A computational literature review of the field of System Dynamics from 1974 to 2017

System Dynamics celebrated its 60th anniversary in 2017. While there have been numerous special issues in diverse journals that bring together work by System Dynamics scholars who share similar research interests, there have been no systematic reviews of scholarly activity across the broad field. This paper presents a computational literature review of the field from 1974 to 2017. A CLR automates the analysis of research articles with analysis of content (topic modelling of abstracts) to identify emergent themes in the literature. We performed a broad review of the field by initially searching using the term “System Dynamics” with more than 8000 articles. However, the results obtained were not satisfactory so we decided to restrict our sample to less than 800 articles from recognised journals and proceedings. After evaluation of the results obtained from topic modelling, we decided to use 51 topics covering most of the articles in our sample. A list of 51 topics provides enough granularity to identify relevant patterns of activity within the community of System Dynamics scholars. For each of these 51 topics, we present a commentary on the key insights obtained

Biophysical, Grazing-Season Management, and Animal Traits Effects on Individual Animal Performance of Cow-Calf Systems: Insights from a Long-Term Experiment in the US Western Great Plains

Beef grazing systems require information on management, biophysical, and individual animal influences on performance metrics. However, long-term controlled experiments are lacking to comprehensively ascertain these individual and likely interacting influences. We used a legacy data set from the USDA Agricultural Research Service where individual weight gains were determined from on and off weights of Hereford cows and calves grazing native northern mixed-grass prairie, during the June through September season, from 1975-2001 near Cheyenne, Wyoming, USA. The herd size varied from a minimum of 10 to a maximum of 48 pairs across years. Management (on and off grazing dates and stocking rate, kg BW/ha), biophysical (forage production estimated through NDVI LANDSAT time series, temperature, and precipitation variability), and individual animal (cow age, cow body weight at beginning of grazing season, and calf gender) influences were evaluated for effects on calf weight gain (WG, kg/head). Linear mixed models were used for analyses where the above mentioned were fixed factors, and year and individual cow were random ones. Calf performance was influenced by three animal traits: gender with steer WG 4 kg more than heifer, cow body weight with calf WG increased 2kg for each 100kg of cow body weight, and cow age as optimum calf WG occurred with 5-year-old cows. Management influenced calf WG through the on and off dates. Delaying the start of a grazing season decreased calf WG by 0.80 kg per delayed day. On the contrary, extending the grazing season increased calf WG by about the same amount. Biophysical effects on calf WG were not significant suggesting that the cow performance was mitigating these effects of variability. Results suggest that calf individual performance in this resilient rangeland ecosystem relies on cows’ body weight at beginning of the grazing, their age, and the timing to enter and remove animals from pastures

Knowledge, Attitudes, and Practice of Pelvic Floor Muscle Training in People With Spinal Cord Injury: A Cross-Sectional Survey

BackgroundThere is emerging evidence that pelvic floor muscle training (PFMT) may be useful for treating some urogenital conditions in people with spinal cord injury (SCI). Future clinical investigations would benefit from understanding the extent to which people with SCI are aware of and practicing PFMT, and their attitude toward this therapy.ObjectiveThe goal of this study was to assess the knowledge, attitudes, and practices related to PFMT among people with SCI.MethodsWe distributed an internet survey internationally via SCI related organizations for 2 months. We used descriptive statistics to summarize each survey item, and Chi-square and Mann-Whitney U tests to explore the differences in results between sexes and level of motor-function.ResultsComplete data from 153 respondents were analyzed. Sixty-two percent of respondents were female and 71% reported having complete paralysis. More than half of respondents reported being aware of PFMT (63%); more females than males reported knowledge of PFMT (p = 0.010). Females (p = 0.052) and people with partial paralysis (p = 0.008) reported a stronger belief that they would benefit from PFMT. Few people with SCI had practiced PFMT (20%), and of those who practiced, most of them had SCI resulting in partial paralysis (p = 0.023).ConclusionsWhile people with SCI may be aware of and have favorable attitudes toward PFMT, few had practiced PFMT and there were notable differences in attitudes toward PFMT depending on the sex and level of motor function of the respondents

Invited viewpoint: how well does the Information Systems discipline fare in the Financial Times’ top 50 Journal list?

