The Evolution of Conformity, Malleability, and Influence in Simulated Online Agents.

The prevalence of artificial intelligence (AI) tools that filter the information given to internet users, such as recommender systems and diverse personalizers, may be creating troubling long-term side effects to the obvious short-term conveniences. Many worry that these automated influencers can subtly and unwittingly nudge individuals toward conformity, thereby (somewhat paradoxically) restricting the choices of each agent and/or the population as a whole. In its various guises, this problem has labels such as filter bubble, echo chamber, and personalization polarization. One key danger of diversity reduction is that it plays into the hands of a cadre of self-interested online actors who can leverage conformity to more easily predict and then control users' sentiments and behaviors, often in the direction of increased conformity and even greater ease of control. This emerging positive feedback loop and the compliance that fuels it are the focal points of this article, which presents several simple, abstract, agent-based models of both peer-to-peer and AI-to-user influence. One of these AI systems functions as a collaborative filter, whereas the other represents an actor the influential power of which derives directly from its ability to predict user behavior. Many versions of the model, with assorted parameter settings, display emergent polarization or universal convergence, but collaborative filtering exerts a weaker homogenizing force than expected. In addition, the combination of basic agents and a self-interested AI predictor yields an emergent positive feedback that can drive the agent population to complete conformity.

Appendectomy in endometriosis: an update on surgical indications and management of uncommon diseases.

PURPOSE OF REVIEW: Abnormal appendiceal disease is commonly encountered following an appendectomy when performed in patients with endometriosis. Appendiceal endometriosis is the most notable finding and can affect up to 39% of patients with endometriosis. Despite this knowledge, guidelines for performing an appendectomy have not been formally established. In this article, we review the surgical indications for an appendectomy at the time of endometriosis surgery and discuss the management of other diseases that may be encountered following the histopathologic evaluation of an excised appendix. RECENT FINDINGS: Removal of the appendix in patients with endometriosis contributes to optimal surgical management. Relying on abnormal appendiceal appearance for removal may leave endometriosis-affected appendices. For this reason, utilizing risk factors to guide surgical management is essential. Common appendiceal diseases are sufficiently managed with appendectomy. Uncommon diseases may require further surveillance. SUMMARY: Emerging data in our field support the performance of an appendectomy at the time of endometriosis surgery. Guidelines for performing a concurrent appendectomy should be formalized to encourage preoperative counselling and management for patients with risk factors for appendiceal endometriosis. Abnormal diseases is frequently encountered after appendectomy in the setting of endometriosis surgery and further management is based on the histopathology of the specimen.

A 33-Year-Old Woman in the Third Trimester of Pregnancy Diagnosed with Advanced-Staged Squamous Cell Cervical Carcinoma by Magnetic Resonance Imaging and Biopsy.

BACKGROUND Cervical cancer is the most common gynecologic malignancy diagnosed in pregnancy. When cervical cancer is diagnosed late in pregnancy, pelvic lymphadenectomy is avoided. Advanced imaging adds an alternative way to assess nodal involvement. The aim of this case report is to demonstrate how magnetic resonance imaging (MRI) can contribute to the clinical staging of cervical cancer and inform treatment decisions when diagnosis is made late in pregnancy. We report the case of a woman in the third trimester who was diagnosed with advanced-stage squamous cell cervical carcinoma by MRI and biopsy. CASE REPORT A 33-year-old woman at 33 weeks of gestation was admitted to our hospital for recurrent vaginal bleeding. Examination revealed a large cervical mass. A gynecologic oncologist was consulted, an examination under anesthesia was performed, and cervical biopsy samples were obtained. Pathology results revealed squamous cell carcinoma of the cervix. A clinical stage of IB3 was assumed. MRI revealed a 5.2×5.8-cm cervical mass and an enlarged left pelvic lymph node. These findings upstaged the patient to IIIC1. Instead of undergoing a radical cesarean hysterectomy, the patient had a cesarean delivery and pelvic lymph node dissection. Four weeks later, she began chemotherapy and pelvic radiation. CONCLUSIONS There is significant value in advanced imaging for cervical cancer staging. This is especially relevant in pregnancy, where the under-staging of disease is a concern. This case report demonstrates the value of MRI in cervical cancer staging, particularly in pregnant women, in whom treatment and the timing of treatment should be individualized.

