Spatial predictions of tree density and tree height across Mexico forests using ensemble learning and forest inventory data.

The National Forestry Commission of Mexico continuously monitors forest structure within the country's continental territory by the implementation of the National Forest and Soils Inventory (INFyS). Due to the challenges involved in collecting data exclusively from field surveys, there are spatial information gaps for important forest attributes. This can produce bias or increase uncertainty when generating estimates required to support forest management decisions. Our objective is to predict the spatial distribution of tree height and tree density in all Mexican forests. We performed wall-to-wall spatial predictions of both attributes in 1-km grids, using ensemble machine learning across each forest type in Mexico. Predictor variables include remote sensing imagery and other geospatial data (e.g., mean precipitation, surface temperature, canopy cover). Training data is from the 2009 to 2014 cycle (n > 26,000 sampling plots). Spatial cross validation suggested that the model had a better performance when predicting tree height r 2 = .35 [.12, .51] (mean [min, max]) than for tree density r 2 = .23 [.05, .42]. The best predictive performance when mapping tree height was for broadleaf and coniferous-broadleaf forests (model explained ~50% of variance). The best predictive performance when mapping tree density was for tropical forest (model explained ~40% of variance). Although most forests had relatively low uncertainty for tree height predictions, e.g., values <60%, arid and semiarid ecosystems had high uncertainty, e.g., values >80%. Uncertainty values for tree density predictions were >80% in most forests. The applied open science approach we present is easily replicable and scalable, thus it is helpful to assist in the decision-making and future of the National Forest and Soils Inventory. This work highlights the need for analytical tools that help us exploit the full potential of the Mexican forest inventory datasets.

Mandibular Metastasis as the First Manifestation of Hepatocellular Carcinoma: A Case Report.

Metastatic malignancies of the oral cavity are rare lesions, accounting for only 1-4% of all oral malignancies, and can occur in the jaw bones, the oral soft tissues, or even both. Although hepatocellular carcinoma is the most common primary hepatic tumor, no more than 1% of the cases show oral involvement. When metastatic tumor involves the oral cavity, the most frequent site is the posterior angle of the mandible. Histologically, hence, immunohistochemical markers are used for diagnosis. Glypican-3 and HepPar1 are the markers that can be used to confirm the microscopic diagnosis of HCC. Very rarely, hepatocellular carcinoma (HCC) metastasizes to the oral cavity, and such cases have a poor prognosis due to delay in diagnosis. We present a 74-year-old male with a metastasis of HCC in the left mandibular body as the first manifestation. Histologic examination confirmed metastatic hepatocellular carcinoma in the oral mucosa with immunohistochemical (IHC) markers. A review of pertinent literature was performed. Given the rarity of the disease, treatment principles are based mainly on retrospective series and case reports. We report an exceptionally unusual presentation with few cases (<70) reported in the literature, thus representing a diagnostic challenge.

Immobilization in Ionogel: A New Way to Improve the Activity and Stability of Candida antarctica Lipase B.

New Candida antarctica lipase B derivatives with higher activity than the free enzyme were obtained by occlusion in an organogel of an ionic liquid (ionogel) based on the ionic liquid [Omim][PF6] and polyvinyl chloride. The inclusion of glutaraldehyde as a crosslinker improved the properties of the ionogel, allowing the enzymatic derivative to reach 5-fold higher activity than the free enzyme and also allowing it to be reused at 70 °C. The new methodology allows enzymatic derivatives to be designed by changing the ionic liquid, thus providing a suitable microenvironment for the enzyme. The ionic liquid may act on substrates to increase their local concentration, while reducing water activity in the enzyme's microenvironment. All this allows the activity and selectivity of the enzyme to be improved and greener processes to be developed. The chemical composition and morphology of the ionogel were also studied by scanning electron microscopy-energy dispersive X-ray spectroscopy, finding that porosity, which was related with the chemical composition, was a key factor for the enzyme activity.

