Showing papers by "University of Massachusetts Amherst published in 1996"
TL;DR: In this article, it was shown that some microorganisms found in soils and sediments are able to use humic substances as an electron acceptor for the anaerobic oxidation of organic compounds and hydrogen.
Abstract: HUMIC substances are heterogeneous high-molecular-weight organic materials which are ubiquitous in terrestrial and aquatic environments. They are resistant to microbial degradation1 and thus are not generally considered to be dynamically involved in microbial metabolism, especially in anoxic habitats. However, we show here that some microorganisms found in soils and sediments are able to use humic substances as an electron acceptor for the anaerobic oxidation of organic compounds and hydrogen. This electron transport yields energy to support growth. Microbial humic reduction also enhances the capacity for microorganisms to reduce other, less accessible electron acceptors, such as insoluble Fe(III) oxides, because humic substances can shuttle electrons between the humic-reducing microorganisms and the Fe(III) oxide. The finding that microorganisms can donate electrons to humic acids has important implications for the mechanisms by which microorganisms oxidize both natural and contaminant organics in anaerobic soils and sediments, and suggests a biological source of electrons for humics-mediated reduction of contaminant metals and organics.
1,651 citations
18 Aug 1996
TL;DR: It is shown that, although global analysis haa some advantages, local analysia is generally more effective than global techniques and using global analysis techniques.
Abstract: Automatic query expansion has long been suggested as a technique for dealing with the fundamental issue of word mismatch in information retrieval. A number of approaches to expansion have been studied and, more recently, attention has focused on techniques that analyze the corpus to discover word relationship (global techniques) and those that analyze documents retrieved by the initial query ( local feedback). In this paper, we compare the effectiveness of these approaches and show that, although global analysis haa some advantages, local analysia is generally more effective. We also show that using global analysis techniques.
1,341 citations
TL;DR: Two studies provide evidence for the reliability and validity of a new self-report measure of individual differences in intuitive-experience and analytical-rational thinking based on cognitive-experiential self-theory (CEST).
Abstract: Two studies provide evidence for the reliability and validity of a new self-report measure of individual differences in intuitive-experiential and analytical-rational thinking based on cognitive-experiential self-theory (CEST). The Rational-Experiential Inventory (REI) was constructed to measure the 2 independent processing modes with a modified Need for Cognition Scale (NFC, J.T. Cacioppo & R.E. Petty, 1982) and a new scale, Faith in Intuition (FI). In Study 1, a factor analysis yielded 2 orthogonal factors corresponding to NFC and FI. Although heuristic processing was determined primarily by FI, NFC also contributed to heuristic responding, in line with CEST. The relation of FI and NFC to coping ability also was examined. In Study 2, the factor structure of the REI was replicated (N = 973). NFC and FI were differentially related to measures of personality, adjustment, achievement, and interpersonal relations.
1,186 citations
TL;DR: In this article, the full set of constraints on gluino and photino-mediated SUSY contributions to FCNC and CP violating phenomena are analyzed and a model-independent parameterization for the mass insertion method is provided.
1,106 citations
TL;DR: A relatively new development—information extraction (IE)—is the subject of this article and can transform the raw material, refining and reducing it to a germ of the original text.
Abstract: here may be more text data in electronic form than ever before, but much of it is ignored. No human can read, understand, and synthesize megabytes of text on an everyday basis. Missed information— and lost opportunities—has spurred researchers to explore various information management strategies to establish order in the text wilderness. The most common strategies are information retrieval (IR) and information filtering [4]. A relatively new development—information extraction (IE)—is the subject of this article. We can view IR systems as combine harvesters that bring back useful material from vast fields of raw material. With large amounts of potentially useful information in hand, an IE system can then transform the raw material, refining and reducing it to a germ of the original text (see Figure 1). Suppose financial analysts are investigating production of semiconductor devices (see Figure 2). They might want to know several things:
962 citations
TL;DR: The mechanisms of action, evidence of clinical efficacy, and risks of therapy with hyperbaric oxygen are reviewed, and the risks and benefits of therapy are reviewed.
