Role of wing color and seasonal changes in ambient temperature and solar irradiation on predicted flight efficiency of the Albatross.

Drag reduction of the wings of migrating birds is crucial to their flight efficiency. Wing color impacts absorption of solar irradiation which may affect drag but there is little known in this area. To this end, the drag reduction induced by the thermal effect of the wing color of migrating birds with unpowered flight modes is presented in this study. Considering this natural phenomenon in the albatross as an example of migrating birds, and applying an energy balance for this biological system, a thermal analysis is performed on the wings during the summer and winter to obtain different ranges of air density, viscosity, and wing surface temperature brought about from a range of ambient temperatures and climatic conditions seen in different seasons and to study their effects. The exact shape of the albatross wing is used and nine different wing colors are considered in order to gain a better understanding of the effect different colors' absorptivities make on the change in aerodynamic performances. The thermal effect is found to be more important during the summer than during the winter due to the higher values of solar irradiation and a maximum drag reduction of 7.8% is found in summer changing the wing color from light white to dark black. The obtained results show that albatrosses with darker colored wings are more efficient (constant lift to drag ratio and drag reduction) and have better endurance due to this drag reduction.

Insights on the thermal impacts of wing colorization of migrating birds on their skin friction drag and the choice of their flight route.

The thermal effects of wing color in flight is investigated in four species of birds with respect to their flight routes, migration time, and geometric and behavioral characteristics. Considering the marine and atmospheric characteristics of these flight routes, a thermal analysis of the birds' wings is performed during their migration. The surrounding fluxes including the ocean flux and the solar irradiance are considered in an energy balance in order to determine the skin temperature of both sides of the wing. Applying the Blasius solution for heated boundary layers, it is shown that the color configuration of these migrating birds, namely black on the top side of the wings and white on the bottom side of the wings ("countershading"), results in a skin drag reduction, if compared to some other configurations, when both day and night are taken into consideration. This drag reduction can be considered as one of the effective factors for long endurance of these migrating birds. This research can provide the evolutionary perspective behind the colorization of these migrating birds.

Thermal impact of migrating birds' wing color on their flight performance: Possibility of new generation of biologically inspired drones.

The thermal impact of the birds' color on their flight performance are investigated. In most of the large migrating birds, the top of their wings is black. Considering this natural phenomenon in the migrating birds, such as albatross, a thermal analysis of the boundary layer of their wings is performed during the year depending on the solar insulation. It is shown that the temperature difference between the bright and dark colored top wing surface is around 10°C. The dark color on the top of the wing increases the temperature of the boundary layer over the wing which consequently reduces the skin drag force over the wing. This reduction in the drag force can be considered as one of the effective factors for long endurance of these migrating birds. This research should lead to improved designs of the drones by applying the inspired colors which can help drones increase their endurance.

Nonlinear electromechanical modeling and robustness of soft robotic fish-like energy harvester: insights and possible issues.

This work investigates the possible integration of an energy harvester in a bioinspired fish-like aquatic unmanned vehicle. The defined fish-like system utilizes a reduced complexity prescribed motion as the representation for energy harvester to be subjected to. Nonlinear electromechanical modeling is performed by considering the geometric and piezoelectric nonlinearities. A convergence analysis is carried out in order to determine the required modes in the Galerkin discretization due to the presence of nonlinear interactions between the prescribed and relative motions. The utilization of higher-order modeling for the strain and material leads to the identification of impactful prescribed motions terms that can activate the nonlinearities in the system, results in more harmonics to consider, and leads to the presence parametric excitation terms. Considering a reduced-complex model by decreasing the value of the quadratic constraint envelope that the fish-like system would be forced with, the soft-robotic system behaves more with a base excitation characteristic. Small damping would allow this prescribed motion with reduced quadratic envelope forcing still induces a hardening behavior, but the other harmonics and parametric resonance seen are greatly reduced. Considering this reduced complexity system, the interaction between the prescribed and base excitations is also investigated to demonstrate that when the two excitations are of similar nature constructive and destructive build of the response waveform can occur when looking at near the first natural resonance. It is shown that the quenching phenomenon can take place which may result in a destructive response of the piezoelectric energy harvester. The results show that the robustness of the fish-like robot is directly dependent on the design parameters including the damping of the structure, importance of the undulatory motion, and activation of the resonances.

