Arbitrary Time Frame Research Articles

A reassessment of graduation modeling for policy design

A vast and diverse literature estimates graduation chances using logistic models set in an arbitrary timeframe, where a graduation indicator is checked at a conventional point in time and associated with covariates measured at some date. Survival models emerged over time as a robust alternative, for being able to estimate time-to-degree and time-varying effects of predictors. This paper reconsiders the effectiveness of both modeling approaches in addressing policy-relevant questions, particularly in light of the increasingly automated and algorithm-based educational policies. We find that both methods exhibit blind spots and limitations, but that adopting a simple pragmatic approach logistic models can achieve a comparable level of effectiveness at depicting graduation dynamics while also being capable of answering questions that are problematic for survival models. We exploit a unique dataset and the nature of discrete-time survival models as combinations of logistic regressions run at different times to illustrate how arbitrary timeframes impact the estimates of a logistic model of graduation. Conversely, we illustrate how separately running and analyzing all the distinct logistic regressions provides insights that are unlikely to come from a survival model.

Machine learning based on functional principal component analysis to quantify the effects of the main drivers of wheat yields

Assessing the response of crop yield to year-to-year climate variability at the field scale is often done using process-based models and regression techniques. Although powerful, these tools rely on strong assumptions and can lead to substantial prediction errors. In this study, we investigate the use of a flexible machine learning algorithm combining Functional Principal Component Analysis and Random Forest, to relate field scale wheat yield to local daily climate variables. Instead of computing seasonal, monthly or any other arbitrary time-frame climate averages, climate time series are decomposed by Functional Principal Component Analysis into a few data-driven basis functions, called Principal Curves, in order to summarize the dynamic of key climate variables by a limited number of interpretable components. Scores associated to these components are then used as inputs of a Random Forest algorithm for yield prediction and for analysing important factors responsible for yield variability. To evaluate our approach, we use a French national database including wheat yield data as well as climate and management practice data for 298 farm fields from 2011 to 2016 in four main producing regions. Depending on the regions, our approach can explain from 62 % to 81 % of the yield variability when both agronomic and climate variables are included, down to 56–81 % when ignoring agronomic variables and 51–74 % when ignoring climate variables. Based on a year-by-year cross-validation, RMSE ranges from 0.5 t ha−1 to 2.1 t ha−1 in non-extreme years (2012–2015). However, prediction error can reach 3.6 t ha−1 in case of exceptional weather conditions, such as those experienced in 2016 in Northern France. We find that this new approach performs in most cases better than the same machine learning algorithm using the usual time averages of climate variables, without the need to choose an arbitrary time-frame. We then show how important patterns in weather time series can be identified and how their effects on yield can be interpreted using the proposed modelling framework.

Peptide Drug Design Using Alchemical Free Energy Calculation: An Application and Validation on Agonists of Ghrelin Receptor.

With recent large-scale applications and validations, the relative binding free energy (RBFE) calculated using alchemical free energy methods has been proven to be an accurate measure to probe the binding of small-molecule drug candidates. On the other hand, given the flexibility of peptides, it is of great interest to find out whether sufficient sampling could be achieved within the typical time scale of such calculation, and a similar level of accuracy could be reached for peptide drugs. However, the systematic evaluation of such calculations on protein-peptide systems has been less reported. Most reported studies of peptides were restricted to a limited number of data points or lacking experimental support. To demonstrate the applicability of the alchemical free energy method for protein-peptide systems in a typical real-world drug discovery project, we report an application of the thermodynamic integration (TI) method to the RBFE calculation of ghrelin receptor and its peptide agonists. Along with the calculation, the synthesis and in vitro EC50 activity of relamorelin and 17 new peptide derivatives were also reported. A cost-effective criterion to determine the data collection time was proposed for peptides in the TI simulation. The average of three TI repeats yielded a mean absolute error of 0.98 kcal/mol and Pearson's correlation coefficient (R) of 0.77 against the experimental free energy derived from the in vitro EC50 activity, showing good repeatability of the proposed method and a slightly better agreement than the results obtained from the arbitrary time frames up to 20 ns. Although it is limited by having one target and a deduced binding pose, we hope that this study can add some insights into alchemical free energy calculation of protein-peptide systems, providing theoretical assistance to the development of peptide drugs.