This paper investigates the performance of the Information Systems (IS) discipline as reflected in the scholarly impact of the three IS journals that are included in the Financial Times’ top 50 journals (FT50), the four IS journals in the top tiers of the Chartered Association of Business Schools’ Academic Journal Guide (CABS AJG), and the eight journals that comprise the Association for Information Systems (AIS) Senior Scholars' Basket of Journals (AIS Basket). Journal lists, when framed as a form of ‘strategic signaling’, are used to by institutions to communicate values and priorities to scholars. Through strategic signaling, journal lists are performative and have the potential to shape and constrain research activity. Given the strategic and performative role of journal lists, it is important that the journals that constitute those lists have substantial impact. To measure the scholarly impact of journals we propose a new measure, the HMJ index, which comprises an equally-weighted combination of journal H-index, median citations per article, and Journal Impact Factor (JIF). Using the HMJ index, the results show that all eight AIS Basket journals are performing at a level that is commensurate with the other journals that make up the FT50. The results further show substantial differences between the FT50 journals, such as the number of articles published per annum. Implications for IS scholars, IS groups, and the IS discipline are identified, together with recommendations for action

Super congruences and Euler numbers

Let $p>3$ be a prime. We prove that $$\sum_{k=0}^{p-1}\binom{2k}{k}/2^k=(-1)^{(p-1)/2}-p^2E_{p-3} (mod p^3),$$ $$\sum_{k=1}^{(p-1)/2}\binom{2k}{k}/k=(-1)^{(p+1)/2}8/3*pE_{p-3} (mod p^2),$$ $$\sum_{k=0}^{(p-1)/2}\binom{2k}{k}^2/16^k=(-1)^{(p-1)/2}+p^2E_{p-3} (mod p^3)$$, where E_0,E_1,E_2,... are Euler numbers. Our new approach is of combinatorial nature. We also formulate many conjectures concerning super congruences and relate most of them to Euler numbers or Bernoulli numbers. Motivated by our investigation of super congruences, we also raise a conjecture on 7 new series for $\pi^2$, $\pi^{-2}$ and the constant $K:=\sum_{k>0}(k/3)/k^2$ (with (-) the Jacobi symbol), two of which are $$\sum_{k=1}^\infty(10k-3)8^k/(k^3\binom{2k}{k}^2\binom{3k}{k})=\pi^2/2$$ and $$\sum_{k>0}(15k-4)(-27)^{k-1}/(k^3\binom{2k}{k}^2\binom{3k}k)=K.$

Ketamine and Midazolam Anesthesia in Pacific Martens (Martes caurina)

The use of midazolam as a tranquilizer for anesthesia in mustelids in conjunction with the cyclohexamine ketamine is not well documented. Because midazolam is fast acting, inexpensive, and quickly metabolized, it may serve as a good alternative to other more commonly used tranquilizers. We trapped and anesthetized 27 Pacific martens (Martes caurina) in Lassen National Forest (northern California, US) August 2010–April 2013. We assessed anesthesia with ketamine at 18 and 25 mg/kg combined with 0.2 mg/kg of midazolam by comparing mean times of induction, return to consciousness, and recovery, plus physiologic parameters. No reversal was used for the midazolam portion of the anesthetic. Mean (±SD) induction for both ketamine dosages was 1.7±0.5 and 1.8±1.0 min, respectively. Return to consciousness mean times were 8.0 min longer (P<0.001) for martens receiving a 25 mg/kg ketamine dosage. Mean recoveries were 15.1 min longer (P<0.003) for the 25 mg/ kg ketamine dosage. Physiologic parameter means were similar for both ketamine dosages with no statistically significant differences. Body temperatures and heart and respiratory rates were generally stable, but percentage of oxygen saturation and end tidal carbon dioxide values were below those seen in previous mustelid studies. The combination of ketamine, at both dosages, and midazolam provided reliable field anesthesia for Pacific martens, and supplemental oxygen is recommended as needed.Keywords: Pacific marten, Ketamine, Anesthesia, Martes caurina, Midazolam, American marten, Martes american

