Showing papers by "Texas A&M University published in 2000"
TL;DR: In this article, the authors examine strategy formulation and implementation by private and public enterprises in several different regional settings and from three primary theoretical perspectives: institutional theory, transaction cost economics, and the resource-based view of the firm.
Abstract: Emerging economies are low-income, rapid-growth countries using economic liberalization as their primary engine of growth. They fall into two groups: developing countries in Asia, Latin America, Africa, and the Middle East and transition economies in the former Soviet Union and China. Private and public enterprises have had to develop unique strategies to cope with the broad scope and rapidity of economic and political change in emerging economies. This Special Research Forum on Emerging Economies examines strategy formulation and implementation by private and public enterprises in several different regional settings and from three primary theoretical perspectives: institutional theory, transaction cost economics, and the resource-based view of the firm. In this introduction, we show how different theoretical perspectives can provide useful insights into enterprise strategies in emerging economies. We discuss the special methodological as well as empirical challenges associated with doing research in emer...
3,391 citations
TL;DR: In this article, a meta-analysis explores factors associated with higher response rates in electronic surveys reported in both published and unpublished research and concludes that response representativeness is more important than response rate in survey research.
Abstract: Response representativeness is more important than response rate in survey research. However, response rate is important if it bears on representativeness. The present meta-analysis explores factors associated with higher response rates in electronic surveys reported in both published and unpublished research. The number of contacts, personalized contacts, and precontacts are the factors most associated with higher response rates in the Web studies that are analyzed.
2,520 citations
TL;DR: In this paper, a structural equations model was used to investigate the effect of perceived performance quality on behavioral intentions and satisfaction, and the results indicated that the perceptions measure of quality fitted the hypothesized model better than data derived from the subjective disconfirmation measure.
2,419 citations
TL;DR: Many genes underlying the classification of this subset of melanomas are differentially regulated in invasive melanomas that form primitive tubular networks in vitro, a feature of some highly aggressive metastatic melanomas.
Abstract: The most common human cancers are malignant neoplasms of the skin. Incidence of cutaneous melanoma is rising especially steeply, with minimal progress in non-surgical treatment of advanced disease. Despite significant effort to identify independent predictors of melanoma outcome, no accepted histopathological, molecular or immunohistochemical marker defines subsets of this neoplasm. Accordingly, though melanoma is thought to present with different 'taxonomic' forms, these are considered part of a continuous spectrum rather than discrete entities. Here we report the discovery of a subset of melanomas identified by mathematical analysis of gene expression in a series of samples. Remarkably, many genes underlying the classification of this subset are differentially regulated in invasive melanomas that form primitive tubular networks in vitro, a feature of some highly aggressive metastatic melanomas. Global transcript analysis can identify unrecognized subtypes of cutaneous melanoma and predict experimentally verifiable phenotypic characteristics that may be of importance to disease progression.
2,058 citations
TL;DR: A 21st-century global warming projection far exceeds the natural variability of the past 1000 years and is greater than the best estimate of global temperature change for the last interglacial.
Abstract: Recent reconstructions of Northern Hemisphere temperatures and climate forcing over the past 1000 years allow the warming of the 20th century to be placed within a historical context and various mechanisms of climate change to be tested. Comparisons of observations with simulations from an energy balance climate model indicate that as much as 41 to 64% of preanthropogenic (pre-1850) decadal-scale temperature variations was due to changes in solar irradiance and volcanism. Removal of the forced response from reconstructed temperature time series yields residuals that show similar variability to those of control runs of coupled models, thereby lending support to the models' value as estimates of low-frequency variability in the climate system. Removal of all forcing except greenhouse gases from the ∼1000-year time series results in a residual with a very large late-20th-century warming that closely agrees with the response predicted from greenhouse gas forcing. The combination of a unique level of temperature increase in the late 20th century and improved constraints on the role of natural variability provides further evidence that the greenhouse effect has already established itself above the level of natural variability in the climate system. A 21st-century global warming projection far exceeds the natural variability of the past 1000 years and is greater than the best estimate of global temperature change for the last interglacial.
1,971 citations
TL;DR: In this paper, the authors examined the role that consumer perceptions of online convenience, merchandising (product offerings and product information), site design, and financial security play in e-satisfaction assessments.