GsNeRF: Fast novel view synthesis of dynamic radiance fields

Synthesis of new views in dynamic 3D scenes is a challenging task in 3D vision. However, most current approaches rely on radiance fields built upon multi-view camera systems for dynamic scenes, which are expensive and time-consuming, and depend on implicit representations based on Neural Radiance Fields . In this study, we introduced a new representation method for dynamic scenes called GsNeRF, which allows for fast reconstruction of objects under motion by moving a single camera in the scene, and it can render high-quality views from arbitrary time frames and camera poses. We utilize five grids to represent the dynamic scene, employing tensor decomposition for each grid to reduce storage space usage. Since the primary task of the entire model is to optimize these planes, we enforce spatio-temporal continuity of these planes through a smoothness loss. GsNeRF is combined with a miniature MLP to regress color outputs and trained using volume rendering. Through testing on a series of synthetic and real datasets, our method reduces the training time by over 100 times compared to implicit methods and achieves better rendering quality compared to explicit methods. Our approach achieves a balance between memory usage, speed, and quality overall.

High probability of successive occurrence of Nankai megathrust earthquakes

Great earthquakes along the Nankai megathrust in south-western Japan feature in the top priority list of Japan’s disaster management agenda. In May 2019, an alert system was incepted to issue public warnings when the probability of an earthquake occurrence along the Nankai megathrust became higher than usual. One of the cases that trigger the issuance of public warnings is when a great earthquake occurred and another one of the same scale is anticipated within a short period of time. Although such “twin ruptures” have occurred multiple times along the Nankai megathrust, the quantification of the probability of such twin ruptures has never been attempted. Based on global statistics and local earthquake occurrence history, we estimated the probability of a successive occurrence of two M8 or larger earthquakes within 3 years globally and along the Nankai megathrust to be 5.3–18% and 4.3–96%, respectively. The timing of the second earthquake followed the Omori–Utsu law in global statistics, which allowed the estimation of the probability for the successive occurrence of Nankai megathrust earthquakes in arbitrary time frames. The predicted probability for the one-week timeframe was 100–3600-fold higher than that of the norm, endorsing the necessity for the warning scheme.

High-Capacity Real-Time Face Retrieval Recognition Algorithm Based on Task Scheduling Model for the Treatment Area of Hospital

This paper presents an in-depth study of face detection, face feature extraction, and face classification from three important components of a high-capacity face recognition system for the treatment area of hospital and a study of a high-capacity real-time face retrieval and recognition algorithm for the treatment area of hospital based on a task scheduling model. Considering the real-time nature of our system, our face feature extraction network is modeled by DeepID, and the network is slightly improved by introducing a central loss verification signal to train a DeepID-like network model using central loss and use it to extract face features. To further investigate and optimize the schedulability analysis problem of the directed graph real-time task model, this paper proposes a rigorous and approximate response time analysis method for the directed graph real-time task model with an arbitrary time frame. Based on the theoretical results of the greatly additive algebra, it is shown that the coherent qualifying function is linearly periodic, i.e., the function can be represented by a finite nonperiodic part and an infinitely repeated periodic part, thus calculating the coherent qualifying function independent of the magnitude of the interval time. The algorithm for high-capacity real-time face retrieval and recognition in the treatment area of hospital based on the task scheduling model is further investigated, and a face database is established by using the PCA dimensionality reduction technique. Based on the internal architecture of the processor, image preprocessing and IP core packaging are implemented, and the hardware engineering of the high-capacity real-time face recognition system for hospital visits is built using the IP-based design concept. The performance tests of the face detection model and feature extraction network show that the face detection model has a significant reduction in false-positive rate, better fitting of border regression, and improved time performance. The face feature extraction network has no overfitting, and the features are highly discriminative with small feature extraction time consumption. The high-capacity real-time face recognition system for the treatment area of hospital combined with the optimized directed graph task scheduling model can approach 25 fps, which meets the real-time requirements, and the face recognition rate surpasses that of real people. It realizes the intelligence, self-help, and autonomy of medical services and satisfies the medical needs of users in all aspects.