Enhanced design considerations on the buckling and dynamics of Gannet-inspired systems during water entry.

To provide a more complete analysis of Gannet birds and Gannet-inspired drones during diving, this work considers an improved beam model to describe the static and dynamic characteristics of Gannet and Gannet-like drones at impact. The beam model consists of two different geometric and material property beams under continuity conditions to better understand the geometrical and material parameters' influence on the structural statics and dynamics of these kinds of systems. Using Hamilton's principle, the equations of motion, continuity, and boundary conditions considering Euler-Bernoulli and Timoshenko theories are derived. Then, applying the continuity and boundary conditions, the static and dynamic analyses are conducted to examine the impact buckling speeds, the buckled shapes, the natural frequencies at different impact velocities for bioinspired drone design, and the post-buckled mode shapes. The buckled configurations suggest that the body of the Gannet most likely has a different bending and torsional stiffness than the neck. The results indicate that the amount of softening in the joints contributes significantly to not only the speed at which the bird will buckle, but also the buckling profile of the bird. To obtain a physical buckling profile of the Gannet, a stiffer boundary condition at the end of the bird body model is needed due to the increased bending stiffness properties of the body compared to the neck as well as the position of the wings and feet surpassing the end of the body. The results also demonstrate that to build a bioinspired diving drone that falls within a smaller air-vehicle range, the amount of error between theories in predicting the static and dynamic buckling behavior of the system becomes significantly more evident. The dynamic characteristics and mode shapes of the Gannet-like systems are provided for further drone design insight on the impact speeds the drone can achieve without responding to an external excitation frequency from a propeller or actuator.

Investigations on the buckling and dynamics of diving-inspired systems when entering water.

This work provides comparative modeling approaches to determine the velocities and natural frequencies of plunge-diving bird and bioinspired drone systems when entering water. These systems are chosen to further explain the survival of diving birds as they impact water and to provide insight into the design geometry and material choice of bioinspired diving drones. A nonlinear reduced-order model is developed and utilized to analyze the dive at impact considering both Timoshenko and Euler-Bernoulli beam theories. Using Hamilton's principle, the equations of motion are first derived. Then, static and dynamic buckling analyses are conducted. For this study, a geometrically simplified cone-beam system is considered, where the cone represents the head and the beam represents both the neck and body of the plunge-diving systems. The first study is to analyze the effects different diving drone materials and cone dimensions play on the sensitivity of the system. The second study applies geometric parameters to the cone-beam system representative of a plunge-diving bird (Northern gannet) and a surface-diving bird (Double-crested cormorant). The results show that choosing a material with a higher Young's modulus and a cone with a smaller half angle increase the velocity at which buckling occurs. The buckling velocities of the predicted Northern gannet model appear to be much greater than the average recorded diving speeds, suggesting that the bird is capable of plunge-diving at more extreme conditions. The natural frequencies are found for the aforementioned plunge-diving systems to predict failure if any external frequencies are known to act on the system while on a mission, such as conditions dependent on the climate or environment. It is shown in all buckling studies that the Euler-Bernoulli beam theory consistently overestimates the responses when compared with the Timoshenko beam theory. In the dynamic responses, Euler-Bernoulli beam theory overestimates for the pre-buckling region, then underestimates at the start of the post-buckling region until a point where the two theories cross paths. The amount of error with Euler-Bernoulli beam theory depends heavily on the slenderness ratio of the beam due to the theory being a simplification of the Timoshenko beam theory. It is noted that as the development of a more realistic bird model improves, the thickness will become significant and the use of Euler-Bernoulli beam theory at the point of impact will no longer be a valid assumption.

Nonlinear modeling and experimental verification of Gannet-inspired beam systems during diving.

