National Security Agency

This paper describes a graph-theoretic complexity measure and illustrates how it can be used to manage and control program complexity. The paper first explains how the graph-theory concepts apply and gives an intuitive explanation of the graph concepts in programming terms. The control graphs of several actual Fortran programs are then presented to illustrate the correlation between intuitive complexity and the graph-theoretic complexity. Several properties of the graph-theoretic complexity are then proved which show, for example, that complexity is independent of physical size (adding or subtracting functional statements leaves complexity unchanged) and complexity depends only on the decision structure of a program.

A tutorial on the design and development of automatic speaker-recognition systems is presented. Automatic speaker recognition is the use of a machine to recognize a person from a spoken phrase. These systems can operate in two modes: to identify a particular person or to verify a person's claimed identity. Speech processing and the basic components of automatic speaker-recognition systems are shown and design tradeoffs are discussed. Then, a new automatic speaker-recognition system is given. This recognizer performs with 98.9% correct decalcification. Last, the performances of various systems are compared.

This report contains a discussion of the difficult problem of key management for multicast communication sessions. It focuses on two main areas of concern with respect to key management, which are, initializing the multicast group with a common net key and rekeying the multicast group. A rekey may be necessary upon the compromise of a user or for other reasons (e.g., periodic rekey). In particular, this report identifies a technique which allows for secure compromise recovery, while also being robust against collusion of excluded users. This is one important feature of multicast key management which has not been addressed in detail by most other multicast key management proposals The benefits of this proposed technique are that it minimizes the number of transmissions required to rekey the multicast group and it imposes minimal storage requirements on the multicast group.

The Simon and Speck families of block ciphers were designed specifically to offer security on constrained devices, where simplicity of design is crucial. However, the intended use cases are diverse and demand flexibility in implementation. Simplicity, security, and flexibility are ever-present yet conflicting goals in cryptographic design. This paper outlines how these goals were balanced in the design of Simon and Speck.

Nanoelectromechanical structures are starting to approach the ultimate quantum mechanical limits for detecting and exciting motion at the nanoscale. Nonclassical states of a mechanical resonator are also on the horizon.

A sender communicates with a receiver who wishes to reliably evaluate a function of their combined data. We show that if only the sender can transmit, the number of bits required is a conditional entropy of a naturally defined graph. We also determine the number of bits needed when the communicators exchange two messages.

As the size of graphs for analysis continues to grow, methods of graph processing that scale well have become increasingly important. One way to handle large datasets is to disperse them across an array of networked computers, each of which implements simple sorting and accumulating, or MapReduce, operations. This cloud computing approach offers many attractive features. If decomposing useful graph operations in terms of MapReduce cycles is possible, it provides incentive for seriously considering cloud computing. Moreover, it offers a way to handle a large graph on a single machine that can't hold the entire graph as well as enables streaming graph processing. This article examines this possibility.

Abstract For applications such as windstorm underwriting or storm-surge forecasting, hurricane wind profiles are often approximated by continuous functions that are zero at the vortex center, increase to a maximum in the eyewall, and then decrease asymptotically to zero far from the center. Comparisons between the most commonly used functions and aircraft observations reveal systematic errors. Although winds near the peak are too strong, they decrease too rapidly with distance away from the peak. Pressure–wind relations for these profiles typically overestimate maximum winds. A promising alternative is a family of sectionally continuous profiles in which the wind increases as a power of radius inside the eye and decays exponentially outside the eye after a smooth polynomial transition across the eyewall. Based upon a sample of 493 observed profiles, the mean exponent for the power law is 0.79 and the mean decay length is 243 km. The database actually contains 606 aircraft sorties, but 113 of these failed quality-control screening. Hurricanes stronger than Saffir–Simpson category 2 often require two exponentials to match the observed rapid decrease of wind with radius just outside the eye and slower decrease farther away. Experimentation showed that a fixed value of 25 km was satisfactory for the faster decay length. The mean value of the slower decay length was 295 km. The mean contribution of the faster exponential to the outer profile was 0.10, but for the most intense hurricanes it sometimes exceeded 0.5. The power-law exponent and proportion of the faster decay length increased with maximum wind speed and decreased with latitude, whereas the slower decay length decreased with intensity and increased with latitude, consistent with the qualitative observation that more intense hurricanes in lower latitudes usually have more sharply peaked wind profiles.