Physical Activity Maintenance: A Critical Narrative Review and Directions for Future Research.

A clear rationale can be made for promoting long-term regular physical activity (PA), yet despite some attempts to operationalize “maintenance,” no robust definition has been agreed upon, beyond arbitrary time frames of regular PA. This has likely impaired the advancement of theory and practice. The purpose of this critical narrative review was to first overview the conception of maintenance and co-requisite theoretical constructs in theories used in PA research. Our subsequent aims were to engage in a critical analysis of this literature to propose a working definition of PA maintenance followed by recommendations for future research. Relevant behavioral theories were parsed for references to maintenance or maintenance-specific constructs and constructs most likely associated with maintenance were overviewed from a recent systematic review. Based on this information, we suggest PA maintenance be operationalized as a process marked by a shift in the mechanisms of action determining behavioral performance, that engender greater perceived behavioral enactment efficiency. We suggest that maintenance should not be considered an absolute state of behavioral performance (e.g., a stage), as some constructs that were critical to behavioral performance during initiation will still be critical during PA continuation. Based on this definition, we propose a method of falsifiability hypothesis testing of theoretical constructs that may determine the maintenance process. Finally, the review concludes with suggestions for future research using this operationalization of maintenance including measure development, tests of latency to reach the peak maintenance process, validating constructs critical to determining maintenance, exploration of the contextual and individual moderators of maintenance formation, and the development of an omnibus dynamic model of initiation, continuation, and maintenance in PA behavior change.

Interactive 3D Time-Integrated Solar Shadow Maps

Abstract. Urban areas are characterized by a complex topography of buildings, terrain, vegetation and temporary structures, which, depending on their extent, geometry, geographic location and daytime, cast shadow on their surroundings. Given the importance of sunlight for various groups of interest and tasks, we argue that a comprehensive, accessible, usable and intuitive way of predicting its availability for specific usage contexts is surprisingly lacking. In our research, we are investigating how to improve the visual communication of urban solar conditions for various real-world usage scenarios like having a coffee in the sun, parking a car in the shade, or taking a photograph of a particular building in a favorable light. All of these activities take place over a period of time, not in a temporal instant, causing solar shadows to move. Hence, a static representation of the light situation at a distinct point in time, such as offered by available 3D urban maps or GIS systems, is often not sufficient for planning above mentioned recreational or professional activities.This factor is incorporated in our system by integrating shadow motion into a shadow map that covers arbitrary timeframes within a given day (Figure 1). Shadows are accumulated by projecting shadow maps from astronomically precise sun positions spanning over the defined timeframe. The number of sampling points directly influences the quality and speed of the rendering. All provided figures currently sample and integrate nine different sun positions.Using our system, questions in a manner of “Given a specific point in space, at which time will this point be in sun/shade again” can be answered. E.g., one would like to spend time in the sun at a specific Viennese “Kaffeehaus” (coffee place), from which time on (and for how long) will this space be sunlit (Figure 2). In the future, this process might even be automated.

Looking at "thunderclap headache" differently? Circa 2016.

