On single server batch arrival queueing system with balking, three types of heterogeneous service and Bernoulli schedule server vacation

This paper investigates a batch arrival queueing system in which customers arrives at the system in a Poisson stream following a compound Poisson process and the system has a single server providing three types of general heterogeneous services. At the beginning of each service, a customer is allowed to choose any one of the three services and as soon as a service of any type gets completed, the server may take a vacation or may continue staying in the system. The vacation time is assumed to follow a general (arbitrary) distribution and the server vacation is based on Bernoulli schedule under a single vacation policy. During the server vacation period, impatient customers are assumed to balk. This paper described the model as a bivariate Markov chain and employed the supplementary variable technique to find closed-form solutions of the steady state probability generating function of number of customers, the steady state probabilities of various states of the system, the average queue size, the average system size, and the average waiting time in the queue as well as the average waiting time in the system. Further, some interesting special cases of the model are also derived. Keywords Batch Arrivals. Queueing System. Balking. Heterogeneous types of Service. Bernoulli schedule server vacation. Bivariate Markov Processes. MSC2020-Mathematics Subject Classification 34B07, 60G05, 62E1

Genome wide distribution of illegitimate recombination events in Kluyveromyces lactis

Illegitimate recombination (IR) is the process by which two DNA molecules not sharing homology to each other are joined. In Kluyveromyces lactis, integration of heterologous DNA occurred very frequently therefore constituting an excellent model organism to study IR. IR was completely dependent on the nonhomologous end-joining (NHEJ) pathway for DNA double strand break (DSB) repair and we detected no other pathways capable of mediating IR. NHEJ was very versatile, capable of repairing both blunt and non-complementary ends efficiently. Mapping the locations of genomic IR-events revealed target site preferences, in which intergenic regions (IGRs) and ribosomal DNA were overrepresented six-fold compared to open reading frames (ORFs). The IGR-events occurred predominantly within transcriptional regulatory regions. In a rad52 mutant strain IR still preferentially occurred at IGRs, indicating that DSBs in ORFs were not primarily repaired by homologous recombination (HR). Introduction of ectopic DSBs resulted in the efficient targeting of IR to these sites, strongly suggesting that IR occurred at spontaneous mitotic DSBs. The targeting efficiency was equal when ectopic breaks were introduced in an ORF or an IGR. We propose that spontaneous DSBs arise more frequently in transcriptional regulatory regions and in rDNA and such DSBs can be mapped by analyzing IR target sites

Crystal Structure of the Hexamerization Domain of N-ethylmaleimide–Sensitive Fusion Protein

AbstractN-ethylmaleimide–sensitive fusion protein (NSF) is a cytosolic ATPase required for many intracellular vesicle fusion reactions. NSF consists of an amino-terminal region that interacts with other components of the vesicle trafficking machinery, followed by two homologous ATP-binding cassettes, designated D1 and D2, that possess essential ATPase and hexamerization activities, respectively. The crystal structure of D2 bound to Mg2PLUSPUSSIGN-AMPPNP has been determined at 1.75 Å resolution. The structure consists of a nucleotide-binding and a helical domain, and it is unexpectedly similar to the first two domains of the clamp-loading subunit δ′ of E. coli DNA polymerase III. The structure suggests several regions responsible for coupling of ATP hydrolysis to structural changes in full-length NSF

Perception of Organic Farming among Urban Vegetable Farmers in Delta Central Agricultural Zone.

This study examined the perception of urban vegetable farmers on organic farming. Data were collected from 102 respondents using a multi stage sampling technique and a structured interview schedule. Results indicate that the majority of the farmers were females (89.2%) with (87.25%) married and mean age 40.8. Only 10.8% had no education. Most respondents (70.59%) went into vegetable farming as a means of secondary income and for home consumption (82.35%). Major constraints faced by respondents include bulkiness of organic materials ( = 3.34), inability to handle/preserve/process organic material ( = 2.99) and no access to training on organic vegetable farming (( = 3.79). Perception of farmers on organic farming was generally unfavourable (58.8%) however, it was significantly correlated to age (r = 0.171), marital status (c2 = 17.96, p = 0.05) and educational attainment (c2 = 6.397, p = 0.05). It concluded that farmers used organic farming to improve on their income and soil nutrient status and as such recommended appropriate institutional support to encourage organic farming.

Perception of Organic Farming among Urban Vegetable Farmers in Delta Central Agricultural Zone.