Abstract: Hyperbaric oxygen — 100 percent oxygen at two to three times the atmospheric pressure at sea level — can result in arterial oxygen tension in excess of 2000 mm Hg1 and oxygen tension in tissue of almost 400 mm Hg.2,3 Such doses of oxygen have a number of beneficial biochemical, cellular, and physiologic effects, and today there are 259 hyperbaric facilities in the United States with 344 single-occupant (“monoplace”) hyperbaric-oxygen chambers.4 In this article, we review the mechanisms of action, evidence of clinical efficacy, and risks of therapy with hyperbaric oxygen. Physiologic Effects For hyperbaric oxygen, pressure is expressed . . .
956 citations
TL;DR: The purpose of this paper is to briefly trace the evolution of DEA from the initial publication by Charnes et al. (1978b) to the current state of the art (SOA).
Abstract: The purpose of this paper is to briefly trace the evolution of DEA from the initial publication by Charnes et al. (1978b) to the current state of the art (SOA). The state of development of DEA is characterized at four points in time to provide a perspective in both directions—past and future. An evolution map is provided which illustrates DEA growth during the 17-year period, the timing of the major events, and the interconnections and influences between topics. An extensive DEA bibliography is provided.
836 citations
TL;DR: High levels of circulating testosterone and low levels of SHBG-both within normal endogenous ranges-are associated with increased risks of prostate cancer, and circulating levels of DHT and AAG do not appear to be strongly related to prostate cancer risk.
Abstract: Background: Sex steroids, particularly androgens, have been implicated in the pathogenesis of prostate cancer. Data from previous studies comparing circulating hormone levels in men with and without prostate cancer are difficult to interpret, since the studies were limited in size, hormone levels were analyzed in blood drawn after the diagnosis of cancer, nonrepresentative control subjects were used, and hormone and hormone-binding protein levels were not simultaneously adjusted. Purpose: We conducted a prospective, nested casecontrol study to investigate whether plasma hormone and sex hormone-binding globulin (SHBG) levels in healthy men were related to the subsequent development of prostate cancer. Methods: Among participants in the Physicians' Health Study who provided plasma samples in 1982, we identified 222 men who developed prostate cancer by March 1992. Three hundred ninety control subjects, matched to the case patients on the bases of age, smoking status, and length of follow-up, were also identified. Immunoassays were used to measure the levels of total testosterone, dihydrotestosterone (DHT), 3a-androstanediol glucuronide (AAG), estradiol, SHBG, and prolactin in the stored (at -82 °C) plasma samples. Correlations between individual hormone levels and between hormone levels and SHBG in the plasma of control subjects were assessed by use of Spearman correlation coefficients (r). Odds ratios (ORs) and 95% confidence intervals (CIs) specifying the prostate cancer risk associated with quartile levels of individual hormones, before and after adjustment for other hormones and SHBG, were calculated by use of conditional logistic regression modeling. Reported P values are two-sided. Results: No clear associations were found between the unadjusted levels of individual hormones or SHBG and the risk of prostate cancer. However, a strong correlation was observed between the levels of testosterone and SHBG (r = .55), and weaker correlations were detected between the levels of testosterone and the levels of both estradiol (r = .28) and DHT (r = .32) (all /> 2.5 ng/mL) were excluded from the analyses. Conclusions: High levels of circulating testosterone and low levels of SHBG—both within normal endogenous ranges—are associated with increased risks of prostate cancer. Low levels of circulating estradiol may represent an additional risk factor. Circulating levels of DHT and AAG do not appear to be strongly related to prostate cancer risk. [J Natl Cancer Inst 1996;88:1118-26] A longstanding and diverse body of evidence suggests that sex steroids, particularly androgens, play a role in the etiology of prostate cancer. Androgens are essential for normal growth and maintenance of the prostate, stimulate the proliferation of human prostate cancer cells in vitro, and, when given in large amounts, can produce prostate cancer in rodents {12)- In addition, eunuchs rarely develop prostate cancer, and androgen ablation frequently causes prostate tumors to regress (3). In contrast, a reduced risk of prostate cancer has been associated with certain hyperestrogenic states (4), and estrogen therapy has a palliative effect in advanced cases (J). These observations on extreme variations in sex-steroid exposure add credibility to the hypothesis that prostate cancer risk is also related to the smaller contrasts in levels of androgens and estrogens that are found within the normal endogenous range (7). However, studies com
798 citations
TL;DR: Collective results indicate that XIST RNA may be an architectural element of the interphase chromosome territory, possibly a component of nonchromatin nuclear structure that specifically associates with Xi.