The term “thunderclap headache” (TCH) was first coined in 1986 by Day and Raskin to describe headache that was the presenting feature of an underlying unruptured cerebral aneurysm. The term is now well established to describe the abrupt onset headache seen with many other conditions and is also now included in The International Classification of Headache Disorders 3rd edition beta version rubric 4.4. An essential to label an acute headache as “TCH” and differentiate it from other “sudden onset, severe headaches” is the arbitrary time frame of 1 min from onset to peak intensity for “TCH.” What happens in practice, however, is that even those “sudden onset, severe headaches” that do not strictly fulfill the definition criteria are also labeled as “TCH” and investigated with the same speed and in the same sequence and managed based on the underlying cause. This article begins by questioning the validity and usefulness of this “one minute” arbitrary time frame to define “TCH,” particularly since this time frame is very difficult to assess in practice and is usually done on a presumptive subjective basis. The article concludes with suggestions for modification of the current investigation protocol for this emergency headache scenario. This proposal for “a change in practice methodology” is essentially based on (1) the fact that in the last two decades, we now have evidence for many more entities other than just subarachnoid hemorrhage that can present as “TCH” or “sudden onset, severe headache” and (2) the evidence from literature which shows that advances in imaging technology using higher magnet strength, better contrast, and newer acquisition sequences will result in a better diagnostic yield. It is therefore time now, in our opinion, to discard current theoretical time frames, use self-explanatory terminologies with practical implications, and move from “lumbar puncture (LP) first” to “LP last!”

Baseline time accounting--reply to the letter to the editor of Martin [Int J Life Cycle Assess (2013) 18(7):1279

After becoming aware of a letter to the editor from Martin (2013), we realize there is a need for further elaboration of the baseline time accounting method laid out in Kloverpris and Mueller (2013). In the following, we addressMartin's comments. Martin states that our method “does not eliminate the need to choose a timeframe .” This is correct and inherent to any life cycle assessment (LCA) when it comes to the use of global warming potentials (GWPs). Later, Martin states that we assert that our “approach removes the need to consider arbitrary timeframes .” We are puzzled by this statement since Sect. 2.3 of our paper explicitly acknowledges that the use of the common 100-year GWP accounting period in LCA is indeed arbitrary. While we cannot avoid this circumstance, our method does eliminate the need to consider an arbitrary production period for biofuels (under the conditions described). We will later get back to the fundamental difference between the GWP accounting period and the assumed biofuels production period since the missing distinction between these two time perspectives appears to be the primary basis of Martin's critique. Martin states that the value of our insights “is diminished by the failure to include a full consideration of the importance of the timeframe of the analysis .” While we (and the three reviewers) did not find it relevant to include results other than GWP100 in our paper, the baseline time accounting concept is not restricted to this metric. To accommodate Martin, Table 1 shows results for GWP20 and (the more unusual) GWP30. As shown in the table, the applied GWP accounting period is certainly of significance for the type of indirect land use change (ILUC) called accelerated expansion. Meanwhile, the sensitivity to the choice of GWP accounting period is not unique as indicated by the GWPs for methane, also included in Table 1. For the type of ILUC called delayed reversion, the GWP accounting period is without significance. We acknowledge that this is due to the simplified assumption of constant carbon sequestration over the GWP accounting period. In reality, there will be some sensitivity to the choice of GWP accounting period for delayed reversion but not to the same extent as for accelerated expansion. For additional discussion, we refer to Sect. 4.1.2 in Electronic supplementary material 1 of Kloverpris and Mueller (2013), particularly. Martin states that “The baseline time accounting approach uses a 100-year timeframe ,” but, as mentioned above, there is no conceptual or methodological restriction on the chosen GWP accounting period. More correctly stated, baseline time accounting converts a time shift in land use emissions from a single batch of biofuels into an ILUC factor that is consistent with the GWP concept, and the results presented by Kloverpris and Mueller (2013) are based on a GWP accounting period of 100 years. The chosen GWP accounting period ensures consistency with the common global warming metric used for greenhouse gas (GHG) emissions. Since the ILUC factor is meant to be added to the GHG emissions from the biofuels supply chain, consistency between addends is necessary. Martin states that “It should come as no great surprise that changing the denominator of a fraction from 30 to 100

Regarding your article “Baseline time accounting: considering global land use dynamics when estimating the climate impact of indirect land use change caused by biofuels.” Int J Life Cycle Assess 18(2):319–330. doi: 10.1007/s11367-012-0488-6

