Showing papers by "Harvard University published in 1980"

Competitive Strategy: Techniques for Analyzing Industries and Competitors

Abstract: Michael Porter presents a comprehensive structural framework and analytical techniques to help a firm to analyze its industry and evolution, understand its competitors and its own position, and translate this understanding into a competitive strategy to allow the firm to compete more effectively to strengthen its market position. The introduction reviews a classic approach to strategy formulation, one that comprises a combination of ends and means (policies), factors that limit what a company can accomplish, tests of consistency, and an approach for developing competitive strategy. A competitive strategy articulates a firm's goals, how it will compete, and its policies for achieving those goals. Competitive advantage is defined in terms of cost and differentiation while linking it to profitability. Part I, "General Analytical Techniques," provides a general framework for analyzing the structure of an industry and understanding the underlying forces of competition (and hence profitability). Five competitive forces act on an industry: (1) threat of new entrants, (2) intensity of rivalry among existing firms, (3) threat of substitute products or services, (4) bargaining power of buyers, and (5) bargaining power of suppliers. Looking at industry structure provides a way to consider how value is created and divided among existing and potential industry participants. One competitive force always captures essential issues in the division of value.There are three generic competitive strategies for coping with the five competitive forces: (1) overall cost leadership, (2) differentiation, and (3) focus. There are risks with each strategy. A firm without a strategy is "stuck in the middle." This framework for examining competition transcends particular industry, technology, or management theories. Building on this framework, techniques are presented for industry forecasting, analysis of competitors, predicting their behavior, and building a response profile. Essential for a competitive strategy are techniques for recognizing and accurately reading market signals. Implications of structural analysis for buyer selection and purchasing strategy are presented. Game theory provides concepts for responding to competitive moves. Using the concept of strategic groups, structural analysis can also explain differences in firm performance (profitability), provide a guide for competitive strategy, and predict industry evolution. Part II, "Generic Industry Environments," shows how firms can use the analytical framework to develop a competitive strategy in industry environments, which reflect differences in industry concentration, state of industry maturity, and exposure to international competition. These environments determine a business's competitive strategic context, available alternatives, and common strategic errors. Five generic industry environments are examined: fragmented industries (where level of industrial concentration is low), emerging industries, transition to industry maturity, declining industries, and global industries. In each, the crucial aspects of industry structure, key strategic issues, characteristic strategic alternatives (including divestment), and strategic pitfalls are identified. Part III, "Strategic Decisions," draws on the analytical framework to examine important types of strategic decisions confronting firms that compete in a single industry: vertical integration, major capacity expansion, and new business entry. Additional use of economic theory and administrative consideration of management and motivation helps a company to make key decisions, and gives insight into how competitors, customers, suppliers, and potential entrants might make them. Appendix A discusses use of techniques for portfolio analysis applied to competitor analysis. Appendix B provides approaches to conducting an industry study, including sources of field and published dat

Relation of Cerebral Vasospasm to Subarachnoid Hemorrhage Visualized by Computerized Tomographic Scanning

Abstract: In 47 cases of verified ruptured saccular aneurysm, we investigated the relationship of the amount and distribution of subarachnoid blood detected by computerized tomography to the later development of cerebral vasospasm. When the subarachnoid blood was not detected or was distributed diffusely, severe vasospasm was almost never encounters (1 of 18 cases). In the presence of subarachnoid blood clots larger than 5 X 3 mm (measured on the reproduced images) or layers of blood 1 mm or more thick in fissures and vertical cisterns, severe spasm followed almost invariably (23 of 24 cases). There was an almost exact correspondence between the site of the major subarachnoid blood clots and the location of severe vasospasm. Every patient with severe vasospasm manifested delayed symptoms and signs. Excellent correlation existed between the particular artery in vasospasm and the delayed clinical syndrome. Severe vasospasm involved the anterior cerebral artery in 20 cases and the middle cerebral artery in only 14. As the grading system used is partly subjective, the findings should be regarded as preliminary. The results, if confirmed, indicate that blood localized in the subarachnoid space in sufficient amount at specific sites is the only important etiological factor in vasospasm. It should be possible to identify patients in jeopardy from vasospasm and institute early preventive measures. (Neurosurgery, 6: 1--9, 1980)

Domestic Saving and International Capital Flows

Abstract: How internationally mobile is the world's supply of capital? Does capital flow among industrial countries to equalize the yield to investors? Alternatively, does the saving that originates in a country remain 'to be invested there? Or does the truth lie somewhere between these two extremes? The answers to these questions are not only important for understanding the international capital market but are also critical for analyzing a wide range of issues including the nation's optimal rate of saving and the incidence of tax changes. (This abstract was borrowed from another version of this item.)