Prevention and management of bowel injury during gynecologic laparoscopy: an update.

PURPOSE OF REVIEW: The current article aims to briefly review recent literature on bowel injury in gynecologic surgery with a focus on minimally invasive techniques, strategies for prevention, and management of injury. RECENT FINDINGS: Recent reviews describe a low incidence of bowel injury that is likely affected by low rates of reporting and inconsistent definitions. The major risk factor for bowel injury is adhesive disease, and assessment and prevention techniques for the presence of adhesive disease are evolving. When bowel injury occurs, prompt diagnosis and intraoperative repair yields more favorable outcomes than delayed diagnosis. Repair can be performed by a gynecologic surgeon, with or without the help of a consultant depending on the extent of the injury and surgeon comfort. SUMMARY: Bowel injury is a potentially catastrophic complication in gynecologic surgery, but its rarity presents a challenge in research. A high index of suspicion and meticulous surgical technique are the cornerstones of managing a bowel injury.

Female Urethral Diverticula: Diagnosis, Pathology, and Surgical Outcomes at an Academic, Urban Medical Center.

OBJECTIVE: To describe the outcomes of a series of women diagnosed with a urethral diverticulum at an urban tertiary care center. METHODS: An Institutional Review Board-approved review of a series of 78 women with a diagnosis of urethral diverticulum from 2009 to 2015 was performed. Clinical, radiographic, and pathologic data was collected by retrospective review of patient medical records. Data regarding treatment selection and postoperative outcomes were collected. A multivariable logistic regression was performed to identify preoperative variables that were associated with undergoing surgical resection. RESULTS: Of the 78 patients reviewed, the median age was 45.5 years (interquartile range (IQR) 36.0-53.8), median body mass index was 30.4 (IQR 24.8-34.4). The most common presenting symptoms included: incontinence (39%), recurrent urinary tract infections (23%), dysuria (18%), discharge (13%), dyspareunia (12%), and hematuria (9%). Additionally, 16 (21%) women were asymptomatic. Of these 78 cases, 40 underwent surgical excision (51%). Of the remaining 38, 13 were symptomatic and lost to follow-up, 23 were managed expectantly, and 2 underwent surgery after the study period. Review of the pathology results revealed that the most common finding was squamous metaplasia (31%). There was 1 adenocarcinoma in the series (2.5%). Of the 40 patients who had surgery, 3 (7.5%) had a diverticular recurrence and 5 (12.5%) developed stress urinary incontinence. The median follow-up was 7.5 months (IQR 1-20.25 months). CONCLUSION: A variety of presenting symptoms existed for women with a urethral diverticulum seeking medical care at an urban medical center. When controlling for age, body mass index, and race, the presence of preoperative symptoms was associated with undergoing surgical resection.

Alterations of elastin in female reproductive tissues arising from advancing parity.

Female reproductive tissues undergo significant alterations during pregnancy, which may compromise the structural integrity of extracellular matrix proteins. Here, we report on modifications of elastic fibers, which are primarily composed of elastin and believed to provide a scaffold to the reproductive tissues, due to parity and parturition. Elastic fibers from the upper vaginal wall of virgin Sprague Dawley rats were investigated and compared to rats having undergone one, three, or more than five pregnancies. Optical microscopy was used to study fiber level changes. Mass spectrometry, 13C and 2H NMR, was applied to study alterations of elastin from the uterine horns. Spectrophotometry was used to measure matrix metalloproteinases-2,9 and tissue inhibitor of metalloproteinase-1 concentration changes in the uterine horns. Elastic fibers were found to exhibit increase in tortuosity and fragmentation with increased pregnancies. Surprisingly, secondary structure, dynamics, and crosslinking of elastin from multiparous cohorts appear similar to healthy mammalian tissues, despite fragmentation observed at the fiber level. In contrast, elastic fibers from virgin and single pregnancy cohorts are less fragmented and comprised of elastin exhibiting structure and dynamics distinguishable from multiparous groups, with reduced crosslinking. These alterations were correlated to matrix metalloproteinases-2,9 and tissue inhibitor of metalloproteinase-1 concentrations. This work indicates that fiber level alterations resulting from pregnancy and/or parturition, such as fragmentation, rather than secondary structure (e.g. elastin crosslinking density), appear to govern scaffolding characteristics in the female reproductive tissues.