A nonlinear model is proposed to answer at which diving speeds and beak angles will cause injury to Gannet-inspired beam systems during plunge-diving. In doing so, the critical velocities at which buckling occurs with various types of boundary conditions are first obtained for vertical dives and the resulting forces at the point of impact are determined. The Gannet-inspired system is modeled as an Euler-Bernoulli beam to represent the neck and body of the Gannet, while the head of the Gannet is modeled as a cone with varying half-angles. The experimental investigations of Gannet-like diving systems are first introduced to present the varying parameters and assumptions of the simplified model. Next, the resulting forces during impact are investigated and a study is conducted to compare various approximations of the drag coefficient for the cone-shaped head. Considering the mid-plane stretching nonlinearity, the equations of motion for the structural system under various types of boundary conditions are derived using the Hamilton's principle. The characteristic equations, buckled configurations, and critical velocities are determined for each set of boundary conditions. The results show that the system with the smallest half-beak angle and thus the lowest drag force and beam length delays the critical velocity and is most representative of a Gannet during diving. The obtained results demonstrate great agreement with the conducted experiments. For clamped-clamped boundary conditions, the critical velocity is found to be the greatest because of the increased stability at both ends of the beam. It is also noted that a nonlinear approximation for the coefficient of drag offers the best fit with the provided experimental values when compared to a hyperbolic tangent approximation, which predicts the coefficient of drag to be less than that obtained in experiments, and thus predicts that the systems will buckle at higher velocities.

Allogeneic hematopoietic stem cell transplantation in Tunisia.

In 1998, the Tunisian team of the 'Centre National de Greffe de Moelle Osseuse' initiated allogeneic hematopoietic SCT (AHSCT) in Tunisia. As of June 2007, information was collected about 299 patients with a first AHSCT and 12 additional retransplants. The median age was 19 years (range 2-49 years). The main indications were aplastic anemia (n=106, 36%), leukemia and nonmalignant disorders (n=153, 51%), Fanconi anemia (n=26, 9%) and other nonmalignant disorders (n=14, 4%). Preparative regimens depended on indication. All donors were HLA geno-identical. The stem cell sources were BM (87%) and PBSCs (13%). At the time of analysis, 200 patients (67%) were alive after a median follow-up of 42 months (range 3-112 months). The overall TRM rate was 17%. Outcome depended on indication. According to our results, allogeneic HSCT is potentially curative for hematological diseases, but it is a toxic approach for malignant disorders.

Detection of catheter-related bloodstream infections by the Gram stain-acridine orange leukocyte cytospin test in hematopoietic stem cell transplant recipients.

In patients with central venous catheters (CVCs), catheter-related bloodstream infections (CRBI) are a prominent cause of morbidity, excess hospital costs, and in some cases mortality. The aim of this prospective study was to assess the validity of the Gram stain-acridine orange leukocyte cytospin (AOLC) test for the diagnosis of CRBI in hematopoietic stem cell transplant (HSCT) recipients with nontunnelled CVCs, using the differential-time-to-positivity (DTP)/clinical criteria as the criterion standard to define CRBIs. CVCs were externalized, nontunnelled, polyurethane double lumen catheters (Arrows, Readings, USA). All CVCs were placed in the subclavian vein by the infraclavicular approach, in the operating room. Catheters were inserted percutaneously, using the Seldinger technique. Study catheters were not exchanged over guidewires. Between May 2002 and December 2004, a total of 245 consecutive patients were included. Twenty-six of the 245 patients (10.6%) had CRBI as determined by the DTP method. The Gram stain-AOLC was positive in only two patients (7.6%) with a CRBI. Our results suggest that the Gram stain-AOLC test is not useful for the diagnosis of catheter-related bloodstream infection in HSCT recipients.2006.

[Prognosis value of the pp65 antigenemia and semi-quantitative PCR in the detection of the CMV reactivation in bone marrow grafted patients]. / Valeur pronostique de l'antigénémie pp65 et de la PCR semi-quantitative dans la détection de la réacti- vation du CMV chez les greffés de moelle osseuse.

In this article a Cytomegalovirus (CMV) antigenemia and semiquantitative PCR retrospective evaluation of 26 bone marrow allo-grafted patients for different haematological disease is reported. Eighteen patients had a CMV reactivation despite a prophylactic treatment, seven of those patients had both positive antigenemia pp65 and positive semi-quantitative CMV PCR. During CMV reactivation, 3 patients developed a CMV disease despite a pre-emptive therapy. The follow up of the antigenemia was performed since D21 until D100 post transplantation, the antigenemia positivity occurred at D53 and was preceded about 7 days by CMV PCR positivity The CMV disease wasn't associated with a high viral load. All patients that had CMV reactivation had a positive CMV serology before the graft, whereas only 37.5% of the patients who did not reactivate had a positive CMV serology. Respectively half patients who reactivated and only 12.5% of those who didn't had a Graft versus host disease (GVHD), witch preceded the reactivation about 21 days in six of the formers. Clinical and biological signs presented by our patients in this cases report, seems to be associated more with the GVHD than with CMV reactivation.