1,933 citations
TL;DR: A method is proposed for designing controllers with arbitrarily small tracking error for uncertain, mismatched nonlinear systems in the strict feedback form and it is shown that these low pass filters allow a design where the model is not differentiated, thus ending the complexity arising due to the "explosion of terms" that has made other methods difficult to implement in practice.
Abstract: A method is proposed for designing controllers with arbitrarily small tracking error for uncertain, mismatched nonlinear systems in the strict feedback form. This method is another "synthetic input technique," similar to backstepping and multiple surface control methods, but with an important addition, /spl tau/-1 low pass filters are included in the design where /spl tau/ is the relative degree of the output to be controlled. It is shown that these low pass filters allow a design where the model is not differentiated, thus ending the complexity arising due to the "explosion of terms" that has made other methods difficult to implement in practice. The backstepping approach, while suffering from the problem of "explosion of terms" guarantees boundedness of tracking errors globally; however, the proposed approach, while being simpler to implement, can only guarantee boundedness of tracking error semiglobally, when the nonlinearities in the system are non-Lipschitz.
1,901 citations
TL;DR: In this paper, the authors present a service-branding model that underscores the salient role of customers' service experiences in brand formation, and four primary strategies that excellent service firms use to cultivate brand equity are discussed and illustrated.
Abstract: In packaged goods, the product is the primary brand. However, with services, the company is the primary brand. This article, based on primary research with 14 mature, high-performance service companies, makes a case for service branding as a cornerstone of services marketing for today and tomorrow. The article presents a service-branding model that underscores the salient role of customers' service experiences in brand formation. Four primary strategies that excellent service firms use to cultivate brand equity are discussed and illustrated. Branding is not just for tangible goods; it is a principal success driver for service organizations as well.
1,715 citations
TL;DR: During human evolutionary history, there were “trade-offs” between expending time and energy on child-rearing and mating, so both men and women evolved conditional mating strategies guided by cues signaling the circumstances.
Abstract: During human evolutionary history, there were "trade-offs" between expending time and energy on child-rearing and mating, so both men and women evolved conditional mating strategies guided by cues signaling the circumstances. Many short-term matings might be successful for some men; others might try to find and keep a single mate, investing their effort in rearing her offspring. Recent evidence suggests that men with features signaling genetic benefits to offspring should be preferred by women as short-term mates, but there are trade-offs between a mate's genetic fitness and his willingness to help in child-rearing. It is these circumstances and the cues that signal them that underlie the variation in short- and long-term mating strategies between and within the sexes.
1,523 citations
TL;DR: In this paper, Navier's solutions of rectangular plates, and finite element models based on the third-order shear deformation plate theory are presented for the analysis of through-thickness functionally graded plates.
Abstract: Theoretical formulation, Navier's solutions of rectangular plates, and finite element models based on the third-order shear deformation plate theory are presented for the analysis of through-thickness functionally graded plates. The plates are assumed to have isotropic, two-constituent material distribution through the thickness, and the modulus of elasticity of the plate is assumed to vary according to a power-law distribution in terms of the volume fractions of the constituents. The formulation accounts for the thermomechanical coupling, time dependency, and the von Karman-type geometric non-linearity. Numerical results of the linear third-order theory and non-linear first-order theory are presented to show the effect of the material distribution on the deflections and stresses. Copyright © 2000 John Wiley & Sons, Ltd.
1,460 citations
TL;DR: The authors examined the resource dependence role of corporate directors and posits that the widely used insider/outsider categorizations do not adequately capture this role of directors, and presented a taxonomy of directors specifically for studying the role of resource dependence.
Abstract: Most research on corporate directors has focused on two roles: agency and resource dependence. While these two roles are theoretically and practically distinct, previous research has used the same classification scheme for measuring board composition regardless of role examined. Our paper examines the resource dependence role of directors and posits that the widely used insider/outsider categorizations do not adequately capture this role of directors. A taxonomy of directors is presented specifically for studying the resource dependence role. We then apply the taxonomy to a sample of US airline firms undergoing deregulation, and examine how board composition changes parallel the changing resource dependence needs of the firms. We conclude that the board’s function as a link to the external environment is an important one, and that firms respond to significant changes in their external environment by altering board composition.
TL;DR: In this paper, a study of the international partner selection of firms from emerging (Mexico, Poland, and Romania) and developed (Canada, France, and the United States) markets supports resource-based and organizational learning explanations of such partner selection, a critical factor for success with international strategic alliances.