Resident Knowledge, Surgical Skill, and Confidence in Transobturator Vaginal Tape Placement: The Value of a Cadaver Laboratory.

OBJECTIVES: The objective of this study is to examine the effect of additional cadaver laboratory use in training obstetrics and gynecology (OBGYN) residents on transobturator vaginal tape (TOT) insertion. METHODS: Thirty-four OBGYN residents were randomized into 2 groups (group 1, control; group 2, intervention; 17 in each group). Before and after the interventions, written knowledge and confidence levels were assessed. Both groups received didactic lectures using a bony pelvis and an instructional video on TOT insertion; group 2 participated in a half day cadaver laboratory. Surgical skills were assessed by placing 1 arm of the TOT trocar on a custom-designed pelvic model simulator while being graded by an Female Pelvic Medicine and Reconstructive Surgery (FPMRS) board-certified proctor. RESULTS: Demographics were comparable. Baseline knowledge and confidence level before interventions were similar. After interventions, knowledge scores improved for both groups (8.8% for group 1; 14.1% for group 2); TOT insertion scores were significantly higher in group 2 (6.76/15 ± 2.54 group 1; 10.24/15 ± 2.73 group 2, P < 0.01); confidence scores improved in both groups. The pelvic model simulator was rated as the most useful method to learn TOT placement by group 1. Group 2 rated TOT simulation (47%) and cadaver laboratory (41%). All trainees reported that the pelvic model was highly realistic. CONCLUSIONS: Cadaver laboratory exposure, along with other educational interventions (lectures and video), improves OBGYN residents' confidence, knowledge, and surgical skills regarding TOT placement. The custom-designed pelvic model allows for a realistic simulation of TOT placement: it can be used to assess resident surgical skills and also aid the training of OBGYN residents.

Pregnancy-Induced Dynamical and Structural Changes of Reproductive Tract Collagen.

The tissues and organs of the female reproductive tract and pelvic floor undergo significant remodeling and alterations to allow for fetal growth and birth. In this work, we report on a study of the alterations of murine reproductive tract collagen resulting from pregnancy and parturition by spectrophotometry, histology, and (13)C, (2)H nuclear magnetic resonance (NMR). Four different cohorts of rats were investigated that included virgin, multiparous, two- and fourteen-day postpartum primiparous rats. (13)C CPMAS NMR revealed small chemical shift differences across the cohorts. The measured H-C internuclear correlation times indicated differences in dynamics of some motifs. However, the dynamics of the major amino acids, e.g., Gly, remained unaltered with respect to parity. (2)H NMR relaxation measurements revealed an additional water reservoir in the postpartum and multiparous cohorts pointing to redistribution of water due to pregnancy and/or parturition. Spectrophotometric measurements indicated that the collagen content in virgin rats was highest. Histological analysis of the upper vaginal wall indicated a signature of collagen fiber dissociation with smooth muscle and a change in the density of collagen fibers in multiparous rats.

Transforming growth factor ß1 and extracellular matrix protease expression in the uterosacral ligaments of patients with and without pelvic organ prolapse.

OBJECTIVES: This study was undertaken to evaluate the expression of transforming growth factor ß1 (TGF-ß1) and matrix metalloproteinase 9 (MMP-9), key regulators of the extracellular matrix composition, in the uterosacral ligaments (USLs) of women with pelvic organ prolapse (POP) compared with controls. METHODS: Under an institutional review board approval, USL samples were obtained from women undergoing vaginal hysterectomy for stage 2 or greater POP (cases, n = 21) and from women without POP undergoing vaginal hysterectomy for benign indications (controls, n = 19). Hematoxylin and eosin and trichrome staining were performed on the USL sections, and the distribution of smooth muscle and fibrous tissue were quantified. Immunohistochemical staining was performed using anti-TGF-ß1 and anti-MMP-9 antibodies. The expressions of TGF-ß1 and MMP-9 were evaluated by the pathologist, who was blinded to all clinical data. RESULTS: Transforming growth factor ß1 expression positively correlated with MMP-9 expression (R = 0.4, P = 0.01). The expressions of TGF-ß1 and MMP-9 were similar in subjects with POP versus controls. There was a significant increase in fibrous tissue (P = 0.008) and a corresponding decrease in smooth muscle (P = 0.03), associated with increasing age. The TGF-ß1 expression, but not MMP-9 expression, also significantly increased with age (P = 0.02). DISCUSSION: Although our study uncovered age-related alterations in USL composition and TGF-ß1 expression, there was no difference in the expression of TGF-ß1 or MMP-9 in the subjects with POP versus controls.

