Trees whose 2-domination subdivision number is 2

A set $S$ of vertices in a graph $G = (V,E)$ is a $2$-dominating set if every vertex of $V\setminus S$ is adjacent to at least two vertices of $S$. The $2$-domination number of a graph $G$, denoted by $\gamma_2(G)$, is the minimum size of a $2$-dominating set of $G$. The $2$-domination subdivision number $sd_{\gamma_2}(G)$ is the minimum number of edges that must be subdivided (each edge in $G$ can be subdivided at most once) in order to increase the $2$-domination number. The authors have recently proved that for any tree $T$ of order at least $3$, $1 \leq sd_{\gamma_2}(T)\leq 2$. In this paper we provide a constructive characterization of the trees whose $2$-domination subdivision number is $2$

Hybrid additive manufacturing of an electron beam powder bed fused Ti6Al4V by transient liquid phase bonding

Hybrid Additive Manufacturing (HAM) is a production strategy enhancing the flexibility of the already versatile Additive Manufacturing (AM) techniques. AM of Ti6Al4V, on the other hand, has been of great interest to numerous research works, thanks to the unique corrosion, biomedical and mechanical properties of the alloy. Hence, this research marks the first report on the HAM of Ti6Al4V by Transient Liquid Phase (TLP) bonding of an Electron Beam Powder Bed Fused (EB-PBF) sample to a conventional one. A copper interlayer was used for bonding, and the TLP process was performed at 890 degrees C and 970 degrees C for 60 min. Shear strength test was carried out and the results showed the highest shear strengths of 579.3 and 662.5 MPa for TLP bonding at 890 degrees C and 970 degrees C, respectively. By increasing the bonding temperature to 970 degrees C, no Cu-rich phases were observed in the microstructure, as opposed to the 890 degrees C samples, and a complete isothermal solidification without intermetallic phases was achieved. Moreover, the 970 degrees C TLP sample was featured with a much better microstructural integrity and homogeneity in both the base metals and the bonded zone. TLP bonding at 970 degrees C resulted in a more ductile fracture surface than that bonded at 890 degrees C. The strong differences between the two TLP bonds were primarily attributed to the faster diffusion rate of elements along the joint and base metal at higher temperatures. (C) 2022 The Author(s). Published by Elsevier B.V

Changes of cryoprotectants in overwintering larvae of beet armyworm, Spodoptera exigua (Lep.: Noctuidae)

The beet armyworm, Spodoptera exigua (Hübner), is a polyphagous pest that causes serious damages to a wide range of agricultural crops including beet, potato and cotton. In order to deepen our understanding of the biology of the pest during the winter, overwintering larvae of beet armyworm were collected from the fields from November 2008 through March 2009. Using HPLC technique, the level of cryoprotectants (antifreeze compounds) inside the body of larvae was measured and the following five compounds were detected: trehalose, glucose, myo-inositol, glycerol and sorbitol. It is found that the amount of polyols and trehalose is always higher than the other compounds and during the coldest days of the winter their level sharply increases from 0.99 mg/g fresh weight in November to 3.9 mg/g fresh weight in January. The results suggest that trehalose is the key cryoprotectant that helps overwintering larvae of beet armyworms survives during the harsh winter days

Effect of temperature on biology of Citrus Leafminer, Phyllocnistis citrella (Lepidoptera: Gracillariidae) under lab conditions

Citrus leafminer, Phyllocnistis citrella Stainton, recently has become a serious pest in Iran, especially in citrus nurseries. This study was aimed to assess the effect of temperature on the biological parameters of the P. citrella at three constant temperatures: 20, 27 and 35°C, 70±10% RH, photoperiod of 14: 10 (L: D) and on seedlings of Citrus sinensis cultivar Valencia as host. Results showed significant reduction in incubation period from 6.22 at 20°C to 2.18 days at 35°C and adversely mortality increase from 7 to 21% at 20 and 35°C, respectively. Larval period was 8.06, 5.26 and 4.14 days and pupal period was 11.18, 6.86 and 5.03 days at 20, 27 and 35°C, respectively. The highest mortality in both larval and pupal periods was observed at 35°C (11.4 and 15.8%, respectively). Both females and males lived longer at 20°C (9.31 and 7.38 days) and shorter at 35°C (5.38 and 4.21 days, respectively). Moth emergence rate was the highest at 27°C (female: 82.2% and male: 84.5%). The sex ratio for the offspring was 1:1.2, 1:1.4 and 1:1.3 male: female at 20, 27 and 35 °C, respectively

