Size, shape, and flexibility of RNA structures

Determination of sizes and flexibilities of RNA molecules is important in understanding the nature of packing in folded structures and in elucidating interactions between RNA and DNA or proteins. Using the coordinates of the structures of RNA in the Protein Data Bank we find that the size of the folded RNA structures, measured using the radius of gyration, $R_G$, follows the Flory scaling law, namely, $R_G =5.5 N^{1/3}$ \AA where N is the number of nucleotides. The shape of RNA molecules is characterized by the asphericity $\Delta$ and the shape $S$ parameters that are computed using the eigenvalues of the moment of inertia tensor. From the distribution of $\Delta$, we find that a large fraction of folded RNA structures are aspherical and the distribution of $S$ values shows that RNA molecules are prolate ($S>0$). The flexibility of folded structures is characterized by the persistence length $l_p$. By fitting the distance distribution function $P(r)$ to the worm-like chain model we extracted the persistence length $l_p$. We find that $l_p\approx 1.5 N^{0.33}$ \AA. The dependence of $l_p$ on $N$ implies the average length of helices should increases as the size of RNA grows. We also analyze packing in the structures of ribosomes (30S, 50S, and 70S) in terms of $R_G$, $\Delta$, $S$, and $l_p$. The 70S and the 50S subunits are more spherical compared to most RNA molecules. The globularity in 50S is due to the presence of an unusually large number (compared to 30S subunit) of small helices that are stitched together by bulges and loops. Comparison of the shapes of the intact 70S ribosome and the constituent particles suggests that folding of the individual molecules might occur prior to assembly.Comment: 28 pages, 8 figures, J. Chem. Phys. in pres

Laparoscopic intraperitoneal on-lay mesh repair for the umbilical hernia using anti-adhesive gel

Curs Chirurgie Generală al Facultăţii Stomatologie, USMF „Nicolae Testemiţanu”, Spitalul Clinic Militar Central, Chişinău, Republica Moldova, Al XII-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” din Republica Moldova cu participare internațională 23-25 septembrie 2015Introducere: Poziţionarea intraperitoneală a plasei chirurgicale în cadrul curei laparoscopice intraperitoneale (IPOM) impune selectarea materialului sintetic. Material şi metode: În clinica noastră de chirurgie (SCMC), în anii 2013-2015 au fost supuşi curei laparoscopice pentru hernie ombilicală 10 pacienţi, 6 femei şi 4 bărbaţi. Vârsta a variat de la 20 pînă la 60 ani. Pentru protezare s-a folosit plasa din polivinilidenftorid (PVDF) de tip „Uniflex” (Rusia), mai mare cu 5 cm decât defectul herniar pe toate dimensiunile. Pentru prevenirea aderenţelor parieto-viscerale a fost utilizat suplimentar, compozitul antiadeziv „Mezogel” (Rusia). Fixarea plasei s-a asigurat prin aplicarea a 5 suturi tip „ancore” transfasciale şi agrafe helicoidale neresorbabile de diametrul – 4 mm, plasate la 1cm de marginea protezei. Algometria s-a efectuat cu utilizarea scalei analog vizuale (VAS). Rezultate: Defectul herniar a avut un diametru median de 3,9 cm. La 4 pacienţi a fost suturat defectul (diametrul = 1-3 cm) herniar prin aplicarea suturii intracorporale. Din particularităţi intraoperatorii se menţionează: reducerea conţinutului sacului herniar, adezioliză, controlul hemoragiei din adeziuni. Durata medie a intervenţiilor a fost de 55 min (45-65 min). În perioada postoperatorie complicaţii nu au fost semnalate. Sindromul dolor postoperator a fost minim (VAS: 1-3); complicaţii parietale – absente. Durata mediană de spitalizare – 3,2 zile. În perioada postoperatorie la distanţă nu s-au constatat dureri şi neuropatii, dereglări de tranzit intestinal sau recidive herniare. Concluzii: Cura laparoscopică a herniei ombilicale cu aplicarea protezei IPOM este o metodă fezabilă, sigură şi minim-invazivă. Plasa şi gelul cu proprietăţi antiadezive reduce semnificativ riscul aderenţelor parieto-viscerale şi a complicaţiilor parietale, asigurând reintegrarea socio-profesională rapidă. Avantajele expuse argumentează perspectivele utilizării tehnicii IPOM în cura herniilor ombilicale.Introduction: In laparoscopic intraperitoneal on-lay mesh repair (IPOM) positioning of a surgical mesh requires the selection of a synthetic material with anti-adhesive properties. Material and methods: Within period of 2013-2015, 10 IPOM hernia repairs have been performed on the group of 10 patients diagnosed with umbilical hernia, 6 male and 4 female. The overall age was 36.4 years (range 20-60). The PVDF monofilament macroporous mesh has been utilized for repair. The mesh overlaped the defect with 5 cm. The combined fixation technique was ensured by applying the “anchor” type sutures and 4 mm non-resorbable spiral tacks plaid up to 1 cm from the edge of the prosthetic mesh. The non-adhesive composite “Mezogel” has been used to ensure the prevention of the adhesions. Algometry was performed using visual analog scale (VAS). Results: The mean diameter of the hernia defect was 3.9 cm. In 4 cases the hernia defect (d=1-3 cm) has been closed by applying intracorporeal suture. The intraoperative features were: reduction the hernia sac content, removal of adhesions, control of the bleeding. The mean time of operations was 55 min. In postoperative period there no reported complications. In the distance postoperative period were not found pain and local neuropathy, bowel disorders or hernia recurrences. Conclusions: Laparoscopic IPOM umbilical hernia repair it is a feasible, safe and minimally-invasive procedure. Prosthesis and gel with anti-adhesive properties significantly reduce the risk of the parieto-visceral adhesions and complications ensuring quick socio-professional reintegration. The exposed advantages arguments the use of IPOM procedure in the umbilical hernia repair