The role of mode of delivery on elastic fiber architecture and vaginal vault elasticity: a rodent model study.

We report on an experimental study of the role of mode of delivery and pregnancy on the architecture of vaginal elastic fibers and vaginal vault elasticity in female Sprague-Dawley rats. In primiparous rats submitted to spontaneous or Cesarean delivery and virgin rats submitted to simulated delivery, the tortuosity of elastic fibers (defined as the ratio of length to end-to-end distance) was observed to decrease when measured from two days to two weeks postpartum. In addition, the measured tortuosity of elastic fibers in multiparous rats was greater than that of virgin rats. The tortuosity of elastic fibers of all rats measured at two days postpartum was found to be similar to that of multiparous rats. At two weeks postpartum the measured tortuosity of vaginal elastic fibers was indistinguishable from virgin rats, regardless of the delivery method. Borrowing from the field of polymer physics, a model is suggested that connects elastic fiber tortuosity to the resulting tension under an applied stress; fibers having high tortuosity are expected to provide less structural support than more linear, low tortuosity fibers. To probe the macroscopic effects in elasticity due to architectural changes observed in elastic fibers, we have measured the stiffness of the vaginal vault in each cohort using a pressure-infusion system. The vaginal vault stiffness of all primiparous rats measured two weeks postpartum was greater than that measured two days postpartum. In addition, the vaginal vault of virgin rats was stiffer than that of multiparous rats. These observations confirmed that vaginal vault elastic fibers undergo significant remodeling due to pregnancy and parturition, and that the complex remodeling may be a significant contributor to tissue elasticity. Remarkably, regardless of the mode of delivery or simulated tissue trauma, elastic fiber tortuosity is observed to decrease from two days to two weeks postpartum indicating the onset of repair and recovery of tissue stiffness.

Large-conductance calcium-activated potassium channel activity, as determined by whole-cell patch clamp recording, is decreased in urinary bladder smooth muscle cells from male rats with partial urethral obstruction.

OBJECTIVES: To examine the effect of partial urethral obstruction (PUO) on bladder smooth muscle outward potassium current and the contribution of the large-conductance calcium-activated potassium (Maxi-K, BKCa) channel to this activity in smooth muscle cells isolated from bladders of sham-operated and PUO male rats using whole-cell patch clamp recording techniques. To determine the effect of PUO on the expression of the Maxi-K channel α and ß1 subunits and in vitro detrusor contractility. MATERIALS AND METHODS: Twenty adult male Sprague-Dawley rats were divided equally into two groups and subjected to surgical ligation of the urethra (PUO) or sham surgery (SHAM). After 2 weeks, the detrusors from PUO and SHAM rats were used for molecular analyses (mRNA and protein quantification of Maxi-K subunits) or organ bath contractility studies, or myocytes were isolated for conventional whole-cell patch clamp analyses. RESULTS: PUO increased bladder mass 2.5-fold and detrusor strips exhibited a more tonic-type contraction and increased contractility compared with controls (SHAM). Iberiotoxin (300 nM) sensitive Maxi-K channel current comprised about 40% of the outward whole-cell current in SHAM bladders but only about 8% in PUO bladders. Expression of the α subunit of the Maxi-K channel was significantly decreased ~40% while the expression of the ß1 subunit was increased ~2-fold at the mRNA level. The increase in ß1 expression was confirmed by Western blotting. CONCLUSIONS: Our findings show that obstruction of the rat bladder is associated with decreased Maxi-K channel activity of bladder smooth muscle cells, determined via direct current measurement. Increased expression of the ß1 subunit points to a compensatory reaction to decreased Maxi-K channel activity. Maxi-K channel openers or gene therapy may therefore provide therapeutic benefit for the overactive bladder.

Uterine prolapse: from antiquity to today.

Uterine prolapse is a condition that has likely affected women for all of time as it is documented in the oldest medical literature. By looking at the watershed moments in its recorded history we are able to appreciate the evolution of urogynecology and to gain perspective on the challenges faced by today's female pelvic medicine and reconstructive surgeons in their attempts to treat uterine and vaginal vault prolapse."He who cannot render an account to himself of at least three thousand years of time, will always grope in the darkness of inexperience"-Goethe, Translation of Panebaker.

