Facing Assessment: Anticipating the Storm With a Plan, Partners, and Provision

Understand the basic parts of the assessment process as demonstrated through survival analogies Be encouraged to develop a culture of assessment that is balanced and strives to save more resources than it costs Open communication channels to learn from others both within one’s own school and within the larger assessment and education community

Fewer Trains for Better Timetables: The Price of Fixed Line Frequencies in the Passenger-Oriented Timetabling Problem

This paper introduces the Passenger-Oriented Timetabling problem with flexible frequencies (POT-flex) in the context of railway planning problems. POT-flex aims at creating feasible railway timetables minimising total perceived passenger travel time. The contribution of the POT-flex lies in its relaxation of the generally adopted assumption that line frequencies should be a fixed part of the input. Instead, we consider flexible line frequencies, encompassing a minimum and maximum frequency per line, allowing the timetabling model to decide on optimal line frequencies to obtain better solutions using fewer train services per line. We develop a mixed-integer programming formulation for POT-flex based on the Passenger-Oriented Timetabling (POT) formulation of [Polinder et al., 2021] and compare the performance of the new formulation against the POT formulation on three instances. We find that POT-flex allows to find feasible timetables in instances containing bottlenecks, and show improvements of up to 2% on the largest instance tested. These improvements highlight the cost that fixed line frequencies can have on timetabling

Integrating Timetabling and Crew

We investigate to what degree we can integrate a Train Timetabling / Engine Scheduling Problem with a Crew Scheduling Problem. In the Timetabling Problem we design a timetable for the desired lines by fixing the departure and arrival times. Also, we allocate time-slots in the network to secure a feasible timetable. Next, we assign engines in the Engine Scheduling Problem to the lines in accordance with the timetable. The overall integration is achieved by obtaining an optimal solution for the Timetabling / Engine Scheduling Problem. We exploit the fact that numerous optimal, and near optimal solutions exists. We consider all solutions that can be obtained from the optimal engine schedule by altering the timetable, while keeping the order of demands in the schedules intact. The Crew Scheduling model is allowed to re-time the service of demands if the additional cost is outweighed by the crew savings. This information is implemented in a mathematical model for the Crew Scheduling Problem. The model is solved using a column generation scheme. Hereby it is possible for the Crew Scheduling algorithm to adjust the timetable and achieve a better overall solution. We perform computational experiments based on a case at a freight railway operator, DB Schenker Rail Scandinavia, and show that significant cost savings can be achieved

MicroRNAs in early embryonic development : dissecting the role of miR-290 through miR-295 in the mouse

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Biology, 2008.Includes bibliographical references.MicroRNAs mediate developmental regulation of gene expression via translational repression of target mRNAs. Targeted deletion of the miRNA biogenesis machinery in the mouse has demonstrated essential roles for miRNAs during early development. In this thesis, I have examined the role of a family of miRNAs, miR-290 through miR-295 (miR-290 cluster), which are specifically expressed during early embryonic and germ cell development. This miRNA family is conserved only among mammals. miR-290 cluster miRNAs are transcribed and processed from a common capped and polyadenylated primary transcript in the mouse. Deletion of the miR-290 cluster in the mouse results in early embryonic lethality and misregulation of primordial germ cell migration, ultimately resulting in germ cell depletion, premature ovarian failure and infertility in the adult female. Loss of miR-290-295 mediated repression results in significant changes in the gene expression profile of embryonic stem cells, allowing for the accumulation and precocious expression of many developmental regulators involved in differentiation. As such, we have shown that the miR-290 cluster miRNAs are critical regulators of embryonic development.by Lucas M. Dennis.Ph.D

