855 research outputs found
The post-disk (or primordial) spin distribution of M dwarf stars
We investigate the influence of an accretion disk on the angular momentum
(AM) evolution of young M dwarfs, which parameters govern the AM distribution
after the disk phase, and whether this leads to a mass-independent distribution
of SAM. We find that above an initial rate accretion "erases" the initial SAM of M dwarfs
during the disk lifetime, and stellar rotation converges to values of SAM that
are largely independent of initial conditions. For stellar masses , we find that observed initial accretion rates
are comparable to or exceed .
Furthermore, stellar SAM after the disk phase scales with the stellar magnetic
field strength as a power-law with an exponent of . For lower stellar
masses, is predicted to be smaller than
and the initial conditions are imprinted in the stellar
SAM after the disk phase. To explain the observed mass-independent distribution
of SAM, the stellar magnetic field strength has to range between 20~G and 500~G
(700~G and 1500~G) for a 0.1~ (0.6~) star.
These values match observed large-scale magnetic field measurements of young
M~dwarfs and the positive relation between stellar mass and magnetic field
strength agrees with a theoretically-motivated scaling relation. The scaling
law between stellar SAM, mass, and the magnetic field strength is consistent
for young stars, where these parameters are constrained by observations. Due to
the very limited number of available data, we advocate for efforts to obtain
more such measurements. Our results provide new constraints on the relation
between stellar mass and magnetic field strength and can be used as initial
conditions for future stellar spin models, starting after the disk phase.
(shortened)Comment: accepted for publication in A&
Overcoming losses with gain in a negative refractive index metamaterial
On the basis of a full-vectorial three-dimensional Maxwell-Bloch approach we
investigate the possibility of using gain to overcome losses in a negative
refractive index fishnet metamaterial. We show that appropriate placing of
optically pumped laser dyes (gain) into the metamaterial structure results in a
frequency band where the nonbianisotropic metamaterial becomes amplifying. In
that region both the real and the imaginary part of the effective refractive
index become simultaneously negative and the figure of merit diverges at two
distinct frequency points.Comment: 4 pages, 4 figure
Venous Thromboembolism in Minimally Invasive Compared With Open Hysterectomy for Endometrial Cancer
OBJECTIVE: To evaluate whether minimally invasive surgery for endometrial cancer is independently associated with a decreased odds of venous thromboembolism compared with open surgery.
METHODS: We performed a secondary analysis cohort study of prospectively collected quality improvement data and examined patients undergoing hysterectomy for endometrial cancer from 2008 to 2013 recorded in the National Surgical Quality Improvement Program database. Patients undergoing minimally invasive (laparoscopic or robotic) surgery were compared with those undergoing open surgery with respect to 30-day postoperative venous thromboembolism. Demographic and procedure variables were examined as potential confounders. Data regarding receipt of perioperative venous thromboembolism prophylaxis were not available. Bivariable tests and logistic regression were used for analysis.
RESULTS: Of 9,948 patients who underwent hysterectomy for the treatment of endometrial cancer, 61.9% underwent minimally invasive surgery and 38.1% underwent open surgery. Patients undergoing minimally invasive surgery had a lower venous thromboembolism incidence (0.7%, n=47) than patients undergoing open surgery (2.2%, n=80) (P<.001). In a multivariate model adjusting for age, body mass index, race, operative time, Charlson comorbidity score, and surgical complexity, minimally invasive surgery remained associated with decreased odds of venous thromboembolism (adjusted odds ratio 0.36, 95% confidence interval 0.24-0.53) compared with open surgery.
CONCLUSION: Minimally invasive surgery for the treatment of endometrial cancer is independently associated with decreased odds of venous thromboembolism compared with open surgery
Trainee participation and perioperative complications in benign hysterectomy: the effect of route of surgery
BACKGROUND: Intraoperative trainee involvement in hysterectomy is common. However, the effect of intraoperative trainee involvement on perioperative complications depending on surgical approach is unknown.
OBJECTIVE: To estimate the effect of intraoperative trainee involvement on perioperative complication after vaginal, laparoscopic, and abdominal hysterectomy for benign disease.
METHODS: Patients undergoing laparoscopic, vaginal, or abdominal hysterectomy for benign disease from 2010 to 2012 were identified from the American College of Surgeons National Surgical Quality Improvement Program database. Patients with and without trainee involvement were compared with regard to perioperative complications. Complications that occurred from the start of surgery to 30-days postoperatively were included. Perioperative complications were defined via the use of the validated Clavien-Dindo scale with ≥grade 3 complications defined as major and ≤grade 2 complications defined as minor. Major complications included myocardial infarction, pneumonia, venous thromboembolism, deep or organ space surgical-site infection, stroke, fascial dehiscence, unplanned return to the operating room, renal failure, cardiopulmonary arrest, sepsis, intubation greater than 48 hours, and death. Minor complications included urinary tract infection, blood transfusion, and superficial wound infection. To estimate the effect of trainee involvement depending on route of surgery, a stratified analysis was performed. Bivariable analysis and adjusted multivariable logistic regression were used.