We formulate some simple conditions under which a Markov chain may be approximated by the solution to a differential equation, with quantifiable error probabilities. The role of a choice of coordinate functions for the Markov chain is emphasised. The general theory is illustrated in three examples: the classical stochastic epidemic, a population process model with fast and slow variables, and core-finding algorithms for large random hypergraphs.

Operating systems must be flexible in their support for security policies, providing sufficient mechanisms for supporting the wide variety of real-world security policies. Such flexibility requires controlling the propagation of access rights, enforcing fine-grained access rights and supporting the revocation of previously granted access rights. Previous systems are lacking in at least one of these areas. In this paper we present an operating system security architecture that solves these problems. Control over propagation is provided by ensuring that the security policy is consulted for every security decision. This control is achieved without significant performance degradation through the use of a security decision caching mechanism that ensures a consistent view of policy decisions. Both fine-grained access rights and revocation support are provided by mechanisms that are directly integrated into the service-providing components of the system. The architecture is described through its prototype implementation in the Flask microkernel-based operating system, and the policy flexibility of the prototype is evaluated. We present initial evidence that the architecture's impact on both performance and code complexity is modest. Moreover, our architecture is applicable to many other types of operating systems and environments.

The authors describe a novel approach to scalable group re-keying for secure multicast. Our approach, which we call Kronos, is based upon the idea of periodic group re-keying. We first motivate our approach by showing that if a group is re-keyed on each membership change, as the size of the group increases and/or the rate at which members leave and join the group increases, the frequency of rekeying becomes the primary bottle neck for scalable group re-keying. In contrast, Kronos can scale to handle large and dynamic groups because the frequency of re-keying is independent of the size and membership dynamics of the group. Next, we describe how Kronos can be used in conjunction with distributed key management frameworks such as IGKMP (T. Hardjono et al., 1998) that use a single group-wide session key for encrypting communications between members of the group. Using a detailed simulation, we compare the performance tradeoffs between Kronos and other key management protocols.

1. Oxygen consumption was measured in resting little brown bats, Myotis l. lucifugus, at ambient temperatures from 0.5° to 44.0° C. Body temperature was shown to approximate the ambient level under the conditions of the experiments, so that in effect the metabolic rate was measured over very nearly this range of body temperatures. 2. The function relating oxygen consumption to body temperature is not linear; the Q10 is 2.94 from 2° to 10° C., 5.54 from 10° to 20° C., 5.09 from 20° to 30° C., 1.69 from 30° to 37° C., and 2.22 from 37° to 41.5° C. The ratio between highest and lowest resting metabolic rates is 138:1; the temperatures represented are 41.5° and 2° C. 3. Some notes on the reaction to temperatures very close to 0° C. are included. Bats increased metabolism over that observed at 2° C. when exposed to near-freezing temperatures. The experiment was not continued long enough to find whether or not they would eventually awake. 4. The data are compared with the findings of other investigators using several species of bats. There is a close correspondence between body temperature and ambient temperature in all species, except that the tropical forms increase heat production by muscular work. Bats of the temperate zone appear to show the usual effect of size on metabolic rate per unit weight at temperatures of 30° C. or above, as Benedict (1938) has demonstrated occurs in a wide variety of homoiotherms. At 2° and at 10° C. this difference is not apparent in a comparison between these measurements and those made by Kayser (1940) on a much larger bat. 5. It is concluded that there is no physiological basis for distinguishing the daily reduction of temperature and metabolic rate in bats from that found in hibernation, except in degree. It appears that this daily phenomenon is due to a lack of thermoregulatory control. 6. Bats are considered as distinct from other heterotherms in that, at all seasons of the year, their resting temperature and metabolic rate is dependent on the ambient temperature. This also is due to their lack of thermoregulation. They are the only mammals in which the resting metabolism is a direct function of the body temperature, rather than of the ambient temperature. Nevertheless, when active, they can maintain body temperatures of 40° C. or above.