El raro caso de una joven con colitis ulcerativa crónica inespecífica grave y atrofia cerebral / The rare case of a young girl with ulcerative colitis and cerebral atrophy

Resumen La enfermedad inflamatoria intestinal es un grupo de enfermedades caracterizadas por inflamación crónica gastrointestinal y en ocasiones con repercusión extraintestinal. Las manifestaciones neurológicas y psiquiátricas corresponden a menos de 3%. Se comunica el caso de una mujer joven con colitis ulcerativa y atrofia cerebral como inicio.

Abstract Inflammatory bowel disease is a group of diseases characterized by chronic gastrointestinal inflammation and occasionally with extraintestinal repercussion. The neurological and psychiatric manifestations correspond to less than 3%. This paper reports the case of a young woman with ulcerative colitis and cerebral atrophy as debut.

Development of simulator guidelines for resident assessment in flexible endoscopy.

Virtual reality (VR) simulators may hold a role in the assessment of trainee abilities independent of their role as instructional instruments. Thus, we piloted a course in flexible endoscopy to surgical trainees who had met Accreditation Council for Graduate Medical Education endoscopy requirements to establish the relationship between metrics produced by a VR endoscopic simulator and trainee ability. After a didactic session, we provided faculty instruction to senior residents for Case 1 upper endoscopy and colonoscopy modules on the CAE EndoscopyVR. Course conclusion was defined as a trainee meeting all proficiency standards in basic endoscopic procedures on the simulator. Simulator metrics and course evaluation comprised data. Eleven and eight residents participated in the colonoscopy and upper endoscopy courses, respectively. Average time to reach proficiency standards for esophagogastroduodenoscopy was 6 and 13 minutes for colonoscopy after a median of one (range, one to two) and one (range, one to four) task repetitions, respectively. Faculty instruction averaged 7.5 minutes of instruction per repetition. A subjective course evaluation demonstrated that the course improved learners' knowledge of the subject and comfort with endoscopic equipment. Within a VR-based curriculum, experienced residents rapidly achieved task proficiency. The resultant scores may be used as simulator guidelines for resident assessment and readiness to perform flexible endoscopy.

Laparoscopic cholecystectomy poses physical injury risk to surgeons: analysis of hand technique and standing position.

BACKGROUND: This study compares surgical techniques and surgeon's standing position during laparoscopic cholecystectomy (LC), investigating each with respect to surgeons' learning, performance, and ergonomics. Little homogeneity exists in LC performance and training. Variations in standing position (side-standing technique vs. between-standing technique) and hand technique (one-handed vs. two-handed) exist. METHODS: Thirty-two LC procedures performed on a virtual reality simulator were video-recorded and analyzed. Each subject performed four different procedures: one-handed/side-standing, one-handed/between-standing, two-handed/side-standing, and two-handed/between-standing. Physical ergonomics were evaluated using Rapid Upper Limb Assessment (RULA). Mental workload assessment was acquired with the National Aeronautics and Space Administration-Task Load Index (NASA-TLX). Virtual reality (VR) simulator-generated performance evaluation and a subjective survey were analyzed. RESULTS: RULA scores were consistently lower (indicating better ergonomics) for the between-standing technique and higher (indicating worse ergonomics) for the side-standing technique, regardless of whether one- or two-handed. Anatomical scores overall showed side-standing to have a detrimental effect on the upper arms and trunk. The NASA-TLX showed significant association between the side-standing position and high physical demand, effort, and frustration (p<0.05). The two-handed technique in the side-standing position required more effort than the one-handed (p<0.05). No difference in operative time or complication rate was demonstrated among the four procedures. The two-handed/between-standing method was chosen as the best procedure to teach and standardize. CONCLUSIONS: Laparoscopic cholecystectomy poses a risk of physical injury to the surgeon. As LC is currently commonly performed in the United States, the left side-standing position may lead to increased physical demand and effort, resulting in ergonomically unsound conditions for the surgeon. Though further investigations should be conducted, adopting the between-standing position deserves serious consideration as it may be the best short-term ergonomic alternative.

A validated subjective rating of display quality: the Maryland Visual Comfort Scale.