RESULTS: We identified 22,499 patients, of whom 42.1% had trainee participation. Surgical approaches were vaginal (22.7%), abdominal (47.1%), and laparoscopic (30.2%). The rate of major complication was 3.2%, and minor complication was 7.2%. In bivariable analysis, trainee involvement was associated with major complications in vaginal hysterectomy (3.3% vs 2.3%, PÂ = .03), but not laparoscopic (3.0% vs 2.9%, PÂ = .78) or abdominal hysterectomy (4.4% vs 3.6%, PÂ = .07). Trainee involvement was also associated with minor complication in vaginal (7.3% vs 5.4%, PÂ = .007), laparoscopic (5.9% vs 4.3%, P < .001), and abdominal hysterectomy (14.1% vs 9.2%, P < .001). In a multivariable analysis in which we adjusted for age, body mass index, medical comorbidity, American Society of Anesthesiologists score, and surgical complexity, the association between trainee involvement in vaginal hysterectomy and major complication persisted (adjusted odds ratio 1.45, 95% confidence interval 1.03-2.04); however, when operative time was added to the model, there was no longer an association between trainee involvement and major complication (adjusted odds ratio 1.26, 95% confidence interval 0.89-1.80).
CONCLUSION: Surgical approach influences the relationship between trainee involvement and perioperative complication. Operative time is a key mediator of the relationship between trainee involvement and complication, and may be a modifiable risk factor
Male Sexual Preference for Female Swimming Activity in the Guppy (Poecilia reticulata)
Mate choice that is based on behavioural traits is a common feature in the animal kingdom. Using the Trinidadian guppy, a species with mutual mate choice, we investigated whether males use female swimming activity—a behavioural trait known to differ consistently among individuals in many species—as a trait relevant for their mate choice. In the first experiment, we assessed male and female activity in an open field test alone (two repeated measures) and afterwards in heterosexual pairs (two repeated measures). In these pairs, we simultaneously assessed males’ mating efforts by counting the number of sexual behaviours (courtship displays and copulations). Male and female guppies showed consistent individual differences in their swimming activity when tested both alone and in a pair, and these differences were maintained across both test situations. When controlling for male swimming behaviour and both male and female body size, males performed more courtship displays towards females with higher swimming activity. In a second experiment, we tested for a directional male preference for swimming activity by presenting males video animations of low- and high-active females in a dichotomous choice test. In congruence with experiment 1, we found males to spend significantly more time in association with the high-active female stimulus. Both experiments thus point towards a directional male preference for higher activity levels in females. We discuss the adaptive significance of this preference as activity patterns might indicate individual female quality, health or reproductive state while, mechanistically, females that are more active might be more detectable to males as well.Leibniz-GemeinschaftDeutsche ForschungsgemeinschaftPeer Reviewe
The health-related quality of life journey of gynecologic oncology surgical patients: Implications for the incorporation of patient-reported outcomes into surgical quality metrics
To report the changes in patient-reported quality of life for women undergoing gynecologic oncology surgeries
Who presents satisfied? Non-modifiable factors associated with patient satisfaction among gynecologic oncology clinic patients
To examine associations between non-modifiable patient factors and patient satisfaction (PS) among women presenting to a gynecologic oncology clinic
Promising novel therapies for the treatment of endometrial cancer
To discuss the novel agents which are being developed for the treatment of advanced and recurrent endometrial carcinoma and to review other molecular targets that may be interesting in the treatment of this disease. While the majority of women with endometrial cancer enjoy a relatively good prognosis, the options for those women who suffer from a disease recurrence are limited and there is a need to identify novel agents
Does the Robotic Platform Reduce Morbidity Associated With Combined Radical Surgery and Adjuvant Radiation for Early Cervical Cancers?
Open radical hysterectomy followed by adjuvant radiation for cervical cancer has been associated with significant rates of morbidity. Radical hysterectomy is now often performed robotically. We sought to examine if the robotic platform decreased the morbidity associated with radical hysterectomy followed by adjuvant radiation
Clinical Benefits Associated With Medicaid Coverage Before Diagnosis of Gynecologic Cancers
Many low-income patients enroll in Medicaid at the time of cancer diagnosis, which improves survival outcomes. Medicaid enrollment before cancer diagnosis may confer additional benefits. Our objective was to compare stage at diagnosis and overall mortality between women with and without Medicaid enrollment before gynecologic cancer diagnosis
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