Abstract: This study of the international partner selection of firms from emerging (Mexico, Poland, and Romania) and developed (Canada, France, and the United States) markets supports resource-based and organizational learning explanations of such partner selection, a critical factor for success with international strategic alliances. Emerging market firms emphasized financial assets, technical capabilities, intangible assets, and willingness to share expertise in selection of partners more than developed market firms. In contrast, developed market firms tried to leverage their resources through partner selection. In particular, they emphasized unique competencies and local market knowledge and access in their partner selection more than emerging market firms.
TL;DR: It is reported that persistence of M. tuberculosis in mice is facilitated by isocitrate lyase (ICL), an enzyme essential for the metabolism of fatty acids, an observation with important implications for the treatment of chronic tuberculosis.
Abstract: Mycobacterium tuberculosis claims more human lives each year than any other bacterial pathogen. Infection is maintained in spite of acquired immunity and resists eradication by antimicrobials. Despite an urgent need for new therapies targeting persistent bacteria, our knowledge of bacterial metabolism throughout the course of infection remains rudimentary. Here we report that persistence of M. tuberculosis in mice is facilitated by isocitrate lyase (ICL), an enzyme essential for the metabolism of fatty acids. Disruption of the icl gene attenuated bacterial persistence and virulence in immune-competent mice without affecting bacterial growth during the acute phase of infection. A link between the requirement for ICL and the immune status of the host was established by the restored virulence of delta icl bacteria in interferon-gamma knockout mice. This link was apparent at the level of the infected macrophage: Activation of infected macrophages increased expression of ICL, and the delta icl mutant was markedly attenuated for survival in activated but not resting macrophages. These data suggest that the metabolism of M. tuberculosis in vivo is profoundly influenced by the host response to infection, an observation with important implications for the treatment of chronic tuberculosis.
TL;DR: An empirical model was identified that describes the roles of lignin content, acetyl contents, and crystallinity indices in enzymatic hydrolysis and the digestibility of several lime-treated biomass samples agreed with the empirical model.
Abstract: Poplar wood was treated with peracetic acid, KOH, and ball milling to produce 147 model lignocelluloses with a broad spectrum of lignin contents, acetyl contents, and crystallinity indices (CrIs), respectively. An empirical model was identified that describes the roles of these three properties in enzymatic hydrolysis. Lignin content and CrI have the greatest impact on biomass digestibility, whereas acetyl content has a minor impact. The digestibility of several lime-treated biomass samples agreed with the empirical model. Lime treatment removes all acetyl groups and a moderate amount of lignin and increases CrI slightly; lignin removal is the dominant benefit from lime treatment.
TL;DR: The Tropical Rainfall Measuring Mission (TRMM) was launched on 27 November 1997, and data from all the instruments first became available approximately 30 days after the launch as mentioned in this paper, and much progress has been made in the calibration of the sensors, the improvement of the rainfall algorithms, and applications of these results to areas such as data assimilation and model initialization.
Abstract: The Tropical Rainfall Measuring Mission (TRMM) satellite was launched on 27 November 1997, and data from all the instruments first became available approximately 30 days after the launch. Since then, much progress has been made in the calibration of the sensors, the improvement of the rainfall algorithms, and applications of these results to areas such as data assimilation and model initialization. The TRMM Microwave Imager (TMI) calibration has been corrected and verified to account for a small source of radiation leaking into the TMI receiver. The precipitation radar calibration has been adjusted upward slightly (by 0.6 dB Z) to match better the ground reference targets; the visible and infrared sensor calibration remains largely unchanged. Two versions of the TRMM rainfall algorithms are discussed. The at-launch (version 4) algorithms showed differences of 40% when averaged over the global Tropics over 30-day periods. The improvements to the rainfall algorithms that were undertaken after launch are presented, and intercomparisons of these products (version 5) show agreement improving to 24% for global tropical monthly averages. The ground-based radar rainfall product generation is discussed. Quality-control issues have delayed the routine production of these products until the summer of 2000, but comparisons of TRMM products with early versions of the ground validation products as well as with rain gauge network data suggest that uncertainties among the TRMM algorithms are of approximately the same magnitude as differences between TRMM products and ground-based rainfall estimates. The TRMM field experiment program is discussed to describe active areas of measurements and plans to use these data for further algorithm improvements. In addition to the many papers in this special issue, results coming from the analysis of TRMM products to study the diurnal cycle, the climatological description of the vertical profile of precipitation, storm types, and the distribution of shallow convection, as well as advances in data assimilation of moisture and model forecast improvements using TRMM data, are discussed in a companion TRMM special issue in the Journal of Climate (1 December 2000, Vol. 13, No. 23).
