex P-43 over the temperature range from room temperature to −40 F. Descriptions are presented of techniques and equipment developed to obtain the modulus of elasticity, the material fringe value, and the thermal-expansion coefficient as a function of temperature. Experimental investigations were conducted into the plane-stress problems of a disk contracting upon an elastic inclusion and the transient thermal-stress field produced by a temperature differential suddenly applied to the upper edge of a long beam. The data are correlated with theory using the material properties obtained in the calibration phase. Also included are photographic results of an exploratory investigation of the thermal-shock phenomenon produced by the sudden application of a temperature differential upon plastic beams of various length-depth ratios.
A Study of the Propagation of Flexural Waves in Elastic Beams
Authors: Ripperger E. A. , Abramson H. Norman
Published: June 2021

Experimental results for flexural wave propagation in elastic beams of circular cross sections resulting from very sharp impacts are presented. It is noted that a well-defined wave system precedes the main pulse. The experimental results are correlated with theoretical predictions from both the Pochhammer-Chree and Timoshenko theories.
Nodal Patterns of the Free Flexural Vibrations of Stiffened Plates
Authors: Hoppmann W. H. , Magness L. S.
Published: June 2021

With the aid of results from previous research on the vibration of stiffened plates, a study is made of the nodal patterns of a particular plate with orthogonally placed stiffeners. The pertinent theory of vibration of stiffened plates is introduced. Experiments are described. The normal modes of vibration are investigated. Frequencies of flexural vibration are given for theory and experiment. The compounding of modes is illustrated by a single but rather convincing example. The rôle of research concerning normal modes of vibration of stiffened plates is discussed.
Force in the Plane of Two Joined Semi-Infinite Plates
Authors: Frasier J. T. , Rongved Leif
Published: June 2021

The stress due to a force parallel to the plane of two joined semi-infinite plates is obtained from the three-dimensional state of stress produced by a force operative at a point interior to one of two joined semi-infinite elastic solids. The variation in the traction on the interface of a steel and aluminum plate is shown graphically.
Photoelectron diffraction: Early demonstrations and alternative modes
Authors: Phil Woodruff David
Published: June 2021

A brief review of the early demonstrations of the utility of photoelectron diffraction to determine the structure of surfaces, contrasting the two fundamentally different approaches of high-energy forward scattering and low-energy backscattering, and the alternative angle-scan and energy-scan different modes of data collection in backscattering experiments is presented. The development and applications of the high-energy angle-scan x-ray photoelectron diffraction version of the technique by Fadley and co-workers is contrasted with those of low-energy backscattering photoelectron diffraction, with particular emphasis on studies of molecular adsorption using the energy-scan mode (PhD).
Exit time as a measure of ecological resilience
Authors: Arani Babak M. S. , Carpenter Stephen R. , Lahti Leo , van Nes Egbert H. , Scheffer Marten
Published: June 2021

Estimating resilience in complex systems

Resilience is an important concept in the study of critical transitions and tipping points in complex systems and is defined by the size of the disturbance that a system can endure before tipping into an alternative stable state. Nevertheless, resilience has proved resistant to measurement. Arani
et al.
show how the mathematical concept of mean exit time, the time it takes for a system to cross a threshold, can help to solve this problem and characterize the resilience of complex systems. They derived a model approach to estimate exit time from time series data and applied it to examples from a grazed plant population model, lake cyanobacterial data, and Pleistocene-Holocene climate data. This approach may improve our understanding of the dynamical properties of complex systems under threat.

Science
, aay4895, this issue p.
eaay4895
Analysis of multispectral imaging with the AstroPath platform informs efficacy of PD-1 blockade
Authors: Berry Sneha , Giraldo Nicolas A. , Green Benjamin F. , Cottrell Tricia R. , Stein Julie E. , Engle Elizabeth L. , Xu Haiying , Ogurtsova Aleksandra , Roberts Charles , Wang Daphne , Nguyen Peter , Zhu Qingfeng , Soto-Diaz Sigfredo , Loyola Jose , Sander Inbal B. , Wong Pok Fai , Jessel Shlomit , Doyle Joshua , Signer Danielle , Wilton Richard , Roskes Jeffrey S. , Eminizer Margaret , Park Seyoun , Sunshine Joel C. , Jaffee Elizabeth M. , Baras Alexander , De Marzo Angelo M. , Topalian Suzanne L. , Kluger Harriet , Cope Leslie , Lipson Evan J. , Danilova Ludmila , Anders Robert A. , Rimm David L. , Pardoll Drew M. , Szalay Alexander S. , Taube Janis M.
Published: June 2021