Quantum ratchets in dissipative chaotic systems

Using the method of quantum trajectories we study a quantum chaotic dissipative ratchet appearing for particles in a pulsed asymmetric potential in the presence of a dissipative environment. The system is characterized by directed transport emerging from a quantum strange attractor. This model exhibits, in the limit of small effective Planck constant, a transition from quantum to classical behavior, in agreement with the correspondence principle. We also discuss parameter values suitable for implementation of the quantum ratchet effect with cold atoms in optical lattices.Comment: Significant changes: Several text improvements and new results. Figure 2 modified. Figure 4 adde

On Semantic Similarity in Video Retrieval

Current video retrieval efforts all found their evaluation on an instance-based assumption, that only a single caption is relevant to a query video and vice versa. We demonstrate that this assumption results in performance comparisons often not indicative of models' retrieval capabilities. We propose a move to semantic similarity video retrieval, where (i) multiple videos/captions can be deemed equally relevant, and their relative ranking does not affect a method's reported performance and (ii) retrieved videos/captions are ranked by their similarity to a query. We propose several proxies to estimate semantic similarities in large-scale retrieval datasets, without additional annotations. Our analysis is performed on three commonly used video retrieval datasets (MSR-VTT, YouCook2 and EPIC-KITCHENS).Comment: Accepted in CVPR 2021. Project Page: https://mwray.github.io/SSVR

Prospects for the use of the laparoscopic transabdominal pre-peritoneal approach (TAPP) in groin hernia repair