Abstract: The XIST gene is implicated in X chromosome inactivation, yet the RNA contains no apparent open reading frame. An accumulation of XIST RNA is observed near its site of transcription, the inactive X chromosome (Xi). A series of molecular cytogenetic studies comparing properties of XIST RNA to other protein coding RNAs, support a critical distinction for XIST RNA; XIST does not concentrate at Xi simply because it is transcribed and processed there. Most notably, morphometric and 3-D analysis reveals that XIST RNA and Xi are coincident in 2- and 3-D space; hence, the XIST RNA essentially paints Xi. Several results indicate that the XIST RNA accumulation has two components, a minor one associated with transcription and processing, and a spliced major component, which stably associates with Xi. Upon transcriptional inhibition the major spliced component remains in the nucleus and often encircles the extra-prominent heterochromatic Barr body. The continually transcribed XIST gene and its polyadenylated RNA consistently localize to a nuclear region devoid of splicing factor/poly A RNA rich domains. XIST RNA remains with the nuclear matrix fraction after removal of chromosomal DNA. XIST RNA is released from its association with Xi during mitosis, but shows a unique highly particulate distribution. Collective results indicate that XIST RNA may be an architectural element of the interphase chromosome territory, possibly a component of nonchromatin nuclear structure that specifically associates with Xi. XIST RNA is a novel nuclear RNA which potentially provides a specific precedent for RNA involvement in nuclear structure and cis-limited gene regulation via higher-order chromatin packaging.
791 citations
TL;DR: Two new temporal diffence algorithms based on the theory of linear least-squares function approximation, LS TD and RLS TD, are introduced and prove probability-one convergence when it is used with a function approximator linear in the adjustable parameters.
Abstract: We introduce two new temporal diffence (TD) algorithms based on the theory of linear least-squares function approximation. We define an algorithm we call Least-Squares TD (LS TD) for which we prove probability-one convergence when it is used with a function approximator linear in the adjustable parameters. We then define a recursive version of this algorithm, Recursive Least-Squares TD (RLS TD). Although these new TD algorithms require more computation per time-step than do Sutton's TD(λ) algorithms, they are more efficient in a statistical sense because they extract more information from training experiences. We describe a simulation experiment showing the substantial improvement in learning rate achieved by RLS TD in an example Markov prediction problem. To quantify this improvement, we introduce theTD error variance of a Markov chain, ωTD, and experimentally conclude that the convergence rate of a TD algorithm depends linearly on ωTD. In addition to converging more rapidly, LS TD and RLS TD do not have control parameters, such as a learning rate parameter, thus eliminating the possibility of achieving poor performance by an unlucky choice of parameters.
741 citations
TL;DR: In the United States, the federal government is increasingly using requirements for informational labeling on food products to influence consumers' knowledge and purchasing patterns and manufacturers' product offerings and marketing practices.
Abstract: In the United States, the federal government is increasingly using requirements for informational labeling on food products to influence 1) consumers' knowledge and purchasing patterns and 2) manufacturers' product offerings and marketing practices. We discuss the economic rationale behind these regulations and issues related to judging their success or failure.
TL;DR: The crystal structure of the βγ dimer of the G protein transducin is solved using multiwavelength anomalous diffraction data to solve the interactions between G protein β- and γ-subunits and highlights regions implicated in effector modulation for the conserved family of G proteinβγ dimers.
Abstract: Many signalling cascades use seven-helical transmembrane receptors coupled to heterotrimeric G proteins (G alpha beta gamma) to convert extracellular signals into intracellular responses. Upon nucleotide exchange catalysed by activated receptors, heterotrimers dissociate into GTP-bound G alpha subunits and G beta gamma dimers, either of which can modulate many downstream effectors. Here we use multiwavelength anomalous diffraction data to solve the crystal structure of the beta gamma dimer of the G protein transducin. The beta-subunit is primarily a seven-bladed beta-propeller that is partially encircled by an extended gamma-subunit. The beta-propeller, which contains seven structurally similar WD repeats, defines the stereochemistry of the WD repeat and the probable architecture of all WD-repeat-containing domains. The structure details interactions between G protein beta- and gamma-subunits and highlights regions implicated in effector modulation for the conserved family of G protein beta gamma dimers.