Astronomy accelerates tumor imaging

Immunohistochemical stains for individual markers revolutionized diagnostic pathology decades ago but cannot capture enough information to accurately predict response to immunotherapy. Newer multiplex immunofluorescent technologies provide the potential to visualize the expression patterns of many functionally relevant molecules but present numerous challenges in accurate image analysis and data handling, particularly over large tumor areas. Drawing from the field of astronomy, in which petabytes of imaging data are routinely analyzed across a wide spectral range, Berry
et al.
developed a platform for multispectral imaging of whole-tumor sections with high-fidelity single-cell resolution. The resultant AstroPath platform was used to develop a multiplex immunofluorescent assay highly predictive of responses and outcomes for melanoma patients receiving immunotherapy.

Science
, aba2609, this issue p.
eaba2609
Using large-scale experiments and machine learning to discover theories of human decision-making
Authors: Peterson Joshua C. , Bourgin David D. , Agrawal Mayank , Reichman Daniel , Griffiths Thomas L.
Published: June 2021

Discovering better theories

Theories of human decision-making have proliferated in recent years. However, these theories are often difficult to distinguish from each other and offer limited improvement in accounting for patterns in decision-making over earlier theories. Peterson
et al.
leverage machine learning to evaluate classical decision theories, increase their predictive power, and generate new theories of decision-making (see the Perspective by Bhatia and He). This method has implications for theory generation in other domains.

Science
, abe2629, this issue p.
1209
; see also abi7668, p.
1150
Time-resolved structured illumination microscopy reveals key principles of Xist RNA spreading
Authors: Rodermund Lisa , Coker Heather , Oldenkamp Roel , Wei Guifeng , Bowness Joseph , Rajkumar Bramman , Nesterova Tatyana , Susano Pinto David Miguel , Schermelleh Lothar , Brockdorff Neil
Published: June 2021

Visualizing Xist RNA dynamics

The noncoding RNA Xist, which controls the process of X chromosome inactivation in mammals, accumulates and spreads over the chromosome from which it is transcribed. The underlying basis for this unusual behavior is poorly understood. Using a new imaging approach called RNA-SPLIT for time-resolved analysis of Xist RNA molecules at super-resolution, Rodermund
et al.
analyzed fundamental parameters of Xist RNA behavior in normal cells and after the perturbation of factors implicated in Xist RNA function. The authors provide new insights into the basis of Xist RNA localization and confinement within the territory of a single X chromosome.

Science
, abe7500, this issue p.
eabe7500
The world of two-dimensional carbides and nitrides (MXenes)
Authors: VahidMohammadi Armin , Rosen Johanna , Gogotsi Yury
Published: June 2021

A family of thin materials

Two-dimensional (2D) materials have attracted interest because of the unusual properties that emerge in these confined structures. There is a growing family of 2D metal carbides and nitrides known as MXenes that contain an odd number of layers in which metals (M) sandwich carbon or nitrogen (X) layers. VahidMohammadi
et al.
reviewed the progress in synthesizing this growing library of materials. Mixed-metal combinations can be used, as well as a range of surface terminations, making it possible to tune the properties. However, there are still challenges in improving the synthesis methods and developing techniques that can be scaled up.