TL;DR: The synthesis of single crystals formed by infinite sheets of this magnetic coordination polymer interleaved with layers of conducting BEDT-TTF cations are reported, and it is shown that this molecule-based compound displays ferromagnetism and metallic conductivity.
Abstract: Crystal engineering--the planning and construction of crystalline supramolecular architectures from modular building blocks--permits the rational design of functional molecular materials that exhibit technologically useful behaviour such as conductivity and superconductivity, ferromagnetism and nonlinear optical properties. Because the presence of two cooperative properties in the same crystal lattice might result in new physical phenomena and novel applications, a particularly attractive goal is the design of molecular materials with two properties that are difficult or impossible to combine in a conventional inorganic solid with a continuous lattice. A promising strategy for creating this type of 'bi-functionality' targets hybrid organic/inorganic crystals comprising two functional sub-lattices exhibiting distinct properties. In this way, the organic pi-electron donor bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) and its derivatives, which form the basis of most known molecular conductors and superconductors, have been combined with molecular magnetic anions, yielding predominantly materials with conventional semiconducting or conducting properties, but also systems that are both superconducting and paramagnetic. But interesting bulk magnetic properties fail to develop, owing to the discrete nature of the inorganic anions. Another strategy for achieving cooperative magnetism involves insertion of functional bulky cations into a polymeric magnetic anion, such as the bimetallic oxalato complex [MnIICrIII(C2O4)3]-, but only insoluble powders have been obtained in most cases. Here we report the synthesis of single crystals formed by infinite sheets of this magnetic coordination polymer interleaved with layers of conducting BEDT-TTF cations, and show that this molecule-based compound displays ferromagnetism and metallic conductivity.
TL;DR: This paper suggests an approach to utilize location information (for instance, obtained using the global positioning system) to improve performance of routing protocols for ad hoc networks by using location information and presents two algorithms to determine the request zone.
Abstract: A mobile ad hoc network consists of wireless hosts that may move often. Movement of hosts results in a change in routes, requiring some mechanism for determining new routes. Several routing protocols have already been proposed for ad hoc networks. This paper suggests an approach to utilize location information (for instance, obtained using the global positioning system) to improve performance of routing protocols for ad hoc networks. By using location information, the proposed Location‐Aided Routing (LAR) protocols limit the search for a new route to a smaller “request zone” of the ad hoc network. This results in a significant reduction in the number of routing messages. We present two algorithms to determine the request zone, and also suggest potential optimizations to our algorithms.
TL;DR: The potential for the production of ethylene or liquid hydrocarbon fuels has not been fully realized as mentioned in this paper, and a number of strategies are being explored at levels that range from fundamental science to engineering technology.
TL;DR: In this article, the authors investigated the impact of failure expectations, recovery expectation, recovery performance, and justice on customers' post-recovery satisfaction after service failure and recovery, and found that customer satisfaction was lower after service failures and recovery than in the case of error free service.
Abstract: Relatively little research has addressed the nature and determinants of customer satisfaction following service failure and recovery. Two studies using scenario-based experiments reveal the impact of failure expectations, recovery expectations, recovery performance, and justice on customers’ postrecovery satisfaction. Customer satisfaction was found to be lower after service failure and recovery (even given high-recovery performance) than in the case of error-free service. The research shows that, in general, companies fare better in the eyes of consumers by avoiding service failure than by responding to failure with superior recovery.
TL;DR: The 312 microsatellite markers reported here provide whole-genome coverage with an average density of one SSLP per 6 cM, and the distribution of polymorphism detected by these markers varies between different regions of the genome.