BACKGROUND: Minimally invasive surgery requires high-quality imaging to provide effective visual displays to surgeons. Whereas objective measures--pixels, resolution, display size, contrast ratio--are used to compare imaging systems, there are no tools for assessing the perceptual impact of these physical measures. We developed the "Maryland Visual Comfort Scale" (MVCS) to measure perceptual qualities in relation to an imaging system. We theorize that what the surgeon perceives as a high-quality image can be summarized by a scoring of seven characteristics related to human perception, and that image quality is not homogenous across a video display such that object location impacts perception and display quality. METHOD: We created a rating scale for seven dimensions of display characteristics (contrast, detail, brightness, lighting uniformity, focus uniformity, color, sharpness). For validation, 30 participants viewed test patterns and manipulated physiologic images, rating the image quality for all seven dimensions as well as giving an overall rating. Image ratings for contrast and detail dimensions were assessed across five locations on the video display. For ratings, two imaging systems were used, differing primarily in the 10-mm zero-degree scope's quality: a standard scope and one taken from service for quality degradation. RESULTS: The rating scale was sensitive to differences in scope quality for all seven items in the MVCS (all p values<0.01). Significant differences existed between quality ratings at central and peripheral locations (p<0.05). CONCLUSIONS: This seven-item rating scale for assessing visual comfort is reliable and sensitive to scope quality differences. The scale is sensitive to degradation of image quality at video display edges. These seven dimensions of display characteristics can be refined to create a psychometric to serve as a composite of perceptual quality in laparoscopy.

Open circuit versus closed circuit enrichment of anodic biofilms in MFC: effect on performance and anodic communities.

The influence of various carbon anodes; graphite, sponge, paper, cloth, felt, fiber, foam and reticulated vitreous carbon (RVC); on microbial fuel cell (MFC) performance is reported. The feed was brewery wastewater diluted in domestic wastewater. Biofilms were grown at open circuit or under an external load. Microbial diversity was analysed as a function of current and anode material. The bacterial community formed at open circuit was influenced by the anode material. However at closed circuit its role in determining the bacterial consortia formed was less important than the passage of current. The rate and extent of organic matter removal were similar for all materials: over 95% under closed circuit. The biofilm in MFCs working at open circuit and in the control reactors, increased COD removal by up to a factor of nine compared with that for baseline reactors. The average voltage output was 0.6 V at closed circuit, with an external resistor of 300 kOmega and 0.75 V at open circuit for all materials except RVC. The poor performance of this material might be related to the surface area available and concentration polarizations caused by the morphology of the material and the structure of the biofilm. Peak power varied from 1.3 mW m(-2) for RVC to 568 mW m(-2) for graphite with biofilm grown at closed circuit.

Live augmented reality: a new visualization method for laparoscopic surgery using continuous volumetric computed tomography.

BACKGROUND: Current laparoscopic images are rich in surface detail but lack information on deeper structures. This report presents a novel method for highlighting these structures during laparoscopic surgery using continuous multislice computed tomography (CT). This has resulted in a more accurate augmented reality (AR) approach, termed "live AR," which merges three-dimensional (3D) anatomy from live low-dose intraoperative CT with live images from the laparoscope. METHODS: A series of procedures with swine was conducted in a CT room with a fully equipped laparoscopic surgical suite. A 64-slice CT scanner was used to image the surgical field approximately once per second. The procedures began with a contrast-enhanced, diagnostic-quality CT scan (initial CT) of the liver followed by continuous intraoperative CT and laparoscopic imaging with an optically tracked laparoscope. Intraoperative anatomic changes included user-applied deformations and those from breathing. Through deformable image registration, an intermediate image processing step, the initial CT was warped to align spatially with the low-dose intraoperative CT scans. The registered initial CT then was rendered and merged with laparoscopic images to create live AR. RESULTS: Superior compensation for soft tissue deformations using the described method led to more accurate spatial registration between laparoscopic and rendered CT images with live AR than with conventional AR. Moreover, substitution of low-dose CT with registered initial CT helped with continuous visualization of the vasculature and offered the potential of at least an eightfold reduction in intraoperative X-ray dose. CONCLUSIONS: The authors proposed and developed live AR, a new surgical visualization approach that merges rich surface detail from a laparoscope with instantaneous 3D anatomy from continuous CT scanning of the surgical field. Through innovative use of deformable image registration, they also demonstrated the feasibility of continuous visualization of the vasculature and considerable X-ray dose reduction. This study provides motivation for further investigation and development of live AR.

