Purpose
To evaluate the outcomes of pre-stented (PS) versus non-pre-stented (NPS) patients who have undergone retrograde intrarenal surgery (RIRS) for renal calculi with subgroup analysis of Asian ...and non-Asian cohorts.
Methods
Protocol is registered in PROSPERO, CRD42021261123. Eligible studies identified from four electronic databases. Meta-analysis was done to enumerate the outcomes of RIRS in between PS and NPS. Secondary sub-analysis was done to look for differences in outcomes in Asian and non-Asian cohorts.
Results
Fourteen studies involving 3831 patients (4 prospective, 10 retrospective studies) were included. PS patients experienced higher success rates of ureteral access sheath (UAS) insertion than NPS (RR 1.09, 95% CI 1.05–1.13,
p
< 0.00001). PS patients had lower risk of ureteral injuries from UAS placement (RR 0.69, 95% CI 0.50–0.96,
p
= 0.03). No significant differences in intra- and postoperative complications between two groups were found. Stone-free rate (SFR) outcomes for residual fragment (RF) cut-off of < 1 mm and < 4 mm favoured the PS patients (RR 1.10, 95% CI 1.04–1.17,
p
= 0.002 for < 4 mm, RR1.10, 95% CI 1.02–1.19,
p
= 0.02 for < 1 mm). In the subgroup analysis, PS Asian patients had similar SFR as NPS patients for SFR(< 4 mm) but non-Asian population showed better outcomes in the PS patients for SFR(< 4 mm) (RR 1.31, 95% CI 1.13–1.52,
p
= 0.0005).
Conclusions
This meta-analysis suggests that pre-stenting results in a higher success for UAS placement, minimising intraoperative ureteric injury, with higher overall SFR for any RF cut-off in PS cohorts. In non-Asian cohort, significant differences occurred at SFR < 4 mm but not for SFR < 1 mm. No difference was seen in our Asian cohort for any SFR cut-off in both PS and NPS patients.
We study the subsets
V
k
(
A
)
of a complex abelian variety
A
consisting in the collection of points
x
∈
A
such that the zero-cycle
{
x
}
-
{
0
A
}
is
k
-nilpotent with respect to the Pontryagin ...product in the Chow group. These sets were introduced recently by Voisin and she showed that
dim
V
k
(
A
)
≤
k
-
1
and
dim
V
k
(
A
)
is countable for a very general abelian variety of dimension at least
2
k
-
1
. We study in particular the locus
V
g
,
2
in the moduli space of abelian varieties of dimension
g
with a fixed polarization, where
V
2
(
A
)
is positive dimensional. We prove that an irreducible subvariety
Y
⊂
V
g
,
2
,
g
≥
3
, such that for a very general
y
∈
Y
there is a curve in
V
2
(
A
y
)
generating
A
satisfies
dim
Y
≤
2
g
-
1
.
The hyperelliptic locus shows that this bound is sharp.
In this note we mainly consider abelian varieties isogenous to hyperelliptic Jacobians. In the first part we prove that a very general hyperelliptic Jacobian of genus g≥4 is not isogenous to a ...non-hyperelliptic Jacobian. As a consequence we obtain that the intermediate Jacobian of a very general cubic threefold is not isogenous to a Jacobian. Another corollary tells that the Jacobian of a very general d-gonal curve of genus g≥4 is not isogenous to a different Jacobian.
In the second part we consider a closed subvariety Y⊂Ag of the moduli space of principally polarized varieties of dimension g≥3. We show that if a very general element of Y is dominated by the Jacobian of a curve C and dimY≥2g, then C is not hyperelliptic. In particular, if the general element in Y is simple, its Kummer variety does not contain rational curves. Finally we show that a closed subvariety Y⊂Mg of dimension 2g−1 such that the Jacobian of a very general element of Y is dominated by a hyperelliptic Jacobian is contained either in the hyperelliptic or in the trigonal locus.
Let
f
:
S
⟶
B
be a non-trivial fibration from a complex projective smooth surface
S
to a smooth curve
B
of genus
b
. Let
c
f
the Clifford index of the general fibre
F
of
f
. In Barja et al. (Journal ...für die reine und angewandte Mathematik,
2016
) it is proved that the relative irregularity of
f
,
q
f
=
h
1
,
0
(
S
)
-
b
is less or equal than or equal to
g
(
F
)
-
c
f
. In particular this proves the (modified) Xiao’s conjecture:
q
f
≤
g
(
F
)
2
+
1
for fibrations of general Clifford index. In this short note we assume that the general fiber of
f
is a plane curve of degree
d
≥
5
and we prove that
q
f
≤
g
(
F
)
-
c
f
-
1
. In particular we obtain the conjecture for families of quintic plane curves. This theorem is implied for the following result on infinitesimal deformations: let
F
a smooth plane curve of degree
d
≥
5
and let
ξ
be an infinitesimal deformation of
F
preserving the planarity of the curve. Then the rank of the cup-product map
H
0
(
F
,
ω
F
)
⟶
·
ξ
H
1
(
F
,
O
F
)
is at least
d
-
3
. We also show that this bound is sharp.