The sphingosine-1-phosphate pathway is upregulated in response to partial urethral obstruction in male rats and activates RhoA/Rho-kinase signalling.

OBJECTIVES: To examine the effect of partial urethral obstruction (PUO) on the sphingosine-1-phosphate (S1P, a bioactive lipid shown to modulate smooth muscle, SM) pathway in the bladders of male rats, and to determine the effect of PUO on the RhoA/Rho-kinase (ROK) pathway, and whether there is a molecular cross-talk with the S1P pathways associated with bladder overactivity (S1P1-S1P3, where S1P1 is associated with nitric oxide-mediated SM relaxation, and S1P2 and S1P3 receptors are associated more with SM contraction via the ROK pathway). MATERIALS AND METHODS: In all, 20 male rats were divided into two groups and underwent PUO or a sham operation (control). After 2 weeks all rats were killed humanely and bladder specimens used for in vitro organ-bath physiological contractility studies, and for mRNA and protein analyses of major S1P/ROK pathway constituents via real-time polymerase chain reaction and Western blotting, respectively. In addition, early-passage SM cells were transfected with recombinant sphingosine kinase (SPHK, the enzyme that converts sphingosine to S1P). RESULTS: Bladders from PUO rats had greater mRNA expression of the S1P2 and S1P3 receptors, as well as SPHK1, than the sham controls (4.78, 2.04 and 2.72 times, respectively). PUO rats also had significantly greater expression of RhoA and ROKalpha (1.76 and 2.19 times, respectively). Western blotting and organ-bath contractility studies showed similar changes at the protein and in vitro functional level, with an increased contractility of bladder strips from PUO rats to exogenous S1P. Transfection of SPHK into isolated SM cells increased ROK expression. CONCLUSIONS: We show for the first time that the S1P signalling pathway is significantly upregulated in response to PUO in male rats at both the molecular and in vitro functional levels, correlating with an activation of the RhoA/ROK pathway. Further, we provide novel data that SPHK overexpression increases ROK expression in vitro, suggesting a novel hypothesis of S1P-induced bladder overactivity in the mechanism for PUO-induced bladder dysfunction and the S1P signalling pathway as a possible therapeutic target for bladder overactivity.

Vertebral osteomyelitis and epidural abscess after laparoscopic uterus-preserving cervicosacropexy.

Abdominal sacrocolpopexy is a standard surgical technique to repair apical vaginal prolapse. When approached laparoscopically, a uterus-preserving technique was suggested as potentially favorable for avoiding mesh-related complications. A 52-year-old Caucasian woman came to the emergency department with right-sided low back pain and vaginal discharge more than 1 year after undergoing a laparoscopic, uterus-preserving, cervicosacropexy with Mersilene (Ethicon Inc., Somerville, NJ) mesh and permanent Gore-Tex (W.L. Gore and Associates, Inc., Flagstaff, AZ) suture. Lumbar spine magnetic resonance imaging revealed diskitis and an epidural abscess at the L5 to S1 vertebral levels, and a fistulous tract was identified extending from the rectovaginal space to the affected vertebrae. The patient underwent a fine-needle aspiration of the epidural abscess and intravenous antibiotic therapy was started. However, because of a lack of symptom resolution she was taken to the operating department on hospital day 11 and underwent a total abdominal hysterectomy, left salpingectomy, right salpingo-oophorectomy, bilateral ureterolysis, and excision of an infected Mersilene mesh. Surgical findings were notable for 2 pinpoint areas in the upper vagina consistent with fistulae tracts communicating with the retroperitoneal space. The patient recovered well from her surgery, and was discharged to a rehabilitation facility. Vertebral osteomyelitis, with or without an epidural abscess, is a rare complication of sacrocolpopexy. The findings of this case suggest this complication likely occurred as a result of a permanent suture being placed entirely (or nearly entirely) through the vaginal mucosa resulting in fistulae formation, bacterial seeding of the Mersilene mesh, and subsequent osteomyelitis. This highlights the importance of mesh and suture selection, and determining the most appropriate sites for mesh attachment.

Racial differences in pelvic floor muscle thickness in asymptomatic nulliparas as seen on magnetic resonance imaging-based three-dimensional color thickness mapping.