Gaze disruptions experienced by the laparoscopic operating surgeon.

BACKGROUND: Disruptions to surgical workflow have been correlated with an increase in surgical errors and suboptimal outcomes in patient safety measures. Yet, our ability to quantify such threats to patient safety remains inadequate. Data are needed to gauge how the laparoscopic operating room work environment, where the visual and motor axes are no longer aligned, contributes to such disruptions. We used time motion analysis techniques to measure surgeon attention during laparoscopic cholecystectomy in order to characterize disruptive events imposed by the work environment of the OR. In this investigation we identify attention disruptions as they occur in terms of the operating surgeon's gaze. We then quantify such disruptions and also seek to establish what occasioned them. METHODS: Ten laparoscopic cholecystectomy procedures were recorded with both intra- and extracorporeal cameras. The views were synchronized to produce a video that was subsequently analyzed by a single independent observer. Each time the surgeon's gaze was diverted from the operation's video display, the event was recorded via time-stamp. The reason for looking away (e.g., instrument exchange), when discernable, was also recorded and categorized. Disruptions were then reviewed and analyzed by an interdisciplinary team of surgeons and human factors experts. RESULTS: Gaze disruptions were classified into one of four causal categories: instrument exchange, extracorporeal work, equipment troubleshooting, and communication. On average, 40 breaks occurred in operating surgeon attention per 15 min of operating time. The most frequent reasons for these disruptions involved instrument exchange (38%) and downward gaze for extracorporeal work (28%). CONCLUSIONS: This study of laparoscopic cholecystectomy performance reveals a high gaze disruption rate in the current operating room work environment. Improvements aimed at reducing such disruptions-and thus potentially surgical error-should center on better instrument design and realigning the axis between surgeon's eye and visual display.

Ergonomic risk associated with assisting in minimally invasive surgery.

BACKGROUND: Given the physical risks associated with performing laparoscopic surgery, ergonomics to date has focused on the primary minimally invasive surgeon. Similar studies have not extended to other operating room staff. Simulation of the assistant's role as camera holder and retractor during a Nissen fundoplication allowed investigation of the ergonomic risks involved in these tasks. METHODS: Seven subjects performed camera navigation and retraction tasks using a box trainer on an operating room table that simulated an adult patient in low lithotomy position. Each subject stood on force plates at the simulated patient's left side. A laparoscope was introduced through a port into the training box with four 2-cm circles as rear-panel targets located in relation to the assistant as distal superior, proximal superior, distal inferior, and proximal inferior target effects. The subjects held the camera with their left hand, pointing it at a target. The task was to match the target to a circle overlaid on the monitor. Simultaneously, a grasper in the right hand grasped and pulled a panel-attached band. A minute signal moved the subject to the next target. Each trial had three four-target repetitions (phase effect). The subjects performed two separate trials: one while holding the camera from the top and one while holding it from the bottom (grip effect). A 4 x 3 x 2 (target x phase x grip) repeated-measures design provided statistics. Dividing the left force-plate vertical ground reaction forces (VGRF) by the total VGRF from both plates provided a weight-loading ratio (WLR). RESULTS: The WLR significantly increased (p < 0.005) with proximal targets (2 by 80% and 4 by 79%). The WLR decreased 75%, 74%, and 71% over time. No difference existed between the grip strategies (grip effect, p > 0.5). CONCLUSIONS: A high-risk ergonomic situation is created by the assistant's left or caudal leg disproportionately bearing 70-80% of body weight over time. A distance increase between the camera head location and the camera holder increases ergonomic risk. The phase effect was interpreted as a compensatory rebalancing to reduce ergonomic risk. Ergonomic solutions minimizing ergonomic risks associated with laparoscopic assistance should be considered.

High yield selective acylation of polyamines: proton as protecting group.