Difference in time to positivity is useful for the diagnosis of catheter-related bloodstream infection in hematopoietic stem cell transplant recipients.

Catheter-related bloodstream infections are associated with recognized morbidity and mortality. Accurate diagnosis of such infections results in proper management of patients and in reducing unnecessary removal of catheters. We carried out a prospective study in a bone marrow transplant unit to assess the validity of a test based on the earlier positivity of central venous blood cultures in comparison with peripheral blood cultures for predicting catheter-related bacteremia. Between May 2002 and June 2004, 38 bloodstream infections with positive simultaneous central venous catheter and peripheral vein blood cultures were included. A total of 22 patients had catheter-related bacteremias and 16 had noncatheter-related bacteremias, using the catheter-tip culture/clinical criteria as the criterion standard to define catheter-related bacteremia. Differential time to positivity of 120 min or more was associated with 86% sensitivity and 87% specificity. In conclusion, differential time to positivity of 120 min or more is sensitive and specific for catheter-related bacteremia in hematopoietic stem cell transplant recipients who have nontunnelled short-term catheters.

Prevalence of inherited prothrombotic abnormalities and central venous catheter-related thrombosis in haematopoietic stem cell transplants recipients.

In this prospective study, we assessed the incidence of central venous catheter (CVC)-related thrombosis in haematopoietic stem cell transplant (HSCT) recipients. We determined the contribution of inherited prothrombotic abnormalities in blood coagulation to CVC-related thrombosis in these patients. The study was conducted between May 2002 and September 2004. CVCs were externalized, nontunneled, polyurethane double lumen catheters. Before catheter insertion, laboratory prothrombotic markers included factor V Leiden, the prothrombin gene Gly20210A mutation, plasma antithrombin levels, and protein C and S activity. All patients were systematically examined by ultrasonography just before, or <24 h after, catheter removal, and in case of clinical signs of thrombosis. A total of 171 patients were included during the 28-month study period. Five (2.9%) and three (1.7%) patients had evidence of protein C and protein S deficiency, respectively. Only one patient had an antithrombin deficiency (0.6%). In total, 10 patients (5.8%) were heterozygous for the factor V Leiden mutation, and one patient had heterozygous prothrombin G20210A mutation (0.6%). We observed a CVC-related thrombosis in 13 patients (7.6%). Thrombosis was diagnosed in four out of 20 patients (20%) with a inherited prothrombotic abnormality compared to nine of 151 patients (6%) who did not have a thrombophilic marker (relative risk 3.3 CI 95% 1.1-9.9). Our results suggest that inherited prothrombotic abnormalities contribute substantially to CVC-related thrombosis in HSCT recipients. In view of physicians' reluctance to prescribe prophylactic anticoagulant treatment in these patients, a priori determination of inherited prothrombotic abnormalities may form a basis to guide these treatment decisions.

First-line thalidomide-dexamethasone therapy in preparation for autologous stem cell transplantation in young patients (<61 years) with symptomatic multiple myeloma.

Thalidomide-dexamethasone therapy was given in patients (<61 years) with previously untreated symptomatic multiple myeloma. The aim of this study was to assess the efficacy and toxicity of this combination as first-line therapy, and to determine its effect on stem cell collection and engraftment. During first-line therapy, thalidomide and dexamethasone were administered for 75 days (200 mg/day) and 3 months, respectively. The monthly dose of dexamethasone was 20 mg/m2/day for 4 days, with cycles repeated on days 9 to 12 and 17 to 20 on the first and the third month of therapy. After first-line therapy, a collection of peripheral blood stem cells (PBSC) was performed. Between May 2003 and September 2004, 60 patients were included. On an intent-to-treat basis, the overall response (> or =partial response) rate was 74%, including 24% of patients who obtained a complete remission. Grade 3-4 toxicities consisted of infections (12%), deep-vein thrombosis (3%), constipation (5%), and neuropathy (5%). A total of 58 patients (96%) proceeded to PBSC mobilisation and yielded a median number of 8 x 10(6) CD34+ cells/kg. First-line thalidomide-dexamethasone therapy is effective and relatively well tolerated in young patients with symptomatic multiple myeloma. This combination does not affect PBSC mobilisation.