THERE is a considerable body of experimental evidence that the therapeutic action of penicillin rests in large part on its direct bactericidal action, and that the factor that primarily determines its therapeutic efficacy is the total time for which the drug remains at effective levels at the focus of infection.1 2 3 4 Thus, the number of streptococci or pneumococci surviving in an intramuscular focus in mice after an injection of aqueous sodium penicillin G was found to decrease rapidly only so long as the penicillin remained at effective levels.3 , 4 Extremely large doses, providing concentrations greatly in excess of the effective level, were . . .

Journal Article Experimental Human Salmonellosis: I. Pathogenicity of Strains of Salmonella Meleagridis and Salmonella Anatum Obtained from Spray-Dried Whole Egg Get access Norman B. McCullough, Norman B. McCullough Department of Medicine, The University of Chicago and the Microbiological Institute of the National Institutes of Health, Public Health Service, Federal Security Agency, Chicago 37, Illinois Search for other works by this author on: Oxford Academic PubMed Google Scholar C. Wesley Eisele C. Wesley Eisele Department of Medicine, The University of Chicago and the Microbiological Institute of the National Institutes of Health, Public Health Service, Federal Security Agency, Chicago 37, Illinois Search for other works by this author on: Oxford Academic PubMed Google Scholar The Journal of Infectious Diseases, Volume 88, Issue 3, May 1951, Pages 278–289, https://doi.org/10.1093/infdis/88.3.278 Published: 01 May 1951 Article history Received: 15 November 1950 Published: 01 May 1951

Historically, mpox has been characterized as an endemic zoonotic disease that transmits through contact with the reservoir rodent host in West and Central Africa. However, in May 2022, human cases of mpox were detected spreading internationally beyond countries with known endemic reservoirs. When the first cases from 2022 were sequenced, they shared 42 nucleotide differences from the closest mpox virus (MPXV) previously sampled. Nearly all these mutations are characteristic of the action of APOBEC3 deaminases, host enzymes with antiviral function. Assuming APOBEC3 editing is characteristic of human MPXV infection, we developed a dual-process phylogenetic molecular clock that-inferring a rate of ~6 APOBEC3 mutations per year-estimates that MPXV has been circulating in humans since 2016. These observations of sustained MPXV transmission present a fundamental shift to the perceived paradigm of MPXV epidemiology as a zoonosis and highlight the need for revising public health messaging around MPXV as well as outbreak management and control.

Inspired by Google's BigTable, a variety of scalable, semi-structured, weak-semantic table stores have been developed and optimized for different priorities such as query speed, ingest speed, availability, and interactivity. As these systems mature, performance benchmarking will advance from measuring the rate of simple workloads to understanding and debugging the performance of advanced features such as ingest speed-up techniques and function shipping filters from client to servers. This paper describes YCSB++, a set of extensions to the Yahoo! Cloud Serving Benchmark (YCSB) to improve performance understanding and debugging of these advanced features. YCSB++ includes multi-tester coordination for increased load and eventual consistency measurement, multi-phase workloads to quantify the consequences of work deferment and the benefits of anticipatory configuration optimization such as B-tree pre-splitting or bulk loading, and abstract APIs for explicit incorporation of advanced features in benchmark tests. To enhance performance debugging, we customized an existing cluster monitoring tool to gather the internal statistics of YCSB++, table stores, system services like HDFS, and operating systems, and to offer easy post-test correlation and reporting of performance behaviors. YCSB++ features are illustrated in case studies of two BigTable-like table stores, Apache HBase and Accumulo, developed to emphasize high ingest rates and finegrained security.