Science
, abf1581, this issue p.
eabf1581
Glaciohydrology of the Himalaya-Karakoram
Authors: Azam Mohd. Farooq , Kargel Jeffrey S. , Shea Joseph M. , Nepal Santosh , Haritashya Umesh K. , Srivastava Smriti , Maussion Fabien , Qazi Nuzhat , Chevallier Pierre , Dimri A. P. , Kulkarni Anil V. , Cogley J. Graham , Bahuguna Ishmohan
Published: June 2021

Waters of high Asia

How the rivers of the Himalaya-Karakoram region of Asia respond to climate change is critical for the billion-plus people who depend on the water that they provide. In a review, Azam
et al
. discuss recent progress in understanding the importance of glacier and snow melt in the hydrological budget there, which is driven largely by advances in remote sensing and modeling. Observational data remain sparse and challenging to collect. —HJS
Evolution of a virus-like architecture and packaging mechanism in a repurposed bacterial protein
Authors: Tetter Stephan , Terasaka Naohiro , Steinauer Angela , Bingham Richard J. , Clark Sam , Scott Andrew J. P. , Patel Nikesh , Leibundgut Marc , Wroblewski Emma , Ban Nenad , Stockley Peter G. , Twarock Reidun , Hilvert Donald
Published: June 2021

Revolution in an RNA-packaging capsid

Artificial nucleocapsid proteins, which could be analogous to those used by viruses to package their genomes, are a promising way to protect and deliver RNAs. Using an escalating challenge by nucleases, Tetter
et al.
evolved a protein that forms multimeric, spherical cages into a highly efficient capsid that selectively packages its own encoding RNA. Cryo–electron microscopy of the final design and intermediates revealed a stepwise expansion in size, enabled by destabilizing amino acid substitutions and a domain swap that results in a change of oligomerization interfaces for the base units of the cage. In addition to altering the protein, directed evolution resulted in changes to the encoding RNA structure that enabled efficient uptake versus other cellular RNAs.

Science
, abg2822, this issue p.
1220
Observation of a prethermal discrete time crystal
Authors: Kyprianidis A. , Machado F. , Morong W. , Becker P. , Collins K. S. , Else D. V. , Feng L. , Hess P. W. , Nayak C. , Pagano G. , Yao N. Y. , Monroe C.
Published: June 2021

Prethermal time crystal

Characterizing and understanding different phases of matter in equilibrium is usually associated with the process of thermalization, where the system equilibrates. Recent efforts probing nonequilibrium systems have revealed that periodic driving of the system can suppress the natural tendency for equilibration yet still form new, nonequilibrium phases. Kyprianidis
et al.
used a quantum simulator composed of 25 trapped ion qubits and spins to observe such a nonequilibrium phase of matter: the disorder-free prethermal discrete time crystal. The flexibility and tunability of their quantum simulator provide a powerful platform with which to study the exotic phases of matter.

Science
, abg8102, this issue p.
1192
Human-food feedback in tropical forests
Authors: Flores Bernardo M. , Levis Carolina
Published: June 2021

Ancient interaction between humans and edible plants can boost tropical food security
A massive rock and ice avalanche caused the 2021 disaster at Chamoli, Indian Himalaya
Authors: Shugar D. H. , Jacquemart M. , Shean D. , Bhushan S. , Upadhyay K. , Sattar A. , Schwanghart W. , McBride S. , de Vries M. Van Wyk , Mergili M. , Emmer A. , Deschamps-Berger C. , McDonnell M. , Bhambri R. , Allen S. , Berthier E. , Carrivick J. L. , Clague J. J. , Dokukin M. , Dunning S. A. , Frey H. , Gascoin S. , Haritashya U. K. , Huggel C. , Kääb A. , Kargel J. S. , Kavanaugh J. L. , Lacroix P. , Petley D. , Rupper S. , Azam M. F. , Cook S. J. , Dimri A. P. , Eriksson M. , Farinotti D. , Fiddes J. , Gnyawali K. R. , Harrison S. , Jha M. , Koppes M. , Kumar A. , Leinss S. , Majeed U. , Mal S. , Muhuri A. , Noetzli J. , Paul F. , Rashid I. , Sain K. , Steiner J. , Ugalde F. , Watson C. S. , Westoby M. J.
Published: June 2021

A deadly cascade

A catastrophic landslide in Uttarakhand state in India on February 2021 damaged two hydropower plants, and more than 200 people were killed or are missing. Shugar
et al.
describe the cascade of events that led to this disaster. A massive rock and ice avalanche roared down a Himalayan valley, turning into a deadly debris flow upstream from the first of the two hydropower plants. The sequence of events highlights the increasing risk in the Himalayas caused by increased warming and development.