BACKGROUNDMedical simulation has become an integral part of modern-day surgical training. Despite its benefits, it is still not widely incorporated in the curriculum of trainees. The Urology Boot ...Camp (USBC) is an innovative 5-day course aimed at trainees entering the UK training scheme. Since its implementation, there's been increasing interest by non-UK trainees. OBJECTIVETo assess the experiences of non-UK trainees in the USBC, both quantitatively and qualitatively, including skills progression analysis. DESIGN, SETTING AND PARTICIPANTSThis double-group cohort retrospective study included 20 delegates from non-UK countries and 76 trainees from UK who attended the USBC in 2017 and 2018. Trainees undertook pre- and post-course MCQs, pre-course operative experience questionnaires and a 12-month post-course survey on the usefulness of the skills acquired. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSISDifferences in mean MCQ scores between UK and non-UK delegates at baseline and after the course were assessed by the independent T-test. Each core urology procedural skill was evaluated by an expert and graded according to a Likert scale (1-5). The Kruskal-Wallis test was used to assess the differences in the scores between both groups on endourological techniques. A Likert scale (1-5) was used to grade the participants' answers to the post-course 12-month survey. RESULTS AND LIMITATIONSTrainees from UK scored significantly higher in the pre-course MCQ assessment, however after completion of the boot camp, no significant difference was noted. There were no differences between the groups at e-BLUS completion times, and both groups significantly improved their results. A 12-month post-course survey on the utility of training during the boot camp and qualitative evaluation of the course by overseas delegates was very positive. CONCLUSIONSThe USBC is a valuable learning experience that leads to improvement of technical and soft skills of UK and non-UK trainees alike.
Laparoscopy is a minimally invasive technique to access the abdominal cavity, for diagnostic or therapeutic applications. Optimizing the access technique is an important step for laparoscopic ...procedures. The aim of this study is to assess the outcomes of different laparoscopic access techniques and to identify the safest one.
Laparoscopic access questionnaire was forwarded via e-mail to the 60 centers who are partners in working group for laparoscopic and robotic surgery of the Italian Urological Society (SIU) and their American and European reference centers.
The response rate was 68.33%. The total number of procedures considered was 65.636. 61.5% of surgeons use Veress needle to create pneumoperitoneum. Blind trocar technique is the most commonly used, but has the greatest number of complications. Optical trocar technique seems to be the safest, but it's the less commonly used. The 28,2% of surgeons adopt open Hasson's technique. Total intra-operative complications rate was 3.3%. Open conversion rate was 0.33%, transfusion rate was 1.13%, and total post-operative complication rate was 2.53%.
Laparoscopic access is a safe technique with low complication rate. Most of complications can be managed conservatively or laparoscopically. The choice of access technique can affect the rate and type of complications and should be planned according to surgeon experience, safety of each technique and patient characteristics. All access types have perioperative complications. According with our study, optical trocar technique seems to be the safest.
We give a bound for the number of rational maps between algebraic varieties of general type under mild hypothesis on the canonical map. We use an idea inspired by Tanabe's work. Instead of attaching ...a morphism of Hodge structures to a rational map we simply associate to it a piece of the integral Hodge lattice. This procedure does not give an injective map, but by means of a geometric argument, we can estimate the number of maps with the same image.
Since the sixties it is well known that there are no non-trivial closed holomorphic \(1\)-forms on the moduli space \(\mathcal{M}_g\) of smooth projective curves of genus \(g>2\). In this paper, we ...strengthen such result proving that for \(g\geq 5\) there are no non-trivial holomorphic \(1\)-forms. With this aim, we prove an extension result for sections of locally free sheaves \(\mathcal{F}\) on a projective variety \(X\). More precisely, we give a characterization for the surjectivity of the restriction map \(\rho_D:H^0(\mathcal{F})\to H^0(\mathcal{F}|_{D})\) for divisors \(D\) in the linear system of a sufficiently large multiple of a big and semiample line bundle \(\mathcal{L}\). Then, we apply this to the line bundle \(\mathcal{L}\) given by the Hodge class on the Deligne Mumford compactification of \(\mathcal{M}_g\).
In this paper, we analyze the Hessian locus associated to a general cubic hypersurface, by describing for every \(n\) its singular locus and its desingularization. The strategy is based on strong ...connections between the Hessian and the quadrics defined as partial derivatives of the cubic polynomial. In particular, we focus our attention on the singularities of the Hessian hypersurface associated to the general cubic fourfold. It turns out to be a minimal surface of general type: its analysis is developed by exploiting the nature of this surface as a degeneracy locus of a symmetric vector bundle map and by describing an unramified double cover, which is constructed in a more general setting.
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