Curs Chirurgie al Facultăţii Stomatologie, USMF “Nicolae Testemiţanu”, Spitalul Clinic Militar Central, Chisinău, Republica Moldova, Al XII-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” din Republica Moldova cu participare internațională 23-25 septembrie 2015Introducere: Abordul laparoscopic în cura herniilor inghinale devine o metodă de elecţie pe plan mondial. Rămîne actuală problema standardizării tehnicii chirurgicale şi optimizării rezultatelor acestui procedeu. Material şi metode: În perioada anilor 2008-2014 în Clinică a fost efectuată cura laparoscopică a herniei inghinale la 271 pacienţi (16 – bilateral). Repartiţia herniilor conform clasificării Nyhus: tip II (n=188), tip IIIa (n=64), tip IIIb (n=18), tip IIIc (n=9), tip IV (n=12). A fost utilizată tehnica transabdominală preperitoneală (TAPP). Rezultate: Durata intervenţiei a constituit în medie 47,8±25,07 min, fiind mai lungă pentru herniile recidivante – 95±48,99 min (60-180) şi bilaterale – 92,78±23,47 min (65-140). Mediana spitalizării – 3 zile, reîntoarcerea în cîmpul muncii – sub 10 zile. Incidentele intraoperatorii au fost corectate laparoscopic. Conversia a fost efectuată la un pacient. Nu au fost constatate cazuri de infecţie a plăgii postoperatorii. Aprecierea rezultatelor tratamentului chirurgical la distanţă a fost realizată la 223 pacienţi. Pentru evaluarea durerii la pacienţii cu diagnosticul hernie inghinală a fost utilizată scala de evaluare numerică NRS – 11. În perioada postoperatorie au prevalat pacienţi cu sindrom algic redus (NRS: 1-3). Algoparestezia postoperatorie persistentă a fost diagnosticată la 4 pacienţi. Recidiva herniei a fost înregistrată la 2 pacienţi, în ambele cazuri recidiva a fost corectată laparoscopic. Concluzii: Experienţa noastră confirmă posibilitatea utilizării procedeului TAPP la diferite tipuri de hernie inghinală. Acumularea experienţei permite de a lărgi indicaţiile pentru abordul laparoscopic la pacienţii cu hernii bilaterale, glisante şi recurente. Avantajele hernioplastiei laparoscopice sunt: micşorarea sindromului algic postoperator, reintegrarea socioprofesională rapidă şi numărul redus de complicaţii parietale.Introduction: The transabdominal pre-peritoneal procedure (TAPP) represents one of the most popular techniques used for inguinal hernia repair. The analysis of the reported cases helps to standardize the relatively new laparoscopic technique and to improve the overall results. Material and methods: The group of 271 patients underwent laparoscopic hernia repair (16 bilateral) for the period 2008-2014. According to Nyhus classification, the groin hernias were classified as type II (n=188), type IIIa (n=64), type IIIb (n=18), type IIIc (n=9), type IV (n=12). The TAPP procedure was utilized. Results: The mean operating time was 47.8±25.07 minutes, being statistically longer for recurrent hernias 95±48.99 min (range, 60-180) and bilateral hernias – 92.78±23.47 min (range, 65-140). The average length of hospital stay was 3 days. Patients returned to work in an average of 10 days. The postoperative morbidity rate was 2.2%. The majority of intraoperative incidents (intraoperative hemorrhage, n=4) were solved laparoscopically without sequelae. One case was converted to Lichtenstein repair. Patients were evaluated at a median follow up of 24 month (range, 12-36 month). A total of 223 patients were assesssed for long-term outcomes. Pain was assessed with Numerical Rating Scale (NRS – 11). The vast majority of post-operative patients had minor pain manifestation of pain (NRS: 1-3). We observed 4 cases of persistent inguinal pain. The hernia recurrence was developed in 2 patients and has been corrected via laparoscopic approach. Conclusions: While laparoscopic hernia repair requires a lengthy learning curve, it represents safe and valid alternative to open hernia repairs and could be effectively used for bilateral, recurrent and sliding hernias. The advantages of laparoscopic repair include less postoperative pain, faster return to normal activities and low wound infection rate

Laparoscopic transperitoneal retromascular (sublay) mesh repair in cure of ventral hernias: first experiences