Science
, abh4455, this issue p.
300
Is lithium the key for nitrogen electroreduction?
Authors: Westhead Olivia , Jervis Rhodri , Stephens Ifan E. L.
Published: June 2021

Why lithium appears critical for electrochemical ammonia synthesis remains elusive
Expanding gliogenesis
Authors: Baldwin Katherine T. , Silver Debra L.
Published: June 2021

The generation of glial cell types in adult mice could provide strategies for brain repair
Giving antibiotics an assist
Authors: Mah Thien-Fah
Published: June 2021

Inhibiting endogenous hydrogen sulfide production makes bacteria more susceptible to antibiotics
Inactivation of Cryptosporidium parvum Oocysts and Clostridium perfringens Spores by a Mixed-Oxidant Disinfectant and by Free Chlorine
Authors: Venczel L V , Arrowood M , Hurd M , Sobsey M D
Published: June 2021

Volume 63, no. 4, p. 1600: The caption to Table 2 should read as follows: "Inactivation of Clostridium perfringens spores by 5-mg/liter doses of mixed oxidants or free chlorine in buffer at pH 7 at 25(deg)C." [This corrects the article on p. 1598 in vol. 63.].
Hemolysis-in-gel and neutralization tests for determination of antibodies to mumps virus
Authors: Grillner L , Blomberg J
Published: June 2021

A hemolysis-in-gel test for the demonstration of antibodies to mumps virus is described. The results were compared with those of neutralization tests using a modified microtechnique. In the neutralization test viral replication was demonstrated by the hemadsorption of guinea pig erythrocytes, the visibility of which could be further enhanced by the use of o-tolidine. Good correlation was found between the results of the two techniques. The hemolysis-in-gel test was simple to perform, rapid, sensitive, and shown to be a useful test for the demonstration of mumps antibodies.
Virological and serological studies of Venezuelan equine encephalomyelitis in humans
Authors: Bowen G S , Calisher C H
Published: June 2021

During the 1971 epidemic of Venezuelan equine encephalomyelitis (VEE) in south Texas, 203 suspect VEE cases were evaluated by the Center for Disease Control. Sixty-seven were confirmed as cases of VEE. Laboratory confirmation was accomplished by isolation of VEE virus from a serum specimen taken during the acute illness in 50 (75%) of the confirmed cases. Serological confirmation was obtained in 17 cases (25%). Virus isolations were most often obtained from sera collected during the first 3 days of illness. Peak serum virus titers (algebraic mean, 10(5-7) suckling mouse intracranial 50% lethal doses [SMICLD50] per ml) occurred on day 2 of illness. One-half of the sera from which virus was isolated contained at least 10(5) SMICLD50/ml, which has been shown to be sufficient to infect some vector mosquitoes. Blood from 13 virus-positive VEE cases was obtained 1 and 11 months after illness. Hemagglutination-inhibiting, complement-fixing, and neutralizing antibodies were formed by all 13 patients 1 month after illness. Hemagglutination-inhibiting antibody titers were essentially unchanged 11 months after illness. Complement-fixing antibody was undetectable 11 months after illness in 23% of cases and was detectable at dilutions of 1:8 or 1:6 in 77%. Neutralizing antibody (measured by log neutralization index) was not detectable 1 year after illness in one person (8%); titers had declined from 1.0 to 2.0 in 46%, were unchanged in 39%, and were not tested in one person (8%). No evidence of intrafamilial spread of VEE virus was obtained in either of two illness and antibody surveys. A randomized household illness and antibody survey of 681 Port Isabel residents revealed an inapparent infection ratio of 1:11 and an overall antibody prevalence of 3.2%.
Improved chamber for the isolation of anaerobic microorganisms
Authors: Cox M E , Mangels J I
Published: June 2021