The development of ocular dominance columns in normal and visually deprived monkeys.

Abstract: The main purpose of this study was to examine the normal postnatal development of ocular dominance columns in the striate cortex of the macaque monkey and to determine how this developmental process is influenced by monocular lid-suture. The physiological pattern of ocular dominance was studied in long, tangential electrode penetrations. For anatomical demonstration of the distribution of afferents we relied principally on the transneuronal transport of [3H]proline injected into one eye, and to a lesser extent on the Liesegang silver method. The effects of deprivation on cell size in the lateral geniculate nucleus (LGN) were also studied. Twenty-six monkeys, divided into 5 groups (A–E), were used. A The process of normal columnar development was examined in four monkeys aged from 1 to 6 weeks. At one week, there was both an anatomical and a physiological mixing of left- and right-eye inputs to layer IVC, but the basic columnar pattern was evident, and some small regions were already monccular. At three weeks the columnar pattern resembled that seen in the adult, except for a suggestion that the borders between columns were not so sharply demarcated. By six weeks an adult degree of columnar segregation was established. B A series of ten monkeys had monocular suture performed at successively later ages, ranging from 2 days to adult, and they were allowed to survive for a long period. It was found that deprivation begun at any age from birth to about 6 weeks had approximately the same effect: the afferents for the open eye formed greatly expanded columns in layer IVC, and the columns for the closed eye were shrunken and fragmented. In the layers above and below IVC the open eye dominated almost completely. At 10 weeks, closure had only a mild effect on columnar size in layer IVC. With closures at 7–14 months there was no change in the size of columns in layer IVC, but when stained with the Liesegang silver method the deprived-eye columns were paler than those for the open eye, suggesting a lower density of fibers. These late deprivations still caused a shift of ocular dominance in the upper cortical layers but not such an extreme change as with earlier closures. Lid suture in an adult had no detectable anatomical or physiological effects. Even monocular enucleation, in an adult, failed to induce sprouting of the geniculocortical afferents for the remaining eye. C In order to investigate the rate at which monocular deprivation produces its effects, six monkeys were examined after short periods of deprivation in infancy. Eye-closure from birth to 3 weeks was sufficient to produce the full anatomical and physiological effects. A nine-day closure at 3 weeks, followed by reopening of the eye, also produced the full effects. A two-week period of deprivation begun at five weeks of age, however, caused relatively mild columnar expansion in layer IVC, suggesting that late closures may require more time to produce anatomical changes than early closures. D The effects of reopening the deprived eye and closing the experienced eye (reverse suture) were studied in three monkeys. The initial lid sutures were performed in the first few days of life. With reverse suture a t 3 weeks the relative sizes of the two sets of columns were reversed. This anatomical reversal was, however, limited to the afferents from the parvocellular laminae of the LGN; the magnocellular afferents remained in the pattern induced by the early deprivation. The layers outside of IVC were strongly dominated by the initially deprived eye. Reverse suture at 6 weeks allowed an anatomical recovery of the parvocellular afferents to a normal columnar size, but not a complete reversal. Again, the magnocellular afferents for the initially deprived eye were not induced t o enlarge their territory. Reverse suture at 1 year of age did not lead to any recovery. E One monkey was reared in complete darkness from 3 days of age until 7 weeks of age. This animal, studied autoradiographically, showed a normal columnar pattern in layer IVC. We draw four conclusions from these experiments. (i) Ocular dominance columns are only partially formed a t birth but develop rapidly in the first few weeks of postnatal life. The process of segregation of the left- and right-eye afferents-in layer IV occurs in the presence or absence of visual experience. (ii) This developmental process may be redirected by early monocular deprivation, causing the segregation of the two sets of afferents into columns of unequal width, (iii) A rearrangement of the afferents can be induced for a short period after their segregation is complete. This is true of both normal and deprived animals. (iv) The eye preference of neurons in the upper and lower layers may be changed even after plasticity in layer-IVC is no longer detectable.