[Infectious complications related to non-tunneled central venous catheters in immunocompromised patients: prospective study about 210 cases]. / Les infections liées aux cathéters veineux centraux non tunnélisés chez des patients immunodéprimés : étude prospective à propos de 210 cas.

OBJECTIVE: To evaluate infectious complications related to non-tunneled central venous catheter in immunocompromised patients, in a bone marrow unit. METHODS: From July to April 2002, we inserted 210 non-tunneled central venous catheters in 139 immunocompromised patients (52 F/87 M). The mean age was 26 years (3-56 years). Our study included 33 children aged from 3 to 15 years, on whom 46 catheters were placed. The catheters were placed for the following indications: 145 catheters were used in subjects who received a bone marrow transplantation, 58 catheters were placed in subjects who received chemotherapy for acute leukemia and seven catheters were used in patients who received immunosuppressive therapy. RESULTS: The mean duration of catheterization was 33 days (7-114 days). There were 3.1 catheter-related infections per 1000 catheter-days. Coagulase-negative Staphylococci were implicated in 64% of cases. We observed two pneumothorax (0.9%), one arterial puncture (0.4%) and two catheter-related thrombosis (0.9%). CONCLUSION: Non-tunneled catheters in immunocompromised patients (adults and children) is a safe technique, and is an alternative to the Hickman catheters which are most widely used today in patients undergoing bone marrow transplantation.

[Allogenic hematopoietic stem cell transplantation in acquired aplastic anemia: first experience of the National Center for Bone Marrow Grafting]. / Allogreffe de cellules souches hematopoietiques dans les aplasies medullaires acquises: experience initiale du Centre National de Greffe de Moelle Osseuse.

Bone marrow transplantation from HLA-identical sibling offers cure and leads to restoration of normal hematopoiesis and long-term survival in 60-80% of recipients. From february 1998 to october 1999, seven patients with aplastic anemia (2 very severe aplastic anemia and 5 severe aplastic anemia), with a median age of 22 years (14-39), received a transplant from an HLA-identical sibling donor. All patients had sustained engraftment. Only one patient developed grade IV acute graft-versus-host disease. One patient died in the 22th day of systemic mycobacterial infection and one in the 79th day of acute graft-versus-host disease. The remaining 5 patients are alive and have a complete hematological recovery, with a median follow-up of 6 months (1,5-12). There are at least two reasons for the improved survival of patients with aplastic anemia who where treated by HLA-indentical bone marrow transplantation. One is the decreased incidence of graft rejection that has resulted from the more judicious use of transfusions before bone marrow transplantation, and improvements in the immunosuppressive qualities of the conditioning programs. Another reason for improved survival is the decrease in the incidence and severity of acute graft-versus-host disease.

[Value of hematopoietic stem cell autotransplantation in the treatment of multiple myeloma: initial experience at the National Bone Marrow Transplantation Center and review of the literature]. / Place de l'autogreffe de cellules souches hematopoïetiques dans le traitement du myélome multiple: expérience initiale du Centre National de Greffe de Moelle Osseuse et revue de la littérature.

Alkylating agents administered with predisone have been the standard therapy for myeloma over the lost three decades. Intensive treatment with autologous hematopoietic support has become the treatment of choice for multiple myeloma patients up to 60 years of age. From march 1999 to january 2000, seven patients with multiple myeloma (stage III) with a median age of 43 years (34-56) received an autologous stem cell transplantation. The myeloablative treatment regimen consisted of high-dose melphalan. All patients had sustained engraftment. The median duration of neutropenia (< 500/mm3) was 12 days (11-140) and the median duration of thrombocytopenia (< 20,000/mm3) was 13 days (11-110). One patient had a complete remission, one a very good partial remission, and 5 patients had a partial remission. With a median follow-up of 8 months (2-12), all patients are alive, without relapse.

[Indications and complications of central venous catheters in hematologic oncology: report of 81 cases]. / Indications et complications des voies veineuses centrales en onco-hematologie: a propos de 81 cas.