An advance in the selective acylation of polyamines having identical or similar amine functions is reported. While nucleophilicity differences between the various amine functions are slight, the corresponding conjugate acids exhibit pKa values over a significant range. We have used proton as polyamine protecting group: the monoamine resulting from single deprotonation of a polyammonium compound has allowed for high yields of selective acylation.

Improved physical properties and rotational dynamics in a molecular gyroscope with an asymmetric stator structure.

[structure: see text] A molecular gyroscope consisting of a 1,4-diethynylphenylene rotator linked to trityl and triptycyl groups (3) showed significantly improved physical properties and faster rotational dynamics than analogous symmetric bis(trityl) (1) or bis(triptycyl) (2) structures. An activation energy of 7.9 kcal/mol for 3 was determined by 2H NMR. This is ca. 4-6 kcal/mol lower than that of compound 1. The different dynamics of the three compounds can be qualitatively understood in terms of their different packing coefficients.

Crystalline molecular machines: a quest toward solid-state dynamics and function.

Complex molecular machinery may be envisioned as densely packed, multicomponent, self-assembling systems built with high structural precision to control the dynamics of one or more internal degrees of freedom. With molecular gyroscopes as a test, we describe a general strategy to design crystals capable of supporting structurally programmed molecular motions, a practical approach to their synthesis, convenient strategies to characterize their solid-state dynamics, and potential applications based on polar structures responding collectively to external fields.

Hinged molecular capsules: synthesis and conformational control via temperature, pH, or solvent composition.

Three new covalently linked molecular capsules were synthesized from their resorcinarene cavitand precursors in good yields. The capsules undergo reversible conformational switching between the closed "vase" form and the open "kite" form upon temperature or pH variation. The kite conformation obtained via either method in CDCl(3) switches to vase conformation upon addition of polar solvents such as acetone-d(6) or THF-d(8).

Molecular crystals with moving parts: synthesis, characterization, and crystal packing of molecular gyroscopes with methyl-substituted triptycyl frames.

We report a highly convergent synthesis for the preparation of molecular gyroscopes consisting of para-phenylene rotors linked by triple bonds to methyl-substituted triptycenes acting as pivots and encapsulating frames. The desired 1,4-bis[2-(2,3,6,7,12,13-hexamethyl-10-alkyl-9-triptycyl)ethynyl]benzenes were prepared from 2,3-dimethyl-1,3-butadiene using Diels-Alder cycloadditions and Pd(0)-catalyzed coupling as the key reactions. The main challenge in the synthesis came about in the preparation of 9-alkynyl-triptycenes by Diels-Alder reaction of benzynes and 9-alkynyl-2,3,6,7-tetramethylanthracenes. These reactions occurred with chemical yields and regioselectivities that were strongly influenced by steric and electronic effects of substituents at C10 of the anthracene core. Anthracenes with methyl, propyl, and phenyl substituents were utilized to complete the synthesis of their corresponding molecular gyroscopes, and their solid-state structures were determined by single-crystal X-ray diffraction analysis. Examination of these results indicated that, as expected, the bulky triptycyl groups encourage crystallization motifs that create more free volume around the phenylene rotor, as needed to facilitate fast gyroscopic motion in the solid state.

Molecular compasses and gyroscopes. II. Synthesis and characterization of molecular rotors with axially substituted bis[2-(9-triptycyl)ethynyl]arenes.

We have developed a simple convergent procedure for the synthesis of molecular rotors consisting of a central aromatic group coupled with two axially positioned ethynyltriptycenes. Molecular rotors with 1,4-phenylene (1), 1,4'-1,1'-biphenylene (2), 9,10-anthracenylene (3), and 2,7-pyrenylene (4) groups were prepared by Pd(0)-catalyzed coupling of ethynyl triptycenes with the corresponding dibromoarenes. Although compounds 1-4 were not expected to have free rotation in the solid state, the rotational potentials of 1 and 3 were analyzed by semiempirical methods and the crystal packing of 1 was analyzed to design the structures most likely to yield a functional rotor in the solid state. Semiempirical PM3 calculations predict compounds 1, 2, and 4 to have frictionless internal rotation even at temperatures as low as 25 K, while compound 3 is expected to have a barrier of ca. 4 kcal/mol.