A small portable chamber for the recovery of anaerobic bacteria is described. This rigid chamber is constructed of clear acrylic with dimensions of 30 inches (ca. 76.2 cm) wide, 18 inches (ca. 44.7 cm) deep, and 18 inches (ca. 44.7 cm) high. Conventional bacteriological techniques can be used inside the chamber to efficiently isolate strict anaerobic organisms. An adapter allows the attachment of a standard anaerobic jar to the outside of the chamber. The jar can be used to store reduced media. Once the jar is attached to the chamber and the media is removed to the interior of the chamber, the jar is available to receive inoculated media. The anaerobic jar can then be removed from the chamber, without contaminating the jar or chamber with oxygen, and be placed in a conventional 37degreesC incubator. This chamber also allows the microbiologist to process cultures without wearing gloves as was necessary with previous anaerobic chambers. Air-tight latex rubber sleeves seal around the microbiologists arms and to the armport flange of the chamber to prevent the introduction of oxygen into the chamber. Anaerobic conditions are maintained by circulating a 80% N2, 10% H2, 10% CO2 gas mixture through alumina pellets coated with palladium. This study indicates that anaerobic conditions obtained in this chamber are sufficient for recovery of obligate anaerobes.
Evaluation of commercial systems for the identification of clinical yeast isolates
Authors: Bowman P I , Ahearn D G
Published: June 2021

The Analytab Products Inc. (API), Micro-Drop (MD), and Uni-Yeast-Tek (UYT) systems for the presumptive identification of common clinical yeast isolates were compared with the oxidation-fermentation (OF) and a conventional procedure. With 229 coded isolates, the identification accuracies were API 94, MD 83, OF 82, and UYT 99%. The API system required the greatest technical ability. The MD materials were prone to malfunction. OF media, if incubated beyond 14 days, gave an accuracy of 87%, but this offered no advantage over the conventional procedure. The UYT system was the easiest to use.
Growth of Streptococcus mutans on various selective media
Authors: Emilson C G , Bratthall D
Published: June 2021

The ability of Streptococcus mutans to grow on mitis-salivarius (MS) agar, MC agar, mitis-sucrose-bacitracin (MSB), BCY agar, and MM10 sucrose agar was studied. Batch cultures of S. mutans serotype a demonstrated no growth on MSB agar. Certain serotype d and g strains did not grow on MC agar. The yield for most strains of other serotypes on these selective media was lower compared with that on MS agar. The number of total colony-forming units on BCY and MM10 sucrose agar was similar to the blood agar results. Similar data were obtained when fermenter-grown strains, harvested in the middle or the end of the logarithmic growth phase, were used for inoculation of the various media. Enumeration of S. mutans from plaque samples plated on MC and MSB agar yielded about 75% of the counts obtained on MS or the nonselective medium. When the proportions of S. mutans were expressed as a percentage of the total cultivable flora, the selective media (MC and MSB agar) showed approximately 10% lower values than the MS, BCY, and MM10 sucrose agar.
Enhancement by sodium chloride of the selectivity of thiosulfate citrate bile salts sucrose agar for isolating Vibrio cholerae biotype El Tor
Authors: Morris G K , DeWitt W E , Gangarosa E J , McCormack W M
Published: June 2021

In this study we utilized the salt-tolerant characteristics of vibrios to develop a more selective medium by addition of NaCl to thiosulfate citrate bile salts sucrose (TCBS) agar. The effect of adding salt to TCBS agar varied greatly among brands of TCBS agar and between lots of the same brand. The addition of salt at concentrations as high as 1.5% (2.5% total NaCl) caused the inhibition of growth of three species of commonly encountered normal bowel flora and one strain of classical Vibrio cholerae but did not compromise the use of TCBS agar for isolation of V. cholerae biotype El Tor.
Rapid spot test for the determination of esculin hydrolysis
Authors: Edberg S C , Gam K , Bottenbley C J , Singer J M
Published: June 2021

Esculin hydrolysis is a useful test in the differentiation of both gram-positive and gram-negative bacteria covering a wide spectrum of aerobes, facultative anaerobes, and anaerobes. Commonly utilized methods require a minimum of 18 h of incubation in broth or agar medium and utilize the production of a brown-black compound, due to the combination of ferric ions with the hydrolysis product esculetin, as indicator. A procedure is presented that requires 15 to 30 min for completion and utilizes fluorescence loss as the indicator of hydrolysis. Esculin fluoresces at 366 nm, whereas the hydrolysis product esculetin does not. Over 1,400 strains of gram-positive and gram-negative bacteria were tested. There was 98.4% of correlation between the spot test and esculin broth and 97% correlation with the bile-esculin agar.
Optimal conditions for elution of hepatitis B antigen after absorption onto colloidal silica
Authors: Pillot J , Goueffon S , Keros R G
Published: June 2021