TL;DR: The present study compared 172 adults diagnosed with ADHD with 30 adults referred to the same adult ADHD clinic who were not so diagnosed to suggest that ADHD in adults is associated with relatively specific risks for disruptive behavior disorders, school and job performance problems, and driving risks.
18 Aug 1996
TL;DR: This work proposes that two machine learning algorithms, the Widrow-Hoff and EG algorithms, be used in training linear text classifiers for IR tasks, and theoretical analysis provides performance guarantees and guidance on parameter settings for these algorithms.
Abstract: Systems for text retrieval, routing, categorization and other IR tasks rely heavily on linear classifiers. We propose that two machine learning algorithms, the Widrow-Hoff and EG algorithms, be used in training linear text classifiers. In contrast to most IR methods, theoretical analysis provides performance guarantees and guidance on parameter settings for these algorithms. Experimental data is presented showing Widrow-Hoff and EG to be more effective than the widely used Rocchio algorithm on several categorization and routing tasks.
TL;DR: A new kind of eligibility trace, thereplacing trace, is introduced theoretically, analyzed theoretically, and it is shown that it results in faster, more reliable learning than the conventional trace, and that replacing traces significantly improve performance and reduce parameter sensitivity on the "Mountain-Car" task.
Abstract: The eligibility trace is one of the basic mechanisms used in reinforcement learning to handle delayed reward. In this paper we introduce a new kind of eligibility trace, thereplacing trace, analyze it theoretically, and show that it results in faster, more reliable learning than the conventional trace. Both kinds of trace assign credit to prior events according to how recently they occurred, but only the conventional trace gives greater credit to repeated events. Our analysis is for conventional and replace-trace versions of the offline TD(1) algorithm applied to undiscounted absorbing Markov chains. First, we show that these methods converge under repeated presentations of the training set to the same predictions as two well known Monte Carlo methods. We then analyze the relative efficiency of the two Monte Carlo methods. We show that the method corresponding to conventional TD is biased, whereas the method corresponding to replace-trace TD is unbiased. In addition, we show that the method corresponding to replacing traces is closely related to the maximum likelihood solution for these tasks, and that its mean squared error is always lower in the long run. Computational results confirm these analyses and show that they are applicable more generally. In particular, we show that replacing traces significantly improve performance and reduce parameter sensitivity on the "Mountain-Car" task, a full reinforcement-learning problem with a continuous state space, when using a feature-based function approximator.
TL;DR: This article presents compiler optimizations to improve data locality based on a simple yet accurate cost model and finds performance improvements were difficult to achieve, but improved several programs.
Abstract: In the past decade, processor speed has become significantly faster than memory speed. Small, fast cache memories are designed to overcome this discrepancy, but they are only effective when programs exhibit data locality. In the this article, we present compiler optimizations to improve data locality based on a simple yet accurate cost model. The model computes both temporal and spatial reuse of cache lines to find desirable loop organizations. The cost model drives the application of compound transformations consisting of loop permutation, loop fusion, loop distribution, and loop reversal. To validate our optimization strategy, we implemented our algorithms and ran experiments on a large collection of scientific programs and kernels. Experiments illustrate that for kernels our model and algorithm can select and achieve the best loop structure for a nest. For over 30 complete applications, we executed the original and transformed versions and simulated cache hit rates. We collected statistics about the inherent characteristics of these programs and our ability to improve their data locality. To our knowledge, these studies are the first of such breadth and depth. We found performance improvements were difficult to achieve bacause benchmark programs typically have high hit rates even for small data caches; however, our optimizations significanty improved several programs.
TL;DR: Teaching physics with a classroom communication system called Classtalk was found to be a useful tool not only for engaging students in active learning during the lecture hour but also for enhancing the overall communication within the classroom.
Abstract: TRADITIONAL METHODS for teaching science courses at the post-secondary level employ a lecture format of instruction in which the majority of students are passively listening to the instructor and jotting down notes. Current views of learning and instruction challenge the wisdom of this traditional pedagogic practice by stressing the need for the learner to play an active role in constructing knowledge. The emerging technology of classroom communication systems offers a promising tool for helping instructors create a more interactive, student-centered classroom, especially when teaching large courses. In this paper we describe our experiences teaching physics with a classroom communication system calledClasstalk. Classtalk facilitated the presentation of questions for small group work as well as the collection of student answers and the display of histograms showing how the class answered, all of which fed into a class-wide discussion of students’ reasoning. We foundClasstalk to be a useful tool not only for engaging students in active learning during the lecture hour but also for enhancing the overall communication within the classroom. Equally important, students were very positive aboutClasstalk-facilitated instruction and believed that they learned more during class than they would have during a traditional lecture.