Abstract: In order to enhance the resolution of an existing genetic map of rice, and to obtain a comprehensive picture of marker utility and genomic distribution of microsatellites in this important grain species, rice DNA sequences containing simple sequence repeats (SSRs) were extracted from several small-insert genomic libraries and from the database. One hundred and eighty eight new microsatellite markers were developed and evaluated for allelic diversity. The new simple sequence length polymorphisms (SSLPs) were incorporated into the existing map previously containing 124 SSR loci. The 312 microsatellite markers reported here provide whole-genome coverage with an average density of one SSLP per 6 cM. In this study, 26 SSLP markers were identified in published sequences of known genes, 65 were developed based on partial cDNA sequences available in GenBank, and 97 were isolated from genomic libraries. Microsatellite markers with different SSR motifs are relatively uniformly distributed along rice chromosomes regardless of whether they were derived from genomic clones or cDNA sequences. However, the distribution of polymorphism detected by these markers varies between different regions of the genome.
TL;DR: This chapter reviews empirical and theoretical developments in research on social influence and message-based persuasion, and considers how attitudes are embedded in social relations, including social identity theory and majority/minority group influence.
Abstract: This chapter reviews empirical and theoretical developments in research on social influence and message-based persuasion. The review emphasizes research published during the period from 1996-1998. Across these literatures, three central motives have been identified that generate attitude change and resistance. These involve concerns with the self, with others and the rewards/punishments they can provide, and with a valid understanding of reality. The motives have implications for information processing and for attitude change in public and private contexts. Motives in persuasion also have been investigated in research on attitude functions and cognitive dissonance theory. In addition, the chapter reviews the relatively unique aspects of each literature: In persuasion, it considers the cognitive and affective mechanisms underlying attitude change, especially dual-mode processing models, recipients' affective reactions, and biased processing. In social influence, the chapter considers how attitudes are embedded in social relations, including social identity theory and majority/minority group influence.
TL;DR: It is concluded that nitroimidazopyrans offer the practical qualities of a small molecule with the potential for the treatment of tuberculosis and bactericidal activity against both replicating and static M. tuberculosis.
Abstract: Mycobacterium tuberculosis, which causes tuberculosis, is the greatest single infectious cause of mortality worldwide, killing roughly two million people annually. Estimates indicate that one-third of the world population is infected with latent M. tuberculosis. The synergy between tuberculosis and the AIDS epidemic, and the surge of multidrug-resistant clinical isolates of M. tuberculosis have reaffirmed tuberculosis as a primary public health threat. However, new antitubercular drugs with new mechanisms of action have not been developed in over thirty years. Here we report a series of compounds containing a nitroimidazopyran nucleus that possess antitubercular activity. After activation by a mechanism dependent on M. tuberculosis F420 cofactor, nitroimidazopyrans inhibited the synthesis of protein and cell wall lipid. In contrast to current antitubercular drugs, nitroimidazopyrans exhibited bactericidal activity against both replicating and static M. tuberculosis. Lead compound PA-824 showed potent bactericidal activity against multidrugresistant M. tuberculosis and promising oral activity in animal infection models. We conclude that nitroimidazopyrans offer the practical qualities of a small molecule with the potential for the treatment of tuberculosis.
TL;DR: The GFEM is introduced as a combination of the classical Finite Element Method (FEM) and the Partition of Unity Method (PUM) to solve problems in domains with complex geometry with less error and less computer resources.
TL;DR: The effects of experimentally induced fear and anxiety on radiant heat pain thresholds suggest that findings from animal studies extend to humans: fear resulted in decreased pain reactivity, while anxiety led to increased reactivity.
Abstract: Animal studies suggest that fear inhibits pain whereas anxiety enhances it; however it is unclear whether these effects generalize to humans. The present study examined the effects of experimentally induced fear and anxiety on radiant heat pain thresholds. Sixty male and female human subjects were randomly assigned to 1 of 3 emotion induction conditions: (1) fear, induced by exposure to three brief shocks; (2) anxiety, elicited by the threat of shock; (3) neutral, with no intervention. Pain thresholds were tested before and after emotion induction. Results suggest that findings from animal studies extend to humans: fear resulted in decreased pain reactivity, while anxiety led to increased reactivity. Pain rating data indicated that participants used consistent subjective criteria to indicate pain thresholds. Both subjective and physiological indicators (skin conductance level, heart rate) confirmed that the treatment conditions produced the targeted emotional states. These results support the view that emotional states modulate human pain reactivity.