Hepatitis B surface antigen (HBSAg) adsorbed from sera onto colloidal silica could be completely eluted through the use of 0.25% sodium deoxycholate in 0.01 M borax, pH 9.3, at 56 degrees C. The HBSAg recovered in the eluate represented 100% of that present in the original serum, and it was contaminated by only trace amounts of serum proteins (in decreasing amounts: beta-lipoprotein, immunoglobulin G, albumin). This preliminary step greatly facilitates purification of large amounts of HBSAg and provides small volumes of highly concentrated material for subsequent purification by density gradient centrifugation.
Use of droplet plating method and cystine-lactose-lactng electrolyte-deficient medium in routine quantitative urine culturing procedure
Authors: Neblett T R
Published: June 2021

Droplet plating of 0.01 ml of 10(-2) dilutions of mixed sonically treated urines onto cystine-lactose electrolyte-deficient agar permits formation of discrete, easily counted colonies within a small circumscribed area without interference by Proteus overswarm. Each colony is considered as arising from a single viable cell. The single dilution permits precise reproducible quantitation of urine bacteria population within the range 10(4) to 10(6) cells/ml of sample. Droplet-plated counts were found to be consistently (approximately) double those determined by standard pour plate quantitation. The method requires only inexpensive readily available materials and has been performed routinely in a large-volume clinical laboratory for several years.
Evaluation of commercial Salmonella O polyvalent and Vi antisera
Authors: Evins G M , Linne L L , Colvin H M
Published: June 2021

Salmonella somatic polyvalent antisera for groups A through E or A through I with or without Vi and Salmonella Vi antisera were purchased from four commercial producers and evaluated. Center for Disease Control (CDC) methods and specifications were used. The four polyvalent and two of the four Vi antisera did not meet CDC performance specifications. Suggestions are made for improving the laboratory usefulness of the reagents and the product labeling.
Evaluation of enrichment, storage, and age of blood agar medium in relation to its ability to support growth of anaerobic bacteria
Authors: Hanson C W , Martin W J
Published: June 2021

By measuring the colony size of a variety of anaerobic bacteria isolated from clinical specimens, an evaluation was made of the benefits derived from the addition of several enrichments to blood agar medium commonly used for the growth of anaerobes. Similar methods were used to study the effects of various storage conditions and age of the medium. The results were compared with those obtained on freshly prepared and enriched blood agar plates as well as commercially available blood agar plates. Freshly prepared and enriched blood agar was found to give substantially larger colonies than could be grown on commercially obtained blood agar plates when both were inoculated and incubated under identical conditions. Storage of plating media under CO2 for periods of up to 72 h had only a minor effect on the growth of the anaerobic bacteria studied, but longer periods of storage under CO2 resulted in a less efficient plating medium. Nonenriched brain heart infusion (BHI) was found to be a better basal medium than Trypticase soy agar (TSA) medium. Colony size on fully enriched BHI blood agar plates was greater than nonenriched BHI greater than nonenriched TSA greater than commercially prepared nonenriched TSA plates. The data suggest that freshness of the plates may be as important as using rich media.
Clinical evaluation of the minitek differential system for identification of Enterobacteriaceae
Authors: Finklea P J , Cole M S , Sodeman T M
Published: June 2021

Forty-one stock organisms and 581 fresh clinical isolates were used in comparing the Minitek system to conventional tubed media to determine if this system is feasible and accurate for a high-volume clinical microbiology laboratory. In addition to comparison with tubed media, the following parameters were tested: (i) reproducibility of disks, (ii) the effect of variation in inoculum size, (iii) the effect of the age of culture, and (iv) the effect of predispensing disks. A total of 5,947 disks were compared with tube reactions; 95.9% agreed on the initial reading. After repeating questionable tube and disk reactions, this agreement rose to 98.2%. Using the disk reactions and the identification schema currently in use with tubed media, 94.9% of the Minitek final identifications agreed with those of tubed media; 1.5% gave differing identifications and 3.6% were inconclusive. This system is accurate, inexpensive, flexible, and convenient.
Ampicillin-resistant Haemophilus paraphrophilus laryngo-epiglottitis
Authors: Jones R N , Slepack J , Bigelow J
Published: June 2021