“Baseline time accounting” does not eliminate the need to choose a timeframe, which remains among the most critical parameters in assessing indirect land use change emissions. The baseline time accounting paper of Kloverpris and Mueller (2013) provides an interesting perspective on an important issue, but the value of their insight is diminished by the failure to include a full consideration of the importance of the timeframe of the analysis. Their examples reevaluate analyses of two existing indirect land use change (ILUC) studies, both of which were based on a 30-year timeframe (Searchinger et al. 2008; Hertel et al. 2010). The baseline time accounting approach uses a 100-year timeframe and the results “are significantly lower (60– 70 %) than the ILUC factors based on the 30-year annualization method.” It should come as no great surprise that changing the denominator of a fraction from 30 to 100 reduces that number by 70 %. The authors assert that their approach removes the need to consider arbitrary timeframes. Their decision to use the global warming potential based on a 100-year timeframe (GWP100) is, they say, “simply ensuring consistency between the ILUC factor estimation and the GWP concept.” But 100 years is certainly not the only timeframe that is routinely used in GWP analyses. If the authors had included in their sensitivity analysis the use of GWP20 and GWP500 or constructed a GWP30 that was consistent with the Hertel and Searchinger analyses, the key importance of the choice of timeframe would have been clear. The authors discuss other papers that make similar use of the GWP methodology, and most of these papers explicitly investigate the effect of timeframe. For example, Cherubini et al. (2011) include results for GWP20, GWP100, and GWP500 in all cases. The baseline accounting methodology converts a prediction problem into a time shift problem. The question of how to compare deforestation/reforestation today with deforestation/reforestation next year clearly requires a methodology to place a value on time preference. The baseline time accounting methodology does not eliminate the need to make a decision about the timeframe for analysis and, in fact, the decision to adopt a 100-year timeframe is the single largest factor that differentiates the results of the baseline time accounting methodology from simpler approaches.

Evaluating care pathways for community psychiatry in England: a qualitative study

In view of forthcoming 'payment by results' (PbR) for mental health, increasing number of National Health Service (NHS) Trusts are reorganizing their community services for working age adults to create care pathways. However, research base for the care pathways model in mental health is limited. Our NHS Foundation Trust was one of the first to introduce care pathways for community psychiatry in the UK. We have carried out a qualitative study to evaluate how this model works out in practice, including its impact on quality of patient care, mental health professionals and primary care. We interviewed doctors, multidisciplinary staff and Trusts managers (19 in total). Transcripts of recorded interviews were coded and analysed thematically using a grounded theory approach. Overall, despite teething problems, working in pathways was generally seen as a positive change. It led to more focused interventions being offered, and practitioners being held to account over clear standards of care. It is more cost-effective and allows for active case management and clear clinical leadership. It is recovery focused and encourages social inclusion. The arbitrary time frame, strict criteria and thresholds for different teams can create issues. Improved communication, flexible and patient-centred approach, staff supervision, and increasing support to primary care were felt to be central to this model working efficiently and effectively. Introduction of care pathways is an important step towards effective implementation of PbR for mental health. Our study would inform future research into care pathways, facilitate organizational learning and help to improve effectiveness of services.

The Earth on Show: Fossils and the Poetics of Popular Science, 1802–1856, by Ralph O'Connor