Angiogenesis in vitro

Abstract: Cloned capillary endothelial cells, cultured in tumour-conditioned medium, form capillary tubes. By light and electron microscopy these tubes resemble capillaries in vivo. This first demonstration of angiogenesis in vitro: (1) shows that all the information necessary to develop an entire capillary network in vitro is expressed by one cell type; (2) suggests a mechanism for lumen formation; and (3) offers a possibility of distinguishing between direct and indirect angiogenesis factors.

Characterization of a human B lymphocyte-specific antigen.

Abstract: A human B lymphocyte-specific antigen (B1) was identified and characterized by the use of a monoclonal antibody. By indirect immunofluorescence, cytotoxicity, and quantitative absorption, B1 was present on approximately 9% of the peripheral blood mononuclear cell fraction and >95% of B cells from blood and lymphoid organs in all individuals tested. Monocytes, resting and activated T cells, null cells, and tumors of T cell and myeloid origin were B1 negative. B1 was distinct from standard B cell phenotypic markers, including Ig and Ia antigen. Removal of the B1 positive population in peripheral blood eliminated all B cells capable or responding to pokeweed mitogen by maturation to Ig-producing cells.

The Future of Elementary Particle Physics

Abstract: We live in interesting times. We have a theory, at last, of strong, weak, and electromagnetic interactions. Many new accelerators are ahuilding to test our theory.

The 5′ ends of Drosophila heat shock genes in chromatin are hypersensitive to DNase I

Abstract: Many specific sites in Drosophila chromatin are hypersensitive to DNase I. The positions of such sites were mapped along the regions of the genome coding for two heat shock proteins. Such sites lie at the 5' ends of heat shock genes and may function as elements for recognition by molecules which regulate gene activity.

Possible Third Order Phase Transition in the Large N Lattice Gauge Theory

Abstract: The large-$N$ limit of the two-dimensional $\mathrm{U}(N)$ (Wilson) lattice gauge theory is explicitly evaluated for all fixed $\ensuremath{\lambda}={g}^{2}N$ by steepest-descent methods. The $\ensuremath{\lambda}$ dependence is discussed and a third-order phase transition, at $\ensuremath{\lambda}=2$, is discovered. The possible existence of such a weak- to strong-coupling third-order phase transition in the large-$N$ four-dimensional lattice gauge theory is suggested, and its meaning and implications are discussed.

Concepts of interaction.

Abstract: Readers of the American Journal of Epidemiology have seen a lively discourse on the topic of synergy, a major conceptual area in epidemiology for which there exists fundamental controversy as to definitions. In 1974, one of us (KJR) (1) proposed that synergy (or its negative counterpart, antagonism) between two or more causes of disease ought to be evaluated in reference to a specific yardstick. The reference point was one that equated independence of the causes with the situation in which the joint effect was equal to the sum of the separate effects, with effect defined as excess risk. Rothman emphasized the distinction between biologic and statistical interaction, arguing that biologic interaction, unlike statistical interaction, could not be defined with arbitrariness in the choice of scale of measurement.

Human sleep: its duration and organization depend on its circadian phase

Abstract: Two- to threefold variations in sleep length were observed in 12 subjects living on self-selected schedules in an environment free of time cues. The duration of polygraphically recorded sleep episodes was highly correlated with the circadian phase of the body temperature rhythm at bedtime and not with the length of prior wakefulness. Furthermore, the rate of REM (rapid eye movement) sleep accumulation , REM latency, bedtime selection, and self-rated alertness assessments were also correlated with the body temperature rhythm.

Nonlinear axially symmetric circulations in a nearly inviscid atmosphere

Abstract: The structure of certain axially symmetric circulations in a stably stratified, differentially heated, rotating Boussinesq fluid on a sphere is analyzed. A simple approximate theory [similar to that introduced by Schneider (1977)] is developed for the case in which the fluid is sufficiently inviscid that the poleward flow in the Hadley cell is nearly angular momentum conserving. The theory predicts the width of the Hadley cell, the total poleward heat flux, the latitude of the upper level jet in the zonal wind, and the distribution of surface easterlies and westerlies. Fundamental differences between such nearly inviscid circulations and the more commonly studied viscous axisymmetric flows are emphasized. The theory is checked against numerical solutions to the model equations.