TL;DR: The authors explored evidence from the General Social Survey and the National Survey of Families and Households, supplemented by data from the American National Election Studies and several small but highly relevant researches, to determine whether owners and renters differ in a variety of ways.
Abstract: Claims that homeownership is beneficial to both owners and society have not been examined empirically. This article explores evidence from the General Social Survey and the National Survey of Families and Households, supplemented by data from the American National Election Studies and several small but highly relevant researches, to determine whether owners and renters differ in a variety of ways. Strong differences in demographics were found. Small differences were found in some respects: Owners tended to be higher in life satisfaction and self‐esteem and more likely to be members of community improvement groups. On a wide variety of social issues—from political partisanship to ethnocentric views—owners and renters were essentially alike. Thus, it appears that the claims for some social and individual benefits from homeownership are supported, but only weakly. Recognizing that the exploratory analyses presented are not definitive, several strategies for more definitive future research are recomm...
TL;DR: It is discovered that all known yeast and vertebrate small nucleolar RNAs (snoRNAs), except for the MRP/7-2 RNA, fall into two major classes: one class is defined by conserved boxes C and D and the other by a novel element: a consensus ACA triplet positioned 3 nt before the 3' end of the RNA.
18 Aug 1996
TL;DR: For this specific medical categorization problem, new query formulation and weighting methods used in the k-nearest-neighbor classifier improved performance.
Abstract: Three different types of classifiers were investigatedin the context of a text categorization problem in the medical domain: the automatic assignment of ICD9 codes to dictated inpatient discharge summaries. K-nearest-neighbor, relevance feedback, and Bayesian independence classifiers were applied individually and in combination. A coknbination of different classifiers produced better results than any single type of classifier. For this specific medical categorization problem, new query formulation and weighting methods used in the k-nearest-neighbor classifier improved performance.
TL;DR: It is confirmed that contextual constraint has a strong influence on eye movements during reading by asking subjects to read sentences that contained a target word that varied in contextual constraint.
Abstract: The effect of contextual constraint on eye movements in reading was examined by asking subjects to read sentences that contained a target word that varied in contextual constraint; high-, medium-, or low-constraint target words were used. Subjects fixated low-constraint target words longer than they did either high- or medium-constraint target words. In addition, they skipped high-constraint words more than they did either medium- or low-constraint target words. The results further confirm that contextual constraint has a strong influence on eye movements during reading.
TL;DR: The 'mobile loop' segment, previously identified as a GroEL binding determinant, is disordered in the crystal structure in six subunits; the single well-ordered copy extends from the bottom outer rim of the GroES dome, suggesting that the cavity within the dome is continuous with the polypeptide binding chamber of GroEL in the chaperonin complex.
Abstract: The GroES heptamer forms a dome, approximately 75 A in diameter and 30 A high, with an 8 A orifice in the centre of its roof. The 'mobile loop' segment, previously identified as a GroEL binding determinant, is disordered in the crystal structure in six subunits; the single well-ordered copy extends from the bottom outer rim of the GroES dome, suggesting that the cavity within the dome is continuous with the polypeptide binding chamber of GroEL in the chaperonin complex.
TL;DR: The metabolic fuels hypothesis is consistent with a large body of evidence and seems to account for the infertility that is seen in a number of situations, including famine, eating disorders, excessive exercise, cold exposure, lactation, some types of obesity, and poorly controlled diabetes mellitus.