Reviewed by: The Earth on Show: Fossils and the Poetics of Popular Science, 1802–1856 Michael Freeman (bio) The Earth on Show: Fossils and the Poetics of Popular Science, 1802–1856, by Ralph O'Connor; pp. xiii + 541. Chicago and London: The University of Chicago Press, 2007, $45.00, £26.50. Ralph O'Connor's The Earth on Show taps into an already vigorous stream of research and writing on nineteenth-century engagements with the prehistoric world. Martin Rudwick, James Secord, and a host of others have, within the last two decades, rescued twentieth-century narratives of geology and palaeontology from dry-as-dust moulds of presentation. They have put in their place exciting new interpretative perspectives that demonstrate the measure by which emerging discoveries about earth history in the nineteenth century were accommodated within an exceptionally broad spectrum of cultural production, covering literature, poetry, and art, not to mention all manner of popular cultural expression. The publisher's dust-jacket evaluation describes O'Connor's book as an "innovative blend of the history of science, literary criticism, book history, and visual culture." Anne Barton, Emerita Professor of English at the University of Cambridge, adds to this endorsement by remarking how O'Connor writes with wit and verve to produce an enthralling story, constructed around the relationship between science and imagination in the period. There is further praise from other scholars on the rear of the dust-jacket. Nigel Leask, for example, remarks upon O'Connor's brilliance in applying "techniques of literary and visual exegesis to the heterogeneous body of early-nineteenth-century writings and images of antediluvian worlds." The Earth on Show is a hefty tome, running to 450 or so pages of text, copiously referenced and with a very substantial index. It bears all the familiar hallmarks of painstaking scholarship and reveals a wide body of primary investigation. In turn, and following the pattern of many of the University of Chicago Press's publications, the book is extensively illustrated with numerous half-tones, together with a small selection of colour plates. The book's structure splits into two parts. The first aims at "building [End Page 384] the story," the second at "staging the show." O'Connor rehearses Gideon Mantell's observation that the literary productions of some nineteenth-century geologists and palaeontologists had the power to exceed in allure the fiction of romance. In tandem, many such productions were performances, "rhetoric of spectacular display," to use Secord's apt phrase (Victorian Sensation [2001] 439). O'Connor closes his absorbing introduction by describing early-nineteenth-century literature on earth history as verging towards a "single cosmic pageant" (27), blending human, sacred, and natural history into a kind of seamless confection. On the face of it, then, this is a volume that has a tantalizing attraction. As one dips further within it, however, some readers will register shades of disappointment. The illustrations are the first to sow seeds of doubt. The vast majority are incredibly familiar. One picks up almost immediately the range of existing modern published works from which the ideas for illustration appear to have been garnered. Then there are the chapter heads and sub-heads: they offer a "cast" that rather dampens the publisher's claim that this is an innovative work. Part 1, for instance, has the following checklist: "Enter the Mammoth"; "William Buckland: Antiquary and Wizard"; "Lizards and Literalists"; "Lyell Steps In." The sequence is predictable almost to the point of tedium, and a proportion of the content suffers likewise. To be fair, O'Connor does, in places, offer the reader important and clever insights. One sees the merit of some of the powerful endorsements on the dust-jacket. Equally, the handling of source materials is almost everywhere sensitive and reflexive. Chapter 7, on time travel and virtual tourism in the age of the apocalyptic painter John Martin, forms a fascinating essay and could almost stand on its own. The problem, though, lies with the broader canvas. The promises of the dust-jacket and the introduction of an innovative framework of analysis are only partially realized. One component of this difficulty may have to do with the somewhat arbitrary time frame that O...

To Be, One Has to Be Somewhere

Among modern exclusionary strategies (state sponsored or otherwise), prison segregation-the isolation of individuals from general inmate populations-is a particularly camouflaged form of exclusion with considerable impact on identity formation. Drawing from extensive documentary and nominal sources, as well as 45 interviews with women having experienced segregation in Canadian prisons from 1995 to 2003, this paper argues that the regimented and predictable time-space continuum of the prison's 'ordinary' life flies into pieces in segregation where (1) arbitrary timeframes, and (2) fluid and frugal spatiality keep women on the margin of collective memory. Such time/space configurations engender a loss of ascendancy on individual and collective sense of time/space, leading to the use of multifarious resistance strategies to negotiate personally suitable identities.

Triage nurses' clinical decision making. An observational study of urgency assessment.