r C O m n l O L l lesion apparently peculiar to man.Bloom has not observed a similar tumor in dogs or cats and knows of no reports of its occurrence in animals.It arises most commonly in the tongue and to a lesser extent in skin, breast, subcutaneous tissue, and niiscellaneous other sites.T h e myoblastoma usually occurs as a single tumor.Recently a case of multiple t.umors arising in the same patient has been described by Ashburn and Rodger.T h e biological nature of the granular-cell myoblastoma is controversial, there being no agreement as to whether it is a neoplasm.T h e non-neoplastic processes considered have included congenital malformation, degeneration and repair, inflammation, and storage disease.Before 1926, the lesion frequently was diagnosed as xanthoma.Since 1926, when Abrikossoff' described the myoblastoma as a distinct pathological entity, four principal tissues of origin have been suggested-striated muscle, histiocytes, fibroblasts, and peripheral nerves.An opportunity to study the pathological material from forty-three specimens of benign granular-cell myoblastoma has prompted a histological and histochemical study of these lesions.It is the purpose of this paper to describe their morphology, stressing certain charactel-istics not generally emphasized, to evaluate critically their staining properties, and to discuss the various theories of their histogenesis.T h e cases of benign myoblastoma studied are listed in Table 1.

This publication from the National Initiative for Cybersecurity Education (NICE) describes the Workforce Framework for Cybersecurity (NICE Framework), a fundamental reference for describing and sharing information about cybersecurity work. It expresses that work as Task statements and describes Knowledge and Skill statements that provide a foundation for learners including students, job seekers, and employees. The use of these statements helps students to develop skills, job seekers to demonstrate competencies, and employees to accomplish tasks. As a common, consistent lexicon that categorizes and describes cybersecurity work, the NICE Framework improves communication about how to identify, recruit, develop, and retain cybersecurity talent. The NICE Framework is a reference source from which organizations or sectors can develop additional publications or tools that meet their needs to define or provide guidance on different aspects of cybersecurity education, training, and workforce development.

By simulating an ergodic Markov chain whose stationary distribution is uniform over the space of n × n Latin squares, we can obtain squares that are (approximately) uniformly distributed; we offer two such chains. The central issue is the construction of “moves” that connect the squares. Our first approach uses the fact that an n × n Latin square is equivalent to an n × n × n contingency table in which each line sum equals 1. We relax the nonnegativity condition on the table's cells, allowing “improper” tables that have a single—1-cell. A simple set of moves connects this expanded space of tables [the diameter of the associated graph is bounded by 2(n − 1)3], and suggests a Markov chain whose subchain of proper tables has the desired uniform stationary distribution (with an average of approximately n steps between proper tables). By grouping these moves appropriately, we derive a class of moves that stay within the space of proper Latin squares [with graph diameter bounded by 4(n − 1)2]; these may also be used to form a suitable Markov chain. © 1996 John Wiley & Sons, Inc.

Journal Article Experimental Human Salmonellosis: III. Pathogenicity of Strains of Salmonella Newport, Salmonella Derby, and Salmonella Bareilly Obtained from Spray-Dried Whole Egg Get access Norman B. McCullough, Norman B. McCullough Department of Medicine, The University of Chicago, Chicago 37, Illinois, and the Microbiological Institute of the National Institutes of Health, Public Health Service, Federal Security Agency, Bethesda, Maryland Search for other works by this author on: Oxford Academic PubMed Google Scholar C. Wesley Eisele C. Wesley Eisele Department of Medicine, The University of Chicago, Chicago 37, Illinois, and the Microbiological Institute of the National Institutes of Health, Public Health Service, Federal Security Agency, Bethesda, Maryland Search for other works by this author on: Oxford Academic PubMed Google Scholar The Journal of Infectious Diseases, Volume 89, Issue 3, November 1951, Pages 209–213, https://doi.org/10.1093/infdis/89.3.209 Published: 01 November 1951 Article history Received: 07 March 1951 Published: 01 November 1951