From february 1998 to july 1999, 81 central venous catheters were placed in 41 patients 28 years old (5 to 51 years). We used the subclavicular anatomic way (Aubaniac) in all cases. The total duration of catheter placement was 2905 days (median of 31 days, range 1 to 165 days). We observed 1 pneumothorax (1.2%), 3 venous thrombosis (3.7%) and 1 arterial puncture (1.2%). Catheter-related infections were seen in 8 catheters (2.7 per 1000 catheter-days). Candida was encountered in 4 cases (50%), Gram-positive cocci in 2 cases (25%), and Gram-negative bacilli in 2 cases (25%). The improvement of preventive ways, diagnosis techniques (simultaneous quantitative cultures, differential positivity time), and therapeutic methods (treatment without removal of the catheter, antibiotic lock technique, catheter exchange by guidewire) should allow a better treatment of catheter-related infections.

Allogeneic hematopoietic stem cell transplantation for acquired aplastic anemia using cyclophosphamide and antithymocyte globulin: a single center experience.

Between February 1998 and October 2007, 97 (69 male, 28 female) patients with acquired aplastic anemia and a median age of 18 years (range, 2-39) received related allogeneic hematopoietic stem cell transplantation. Ninety-five patients received bone marrow grafts and two patients G-CSF primed peripheral blood stem cell transplantation. The donors were genotypically HLA-identical siblings in 94 cases, HLA-matched parents in 2 cases and a syngeneic twin in 1 case. Median time from diagnosis to transplantation was 2 months (range, 1-15). Conditioning regimen consisted of cyclophosphamide combined with antithymocyte globulin in all patients. For graft versus host disease (GVHD) prophylaxis, all patients received methotrexate and cyclosporine. Eighty-six patients showed evidence of hematopoietic engraftment. Eight patients died before engraftment. Rejection rate was 14.8% with three primary graft failures and eight secondary graft rejections occurring between 2 and 27 months post transplantation. Of the 11 rejecting patients, 3 died from infection and 8 proceeded to a second transplantation. Among the eight patients re-transplanted, seven are alive with successful second engraftments and one died from acute grade III GVHD. Acute GVHD occurred in 15.5% and extensive chronic GVHD in only 5.3% of patients. The 4-year overall probability of survival was 76.8%. Infection was the cause of 81.1% of deaths. The major factor affecting survival was onset of infection before transplantation. Major ABO donor-recipient incompatibility, disease severity and acute GVHD had also negative impact on survival. These results could be improved by reducing the time to transplant and by a more efficient supportive care policy.Bone Marrow Transplantation advance online publication, 27 July 2009; doi:10.1038/bmt.2009.175.

Analysis of cytomegalovirus (CMV) viremia using the pp65 antigenemia assay, the amplicor CMV test, and a semi-quantitative polymerase chain reaction test after allogeneic marrow transplantation.

A pp65 antigenemia assay for polymorphonuclear leukocytes (PMNLs) (CINAkit Rapid Antigenemia), and a qualitative polymerase chain reaction (PCR) test for plasma 'PCR-P qual' (Amplicor cytomegalovirus [CMV] test) were performed for 126 samples (blood and plasma) obtained from 18 bone marrow transplant patients, over a 9-month surveillance period. Among those samples, 92 were assayed with a semi-quantitative PCR test for PMNLs 'PCR-L quant.' The number of samples with a positive CMV test for antigenemia and PCR-P qual assays was 20.63% and 12.7%, respectively, whereas the PCR-L quant assay was positive in 48 of the 92 samples assayed (52.17%). The rates of concordance of the results of PCR-P qual and antigenemia, PCR-P qual and PCR-L quant, antigenemia and PCR-L quant were 92%, 65.2% and 66.8%, respectively. The analysis of the results for the 92 specimens tested by all 3 methods showed a rate of concordance of 63% among all methods. Good agreement (kappa=0.72) was found only between pp65 Ag and PCR-P qual assays. Clinical disease correlates with an antigenemia high viral load. Three patients had CMV disease despite preemptive therapy, and all of them had graft-versus-host-disease (GVHD). PMNLs-based assays are more efficient in monitoring CMV reactivation, but for high-risk patients with GVHD, more sensitive assays (real-time PCR) must be done.