OBJECTIVE: The objective of the study was to compare levator and obturator thickness between asymptomatic black and white nulliparas using three-dimensional (3D) magnetic resonance imaging (MRI) color mapping. STUDY DESIGN: 3D color-mapped MRI of pelvic muscles were evaluated in 22 similar nulliparas (12 black, 10 white). Levator and obturator (OI) were divided into right and left. Levator was subdivided into puborectalis (PR) and ileococcygeus (IC) portions. Maximal thickness of each muscle was recorded and compared between groups. Nonparametric testing was applied, with significance at P = .05. RESULTS: Levator thickness was significantly greater in blacks bilaterally (median right PR, 8.5 vs 6.0 mm; P = .001; right IC, 6.5 vs 4.5 mm; P = .002; left PR, 9.5 vs 5.75 mm; P = .0002; left IC, 6.5 vs 5.75 mm; P = .02). Obturator thicknesses were similar (right OI, 20.0 vs 19.5 mm; left OI, 19.25 vs 19.25 mm; P = NS). CONCLUSION: Significantly thicker levators but similar obturators were seen in black nulliparas, compared with white nulliparas. These levator differences may influence pelvic floor dysfunction risk. The clinical significance of these findings is under study.

Evolution and development of a multicellular organism: scalability, resilience, and neutral complexification.

To increase the evolvability of larger search spaces, several indirect encoding strategies have been proposed. Among these, multicellular developmental systems are believed to offer great potential for the evolution of general, scalable, and self-repairing organisms. We reinforce this view, presenting the results achieved by such a model and comparing it against direct encoding. Extra effort has been made to make this comparison both general and meaningful. Embryonal stages, a generic method showing increased evolvability and applicable to any developmental model, are introduced. Development with embryonal stages implements what we refer to as direct neutral complexification: direct genotype complexification by neutral duplication of expressed genes. The results show that, even for high-complexity evolutionary targets, the developmental model proves more scalable. The model also shows emergent self-repair, which is used to produce highly resilient organisms.

Development and the Baldwin effect.

Baldwin's classic hypothesis states that behavioral plasticity can speed evolution by (a) smoothing the fitness landscape and (b) indirect genetic assimilation of acquired characteristics. This latter phase demands a strong correlation between genotype and phenotype space. But the natural world shows signs of this correlation at only a very coarse level, since the intervening developmental process greatly complicates the mapping from genetics to physiology and ethology. Hence, development appears to preclude a strong Baldwin effect. However, by adding a simple developmental mechanism to Hinton and Nowlan's classic model of the Baldwin effect, and by allowing evolution to determine the proper balance between direct and indirect mapping of genome to phenotype, this research reveals several different effects of development on the Baldwin effect, some promoting and others inhibiting. Perhaps the most interesting result is an evolved cooperation between direct blueprints and indirect developmental recipes in searching for unstructured and partially structured target patterns in large, needle-in-the-haystack fitness landscapes.

The simulated emergence of distributed environmental control in evolving microcosms.

This work continues investigation into Gaia theory [Lovelock, (1995) The ages of Gaia, Oxford University Press] from an artificial life perspective [Downing, (2000) in Proceedings of the 7th International Conference on Artificial Life, (pp. 90-99) MIT Press], with the aim of assessing the general compatibility of emergent distributed environmental control with conventional natural selection. Our earlier system, GUILD [Downing and Zvirinsky, (1999) Artificial Life, 5, 291-318], displayed emergent regulation of the chemical environment by a population of metabolizing agents, but the chemical model underlying those results was trivial, essentially admitting all possible reactions at a single energy cost. The new model, METAMIC, utilizes abstract chemistries that are both (a) constrained to a small set of legal reactions, and (b) grounded in basic fundamental relationships between energy, entropy, and biomass synthesis/breakdown. To explore the general phenomena of emergent homeostasis, we generate 100 different chemistries and use each as the basis for several METAMIC runs, as part of a Gaia hunt. This search discovers 20 chemistries that support microbial populations capable of regulating a physical environmental factor within their growth-optimal range, despite the extra metabolic cost. Case studies from the Gaia hunt illustrate a few simple mechanisms by which real biota might exploit the underlying chemistry to achieve some control over their physical environment. Although these results shed little light on the question of Gaia on Earth, they support the possibility of emergent environmental control at the microcosmic level.