Semi-Quantitative Models for Identifying Potent and Selective Transthyretin Amyloidogenesis Inhibitors

Rate-limiting dissociation of the tetrameric protein transthyretin (TTR), followed by monomer misfolding and misassembly, appears to cause degenerative diseases in humans known as the transthyretin amyloidoses, based on human genetic, biochemical and pharmacologic evidence. Small molecules that bind to the generally unoccupied thyroxine binding pockets in the native TTR tetramer kinetically stabilize the tetramer, slowing subunit dissociation proportional to the extent that the molecules stabilize the native state over the dissociative transition state—thereby inhibiting amyloidogenesis. Herein, we use previously reported structure-activity relationship data to develop two semi-quantitative algorithms for identifying the structures of potent and selective transthyretin kinetic stabilizers/amyloidogenesis inhibitors. The viability of these prediction algorithms, in particular the more robust in silico docking model, is perhaps best validated by the clinical success of tafamidis, the first-in-class drug approved in Europe, Japan, South America, and elsewhere for treating transthyretin aggregation-associated familial amyloid polyneuropathy. Tafamidis is also being evaluated in a fully-enrolled placebo-controlled clinical trial for its efficacy against TTR cardiomyopathy. These prediction algorithms will be useful for identifying second generation TTR kinetic stabilizers, should these be needed to ameliorate the central nervous system or ophthalmologic pathology caused by TTR aggregation in organs not accessed by oral tafamidis administration

\u3ci\u3eParelaphostrongylus odocoilei\u3c/i\u3e in Columbia Black-Tailed Deer from Oregon

Documenting the occurrence of Parelaphostrongylus odocoilei has historically relied on the morphological examination of adult worms collected from the skeletal muscle of definitive hosts, including deer. Recent advances in the knowledge of protostrongylid genetic sequences now permit larvae to be identified. Dorsal-spined larvae (DSLs) collected in 2003–2004 from the lung and feces of six Columbian black-tailed deer (Odocoileus hemionus columbianus) from Oregon were characterized genetically. The sequences from unknown DSLs were compared to those from morphologically validated adults and larvae of P. odocoilei at both the second internal transcribed spacer (ITS-2) of ribosomal DNA and the mitochondrial cytochrome oxidase II gene. We provide the first unequivocal identification of P. odocoilei in Columbian black-tailed deer from Oregon. The broader geographic distribution, prevalence, and pathology of P. odocoilei are not known in populations of Oregon deer

Which comforting messages really work best? A different perspective on Lemieux and Tighe’s “receiver perspective”

Abstract OnlyThis article responds critically to a recent article by Lemieux and Tighe (Communication Research Reports, 21, 144–153, 2004) in which the authors conclude that recipients of comforting efforts prefer messages that exhibit a moderate rather than high level of person centeredness. It is argued that an erroneous assumption made by Lemieux and Tighe about the status of “receiver perspective” research on the comforting process led to faulty interpretations of the data and unwarranted conclusions about recipient preferences regarding comforting messages. Alternative interpretations of Lemieux and Tighe's data are presented; these are guided by the extensive previous research that has assessed evaluations and outcomes of comforting messages

Chiral potentials, perturbation theory, and the 1S0 channel of NN scattering

We use nucleon-nucleon phase shifts obtained from experimental data, together with the chiral expansion for the long-distance part of the NN interaction, to obtain information about the short-distance piece of the NN potential that is at work in the 1S0 channel. We find that if the scale R that defines the separation between "long-" and "short-" distance is chosen to be \lsim 1.8 fm then the energy dependence produced by short-distance dynamics is well approximated by a two-term polynomial for Tlab < 200 MeV. We also find that a quantitative description of NN dynamics is possible, at least in this channel, if one treats the long-distance parts of the chiral NN potential in perturbation theory. However, in order to achieve this we have to choose a separation scale R that is larger than 1.0 fm.Comment: 19 pages, 4 figure