Catedra Chirurgie nr.5, Universitatea de Stat de Medicină și Farmacie „Nicolae Testemiţanu”, Spitalul Clinic Militar Central, Chişinău, Republica Moldova, Al XIII-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” și al III-lea Congres al Societății de Endoscopie, Chirurgie miniminvazivă și Ultrasonografie ”V.M.Guțu” din Republica MoldovaIntroducere: Poziționarea laparoscopică, retromusculară (sublay) a plasei chirurgicale. Material și metode: În clinica chirurgie Nr 5, (SCMC), în anii 2018-2019 au fost supuși curei laparoscopice pentru hernii ventrale 8 pacienți, 4 femei și 4 barbați. Vîrsta medie 25-70 ani. Pentru protezare s-a folosit plasa din polipropilen light, mai mare cu 5 cm decât defectul herniar pe toate dimensiunile. Proteza a fost amplasată retromuscular, prin abord laparoscopic transperitoneal. Fixarea plasei sa asigurat prin aplicarea agrafelor helicoidale nerezorbabile de ø 4 mm, plasate la 1cm de marginea protezei. Algometria sa efectuat cu utilizarea scalei analog vizuale (VAS). Rezultate: Defectul herniar a avut un diametru median de 3,7 cm. La toți pacienți defectul herniar a fost suturat prin aplicarea suturii intracorporale. Din particularități intraoperatorii se menționează: reducerea conținutului sacului herniar, adezioliză, controlul hemoragiei din adeziuni și decolarea peritoneului și tunicii retromusculare prin incizie longitudinală. Durata medie a intervențiilor a fost de 45 min (35-65 min). În perioada postoperatorie complicații nu au fost semnalate. Sindromul dolor postoperator a fost minim (VAS 1 – 3), complicații parietale absente. Durata mediana de spitalizăre 3,1 zile. În perioada postoperatorie la distanța nu s-au constatat dureri și neuropatii, dereglări de tranzit intestinal, recidive herniare. Concluzii: Cura laparoscopică intraperitoneală retromusculară (sublay) a herniilor ventrale cu aplicarea protezei din polipropilen este o metodă sigură și miniminvazivă, cu costuri reduse la consumabile. Amplasarea retromusculară a plasei exclude aderențele parietoviscerale și complicațiile parietale, asigurând reintegrarea socio-profesională rapidă. Avantajele expuse argumentează perspectivele utilizării tehnicii laparoscopice retromusculare în cura herniilor ventrale.Introduction: Transperitoneal retromuscular sublay positioning of a surgical mesh. Materials and methods: Within period of 2018-2019, 8 retromuscular hernia repairs have been performed on the group of 8 patients diagnosed with ventral hernias, 4 male and 4 female. The overall age was 47,2 years (range 25 - 70). Polypropylene mesh has been utilized for repair. The mesh overlaped the defect with 5 cm. The fixation technique was ensured by applying ø 4 mm non-resorbable spiral tacks plaid up to 1cm from the edge of the prosthetic mesh. Algometry was performed using visual analog scale (VAS). Results: The mean diameter of the hernia defect was 3.7 cm. In all cases the hernia defect has been closed by applying intracorporeal suture. The intraoperative features were: reduction the hernia sac content, removal of adhesions, control of the bleeding with peritoneum and posterior rectus are opened by a longitudinal incision. The mean time of operations was 45 min. In postoperative period there no reported complications. In the distance postoperative period were not found pain and local neuropathy, bowel disorders, hernia recurrences. Conclusions: Laparoscopic transperitoneal retromuscular hernia repair is a safe and minimally-invasive procedure with low cost of consumables. Retromuscular location of the prosthesis exclude the risk of the parietovisceral adhesions and complications ensuring quick socio-professional reintegration. The exposed advantages argument the use of transperitoneal retromuscular procedure in the ventral hernia repair

Teachers developing assessment for learning: impact on student achievement

While it is generally acknowledged that increased use of formative assessment (or assessment for learning) leads to higher quality learning, it is often claimed that the pressure in schools to improve the results achieved by students in externally-set tests and examinations precludes its use. This paper reports on the achievement of secondary school students who worked in classrooms where teachers made time to develop formative assessment strategies. A total of 24 teachers (2 science and 2 mathematics teachers, in each of six schools in two LEAs) were supported over a six-month period in exploring and planning their approach to formative assessment, and then, beginning in September 1999, the teachers put these plans into action with selected classes. In order to compute effect sizes, a measure of prior attainment and at least one comparison group was established for each class (typically either an equivalent class taught in the previous year by the same teacher, or a parallel class taught by another teacher). The mean effect size was 0.32