SEX-SPECIFIC RESTORATION OF MK-801-INDUCED SENSORIMOTOR GATING DEFICIT BY ENVIRONMENTAL ENRICHMENT

Despite ample evidence of N-methyl-D-aspartate (NMDA) receptor dysfunction in schizophrenia, no study has addressed the effects of enriched environment (EE) on sensorimotor gating deficits induced by postnatal NMDA receptor blockade. We evaluated the effect of EE on sensorimotor gating (measured by prepulse inhibition, PPI), or on sensorimotor gating deficit induced by the NMDA receptor antagonist (+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cy clohepten-5,10-imine maleate (MK-801) in both sexes of Wistar rats. Rats were injected with MK-801 (1 mg/kg) on postnatal days (P) 6–10. EE was provided from birth up to the time of experiments on P28–30 or P58–60. PPI data were collected at three prepulse intensities and then averaged to yield global PPI. MK-801 treatment reduced PPI significantly in both sexes. While EE per se had no significant effect on PPI, it restored MK-801-induced PPI deficit only in male rats. An extended period of EE did not influence PPI deficit in female rats. Our results indicate that postnatal exposure to MK-801 may exert long-lasting effects on neuronal circuits underlying sensorimotor gating. Sex-specific modulation of such effects by EE suggests sexually dimorphic mechanisms are involved. � 2015 IBRO. Published by Elsevier Ltd. All rights reserved

Mathematical Models for Estimating the Risk of vCJD Transmission

We present two different simple models for vCJD transmission by blood transfusion. Both models indicate that transfusions alone are unlikely to cause more than a few infections, unless the number of primary cases increases. To improve our models, future work should pursue data collection, empirical estimation of the model parameters, and examination of the underlying assumptions of our frameworks. Further improvements could also include examining susceptibility to vCJD infection by age group and iatrogenic infections introduced through surgical instruments. Regarding the latter, it may be worthwhile to conduct experiments to quantify the transmission of prions from an infected surgical instrument after repeated sterilization procedures

Cryoprotectant contents of overwintering adults of elm leaf beetle, Xanthogaleruca luteola (Col.: Chrysomelidae)

The elm leaf beetle, Xanthogaleruca luteola (Muller), is one of the most destructive pests of elm trees that overwinters as diapausing adult. The main cryoprotectants and their seasonal fluctuations in the elm leaf beetles were analyzed based on the monthly level of polyhydric alcohol from October 2008 through June 2009, using high performance liquid chromatography (HPLC). The compounds myo-inositol, trehalose, glucose and glycerol were found to be the most important polyols in the overwintering adults, of which myo-inositol content exhibited an inversely significant correlation with temperature fluctuations (r = -0.814, P = 0.014). The highest level of myo-inositol was observed in December (32.6 ± 2.7 µmol g-1 fresh body weight), while its lowest level was recorded in April (3.0 ± 0.4 µmol g-1 fresh body weight). The total concentration of all cryoprotectants was 100.7 ± 7.6 µmol g-1 fresh body weights in January. The results underline the influential role of myo-inositol, trehalose and glucose compounds in enhancing the cold tolerance of elm leaf beetles and their chance of survival during freezing winter days

Changes of supercooling point and cold tolerance in overwintering adults of Brevicoryne brassicae (Hem.: Aphididae) in Tehran, Iran

The cabbage aphid, Brevicoryne brassicae (L.), is one of the major pests of the plant family Brassicaceae that causes serious damages to cabbage and oilseed rape. The cabbage aphid is also able to build up populations on ornamental cabbage during the winter months. To determine the level of cold tolerance in its overwintering populations, adult aphids were collected on cabbages planted in the field of Faculty of Agriculture, Tarbiat Modares University in autumn 2008 and winter 2009. The supercooling points and survivorship of the adults were studied at sub-zero temperatures for 24 h. The mean supercoolig point varied from -23.9 ± 0.46ºC in November to -19.8 ± 0.34ºC in May. About 70-95% of the cabbage aphid adults could tolerate -5°C/24 h in all months. The survival rate for the treated adults at -10ºC/24 was about 55% from October through November and 87% in December. The LT80 (the temperature at which 80% of population die after 24 h exposure to cold temperatures) was at its highest(-11.32°C) in May, showing the lowest level of cold tolerance in the population. The LT80 ranged from-13.81 to -14.79 °C from December to February, showing the highest level of cold tolerance. Findings indicated that cabbage aphid populations hold a high capacity to tolerate cold temperatures in the course of winter while being active and sexually reproductive at the same time that leads to their quick grow and emergence as an economic severe pest early in the next season

Twin signed domination numbers in directed graphs

Let D=(V,A) be a finite simple directed graph (shortly digraph). A function f:V⟶{−1,1} is called a twin signed dominating function (TSDF) if f(N⁻[v])≥1 and f(N⁺[v])≥1 for each vertex v∈V. The twin signed domination number of D is γs*(D)=min{ω(f)∣f is a TSDF of D}. In this paper, we initiate the study of twin signed domination in digraphs and we present sharp lower bounds for γs*(D) in terms of the order, size and maximum and minimum indegrees and outdegrees. Some of our results are extensions of well-known lower bounds of the classical signed domination numbers of graphs