The Uses of Comparative History in Macrosocial Inquiry

Abstract: Comparative history is not new. As long as people have investigated social life, there has been recurrent fascination with juxtaposing historical patterns from two or more times or places. Part of the appeal comes from the general usefulness of looking at historical trajectories in order to study social change. Indeed, practitioners of comparative history from Alexis de Tocqueville and Max Weber to Marc Bloch, Reinhard Bendix, and Barrington Moore, Jr. have typically been concerned with understanding societal dynamics and epochal transformations of cultures and social structures. Attention to historical sequences is indispensable to such understanding. Obviously, though, not all investigations of social change use explicit juxtapositions of distinct histories. We may wonder, therefore: What motivates the use of comparisons as opposed to focussing on single historical trajectories? What purposes are pursued—and how—through the specific modalities of comparative history?

Production of NO2- and N2O by Nitrifying Bacteria at Reduced Concentrations of Oxygen

Abstract: Pure cultures of the marine ammonium-oxidizing bacterium Nitrosomonas sp. were grown in the laboratory at oxygen partial pressures between 0.005 and 0.2 atm (0.18 to 7 mg/liter). Low oxygen conditions induced a marked decrease in the rate for production of NO2-, from 3.6 × 10−10 to 0.5 × 10−10 mmol of NO2- per cell per day. In contrast, evolution of N2O increased from 1 × 10−12 to 4.3 × 10−12 mmol of N per cell per day. The yield of N2O relative to NO2- increased from 0.3% to nearly 10% (moles of N in N2O per mole of NO2-) as the oxygen level was reduced, although bacterial growth rates changed by less than 30%. Nitrifying bacteria from the genera Nitrosomonas, Nitrosolobus, Nitrosospira, and Nitrosococcus exhibited similar yields of N2O at atmospheric oxygen levels. Nitrite-oxidizing bacteria (Nitrobacter sp.) and the dinoflagellate Exuviaella sp. did not produce detectable quantities of N2O during growth. The results support the view that nitrification is an important source of N2O in the environment.

A monoclonal antibody to human acute lymphoblastic leukaemia antigen

Abstract: Previous studies by Greaves1 and others2–6 have demonstrated the existence of an antigen associated with cells from many patients with acute lymphoblastic leukaemia (ALL) and some patients with chronic myelocytic leukaemia (CML) in blast crisis. Antisera to this common ALL antigen (CALLA) have been produced in rabbits and require extensive absorption which limits both the titre and quantity of antisera that can be generated and may result in variable specificity in different laboratories. The method for generation of specific antibody by somatic cell hybridisation introduced by Kohler and Milstein7 has been successfully used to produce monoclonal antibodies against various normal human cell-surface proteins, including β2 microglobulin8, histocompatibility antigens9, thymocyte and peripheral T-cell antigens10–12 and Ia-like antigens13. The present report describes the generation and characterisation of a monoclonal antibody specific for a common ALL antigen (CALLA) previously identified by conventional heteroantisera.

Photosynthesis of previtamin D3 in human skin and the physiologic consequences.

Abstract: Photosynthesis of previtamin D3 can occur throughout the epidermis in the dermis when hypopigmented Caucasian skin is exposed to solar ultraviolet radiation. Once previtamin D3 is formed in the skin, it undergoes a temperature-dependent thermal isomerization that takes at least 3 days to complete. The vitamin D-binding protein preferentially translocates the thermal product, vitamin D3, into the circulation. These processes suggest a unique mechanism for the synthesis, storage, and slow, steady release of vitamin D3 from the skin into the circulation.

A physiological mechanism of bradykinesia

Abstract: Patients with Parkinson's disease were asked to make ballistic elbow flexion movements of 10, 20 and 40 degrees. Normal subjects made all these movements in the same amount of time with a single 'triphasic' EMG pattern of successive bursts in biceps, triceps and biceps. Almost all the patients made some movements requiring additional cycles of alternating biceps and triceps activity. Most of the patients exhibited at least one example of a longer movement taking more cycles than a shorter movement. It is argued that this behaviour explains previous kinematic analyses of movement in patients with Parkinson's disease and represents a physiological mechanism of bradykinesia. In part on the basis of the data presented here, it is suggested that a normal role of the basal ganglia in movement is to energize the appropriate muscles required to make the movement.