Abstract: In female mammals, reproduction is extremely sensitive to the availability of oxidizable metabolic fuels. When food intake is limited or when an inordinate fraction of the available energy is diverted to other uses such as exercise or fattening, reproductive attempts are suspended in favor of processes necessary for individual survival. Both reproductive physiology and sexual behaviors are influenced by food availability. Nutritional effects on reproductive physiology are mediated by changes in the activity of gonadotropin-releasing hormone (GnRH) neurons in the forebrain, whereas the suppression of sexual behaviors appears to be due, at least in part, to decreases in estrogen receptor in the ventromedial hypothalamus. Work using pharmacological inhibitors of glucose and fatty acid oxidation indicates that reproductive physiology and behavior respond to short-term (minute-to-minute or hour-to-hour) changes in metabolic fuel oxidation, rather than to any aspect of body size or composition (e.g., body fat content or fat-to-lean ratio). These metabolic cues seem to be detected in the viscera (most likely in the liver) and in the caudal hindbrain (probably in the area postrema). This metabolic information is then transmitted to the GnRH-secreting or estradiol-binding effector neurons in the forebrain. There is no evidence to date for direct detection of metabolic cues by these forebrain effector neurons. This metabolic fuels hypothesis is consistent with a large body of evidence and seems to account for the infertility that is seen in a number of situations, including famine, eating disorders, excessive exercise, cold exposure, lactation, some types of obesity, and poorly controlled diabetes mellitus.
TL;DR: This review focuses on components of transcriptional regulation that function in growth control during osteoblast proliferation and those that postproliferatively contribute to maturation of the bone phenotype.
Abstract: Osteoblast differentiation is a multistep series of events modulated by an integrated cascade of gene expression that initially supports proliferation and the sequential expression of genes associated with the biosynthesis, organization, and mineralization of the bone extracellular matrix. Transcriptional control defines regulatory events operative both developmentally and for support of bone tissue-specific properties. This review focuses on components of transcriptional regulation that function in growth control during osteoblast proliferation and those that postproliferatively contribute to maturation of the bone phenotype. Emphasis is on transcription of the cell cycle-regulated histone gene and the bone-specific osteocalcin gene as paradigms for genes with promoter elements exhibiting responsiveness to a broad spectrum of physiological regulatory signals. Additionally, the potential contributions provided by the three-dimensional organization of the histone and osteocalcin gene promoters to integration of regulatory activities at multiple, independent, and overlapping regulatory domains are explored.
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13 May 1996TL;DR: In this paper, a system for spectroscopic imaging of bodily tissue in which a scintillation screen and a charged coupled device (CCD) are used to accurately image selected tissue.
Abstract: A system for spectroscopic imaging of bodily tissue in which a scintillation screen and a charged coupled device (CCD) are used to accurately image selected tissue. An x-ray source generates x-rays which pass through a region of a subject's body, forming an x-ray image which reaches the scintillation screen. The scintillation screen reradiates a spatial intensity pattern corresponding to the image, the pattern being detected by a CCD sensor. The image is digitized by the sensor and processed by a controller before being stored as an electronic image. Each image is directed onto an associated respective CCD or amorphous silicon detector to generate individual electronic representations of the separate images.
TL;DR: In this paper, the authors provide an overview of what happens during grinding as abrasive grains cut through ceramic workpiece materials and provide important insights into the grinding mechanisms for ceramic materials.
TL;DR: In this article, the authors considered the properties of particular geometrical forms which they define as "ideal" for a knot with a given topology and assembled from a tube of uniform diameter.
Abstract: KNOTS are usually categorized in terms of topological properties that are invariant under changes in a knot's spatial configuration1–4. Here we approach knot identification from a different angle, by considering the properties of particular geometrical forms which we define as 'ideal'. For a knot with a given topology and assembled from a tube of uniform diameter, the ideal form is the geometrical configuration having the highest ratio of volume to surface area. Practically, this is equivalent to determining the shortest piece of tube that can be closed to form the knot. Because the notion of an ideal form is independent of absolute spatial scale, the length-to-diameter ratio of a tube providing an ideal representation is constant, irrespective of the tube's actual dimensions. We report the results of computer simulations which show that these ideal representations of knots have surprisingly simple geometrical properties. In particular, there is a simple linear relationship between the length-to-diameter ratio and the crossing number—the number of intersections in a two-dimensional projection of the knot averaged over all directions. We have also found that the average shape of knotted polymeric chains in thermal equilibrium is closely related to the ideal representation of the corresponding knot type. Our observations provide a link between ideal geometrical objects and the behaviour of seemingly disordered systems, and allow the prediction of properties of knotted polymers such as their electrophoretic mobility5.
TL;DR: The fusion tube–generated membrane network signals the end of the first stage of cell plate formation, a series of steps that both mechanically stabilizes the initial delicate, interwoven membrane network and then transforms it into two new plasma membranes and a new cell wall.