Railway Crew Rescheduling with Retiming

Railway operations are disrupted frequently, e.g. the Dutch railway network experiences about three large disruptions per day on average. In such a disrupted situation railway operators need to quickly adjust their resource schedules. Nowadays, the timetable, the rolling stock and the crew schedule are recovered in a sequential way. In this paper, we model and solve the crew rescheduling problem with retiming. This problem extends the crew rescheduling problem by the possibility to delay the departure of some trains. In this way we partly integrate timetable adjustment and crew rescheduling. The algorithm is based on column generation techniques combined with Lagrangian heuristics. In order to prevent a large increase in computational time, retiming is allowed only for a limited number of trains where it seems very promising. Computational experiments with real-life disruption data show that, compared to the classical approach, it is possible to find better solutions by using crew rescheduling with retiming

Ecological Processes Shaping Bulk Soil and Rhizosphere Microbiome Assembly in a Long-Term Amazon Forest-to-Agriculture Conversion.

Forest-to-agriculture conversion has been identified as a major threat to soil biodiversity and soil processes resilience, although the consequences of long-term land use change to microbial community assembly and ecological processes have been often neglected. Here, we combined metagenomic approach with a large environmental dataset, to (i) identify the microbial assembly patterns and, (ii) to evaluate the ecological processes governing microbial assembly, in bulk soil and soybean rhizosphere, along a long-term forest-to-agriculture conversion chronosequence, in Eastern Amazon. We hypothesized that (i) microbial communities in bulk soil and rhizosphere have different assembly patterns and (ii) the weight of the four ecological processes governing assembly differs between bulk soil and rhizosphere and along the chronosequence in the same fraction. Community assembly in bulk soil fitted most the zero-sum multinomial (ZSM) neutral-based model, regardless of time. Low to intermediate dispersal was observed. Decreasing influence of abiotic factors was counterbalanced by increasing influence of biotic factors, as the chronosequence advanced. Undominated ecological processes of dispersal limitation and variable selection governing community assembly were observed in this soil fraction. For soybean rhizosphere, community assembly fitted most the lognormal niche-based model in all chronosequence areas. High dispersal and an increasing influence of abiotic factors coupled with a decreasing influence of biotic factors were found along the chronosequence. Thus, we found a dominant role of dispersal process governing microbial assembly with a secondary effect of homogeneous selection process, mainly driven by decreasing aluminum and increased cations saturation in soil solution, due to long-term no-till cropping. Together, our results indicate that long-term no-till lead community abundances in bulk soil to be in a transient and conditional state, while for soybean rhizosphere, community abundances reach a periodic and permanent distribution state. Dominant dispersal process in rhizosphere, coupled with homogeneous selection, brings evidences that soybean root system selects microbial taxa via trade-offs in order to keep functional resilience of soil processes

Extended Lateral Approach for Intra-articular Calcaneal Fractures: An Inverse Relationship between Surgeon Experience and Wound Complications

The current reference standard for the treatment of displaced intra-articular calcaneal fractures is open reduction and internal fixation using an extended lateral approach. In the present retrospective study, we evaluated the results of a consecutive series of patients treated in the same fashion from June 2005 to September 2011 using a subcuticular single-layer closure technique. We also determined the risk factors for the development of wound complications and the rate of wound complications. Also, we assessed which patient, fracture, and surgical characteristics affected these complications. During the 75-month study period, we operated on 53 displaced intra-articular calcaneal fractures in 50 patients using the extended lateral approach. The incision was closed using the subcuticular technique in 49 cases (92.45%). In the subcuticular closure group 2 (4.1%) deep infections and 2 (4.1%) superficial wound complications (1 dehiscence and 1 infection) occurred. Wound edge or flap necrosis was not encountered. The use of bone-void filler and the experience of the surgical team were significantly (p < .001 and p = .026, respectively) associated with the occurrence of wound complications. The subcuticular single-layer suture technique is a suitable closure technique in the treatment of displaced intra-articular calcaneal fractures. It was associated with a low complication rate combined with the extended lateral approach. The effect of bone void fillers on the incidence of complications should receive more attention in future research. The association between wound complications and the experience level of the surgical team supports the need for centralization of this complex injury