A case of life-threatening laryngo-epiglottitis is reported, caused by ampicillin-resistant Haemophilus paraphrophilus. Clinicians and microbiologists should be aware of a beta-lactamase-mediated resistance among Haemophilus species other than H. influenzae.
Factors affecting pharyngeal Haemophilus influenzae type b colonization rates in children
Authors: Michaels R H , Poziviak C S , Stonebraker F E , Norden C W
Published: June 2021

Over 1,300 children were studied in an analysis of factors that might affect pharyngeal colonization with Haemophilus influenzae type b. Our semiquantitative methods for the culture of H. influenzae type b, consisting of inoculation of 0.001 ml of throat swab fluid on antiserum agar plates and division of the results into three grades of intensity, showed agreement as to intensity of colonization in over 80% of repeat throat cultures. Our data also suggest that throat swabs are more efficient than nasopharyngeal swabs for detecting colonization, particularly for older children. All 17 H. influenzae type b carriers found with either method were detected with throat swabs, but six had negative nasopharyngeal cultures; four of these six were lightly colonized older children. Furthermore, colony counts were apt to be higher on plates inoculated with throat swab fluids. The frequency of pharyngeal H. influenzae type b colonization in children visiting health department clinics and pediatricians' offices was low during the first 6 months of life (0.7%) but averaged 3 to 5% throughout the rest of childhood. Approximately two-thirds of the carriers were colonized at an intensity too low to be detected by standard laboratory techniques. No influence on colonization rates was found for sex, race, season, economic status, or common childhood infectious diseases such as coryza or otitis media.
Evaluation of the fluorescent gonococcal test-heated
Authors: Gaafar H A
Published: June 2021

In a 1-year evaluation of the indirect fluorescent antibody test for gonorrhea, 16,127 specimens from low-and high-risk groups were examined, and the results were compared with culture, history of exposure to a known patient, and clinical signs and symptoms. The results confirmed the usefulness of the indirect fluorescent antibody test for gonorrhea as a screening procedure, especially for women in the low-risk group. The test is more economic and probably more sensitive than culture for mass screening of asymptomatic women.
Extracellular enzymes of the genus Bacteroides
Authors: Rudek W , Haque R U
Published: June 2021

The extracellular production of hyaluronidase and chondroitin sulfatase was demonstrated in all of the subspecies of Bacteroides fragilis tested with the exception of B. fragilis subsp. vulgatus. Elastase was found only in one strain of B. coagulans tested. This appears to be the first report of these enzyme activities in this genus. Additional enzymes found to be produced by certain members othis genus were fibrinolysin, penicillinase, lysozyme, lecithinase, deoxyribonuclease, phosphatase, protease, and lipase.
Cellular fatty acids and metabolic products of Pseudomonas species obtained from clinical specimens
Authors: Moss C W , Dees S B
Published: June 2021

The cellular fatty acid composition of 112 reference strains and clinical isolates of Pseudomonas species was determined by gas-liquid chromatography (GLC). The presence and relative amounts of cyclopropane, hydroxy, and branched-chain fatty acids were distinguishing features of these strains. Determination of short-chain fatty acids extracted from spent growth media provided an additional means for identifying some strains. Our results show that clinical isolates of pseudomonads can be divided into eight distinct GLC groups. The procedures were especially useful for distinguishing glucose-nonoxidizing pseudomonads, which are difficult to identify by conventional criteria. Since the GLC procedures are simple, rapid, and highly reproducible, they are useful in diagnostic laboratories that process large numbers of cultures. Coupled with selected conventional tests, the analysis of short-chain and cellular fatty acids can be very useful for rapid screening of clinical isolates of Pseudomonas species.