Researchers have described both the various decision tasks performed by triage nurses using self-report methods and identified time as a factor influencing the quality of triage decisions. However, little is known about the decision tasks performed by triage nurses when making acuity assessments, or the factors influencing triage duration in the real world. The aims of this study were to: describe the data triage nurses collect from patients in order to allocate a triage priority using the Australasian Triage Scale (ATS); describe the duration of nurses' decision making for ATS categories 2-5; and to explore the impact of patient and nurse variables on the duration of the triage nurses' decision making in the clinical setting. A structured observational study was employed to address the research aims. Observational data was collected in one adult emergency department located in metropolitan Melbourne, Australia. A total of 26 triage nurses consented and were observed performing 404 occasions of triage. Data was collected by a single observer using a 20-item instrument that recorded the performance frequencies of a range of decision tasks and a number of observable patient, nurse and environmental variables. Additionally, the nurse-patient interaction was recorded as time in minutes. It was found that there was limited use of objective physiological data collected by the nurses' in order to decide patient acuity, and large variability in the duration of triage decisions observed. In addition, analysis of variance indicated strong evidence of a true difference between triage duration and a range of nurse, patient and environmental variables. These findings have implications for the development of practice standards and triage education. In particular, it is argued that practice standards should include routine measurement of physiological parameters in all but the collapsed or obviously unwell patient, where further delay may impede the delivery of time-critical intervention. Furthermore, the inclusion of arbitrary time frames for triage assessment in practice standards are not an appropriate method of evaluating triage decision making in the real world.

Transient climatic change to 3×CO 2 conditions

The CSIRO coupled global climatic model has been integrated for transient increasing atmospheric CO 2 conditions from 1 to 3×CO 2. The basis for this experiment is that there is little expectation that atmospheric CO 2 levels will be stabilised at or below 2×CO 2 concentrations given projected emission levels. Examination of changes in climatic variables between 1 and 2×CO 2 and 2 and 3×CO 2 states revealed an expected general diminution in the magnitude of the changes for the latter state. This is attributed to the progressive saturation of the CO 2 absorption spectrum at the higher CO 2 concentrations. An examination of annual mean surface temperature changes at decadal intervals associated with the increasing CO 2 indicated that it takes 60–70 years before temperature fluctuations due to natural climatic variability are finally overwhelmed by the greenhouse effect. Surface temperatures at 3×CO 2 under transient conditions were similar to those obtained under 2×CO 2 equilibrium conditions with a slab ocean, except for much reduced warmings in high southern latitudes. Time series of climatic variables for selected variables for the control and transient runs revealed noticeable interannual and decadal fluctuations in both runs, and highlighted the potential problems of `sampling' data at arbitrary timeframes. The model maintained El Niño/Southern Oscillation events throughout the transient run, suggesting that this feature is a robust characteristic of the climatic system. No untoward climatic fluctuations were noted during the transient run, implying that climatic `surprises' are unlikely, at least for present model formulations.

Knee Rehabilitation Following Arthroscopic Meniscectomy

Guidelines for knee rehabilitation after conventional open meniscectomy are generally well known. Less agreement exists on rehabilitation following arthroscopic meniscectomy. The program is sometimes arbitrary. Rehabilitation should follow a logical progression regardless of the type of surgery performed. Rehabilitation following knee surgery can be divided into four phases: immediate post-operative period, early healing phase, late healing phase, and conditioning for return to preinjury activity. Following arthroscopic surgery, the overall recovery time can be significantly shortened compared to conventional arthrotomy, primarily by decreasing the length of the early postoperative phases. A smaller incision causes less soft-tissue injury to skin, capsule, synovium, and other periarticular structures, resulting in less quadriceps inhibition and a more rapid recovery. The rate of tissue healing is not altered, however, and the knee must still heal completely before the patient can return to a full functional level. Not all patients are rehabilitated uniformly, and a great deal of variability exists following arthroscopic surgery. Factors that affect the speed of rehabilitation and return to normal function are the extent of meniscectomy performed, the coexistence of additional intra- or extra-articular pathology, and individual patient differences. Therefore, an arbitrary time frame for rehabilitation following arthroscopic meniscectomy is not recommended. Rather, each patient should progress from one stage of rehabilitation to the next, based on objective knee findings.