TL;DR: This article tested three models of how the relationship evaluation components of satisfaction, commitment, intimacy, trust, passion, and love are structured and cognitively represented, and found that the best fitting model was one in which the appropriate items loaded reliably on the six first-order factors, which in turn load reliably on one second-order factor reflecting overall perceived relationship quality.
Abstract: This research tested three models of how the relationship evaluation components of satisfaction, commitment, intimacy, trust, passion, and love are structured and cognitively represented. Participants in Study 1 rated their intimate relationships on six previously developed scales that measured each construct and on a new inventory—the Perceived Relationship Quality Components (PRQC) Inventory. As predicted, confirmatory factor analysis revealed that, for both sets of scales, the best-fitting model was one in which the appropriate items loaded reliably on the six first-order factors, which in turn loaded reliably on one second-order factor reflecting overall perceived relationship quality. These results were replicated on a different sample in Study 2 and across sex. Implications and advantages of the PRQC Inventory are discussed.
26 Mar 2000
TL;DR: This paper attempts to design new MAC protocols suitable for ad hoc networks based on directional antennas, such as the IEEE 802.11 standard, which do not benefit when using directional antennas because they have been designed for omnidirectional antennas.
Abstract: Using directional antennas can be beneficial for wireless ad hoc networks consisting of a collection of wireless hosts. To best utilize directional antennas, a suitable medium access control (MAC) protocol must be designed. Current MAC protocols, such as the IEEE 802.11 standard, do not benefit when using directional antennas, because these protocols have been designed for omnidirectional antennas. In this paper, we attempt to design new MAC protocols suitable for ad hoc networks based on directional antennas.
TL;DR: Understanding mechanisms of abiotic stress tolerance in endophyte-infected grasses is essential for continued improvement and persistence of grasses for a range of applications, e.g., forage for semi-arid areas or cover plants for soil renovation.
Abstract: Cool-season grasses infected with Neotyphodium spp. endophytes have an extraordinary impact on the ecology and economy of pasture and turf. A range of adaptations of endophyte-infected grasses to biotic and abiotic stresses has been identified but mechanisms of these adaptations are not clearly understood. In this review, we present recent research progress on endophyte-related mechanisms affecting abiotic (drought, mineral) and selected aspects of biotic stress tolerance in cool-season grasses. Endophytes induce mechanisms of drought avoidance (morphological adaptations), drought tolerance (physiological and biochemical adaptations), and drought recovery in infected grasses. Mineral nutrition (nitrogen, phosphorus, calcium) affects production of ergot alkaloids, thus understanding mechanisms involved in mineral economy of endophyte-infected grasses will help in developing management practices to reduce forage toxicity to livestock. Previous research resolved the role of endophyte in nitrogen (N) economy of tall fescue. We identified two endophyte-related mechanisms in tall fescue operating in response to phosphorus (P) deficiency. The mechanisms are altered root morphology (reduced root diameters and longer root hairs) and chemical modification of the rhizosphere resulting from exudation of phenolic-like compounds. These mechanisms were shown to benefit endophyte-infected plants grown under P deficiency. We also report a mechanism of aluminum (Al) sequestration on root surfaces in endophyte-infected tall fescue, which appears to be related to exudation of phenolic-like compounds with Al-chelating activity. Understanding mechanisms of abiotic stress tolerance in endophyte-infected grasses is essential for continued improvement and persistence of grasses for a range of applications, e.g., forage for semi-arid areas or cover plants for soil renovation.
TL;DR: Two proteins, an endolysin and a holin, are essential for host lysis by bacteriophage, and constitute one of the most diverse functional groups, with >100 known or putative holin sequences, which form >30 ortholog groups.
Abstract: Two proteins, an endolysin and a holin, are essential for host lysis by bacteriophage. Endolysin is the term for muralytic enzymes that degrade the cell wall; endolysins accumulate in the cytosol fully folded during the vegetative cycle. Holins are small membrane proteins that accumulate in the membrane until, at a specific time that is "programmed" into the holin gene, the membrane suddenly becomes permeabilized to the fully folded endolysin. Destruction of the murein and bursting of the cell are immediate sequelae. Holins control the length of the infective cycle for lytic phages and so are subject to intense evolutionary pressure to achieve lysis at an optimal time. Holins are regulated by protein inhibitors of several different kinds. Holins constitute one of the most diverse functional groups, with >100 known or putative holin sequences, which form >30 ortholog groups.