Intrathecal morphine inhibits substance P release from mammalian spinal cord in vivo

Abstract: The central terminals of small diameter primary sensory neurones associated with the transmission of noxious cutaneous stimuli are located predominantly in the superficial dorsal horn of the spinal cord1–3. Some of these neurones synthesize substance P (ref. 4) and transport this peptide to their central and peripheral terminals5–7. Substance P is released from the dorsal horn in vitro following potassium depolarization8,9; from spinal cord after electrical stimulation of dorsal roots10 and from dissociated sensory neurones grown in culture11. The iontophoretic application of substance P produces a long-lasting excitation of dorsal horn neurones that are also excited by noxious cutaneous stimuli12–14. One population of opiate receptors in the dorsal horn seems to be located on primary afferent terminals15–16; the release of substance P from primary sensory neurones is inhibited by opiates in vitro8,11. At present, however, there is no direct evidence that substance P is released from sensory neurones, in vivo, following activation of nociceptive afferents. We report here that substance P-like immunoreactivity is released from the mammalian spinal cord, in vivo, following chemical stimulation of sensory neurones with capsaicin and by the activation of high threshold peripheral afferents. Furthermore, release of substance P evoked by high intensity stimuli is completely inhibited by intrathecal morphine.

Cytoarchitectonic organization of the human auditory cortex.

Abstract: A new cytoarchitectonic study of the human auditory cortex was undertaken in the light of recent knowledge concerning the architecture, fiber connectivity, and physiology of this region in the monkey. The survey of three normative human brains (six hemispheres) processed in whole-brain serial sections disclosed a cytoarchitectonic organization of the cortical auditory region similar to that in the macaque. Unlike the monkey, auditory-related cortex was found in parietal operculum and inferior parietal lobule. Similarities in cortical architectonics between human and monkey brains may provide a rationale for the application of knowledge concerning animal physiology and connectivity to man.

Output Effects of Government Purchases

Abstract: Because of a small direct negative effect on private spending, temporary variations in government purchases as in wartime, would have a strong positive effect on aggregate demand. Intertemporal substitution effects would direct work and production toward these periods where output was valued unusually highly. Defense purchases are divided empirically into "permanent" and "temporary" components by considering the role of (temporary) wars. Shifts in non-defense purchases are mostly permanent. Empirical results verify a strong expansionary effect on output of temporary purchases, but contradict some more specific expectational propositions.

Is a new and general theory of evolution emerging

Abstract: The “modern synthetic” view of evolution has broken down, at least as an exclusive proposition, on both of its fundamental claims: (1) “extrapolationism” (gradual substitution of different alleles in many genes as the exclusive process underlying all evolutionary change) and (2) nearly exclusive reliance on selection leading to adaptation. Evolution is a hierarchical process with complementary, but different modes of change at its three large-scale levels: (a) variation within populations, (b) speciation, and (c) very long-term macroevolutionary trends. Speciation is not always an extension of gradual, adaptive allelic substitution, but may represent, as Goldschmidt argued, a different style of genetic change—rapid reorganization of the genome, perhaps nonadaptive. Macroevolutionary trends do not arise from the gradual, adaptive transformation of populations, but usually from a higher-order selection operating upon groups of species. Individual species generally do not change much after their “instantaneous” (in geological time) origin. These two discontinuities in the evolutionary hierarchy can be called the Goldschmidt break (change in populations is different from speciation) and the Wright break (speciation is different from macroevolutionary trending that translates differential success among different species).

Knowledge Creep and Decision Accretion

Abstract: The conventional title for this article would be &dquo;Knowledge Utilization in Decision-Making.&dquo; I have chosen the mangled terminology to make a point-in fact, two points. The first is that knowledge, at least the subcategory of knowledge that derives from systematic research and analysis, is not often &dquo;utilized&dquo; in direct and instrumental fashion in the formulation of policy. Only occasionally does it supply an &dquo;answer&dquo; that