This study examined the perception of urban vegetable farmers on organic farming. Data were collected from 102 respondents using a multi stage sampling technique and a structured interview schedule. Results indicate that the majority of the farmers were females (89.2%) with (87.25%) married and mean age 40.8. Only 10.8% had no education. Most respondents (70.59%) went into vegetable farming as a means of secondary income and for home consumption (82.35%). Major constraints faced by respondents include bulkiness of organic materials ( = 3.34), inability to handle/preserve/process organic material ( = 2.99) and no access to training on organic vegetable farming (( = 3.79). Perception of farmers on organic farming was generally unfavourable (58.8%) however, it was significantly correlated to age (r = 0.171), marital status (c2 = 17.96, p = 0.05) and educational attainment (c2 = 6.397, p = 0.05). It concluded that farmers used organic farming to improve on their income and soil nutrient status and as such recommended appropriate institutional support to encourage organic farming.

Signatures of granular microstructure in dense shear flows

Granular materials react to shear stresses differently than do ordinary fluids. Rather than deforming uniformly, materials such as dry sand or cohesionless powders develop shear bands: narrow zones containing large relative particle motion leaving adjacent regions essentially rigid[1,2,3,4,5]. Since shear bands mark areas of flow, material failure and energy dissipation, they play a crucial role for many industrial, civil engineering and geophysical processes[6]. They also appear in related contexts, such as in lubricating fluids confined to ultra-thin molecular layers[7]. Detailed information on motion within a shear band in a three-dimensional geometry, including the degree of particle rotation and inter-particle slip, is lacking. Similarly, only little is known about how properties of the individual grains - their microstructure - affect movement in densely packed material[5]. Combining magnetic resonance imaging, x-ray tomography, and high-speed video particle tracking, we obtain the local steady-state particle velocity, rotation and packing density for shear flow in a three-dimensional Couette geometry. We find that key characteristics of the granular microstructure determine the shape of the velocity profile.Comment: 5 pages, incl. 4 figure

Insights into the late Cenozoic configuration of the laurentide Ice Sheet from ⁴⁰Ar/³⁹Ar dating of glacially transported minerals in midcontinent tills

Glacial sedimentary sequences in the north central United States record multiple advances of the Laurentide Ice Sheet (LIS) since ~2 Ma. Although the tills found in these sequences were deposited by southward flowing glacial lobes, little information is available on the geometry of flow lines in the interior of the LIS during any one glaciation, and the provenance of glacial deposits older than the last ice advance is largely unknown. Systematic changes in the composition of midcontinent tills and other paleogeographic considerations, however, raise the possibility of significant shifts in the trajectory of flow lines feeding the lobes of the southwestern LIS margin. Here we constrain till provenance using ⁴⁰Ar/³⁹Ar ages of individual hornblende and feldspar grains retrieved from tills representing several glaciations since ~2 Ma. Hornblende grains show ⁴⁰Ar/³⁹Ar ages that indicate erosion of Paleoproterozoic (~1.7–2.0 Ga) and late Archean (>2.5 Ga) rock sources, whereas feldspar grains show a broad range of Paleoproterozoic ages (~1.4–2.4 Ga). Dating of hornblende and feldspar minerals in single pebbles suggests that this latter distribution of ages is related to the greater sensitivity of feldspars to thermal resetting during minor tectonic events. Accordingly, the range of ⁴⁰Ar/³⁹Ar ages for the predominant population of Paleoproterozoic hornblende and feldspar grains in our samples is consistent with a source from terrains forming the Churchill province of the Canadian Shield, while the small population of Archean-age grains likely reflects a source from the southwestern tip of the Archean Superior province that crops out near the study area. These results indicate that midcontinent tills were deposited by ice derived from the northwestern (Keewatin) sector of the LIS. The nearly identical distribution of hornblende and feldspar ages in the till samples identifies the Keewatin ice dome and the related ice flow to the midcontinent as long-standing features of the LIS throughout the late Pliocene-Pleistocene glaciations

Preventing tumor escape by targeting a post-proteasomal trimming independent epitope

Adoptive T cell therapy (ATT) can achieve regression of large tumors in mice and humans; however, tumors frequently recur. High target peptide-major histocompatibility complex-I (pMHC) affinity and T cell receptor (TCR)-pMHC affinity are thought to be critical to preventing relapse. Here, we show that targeting two epitopes of the same antigen in the same cancer cells via monospecific T cells, which have similar pMHC and pMHC-TCR affinity, results in eradication of large, established tumors when targeting the apparently subdominant but not the dominant epitope. Only the escape but not the rejection epitope required postproteasomal trimming, which was regulated by IFN-gamma, allowing IFN-gamma-unresponsive cancer variants to evade. The data describe a novel immune escape mechanism and better define suitable target epitopes for ATT